Bryant 345MAV User Manual

installation, start-up,
and operating instructions

4-WAY MULTIPOISE
FIXED-CAPACITY
CONDENSING GAS FURNACE

345MAV

Series F

Cancels: II 345M-40-7 II 345M-40-8

12-03

AIRFLOW

UPFLOW

A93040

NOTE: Read the entire instruction manual before starting the
installation.

This symbol → indicates a change since the last issue.
Table of Contents Page

DIMENSIONAL DRAWING........................................................2

SAFETY CONSIDERATIONS.....................................................3

Clearances to Combustibles......................................................3

CODES AND STANDARDS........................................................4

ELECTROSTATIC DISCHARGE (ESD) PRECAUTIONS........5

INTRODUCTION..........................................................................5

APPLICATIONS............................................................................5

General......................................................................................5

Upflow Applications.................................................................6

Downflow Applications............................................................7

Horizontal Left (Supply-Air Discharge) Applications ............9

Horizontal Right (Supply-Air Discharge) Applications........11

LOCATION..................................................................................12

General....................................................................................12

Furnace Location Relative to Cooling Equipment................13

Hazardous Locations...............................................................13

AIR FOR COMBUSTION AND VENTILATION....................13

General....................................................................................13

Unconfined Space...................................................................14

Confined Space.......................................................................14

INSTALLATION.........................................................................15

Leveling Legs (If Desired).....................................................15

Installation In Upflow or Downflow Applications................17

Installation In Horizontal Applications..................................17

Air Ducts.................................................................................17

General Requirements .......................................................17

Ductwork Acoustical Treatment .......................................17

Supply Air Connections....................................................17

Return Air Connections.....................................................18

Filter Arrangement ............................................................18

Bottom Closure Panel........................................................19

Gas Piping..........................................................................19

Electrical Connections............................................................20

115-v Wiring......................................................................21

24-v Wiring........................................................................21

Accessories ........................................................................22

Venting....................................................................................22

Removal of Existing Furnaces from Common

Vent Systems.....................................................................22

Combustion-Air and Vent Piping .....................................23

Vent Termination...............................................................31

Multiventing.......................................................................31

—1—

AIRFLOW

HORIZONTAL

LEFT

DOWNFLOW

AIRFLOW

HORIZONTAL

RIGHT

AIRFLOW

Fig. 1—Multipoise Orientations

As an ENERGY STAR® Part­ner, BRYANT Heating & Cool­ing Systems Company has de­termined that this product meets
the ENERGY STAR® guide­lines for energy efficiency.

ama

REGISTERED QUALITY SYSTEM

CERTIFIED

Condensate Drain....................................................................31

General...............................................................................31

Application.........................................................................33

Condensate Drain Protection.............................................33

START-UP, ADJUSTMENTS AND

SAFETY CHECK...................................................................33

General...............................................................................33

Prime Condensate Trap With Water.................................34

Purge Gas Lines ................................................................34

Sequence of Operation......................................................34

Heating Mode...............................................................34

Cooling Mode...............................................................35

Continuous Blower Mode............................................35

Heat Pump Mode .........................................................35

Component Test ...........................................................35

Adjustments .......................................................................36

Set Gas Input Rate.......................................................36

Set Temperature Rise...................................................40

Blower Off Delay (Heat Mode) ..................................41

Set Thermostat Heat Anticipator.................................41

Check Safety Controls.......................................................41

Check Primary Limit Control......................................41

A93041

Check Pressure Switch.................................................41

CHECKLIST......................................................................42

SAFETY CONSIDERATIONS

CAUTION: Application of this furnace should be in-

doors with special attention given to vent sizing and
material, gas input rate, air temperature rise, unit leveling,
and unit sizing. Improper installation or misapplication of
furnace can require excessive servicing or cause prema­ture component failure.

WARNING: Improper installation, adjustment, alter­ation, service, maintenance, or use can cause carbon
monoxide poisoning, explosion, fire, electrical shock, or
other conditions which may cause personal injury or
property damage. Consult a qualified installer, service
agency, local gas supplier, or your distributor or branch
for information or assistance. The qualified installer or
agency must use only factory-authorized and listed kits or
accessories when modifying this product. Failure to
follow this warning could result in electrical shock, fire,
personal injury, or death.

Installing and servicing heating equipment can be hazardous due to
gas and electrical components. Only trained and qualified

personnel should install, repair, or service heating equipment.

Untrained personnel can perform basic maintenance functions
such as cleaning and replacing air filters. All other operations must

be performed by trained service personnel. When working on
heating equipment, observe precautions in literature, on tags, and
on labels attached to or shipped with unit and other safety
precautions that may apply.

These instructions cover the minimum requirements and conform
to existing national standards and safety codes. In some instances,
these instructions exceed certain local codes and ordinances,
especially those that may not have kept up with changing residen­tial construction practices. We require these instructions as a
minimum for a safe installation.

Wear safety glasses and work gloves. Have a fire extinguisher
available during start-up and adjustment procedures and service
calls.

CAUTION: Sheet metal parts may have sharp edges or
burrs. Use care and wear appropriate protective clothing
and gloves when handling parts. Failure to follow this
caution could result in personal injury.

Recognize safety information. This is the safety-alert symbol .
When you see this symbol on the unit and in instructions or
manuals, be alert to the potential for personal injury.

Understand these signal words DANGER, WARNING, CAU­TION, and NOTE. These words are used with the safety-alert
symbol. DANGER identifies the most serious hazards which will
result in severe personal injury or death. WARNING signifies
hazards which could result in personal injury or death. CAUTION

This forced air furnace is equipped for use with natural gas at altitudes 0 - 10,000 ft (0 - 3,050m), except 140 size furnaces are only appro ved for altitudes 0 - 7,000 ft.

INST ALLATION

(0 - 2,135 m ).
An accessory kit, supplied by the manufacturer, shall be used to convert to propane gas use or may be required for some natural gas applications.
This furnace is for indoor installation in a building constructed on site. This furnace m a y be installed in a manufactured (mobile) home when stated on rating plate and
using factory au thorized kit.
This furnace may be installed on combustible flooring in alcove or closet at
This furna ce re qu ires a spe cial ve nting s yste m . Re fer to the insta llation instru ction s for parts list and method of installation. This furnace is for use with schedule -40 PVC,
PVC-DWV, CPV C, or ABS-DW V pipe, and must not be vented in common with other gas-fired appliances. Construction through which vent/air intake pipes ma y be
installed is maxim um 24 inches (600 mm ), minimum 3/4 inches (19 mm) thickness (including roofing materials).

For upflow and downflow applications, furnace must be installed level, or pitched within 1/2" of level. For a
horizontal application, the furnace must be pitched minimum 1/4" to m aximum of 1/2" forward for proper
drainage. S ee Installation Manual for IM PO R TANT unit support details on horizontal applications.

MINIMUM INCHES CLEARANCE T O COMBUSTIBLE CONSTRUCTION

ALL POSITIONS:

Minimum front clearance for service 30 inches (762mm).

*

†

†

140 size furnaces require 1 inch back clearance to combustible materials.

DOWNFLOW POSITIONS:

†

For installation on combustible floors only when installed on special base No. KGASB0201ALL,
Coil Assem bly, Part No. CD5 or CK5, or Coil Casing, Part No. KCAKC.

HORIZONTAL POSITIONS:

Line contact is permissible only between lines form ed by intersections of top and two sides of
furnace jacket, and building joists, studs, or framing.
Clearance shown is for air inlet an d air outlet ends.

§

120 and 140 size furnaces require 1 inch bottom clearance to combustible materials.

Ø

Minimum Inches Clearance To Combustible Construction

LEVEL (0")

UPFLOW OR
DOWNFLOW

This furnace is approved for UPFLOW, DOW NF LOW and
HORIZONTAL installations.

Clearance arrows
do not change with
furnace orientatio n.

†

†

1/2" MAX

0"

B

A

0"

TO

C

K

E

D

I

S

§

as described below.

MIN 1/4" TO 1/2 " MAX

FRONT

1"

TOP/PLENUM

E

C

A

N

R

U

F

N

O

R

F

F

R

O

N

FRONT

HORIZONTAL

S

T

S

E

T

3"

D

I

R

V

§

0"

E

I

C

E

*

30

MIN

328066-201 REV. A
LIT -TO P

Fig. 3—Clearances to Combustibles

—2—

Clearance in inches.

BOTTOM

0"

Ø

†

Vent clearance to
combustibles 0".

A02248

"

8

⁄

"

16

"

16

⁄

13

⁄

5

"

8

⁄

5

7

39

1"

"

"

16

⁄

16

⁄

7

11

A02147

"

16

⁄

5

19"

"

22

4

⁄

1

"

16

⁄

26

15

"

2

⁄

26

1

OUTLET

2-IN. COMBUSTION-

AIR CONN

⁄2-IN. DIA

1

GAS CONN

⁄8-IN. DIA

7

POWER CONN

⁄2-IN. DIA

1

THERMOSTAT ENTRY

2-IN. VENT CONN

"

16

⁄

11

22

SIDE INLET

1

" TYP

4

⁄

22

"

16

⁄

3

24

BOTTOM INLET

28

"

16

⁄

9

TYP

"

4

⁄

1

18

"

2

⁄

1

30

(DOWNFLOW &

OR ALTERNATE

TRAP LOCATION

"

16

/

13

A

D

"

16

/

13

OUTLET

AIRFLOW

HORIZONTAL RIGHT)

CONDENSATE DRAIN

-IN. DIA GAS CONN

2

⁄

1

"

4

⁄

1

TYP

33

"

8

⁄

5

32

TYP

13

"

16

⁄

30

"

16

⁄

11

TYP

29

"

8

⁄

5

27

"

16

⁄

9

TYP

"

27

2

⁄

1

24

"

16

⁄

5

CONDENSATE

INLET

17

(UPFLOW)

DRAIN LOCATION

"

16

/

11

E

"

16

/

11

DIMPLE LOCATORS

FOR HORIZONTAL

HANGING

x 12-in. rectangle.

/2

1

see flex duct manufacturer’s recommendations for equivalent diameters.

a. For 800 CFM–16-in. round or 14

2. Minimum return-air opening at furnace:

-in. rectangle.

-in. rectangle.

/2

/4

1

1

x 19

x 23

/2

/2

1

1

literature for specific use of single side inlets. The use of both side inlets, a

combination of 1 side and the bottom, or the bottom only will ensure adequate

c. For 1600 CFM–22-in. round or 14

d. For airflow requirements above 1800 CFM, see Air Delivery table in Product Data

b. For 1200 CFM–20-in. round or 14

DIMENSIONS (IN.)

Fig. 2—Dimensional Drawing

return air openings for airflow requirements above 1800 CFM at 0.5” W.C. ESP.

"

16

(ALTERNATE

UPFLOW)

SIDE INLET

"

2

⁄

1

14

TYP

⁄

7

TYP

9

CONDENSATE

1

"

4

⁄

1

1

DRAIN LOCATION

(UPFLOW)

" TYP

" TYP

16

4

⁄

⁄

15

23

SIDE INLET

26

1"

NOTES: 1. Minimum return-air openings at furnace, based on metal duct. If flex duct is used,

024040 17-1/2 15-7/8 16

036040 17-1/2 15-7/8 16

024060 17-1/2 15-7/8 16

036060 17-1/2 15-7/8 16

048060 17-1/2 15-7/8 16

036080 17-1/2 15-7/8 16

048080 17-1/2 15-7/8 16

060080 21 19-3/8 19-1/2

048100 21 19-3/8 19-1/2

060100 21 19-3/8 19-1/2

UNIT SIZE A D E

060120 24-1/2 22-7/8 23

⁄8-IN. DIA

POWER CONN

7

CONDENSATE

DRAIN TRAP

CONDENSATE DRAIN

TRAP LOCATION

(DOWNFLOW &

HORIZONTAL LEFT)

"

16

⁄

"

15

4

⁄

1

"

26

2

⁄

1

26

"

16

⁄

24

5

22

⁄2-IN. DIA

2-IN. COMBUSTION-

AIR CONN

1

GAS CONN

2-IN. VENT CONN

⁄8-IN. DIA

ACCESSORY

7

ENTRY

"

16

⁄

11

22

⁄2-IN. DIA THERMOSTAT

1

LOCATION

POWER ENTRY

—3—

is used to identify unsafe practices which would result in minor
personal injury or product and property damage. NOTE is used to
highlight suggestions which will result in enhanced installation,
reliability, or operation.

The 345MAV Multipoise Condensing Gas-Fired Furnaces are
CSA (formerly AGA and CGA) design-certified for natural and
propane gases (see furnace rating plate) and for installation in
alcoves, attics, basements, closets, utility rooms, crawlspaces, and
garages. The furnace is factory-shipped for use with natural gas. A
CSA (formerly AGA and CGA) listed gas conversion kit is
required to convert furnace for use with propane gas.

See Fig. 3 for required clearances to combustibles.
Maintain a 1-in. clearance from combustible materials to supply air

ductwork for a distance of 36 inches horizontally from the furnace.
See NFPA 90B or local code for further requirements.

These furnaces SHALL NOT be installed directly on carpeting,
tile, or any other combustible material other than wood flooring. In
downflow installations, factory accessory floor base MUST be
used when installed on combustible materials and wood flooring.
Special base is not required when this furnace is installed on
manufacturer’s Coil Assembly Part No. CD5 or CK5, or when Coil
Box Part No. KCAKC is used.

The design of this furnace is NOT CSA (formerly AGA and CGA)
design-certified for installation in recreation vehicles or outdoors.

This furnace is designed for continuous return-air minimum
temperature of 60°F db or intermittent operation down to 55°F db
such as when used with a night setback thermostat. Return-air
temperature must not exceed 85°F db. Failure to follow these
return-air limits may affect reliability of heat exchangers, motors,
and controls. (See Fig. 4.)

These furnaces are shipped with the drain and pressure tubes
connected for UPFLOW applications. Minor modifications are
required when used in DOWNFLOW, HORIZONTAL RIGHT, or
HORIZONTAL LEFT (supply-air discharge direction) applica­tions as shown in Fig. 1. See details in Applications section.

These furnaces are shipped with the following materials to assist in
proper furnace installation. These materials are shipped in the main
blower compartment.

A94163

Fig. 4—Return-Air Temperature

Installer Packet includes:

Installation, Startup, and Operating Instructions
Service and Maintenance Instructions
User’s Information Manual
Warranty Certificate

Loose Parts Bag includes: Quantity

Pressure tube extension 1
Collector Box or condensate trap extension tube 1
Inducer housing drain tube 1
1/2-in CPVC street elbow 2
Drain tube coupling 1
Drain tube coupling grommet 1
Vent and combustion-air pipe support 2
Condensate trap hole filler plug 3
Vent and combustion-air intake hole filler plug 2
Combustion-air pipe perforated disk assembly 1

Vent Pipe Extension 1*

* ONLY supplied with some furnaces.

CODES AND STANDARDS

Follow all national and local codes and standards in addition to
these instructions. The installation must comply with regulations

of the serving gas supplier, local building, heating, plumbing, and
other codes. In absence of local codes, the installation must
comply with the national codes listed below and all authorities
having jurisdiction.

In the United States and Canada, follow all codes and standards for
the following:

I. SAFETY

• US: National Fuel Gas Code (NFGC) NFPA 54-2002/ANSI
Z223.1-2002 and the Installation Standards, Warm Air Heating
and Air Conditioning Systems ANSI/NFPA 90B

• CANADA: National Standard of Canada, Natural Gas and
Propane Installation Code (NSCNGPIC) CSA B149.1-00.

II. GENERAL INSTALLATION

• US: NFGC and the NFPA 90B. For copies, contact the National
Fire Protection Association Inc., Batterymarch Park, Quincy,
MA 02269; or for only the NFGC contact the American Gas
Association, 400 N. Capitol, N.W., Washington DC 20001

• CANADA: NSCNGPIC. For a copy, contact Standard Sales,
CSA International, 178 Rexdale Boulevard, Etobicoke
(Toronto), Ontario, M9W 1R3, Canada.

III. COMBUSTION AND VENTILATION AIR

• US: Section 5.3 of the NFGC, Air for Combustion and
Ventilation

• CANADA: Part 7 of the NSCNGPIC, Venting Systems and Air
Supply for Appliances

IV. DUCT SYSTEMS

• US and CANADA: Air Conditioning Contractors Association
(ACCA) Manual D, Sheet Metal and Air Conditioning Con­tractors National Association (SMACNA), or American Soci­ety of Heating, Refrigeration, and Air Conditioning Engineers
(ASHRAE) 2001 Fundamentals Handbook Chapter 34.

V. ACOUSTICAL LINING AND FIBROUS GLASS DUCT

• US and CANADA: current edition of SMACNA, NFPA 90B as
tested by UL Standard 181 for Class I Rigid Air Ducts

VI. GAS PIPING AND GAS PIPE PRESSURE TESTING

• US: NFGC; chapters 2, 3, 4, and 9 and national plumbing codes

• CANADA: NSCNGPIC Parts 3, 4, 5, A, B, E, and H.

VII. ELECTRICAL CONNECTIONS

• US: National Electrical Code (NEC) ANSI/NFPA 70-2002

• CANADA: Canadian Electrical Code CSA C22.1

—4—

BLOWER SHELF

CONDENSATE
TRAP (INSIDE)

ALTERNATE DRAIN
TUBE LOCATION

CONDENSATE TRAP

DRAIN TUBE LOCATION

UPFLOW APPLICATIONS

FURNACE
DOOR

FIELD

DRAIN

CONN

EXTERNAL UPFLOW APPLICATIONS

SLOT FOR SCREW

HORIZONTAL

APPLICATION

(OPTIONAL)

1

1

2

3

4

WIRE TIE
GUIDES
(WHEN USED)

CONDENSATE
TRAP

FURNACE

SIDE

7

4

8

1

26

4

1

1

2

FURNACE
DOOR

FIELD

DRAIN

CONN

FURNACE
SIDE

4

3

5

4

4

1

26

4

3

5

3

4

SIDE VIEW FRONT VIEW END VIEW FRONT VIEW

DOWNFLOW AND ALTERNATE

1

7

8

3

1

4

7

8

1

2

4

1

⁄4 OD
COLLECTOR BOX TO
TRAP RELIEF PORT

1

⁄2 OD
INDUCER HOUSING
DRAIN CONNECTION

5

⁄8 OD
COLLECTOR BOX
DRAIN CONNECTION

SCREW HOLE FOR
UPFLOW OR DOWN­FLOW APPLICATIONS
(OPTIONAL)

1

⁄2-IN. PVC OR CPVC

HORIZONTAL

APPLICATIONS

4

FRONT VIEW SIDE VIEW

Fig. 5—Condensate Trap

ELECTROSTATIC DISCHARGE (ESD) PRECAUTIONS

CAUTION: Electrostatic discharge can affect electronic

components. Take precautions during furnace installation
and servicing to protect the furnace electronic control.
Precautions will prevent electrostatic discharges from
personnel and hand tools which are held during the
procedure. These precautions will help to avoid exposing
the control to electrostatic discharge by putting the
furnace, the control, and the person at the same electro­static potential.

1. Disconnect all power to the furnace. Multiple disconnects
may be required. DO NOT TOUCH THE CONTROL OR
ANY WIRE CONNECTED TO THE CONTROL PRIOR
TO DISCHARGING YOUR BODY’S ELECTROSTATIC
CHARGE TO GROUND.

2. Firmly touch a clean, unpainted, metal surface of the
furnace chassis which is close to the control. Tools held in
a person’s hand during grounding will be satisfactorily
discharged.

3. After touching the chassis, you may proceed to service the
control or connecting wires as long as you do nothing that
recharges your body with static electricity (for example; DO
NOT move or shuffle your feet, DO NOT touch un­grounded objects, etc.).

4. If you touch ungrounded objects (recharge your body with
static electricity), firmly touch metal surface again before
touching control or wires.

A93026

5. Use this procedure for installed and uninstalled (un­grounded) furnaces.

6. Before removing a new control from its container, dis­charge your body’s electrostatic charge to ground to protect
the control from damage. If the control is to be installed in
a furnace, follow items 1 through 5 before bringing the
control or yourself into contact with the furnace. Put all
used AND new controls into containers before touching
ungrounded objects.

7. An ESD service kit (available from commercial sources)
may also be used to prevent ESD damage.

INTRODUCTION

The model 345MAV 4-way multipoise, Gas-Fired, Category IV,
condensing furnaces are available in model sizes ranging in gas
input rates of 40,000 to 120,000 Btuh.
For accessory installation details, refer to applicable installation
literature.

APPLICATIONS

CAUTION: Local codes may require a drain pan under

entire furnace and condensate trap when a condensing
furnace is used in an attic application or over a finished
ceiling. Failure to follow this caution will result in minor
property damage.

I. GENERAL

Some assembly and modifications are required for furnaces
installed in any of the 4 applications shown in Fig. 1. All drain and
pressure tubes are connected as shown in Fig. 6. See appropriate
application instructions for these procedures.

—5—

PLUG

CAP

COLLECTOR BOX

DRAIN TUBE (BLUE

& WHITE STRIPED)

COLLECTOR BOX

TUBE (PINK)

PLUG

CAP

COLLECTOR BOX

DRAIN TUBE (BLUE

& WHITE STRIPED)

COLLECTOR BOX

TUBE (PINK)

COLLECTOR BOX

TUBE (GREEN)

INDUCER HOUSING

(MOLDED) DRAIN

TUBE (BEHIND

COLLECTOR BOX

DRAIN TUBE)

COLLECTOR BOX

DRAIN TUBE (BLUE)

FIELD-INSTALLED

FACTORY-SUPPLIED

DRAIN TUBE

COUPLING (LEFT

DRAIN OPTION)

FIELD-INSTALLED

FACTORY-SUPPLIED

DRAIN TUBE

FIELD-INSTALLED

FACTORY-SUPPLIED

1

⁄2-IN. CPVC STREET

ELBOWS (2) FOR

LEFT DRAIN OPTION

FIELD-INSTALLED

FACTORY-SUPPLIED

COUPLING (RIGHT

CONDENSATE
TRAP

DRAIN TUBE

DRAIN OPTION)

A94163

Fig. 6—Factory-Shipped Upflow Tube Configuration

(Shown With Blower Access Panel Removed)

II. UPFLOW APPLICATIONS

An upflow furnace application is where furnace blower is located
below combustion and controls section of furnace, and conditioned
air is discharged upwards.

A. Condensate Trap Location (Factory-Shipped
Orientation)

The condensate trap is factory installed in the blower shelf and
factory connected for UPFLOW applications. A factory-supplied
tube is used to extend the condensate trap drain connection to the
desired furnace side for field drain attachment. See Condensate
Trap Tubing (Factory-Shipped Orientation) section for drain tube
extension details. (See Fig. 6.)

B. Condensate Trap Tubing (Factory-Shipped
Orientation)

NOTE: See Fig. 6 or tube routing label on main furnace door to

confirm location of these tubes.

1. Collector Box Drain, Inducer Housing Drain, Relief Port,
and Pressure Switch Tubes

These tubes are factory attached to the condensate trap and
pressure switch ready for use in UPFLOW applications.
These tubes can be identified by their connection location
and also by a color label on each tube. These tubes are
identified as follows: collector box drain tube (blue label),
inducer housing drain tube (violet label or molded), relief
port tube (green label), and pressure switch tube (pink
label).

COLLECTOR BOX

TUBE (GREEN)

COLLECTOR BOX

DRAIN TUBE (BLUE)

CONDENSATE

TRAP

INDUCER
HOUSING

DRAIN TUBE

(VIOLET)

A94164

Fig. 7—Alternate Upflow Tube Configuration and

Trap Location

2. Condensate Trap Drain Tube
The condensate trap drain connection must be extended for

field attachment by doing the following:
a. Determine location of field drain connection. (See Fig. 2

or 6.)

NOTE: If internal filter is used, drain tube should be located to
opposite side of casing from return duct attachment to assist in
filter removal.

b. Remove and discard casing drain hole plug button from

desired side.

c. Install drain tube coupling grommet (factory-supplied in

loose parts bag) in selected casing hole.

d. Slide drain tube coupling (factory-supplied in loose parts

bag) through grommet ensuring long end of coupling
faces blower.

e. Cement 2 factory-supplied 1/2-in. street CPVC elbows to

the rigid drain tube connection on the condensate trap.
(See Fig. 6.) These elbows must be cemented together
and cemented to condensate trap drain connection.

NOTE: Failure to use CPVC elbows may allow drain to kink and
prevent draining.

f. Connect larger diameter drain tube and clamp (factory-

supplied in loose parts bag) to condensate trap and clamp

securely.
g. Route tube to coupling and cut to appropriate length.
h. Attach tube to coupling and clamp securely.

—6—

C. Condensate Trap Location (Alternate Upflow
Orientation)

An alternate location for the condensate trap is the left-hand side
of casing. (See Fig. 2 and 7.)

NOTE: If the alternate left-hand side of casing location is used,
the factory-connected drain and relief port tubes must be discon­nected and modified for attachment. See Condensate Trap Tubing
(Alternate Upflow Orientation) section for tubing attachment.

To relocate condensate trap to the left-hand side, perform the
following:

1. Remove 3 tubes connected to condensate trap.

2. Remove trap from blower shelf by gently pushing tabs
inward and rotating trap.

3. Install casing hole filler cap (factory-supplied in loose parts
bag) into blower shelf hole where trap was removed.

WARNING: Casing hole filler cap must be installed in
blower shelf hole when condensate trap is relocated.
Failure to follow this warning could result in electrical
shock, fire, personal injury or death.

4. Install condensate trap into left-hand side casing hole by
inserting tube connection stubs through casing hole and
rotating until tabs snap into locking position.

5. Fill unused condensate trap casing holes with plastic filler
caps (factory-supplied in loose parts bag).

D. Condensate Trap Tubing (Alternate Upflow
Orientation)

NOTE: See Fig. 7 or tube routing label on main furnace door to

confirm location of these tubes.

1. Collector Box Drain Tube
Connect collector box drain tube (blue label) to condensate

trap.

NOTE: On 17-1/2-in. wide furnaces ONLY, cut tube between
corrugated sections to prevent kinks from occurring.

2. Inducer Housing Drain Tube
a. Remove and discard LOWER (molded) inducer housing

drain tube which was previously connected to conden­sate trap.

b. Use inducer housing drain extension tube (violet label

and factory-supplied in loose parts bag) to connect
LOWER inducer housing drain connection to the con-

densate trap.
c. Determine appropriate length, cut, and connect tube.
d. Clamp tube to prevent any condensate leakage.

3. Relief Port Tube
a. Connect relief port tube (green label) to condensate trap.

b. Use smaller diameter tube (factory-supplied in loose

parts bag) to extend this tube if required.

c. Determine appropriate length, cut, and connect tube.

E. Condensate Trap Field Drain Attachment

Refer to Condensate Drain section for recommendations and
procedures.

F. Pressure Switch Tubing

The LOWER collector box pressure tube (pink label) is factory
connected to the pressure switch and should not require any
modification.

NOTE: See Fig. 6 or 7 or tube routing label on main furnace door
to check for proper connections.

G. Upper Collector Box and Inducer Housing (Unused)
Drain Connections

UPPER COLLECTOR BOX DRAIN CONNECTION

Attached to the UPPER collector box drain connection is a
factory-installed corrugated, plugged tube (blue and white striped
label). This tube is plugged to prevent condensate leakage in this
application. Ensure this tube is plugged.

NOTE: See Fig. 6 or 7 or tube routing label on main furnace door
to check for proper connections.

UPPER INDUCER HOUSING DRAIN CONNECTION

Attached to the UPPER (unused) inducer housing drain connection
is a cap and clamp. This cap is used to prevent condensate leakage
in this application. Ensure this connection is capped.

NOTE: See Fig. 6 or 7 or tube routing label on main furnace door
to check for proper connections.

H. Condensate Trap Freeze Protection

Refer to Condensate Drain Protection section for recommenda­tions and procedures.

III. DOWNFLOW APPLICATIONS

A downflow furnace application is where furnace blower is located
above combustion and controls section of furnace, and conditioned
air is discharged downwards.

A. Condensate Trap Location

The condensate trap must be removed from the factory-installed
blower shelf location and relocated in selected application location
as shown in Fig. 2, 8, or 9.

To relocate condensate trap from the blower shelf to desired
location, perform the following:

1. Remove 3 tubes connected to condensate trap.

2. Remove trap from blower shelf by gently pushing tabs
inward and rotating trap.

3. Install casing hole filler cap (factory-supplied in loose parts
bag) into blower shelf hole where trap was removed.

WARNING: Casing hole filler cap must be installed in
blower shelf hole when condensate trap is relocated.
Failure to follow this warning could result in electrical
shock, fire, personal injury or death.

4. Install condensate trap into left-hand side casing hole by
inserting tube connection stubs through casing hole and
rotating until tabs snap into locking position.

5. Fill unused condensate trap casing holes with plastic filler
caps (factory-supplied in loose parts bag).

B. Condensate Trap Tubing
NOTE: See Fig. 8 or 9 or tube routing label on main furnace door

to check for proper connections.

1. Collector Box Drain Tube
a. Remove factory-installed plug from LOWER collector

box drain tube (blue and white striped label).

b. Install removed clamp and plug into UPPER collector

box drain tube (blue label) which was connected to
condensate trap.

c. Connect LOWER collector box drain connection to

condensate trap.
(1.) Condensate Trap Located on Left Side of Casing

(a.) Connect LOWER collector box drain tube

(blue and white striped label) to condensate
trap. Tube does not need to be cut.

—7—

COLLECTOR BOX

DRAIN TUBE (BLUE)

CAP

PLUG

COLLECTOR BOX

TUBE (GREEN)

COLLECTOR BOX

EXTENSION TUBE

COLLECTOR BOX

TUBE (PINK)

COLLECTOR BOX

DRAIN TUBE (BLUE

& WHITE STRIPED)

COLLECTOR BOX
EXTENSION TUBE

CONDENSATE

TRAP

INDUCER HOUSING

DRAIN TUBE (VIOLET)

PLUG
CAP

COLLECTOR BOX
DRAIN TUBE (BLUE)

COLLECTOR BOX
TUBE (PINK)

COLLECTOR BOX
TUBE (GREEN)

COLLECTOR BOX
EXTENSION TUBE

COLLECTOR BOX
DRAIN TUBE (BLUE
& WHITE STRIPED)

COLLECTOR BOX
EXTENSION TUBE

INDUCER HOUSING
DRAIN TUBE
(VIOLET)

CONDENSATE
TRAP

COLLECTOR BOX
EXTENSION
DRAIN TUBE

DRAIN TUBE
COUPLING

Fig. 8—Downflow Tube Configuration

(Left-Hand Trap Installation)

(b.) Clamp tube to prevent any condensate leakage.

(2.) Condensate Trap Located on Right Side of Casing

(a.) Install drain tube coupling (factory-supplied in

loose parts bag) into collector box drain tube
(blue and white striped label) which was pre­viously plugged.

(b.) Connect larger diameter drain tube (factory-

supplied in loose parts bag) to drain tube
coupling, extending collector box drain tube
for connection to condensate trap.

(c.) Route extended collector box drain tube be-

tween gas valve and inlet housing as shown in

Fig. 9.
(d.) Determine appropriate length and cut.
(e.) Connect to condensate trap.
(f.) Clamp tube to prevent any condensate leakage.

2. Inducer Housing Drain Tube
a. Remove factory-installed cap and clamp from LOWER

inducer housing drain connection.

b. Remove and discard UPPER (molded) inducer housing

drain tube which was previously connected to conden­sate trap.

c. Install cap and clamp on UPPER inducer housing drain

connection where molded drain tube was removed.

d. Use inducer housing drain tube (violet label and factory-

supplied in loose parts bag) to connect LOWER inducer
housing drain connection to the condensate trap.

e. Connect inducer housing drain connection to condensate

trap.

A94165

A94166

Fig. 9—Downflow Tube Configuration

(Right-Hand Trap Installation)

(1.) Condensate Trap Located on Left Side of Casing

(a.) Determine appropriate length and cut.
(b.) Connect tube to condensate trap.
(c.) Clamp tube to prevent any condensate leakage.

(2.) Condensate Trap Located on Right Side of Casing

(a.) Route inducer housing drain tube (violet label)

between gas valve and inlet housing behind

collector box drain tube.
(b.) Determine appropriate length and cut.
(c.) Connect tube to condensate trap.
(d.) Clamp tube to prevent any condensate leakage.

3. Relief Port Tube
Refer to Pressure Switch Tubing section for connection
procedure.

C. Condensate Trap Field Drain Attachment

Refer to Condensate Drain section for recommendations and
procedures.

D. Pressure Switch Tubing

One collector box pressure tube (pink label) is factory connected to
the pressure switch for use when furnace is installed in UPFLOW
applications. This tube MUST be disconnected and used for the
condensate trap relief port tube. The other collector box pressure
tube (green label) which was factory connected to the condensate
trap relief port connection MUST be connected to the pressure
switch in DOWNFLOW or HORIZONTAL RIGHT applications.
NOTE: See Fig. 8 or 9 or tube routing label on main furnace door
to check for proper connections.
Relocate tubes as described below.

1. Disconnect collector box pressure tube (pink label) attached
to pressure switch.

—8—

2. Use smaller diameter tube (factory-supplied in loose parts
bag) to extend collector box pressure tube (green label)
which was previously connected to condensate trap relief
port connection.

3. Connect collector box pressure tube (green label) to pres­sure switch connection labeled "collector box."

4. Use remaining smaller diameter tube (factory-supplied in
loose parts bag) to extend collector box pressure tube (pink
label) which was previously connected to pressure switch.

5. Route this extended tube (pink label) to condensate trap
relief port connection.

6. Determine appropriate length, cut, and connect tube.

7. Clamp tube to relief port connection.

E. Condensate Trap Freeze Protection

Refer to Condensate Drain Protection section for recommenda­tions and procedures.

IV. HORIZONTAL LEFT (SUPPLY-AIR DISCHARGE)
APPLICATIONS

A horizontal left furnace application is where furnace blower is
located to the right of combustion and controls section of furnace,
and conditioned air is discharged to the left.

NOTE: The auxiliary junction box (J-Box) MUST be relocated to
opposite side of furnace casing. (See Fig. 10.) See Electrical
Connection section for J-Box relocation.

A. Condensate Trap Location

The condensate trap must be removed from the factory-installed
blower shelf location and relocated in selected application location
as shown in Fig. 2 or 10.

To relocate condensate trap from the blower shelf to desired
location, perform the following:

PLUG

AUXILIARY "J" BOX

1. Remove 3 tubes connected to condensate trap.

2. Remove trap from blower shelf by gently pushing tabs
inward and rotating trap.

3. Install casing hole filler cap (factory-supplied in loose parts
bag) into blower shelf hole where trap was removed.

WARNING: Casing hole filler cap must be installed in
blower shelf hole when condensate trap is relocated.
Failure to follow this warning could result in electrical
shock, fire, personal injury or death.

4. Install condensate trap into casing hole by inserting tube
connection stubs through casing hole and rotating until tabs
snap into locking position.

5. Fill unused condensate trap casing holes with plastic filler
caps (factory-supplied in loose parts bag).

B. Condensate Trap Tubing
NOTE: See Fig. 10 or tube routing label on main furnace door to

check for proper connections.

1. Collector Box Drain Tube
a. Install drain tube coupling (factory-supplied in loose

parts bag) into collector box drain tube (blue label)
which was previously connected to condensate trap.

b. Connect large diameter drain tube and clamp (factory-

supplied in loose parts bag) to drain tube coupling,
extending collector box drain tube.

c. Route extended tube (blue label) to condensate trap and

cut to appropriate length.

d. Clamp tube to prevent any condensate leakage.

CAP

COLLECTOR BOX
DRAIN TUBE
(BLUE AND WHITE STRIPED)

CONDENSATE

TRAP

COLLECTOR

BOX EXTENSION

DRAIN TUBE

COLLECTOR BOX

EXTENSION TUBE

DRAIN TUBE COUPLING

COLLECTOR BOX TUBE (PINK)

RELOCATE TUBE BETWEEN BLOWER SHELF AND INDUCER HOUSING FOR

040, 060, AND 080 HEATING INPUT FURNACES

Fig. 10—Horizontal Left Tube Configuration

—9—

COLLECTOR BOX
TUBE (GREEN)

INDUCER HOUSING
DRAIN TUBE (VIOLET)

COLLECTOR BOX
DRAIN TUBE (BLUE)

A00215

A 3-IN. MINIMUM CLEARANCE
TO COMBUSTION-AIR INTAKE
IS REQUIRED.

VENT

COMBUSTION–AIR

GAS VALVE

INTAKE

MANUAL

SHUTOFF

3

5

⁄

″

4

SEDIMENT
TRAP

NOTE: LOCAL CODES MAY REQUIRE A DRAIN PAN UNDER THE

FURNACE AND CONDENSATE TRAP WHEN A CONDENSING
FURNACE IS INSTALLED ABOVE FINISHED CEILINGS.

CONDENSATE
TRAP

Fig. 11—Attic Location and Working Platform

2. Inducer Housing Drain Tube
a. Remove and discard LOWER (molded) inducer housing

drain tube which was previously connected to conden­sate trap.

b. Use inducer housing drain extension tube (violet label

and factory-supplied in loose parts bag) to connect
LOWER inducer housing drain connection to the con-

densate trap.
c. Determine appropriate length, cut, and connect tube.
d. Clamp tube to prevent any condensate leakage.

3. Relief Port Tube
a. Use smaller diameter tube (factory-supplied in loose

parts bag) to extend collector box tube (green label)
which was previously connected to the condensate trap.

b. Route extended collector box pressure tube to relief port

connection on the condensate trap.
c. Determine appropriate length, cut, and connect tube.
d. Clamp tube to prevent any condensate leakage.

C. Condensate Trap Field Drain Attachment

Refer to Condensate Drain section for recommendations and
procedures.

D. Pressure Switch Tubing

The LOWER collector box pressure tube (pink label) is factory
connected to the pressure switch for use when furnace is installed
in UPFLOW applications. This tube MUST be disconnected,
extended, rerouted, and then reconnected to the pressure switch in
HORIZONTAL LEFT applications.

NOTE: See Fig. 10 or tube routing label on main furnace door to
check for proper connections.

A 12-IN. MIN HORIZONTAL PIPE
SECTION IS RECOMMENDED WITH
SHORT (5 TO 8 FT) VENT SYSTEMS
TO REDUCE EXCESSIVE
CONDENSATE DROPLETS FROM

30-IN. MIN
WORK AREA

DRAIN

EXITING THE VENT PIPE.

ACCESS OPENING
FOR TRAP

A96184

Modify tube as described below.

1. Disconnect collector box pressure tube (pink label) attached
to pressure switch.

2. Use smaller diameter tube (factory-supplied in loose parts
bag) to extend tube disconnected in item 1.

3. Route extended tube:
a. Behind inducer housing.

b. Between blower shelf and inducer housing.
c. Behind inducer motor bracket.
d. Between inducer motor and pressure switch.

4. Determine appropriate length, cut, and reconnect tube to
pressure switch connection labeled COLLECTOR BOX.

E. Condensate Trap Freeze Protection

Refer to Condensate Drain Protection section for recommenda­tions and procedures.

F. Construct a Working Platform

Construct working platform where all required furnace clearances
are met. (See Fig. 3 and 11.)

CAUTION: The condensate trap MUST be installed
below furnace. See Fig. 5 for dimensions. The drain
connection to condensate trap must also be properly
sloped to an open drain. Failure to follow this caution will
result in intermittent unit operation.

NOTE: Vent pipe length is restricted to a minimum of 5 ft. (See
Table 6.)

—10—

CAP

PLUG

COLLECTOR BOX DRAIN TUBE

(BLUE AND WHITE STRIPED)

INDUCER HOUSING

DRAIN TUBE (VIOLET)

COLLECTOR BOX

EXTENSION TUBE

Fig. 12—Horizontal Right Tube Configuration

COLLECTOR BOX DRAIN TUBE (BLUE)

COLLECTOR BOX TUBE (GREEN)

COLLECTOR BOX EXTENSION TUBE

COLLECTOR BOX TUBE (PINK)

AUXILARY “J” BOX RELOCATED HERE

CONDENSATE
TRAP

A00214

NOTE: A 12-in. minimum horizontal pipe section is recom­mended with short (5 to 8 ft) vent systems. This recommendation
is to reduce excessive condensate droplets from exiting the vent
pipe. (See Fig. 11 or 38.)

V. HORIZONTAL RIGHT (SUPPLY-AIR DISCHARGE)
APPLICATIONS

A horizontal right furnace application is where furnace blower is
located to the left of combustion and controls section of furnace,
and conditioned air is discharged to the right.

CAUTION: Local codes may require a drain pan under
entire furnace and condensate trap when a condensing
furnace is used in attic application or over a finished
ceiling. Failure to follow this caution will result in minor
property damage.

NOTE: In Canada, installations shall be in accordance with
current NSCNGPIC Installation Codes and/or local codes.

A. Condensate Trap Location

The condensate trap must be removed from the factory-installed
blower shelf location and relocated in selected application location
as shown in Fig. 2 or 12.

To relocate condensate trap from the blower shelf to desired
location, perform the following:

1. Remove 3 tubes connected to condensate trap.

2. Remove trap from blower shelf by gently pushing tabs
inward and rotating trap.

3. Install casing hole filler cap (factory-supplied in loose parts
bag) into blower shelf hole where trap was removed.

WARNING: Casing hole filler cap must be installed in
blower shelf hole when condensate trap is relocated.
Failure to follow this warning could result in electrical
shock, fire, personal injury or death.

4. Install condensate trap into left-hand side casing hole by
inserting tube connection stubs through casing hole and
rotating until tabs snap into locking position.

5. Fill unused condensate trap casing holes with plastic filler
caps (factory-supplied in loose parts bag).

B. Condensate Trap Tubing
NOTE: See Fig. 12 or tube routing label on main furnace door to

check for proper connections.

1. Collector Box Drain Tube
a. Remove factory-installed plug from LOWER collector

box drain tube (blue and white striped label).

b. Install removed clamp and plug into UPPER collector

box drain tube (blue label) which was previously con­nected to condensate trap.

c. Connect LOWER collector box drain tube (blue and

white striped label) to condensate trap. Tube does not
need to be cut.

d. Clamp tube to prevent any condensate leakage.

2. Inducer Housing Drain Tube
a. Remove factory-installed cap and clamp from LOWER

inducer housing drain connection.

—11—

b. Remove and discard UPPER (molded) inducer housing

drain tube which was previously connected to conden­sate trap.

c. Install cap and clamp on UPPER inducer housing drain

connection where molded drain tube was removed.

d. Use inducer housing drain extension tube (violet label

and factory-supplied in loose parts bag) to connect
LOWER inducer housing drain connection to conden­sate trap.

e. Determine appropriate length, cut, and connect tube to

condensate trap.

f. Clamp tube to prevent any condensate leakage.

3. Relief Port Tube
Refer to Pressure Switch Tubing section for connection

procedure.

C. Condensate Trap Field Drain Attachment

Refer to Condensate Drain section for recommendations and
procedures.

D. Pressure Switch Tubing

One collector box pressure tube (pink label) is factory connected to
the pressure switch for use when furnace is installed in UPFLOW
applications. This tube MUST be disconnected and used for the
condensate trap relief port tube. The other collector box pressure
tube (green label) which was factory connected to the condensate
trap relief port connection MUST be connected to the pressure
switch in DOWNFLOW or HORIZONTAL RIGHT applications.

NOTE: See Fig. 12 or tube routing label on main furnace door to
check for proper connections.

Relocate tubes as described below.

1. Disconnect collector box pressure tube (pink label) attached
to pressure switch.

2. Use smaller diameter tube (factory-supplied in loose parts
bag) to extend collector box pressure tube (green label)
which was previously connected to condensate trap relief
port connection.

3. Route extended collector box pressure tube behind inducer
motor bracket then between inducer motor and pressure
switch.

4. Connect collector box pressure tube (green label) to pres­sure switch connection labeled COLLECTOR BOX.

5. Use remaining smaller diameter tube (factory-supplied in
loose parts bag) to extend collector box pressure tube (pink
label) which was previously connected to pressure switch.

6. Route this extended tube (pink label) to condensate trap
relief port connection.

7. Determine appropriate length, cut, and connect tube.

8. Clamp tube to relief port connection.

E. Condensate Trap Freeze Protection

Refer to Condensate Drain Protection section for recommenda­tions and procedures.

F. Construct a Working Platform

Construct working platform where all required furnace clearances
are met. (See Fig. 3 and 11.)

CAUTION: The condensate trap MUST be installed
below furnace. See Fig. 5 for dimensions. The drain
connection to condensate trap must also be properly
sloped to an open drain. Failure to follow this caution will
result in intermittent unit operation.

NOTE: Vent pipe length is restricted to a minimum of 5 ft. (See
Table 6.)

NOTE: A 12-in. minimum horizontal pipe section is recom­mended with short (5 to 8 ft) vent systems. This recommendation
is to reduce excessive condensate droplets from exiting the vent
pipe. (See Fig. 11 or 38.)

LOCATION

I. GENERAL

This furnace must:

• be provided with air for combustion, ventilation, and dilution of
flue gases in accordance with the NFGC or NSCNGPIC. The
furnace MUST NOT be located in a confined space without
special provisions for dilution or ventilation air. See AIR FOR
COMBUSTION AND VENTILATION section.

• be installed so the electrical components are protected from
water.

• not be installed directly on any combustible material other than
wood flooring (refer to SAFETY CONSIDERATIONS).

• be located so combustion-air and vent pipe maximum lengths
are not exceeded. Refer to Table 6.

• be located where available electric power and gas supplies meet
specifications on the furnace rating plate.

• be attached to an air distribution system and be located as close
to the center of the distribution system as possible. Refer to Air
Ducts section.

FRONT

B
A
C
K

BACK

→

LEVEL (0″)

TO

1

⁄2″ MAX

UPFLOW OR DOWNFLOW HORIZONTAL

FRONT

MIN

TO

1

⁄2″ MAX

1

⁄4″

FRONT

Fig. 13—Proper Condensate Drainage

A02146

FRONT

A93043

Fig. 14—Prohibit Installation on Back

WARNING: Do not install furnace on its back. Safety

control operation will be adversely affected. Never con­nect return-air ducts to back of furnace. Failure to follow
this warning could result in fire, personal injury, or death.
(See Fig. 14.)

—12—

• be provided with ample space for servicing and cleaning.
Always comply with minimum fire protection clearances
shown on the furnace clearance-to-combustibles label.

NOTE: For upflow/downflow applications install furnace so that
it is level or pitched forward within 1/2-in. for proper furnace
operation. For horizontal applications pitch 1/4-in. minimum to
1/2-in. maximum forward to ensure proper condensate drainage
from secondary heat exchangers. (See Fig. 13.)

When a furnace is installed so that supply ducts carry air circulated
by the furnace to areas outside the space containing the furnace,
the return air shall also be handled by duct(s) sealed to furnace
casing and terminating outside the space containing the furnace to

32°F MINIMUM INSTALLED
AMBIENT OR FREEZE
PROTECTION REQUIRED

ensure there will not be a negative pressure condition within
equipment room or space.

Fig. 15—Freeze Protection

CAUTION: This gas furnace may be used for construction heat provided that:

-The furnace is permanently installed with all electrical wiring, piping, venting and ducting installed according to these installation
instructions. A return air duct is provided, sealed to the furnace casing, and terminated outside the space containing the furnace. This
prevents a negative pressure condition as created by the circulating air blower, causing a flame rollout and/or drawing combustion
products into the structure.

-The furnace is controlled by a thermostat. It may not be ″hot wired″ to provide heat continuously to the structure without thermostatic
control.

-Clean outside air is provided for combustion. This is to minimize the corrosive effects of adhesives, sealers and other construction
materials. It also prevents the entrainment of drywall dust into combustion air, which can cause fouling and plugging of furnace
components.

-The temperature of the return air to the furnace is no less than 55°F, with no evening setback or shutdown. The use of the furnace while
the structure is under construction is deemed to be intermittent operation per our installation instructions.

-The air temperature rise is within the rated rise range on the furnace rating plate, and the firing rate has been set to the nameplate value.

-The filters used to clean the circulating air during the construction process must be either changed or thoroughly cleaned prior to
occupancy.

-The furnace, ductwork and filters are cleaned as necessary to remove drywall dust and construction debris from all HVAC system
components after construction is completed.

A93058

CAUTION: Do not install furnace in a corrosive or
contaminated atmosphere. Make sure all combustion and
circulating air requirements are met. Failure to follow this
caution will result in intermittent unit operation or per­formance satisfaction.

CAUTION: If these furnaces are installed in an uncon­ditioned space where ambient temperatures may be 32°F
or lower, freeze protection measures must be taken. (See
Fig. 15.) Failure to follow this caution will result in minor
property damage.

II. FURNACE LOCATION RELATIVE TO COOLING
EQUIPMENT

The cooling coil must be installed parallel with or on downstream
side of furnace to avoid condensation in heat exchanger. When
installed parallel with a furnace, dampers or other means used to
control flow of air shall be adequate to prevent chilled air from
entering furnace. If dampers are manually operated, they must be
equipped with a means to prevent operation of either unit unless
damper is in full-heat or full-cool position.

III. HAZARDOUS LOCATIONS

WARNING: When the furnace is installed in a residen-

tial garage, it must be installed so that burners and
ignition sources are located a minimum of 18 in. above
floor. The furnace must be located or protected to avoid
physical damage by vehicles. When furnace is installed in
a public garage, airplane hangar, or other building having
a hazardous atmosphere, unit must be installed in accor­dance with requirements of National Fire Protection
Association, Inc. (See Fig. 16.)

AIR FOR COMBUSTION AND VENTILATION

I. GENERAL

Provisions for adequate combustion and ventilation air must be
provided in accordance with Section 5.3, Air for Combustion and
Ventilation, of the NFGC or applicable provisions of the local
building codes.

Canadian installations must be in accordance with Section 7.2 of
the Air Supply Determination for Central Heating Furnaces,
Boilers, and Hot Water Heaters, and 7.3, Air Supply Openings and
Ducts, of the NSCNGPIC and all authorities having jurisdiction.

—13—

18-IN. MINIMUM

TO BURNERS

A89014

Fig. 16—Leveling Legs

CAUTION: Air for combustion must not be contami-

nated by halogen compounds, which include fluoride,
chloride, bromide, and iodide. These elements are found
in aerosol sprays, detergents, bleaches, cleaning solvents,
salts, air fresheners, and other household products. Fail­ure to follow this caution will result in minor unit
damage.

All fuel-burning equipment must be supplied with air for combus­tion of the fuel. Sufficient air MUST be provided to ensure there
will not be a negative pressure in the equipment room or space. In
addition, a positive seal MUST be made between the furnace
cabinet and the return-air duct to prevent pulling air from the
burner area and draft safeguard opening into the circulating air.

CAUTION: The operation of exhaust fans, kitchen ven­tilation fans, clothes dryers, fireplaces, or other appli­ances including attic and crawlspace exhaust fans could
create a negative air pressure condition at the furnace.
Make-up air must be provided for these devices, in
addition to that required by the furnace. Failure to follow
this caution will result in intermittent unit operation or
performance satisfaction.

The requirements for combustion and ventilation air depend upon
whether the furnace is located in a CONFINED or UNCONFINED
space.

II. UNCONFINED SPACE

An unconfined space must have at least 50 cu ft for each 1000
Btuh of total input for all the appliances (such as furnaces, clothes
dryers, water heaters, etc.) in the space.

For Example:

MINIMUM FLOOR AREA FOR UNCONFINED SPACE

345MAV Furnace

Input Btuh

40,000 267
60,000 400

80,000 533
100,000 667
120,000 800

Minimum Sq Ft With

7-1/2 Ft Ceiling

If the unconfined space is of unusually tight construction, air for
combustion and ventilation MUST come from either the outdoors
or spaces freely communicating with the outdoors. Combustion

and ventilation openings must be sized the same as for a confined
space as defined below. Return air must not be taken from the
room unless an equal or greater amount of air is supplied to the
room.

III. CONFINED SPACE

A confined space has a volume of less than 50 cu ft per 1000 Btuh
of the total input rating for all appliances installed in that space. A
confined space MUST have 2 permanent openings, 1 within 12 in.
of the ceiling, and the other within 12 in. of the floor which freely
communicate with an unconfined space or the outdoors. (See Fig.
17 or 18.)

NOTE: In determining the free area of an opening, the blocking
effect of the louvers, grilles, and screens must be considered. If the
free area of a louver or grille design is unknown, it may be
assumed that wood louvers have a 20 percent free area, and metal
louvers or grilles have a 60 percent free area. Screens, when used,
must not be smaller than 1/4-in. mesh. Louvers and grilles must be
constructed so they cannot be closed.

The size of the openings depends upon whether the air comes from
outside of the structure or an unconfined space inside the structure.

A. All Air from Inside the Structure

1. Each opening MUST have at least 1 sq in. of free area per
1000 Btuh of the total input for all equipment within the
confined space, but not less than 100 sq in. per opening.
(See Fig. 17.) The minimum dimension of air openings shall
not be less than 3 in.

For Example:

COMBUSTION AIR FROM UNCONFINED SPACE

345MAV Furnace

Input Btuh

40,000 100
60,000 100

80,000 100
100,000 100
120,000 120

Free Area per Opening

(Sq In.)

2. If the building is constructed unusually tight, in addition to
the 2 permanent openings that freely communicate with an
unconfined space, a permanent opening directly communi­cating with the outdoors should be provided. This opening
shall have a minimum free area of 1 sq in. per 4000 Btuh of
total input rating for all equipment in the enclosure.

3. If the furnace is installed on a raised platform to provide a
return-air plenum, and return air is taken directly from the
hallway or space adjacent to the furnace, all air for
combustion must come from outdoors. (See Fig. 18.)

B. All Air from Outside the Structure

1. If combustion air is taken from outdoors through vertical
ducts, the openings and ducts MUST have at least 1 sq in.
of free area per 4000 Btuh of the total input for all
equipment within the confined space. (See Fig. 18.)

For Example:

COMBUSTION AIR FROM OUTDOORS THROUGH

345MAV Furnace

Input Btuh

40,000 10.0 4
60,000 15.0 5

80,000 20.0 6
100,000 25.0 6
120,000 30.0 7

VERTICAL DUCTS

Free Area per Opening

(Sq In.)

Round Pipe

(In. Dia)

—14—

SUPPLY

AIR

VENT THROUGH ROOF

OR SIDEWALL

NOTE: The maximum length of bolt should not exceed 1-1/2 in.

DUCTS

TO

OUTDOORS

1 SQ IN.
PER 4000
BTUH

*

12″ MAX

1 SQ IN.
PER 1000
BTUH* IN DOOR
OR WALL

INTERIOR

HEATED

SPACE

RETURN AIR

* Minimum opening size is 100 sq. in. with
minimum dimensions of 3-In.

NOTE:

Side clearance required as needed for
combustion-air pipe and termination,
vent pipe, and gas and electrical connections.

UNCONFINED
SPACE

CONFINED

SPACE

3″ MIN
(FRONT)

1 SQ IN.
PER 1000
BTUH* IN DOOR
OR WALL

12″ MAX

A96185

Fig. 17—Confined Space: Air for Combustion and

Ventilation from an Unconfined Space

2. If combustion air is taken from outdoors through horizontal
ducts, the openings and ducts MUST have at least 1 sq in.
of free area per 2000 Btuh of the total input for all
equipment within the confined space. (See Fig. 18.)

For Example:

COMBUSTION AIR FROM OUTDOORS THROUGH

345MAV Furnace

Input Btuh

40,000 20.0 6
60,000 30.0 7

80,000 40.0 8
100,000 50.0 8
120,000 60.0 9

HORIZONTAL DUCTS

Free Area per Opening

(Sq In.)

Round Pipe

(In. Dia)

3. When ducts are used, they must be of the same cross­sectional area as the free area of the openings to which they
connect. The minimum dimension of ducts must not be less
than 3 in. (See Fig. 18.)

INSTALLATION

I. LEVELING LEGS (IF DESIRED)

When furnace is used in upflow position with side inlet(s), leveling
legs may be desired. (See Fig. 19.) Install field-supplied,
corrosion-resistant 5/16-in. machine bolts and nuts.

12″ MAX

1 SQ IN.
PER 2000
BTUH

*

DUCTS

TO

OUTDOORS

1 SQ IN.
PER 2000
BTUH

*

12

″ MAX

RETURN AIR

Minimum dimensions of 3-In.

*

NOTES:

1. Use any of the following
combinations of openings:
A & B C & D D & E F & G

2. Side clearance required as needed for
combustion-air pipe and termination,
vent pipe, and gas and electrical connections.

A

B

SUPPLY

AIR

D

VENT
THROUGH
ROOF

OR
SIDEWALL

CONFINED

C

DUCT

TO

OUTDOORS

SPACE

E

12″ MAX

Fig. 18—Confined Space: Air for Combustion and

Ventilation from Outdoors

5

⁄16″

5

⁄16″

1 3⁄4″

3

1

⁄4″

5

⁄16″

5

⁄16″

3

1

⁄4″

3

1

⁄4″

Fig. 19—Leveling Legs

12
MAX

F

1 SQ IN.
PER 4000
BTUH

1 SQ IN.
PER 4000
BTUH

G

12
MAX

1 SQ IN.
PER 4000
BTUH

*

″

*

OUTDOORS

*

″

A96186

A89014

—15—

A

PLENUM

OPENING

B

FLOOR

OPENING

C

D

A96283

Fig. 20—Floor and Plenum Opening Dimensions

FURNACE

(OR COIL CASING

WHEN USED)

COMBUSTIBLE

FLOORING

DOWNFLOW

SUBBASE

SHEET METAL

PLENUM

FLOOR

OPENING

A96285

Fig. 21—Furnace, Plenum, and Subbase

Installed on a Combustible Floor

FURNACE

CASING

WIDTH

Upflow Applications 16 24-1/8 16-5/8 24-3/4

Downflow Applications on Non-Combustible Flooring 15-7/8 19 16-1/2 19-5/8

17-1/2

21

24-1/2

Downflow Applications on Combustible Flooring Using KGASB Subbase

Furnace with or without CD5 or CK5 Coil Assembly or KCAKC Coil Box

Downflow Applications on Combustible Flooring NOT Using KGASB Subbase

Furnace with CD5 or CK5 Coil Assembly or KCAKC Coil Box

Upflow Applications 19-1/2 24-1/8 20-1/8 24-3/4

Downflow Applications on Non-Combustible Flooring 19-3/8 19 20 19-5/8

Downflow Applications on Combustible Flooring Using KGASB Subbase

Furnace with or without CD5 or CK5 Coil Assembly or KCAKC Coil Box

Downflow Applications on Combustible Flooring NOT Using KGASB Subbase

Furnace with CD5 or CK5 Coil Assembly or KCAKC Coil Box

Upflow Applications 23 24-1/8 23-5/8 24-3/4

Downflow Applications on Non-Combustible Flooring 22-7/8 19 23-1/2 19-5/8

Downflow Applications on Combustible Flooring Using KGASB Subbase

Furnace with or without CD5 or CK5 Coil Assembly or KCAKC Coil Box

Downflow Applications on Combustible Flooring NOT Using KGASB Subbase

Furnace with CD5 or CK5 Coil Assembly or KCAKC Coil Box

TABLE 1—OPENING DIMENSIONS (IN.)

APPLICATION

FURNACE

CD5 OR CK5

COIL ASSEMBLY

OR KCAKC

COIL BOX

COMBUSTIBLE

FLOORING

SHEET METAL

PLENUM

FLOOR

OPENING

A96284

Fig. 22—Furnace, Plenum, and Coil

Assembly or Coil Box Installed

on a Combustible Floor

PLENUM OPENING FLOOR OPENING

ABCD

15-1/8 19 16-3/4 20-3/8

15-1/2 19 16-1/2 20

18-5/8 19 20-1/4 20-3/8

19 19 20 20

22-1/8 19 23-3/4 20-3/8

22-1/2 19 23-1/2 20

—16—

1. Position furnace on its back. Locate and drill a 5/16-in.
diameter hole in each bottom corner of furnace. (See Fig.

19.) Holes in bottom closure panel may be used as guide
locations.

2. For each hole, install nut on bolt and then install bolt and
nut in hole. (Install flat washer if desired.)

3. Install another nut on other side of furnace base. (Install flat
washer if desired.)

4. Adjust outside nut to provide desired height, and tighten
inside nut to secure arrangement.

NOTE: Bottom closure must be used when leveling legs are used.
See Bottom Closure Panel section.

II. INSTALLATION IN UPFLOW OR DOWNFLOW
APPLICATIONS

NOTE: For downflow applications, this furnace is approved for

use on combustible flooring when special base (available from
manufacturer) Part No. KGASB0201ALL is used. Special base is
not required when this furnace is installed on manufacturer’s Coil
Assembly Part No. CD5 or CK5, or Coil Box Part No. KCAKC is
used.

1. Determine application being installed from Table 1.

2. Construct hole in floor per dimensions specified in Table 1
and Fig. 20.

3. Construct plenum to dimensions specified in Table 1 and
Fig. 20.

4. If downflow subbase (KGASB) is used, install as shown in
Fig. 21.
If Coil Assembly Part No. CD5 or CK5 or Coil Box Part
No. KCAKC is used, install as shown in Fig. 22.

NOTE: Remove furnace perforated, discharge duct flanges when
they interfere with mating flanges on coil on downflow subbase.
To remove furnace perforated, discharge duct flange, use wide
duct pliers or duct flange tool to bend flange back and forth until
it breaks off. Be careful of sharp edges. (See Fig. 23.)

WARNING: Do not bend duct flanges inward as shown
in Fig. 23. This will affect airflow across heat exchangers
and may cause limited cycling or premature heat ex­changer failure. Remove duct flange completely or bend
it inward a minimum of 210° as shown in Fig. 23.

III. INSTALLATION IN HORIZONTAL APPLICATIONS

CAUTION: The entire length of furnace MUST be

supported when furnace is used in a horizontal position to
ensure proper draining. When suspended, bottom brace
supports sides and center blower shelf. When unit is
supported from the ground, blocks or pad should support
sides and center blower shelf area. Failure to follow this
caution will result in intermittent unit operation or per­formance satisfaction.

These furnaces can be installed horizontally in either horizontal
left or right discharge position. In a crawlspace, furnace can either
be hung from floor joist or installed on suitable blocks or pad.
Furnace can be suspended from each corner by hanger bolts and
angle iron supports. (See Fig. 24.) Cut hanger bolts (4 each 3/8-in.
all-thread rod) to desired length. Use 1 X 3/8-in. flat washers,
3/8-in. lockwashers, and 3/8-in. nuts on hanger rods as shown in
Fig. 24. Dimples are provided for hole locations. (See Fig. 2.)

IV. AIR DUCTS
A. General Requirements

The duct system should be designed and sized according to
accepted national standards such as those published by: Air
Conditioning Contractors Association (ACCA), Sheet Metal and

PERFORATED
DISCHARGE DUCT
FLANGE

NO

YES

210°

MIN

YES

Fig. 23—Duct Flanges

A93029

Air Conditioning Contractors National Association (SMACNA) or
American Society of Heating, Refrigerating and Air Conditioning
Engineers (ASHRAE) or consult The Air Systems Design Guide-
lines reference tables available from your local distributor. The
duct system should be sized to handle the required system design
CFM at the design static pressure.

When a furnace is installed so that the supply ducts carry air
circulated by the furnace to areas outside the space containing the
furnace, the return air shall also be handled by a duct(s) sealed to
the furnace casing and terminating outside the space containing the
furnace.

Secure ductwork with proper fasteners for type of ductwork used.
Seal supply- and return-duct connections to furnace with code
approved tape or duct sealer.

Flexible connections should be used between ductwork and
furnace to prevent transmission of vibration. Ductwork passing
through unconditioned space should be insulated to enhance
system performance. When air conditioning is used, a vapor
barrier is recommended.

Maintain a 1-in. clearance from combustible materials to supply air
ductwork for a distance of 36 in. horizontally from the furnace. See
NFPA 90B or local code for further requirements.

For a furnace not equipped with a cooling coil, the outlet duct shall
be provided with a removable access panel. This opening shall be
accessible when the furnace is installed and shall be of such a size
that the heat exchanger can be viewed for possible openings using
light assistance or a probe can be inserted for sampling the air
stream. The cover attachment shall prevent leaks.

B. Ductwork Acoustical Treatment

Metal duct systems that do not have a 90 degree elbow and 10 ft
of main duct to the first branch take-off may require internal
acoustical lining. As an alternative, fibrous ductwork may be used
if constructed and installed in accordance with the latest edition of
SMACNA construction standard on fibrous glass ducts. Both
acoustical lining and fibrous ductwork shall comply with NFPA
90B as tested by UL Standard 181 for Class 1 Rigid air ducts.

C. Supply Air Connections

UPFLOW FURNACES

Connect supply-air duct to 3/4-in. flange on furnace supply-air
outlet. The supply-air duct attachment must ONLY be connected
to furnace supply-/outlet-air duct flanges or air conditioning coil
casing (when used). DO NOT cut main furnace casing to attach
supply side air duct, humidifier, or other accessories. All accesso­ries MUST be connected external to furnace main casing.

—17—

DOWNFLOW FURNACES

Connect supply-air duct to supply-air opening on furnace. The
supply-air duct attachment must ONLY be connected to furnace
supply/outlet or air conditioning coil casing (when used), when
installed on non-combustible material. When installed on combus­tible material, supply-air duct attachment must ONLY be con­nected to an accessory subbase or factory approved air condition­ing coil casing. DO NOT cut main furnace casing to attach supply
side air duct, humidifier, or other accessories. All accessories
MUST be connected external to furnace main casing.

HORIZONTAL FURNACES

Connect supply-air duct to supply air opening on furnace. The
supply-air duct attachment must ONLY be connected to furnace
supply/outlet or air conditioning coil casing (when used). DO NOT
cut main furnace casing to attach supply side air duct, humidifier,
or other accessories. All accessories MUST be connected external
to furnace main casing.

D. Return Air Connections

The furnace and its return air system shall be designed and
installed so that negative pressure created by the air ciculating fan
cannot affect another appliance’s combustion air supply or act to
mix products of combustion with circulating air, and that the air
circulating fan of the furnace, if installed in an enclosure commu­nicating with another fuel-burning appliance not of the direct-vent
type, shall be operable only when any door or panel covering an
opening in the furnace fan compartment or in a return air plenum
on ducts is in the closed position.

WARNING: Never connect return-air ducts to the back
of the furnace. Return-air duct connections on furnace
side(s) permitted in upflow applications only. A failure to
follow this warning could result in fire, personal injury, or
death.

UPFLOW FURNACES

The return-air duct must be connected to bottom, sides (left or
right), or a combination of bottom and side(s) of main furnace
casing as shown in Fig. 2. Bypass humidifier may be attached into
unused side return air portion of the furnace casing. DO NOT
connect any portion of return-air duct to back of furnace casing.

DOWNFLOW AND HORIZONTAL FURNACES

The return-air duct must be connected to return-air opening
provided as shown in Fig. 2. DO NOT cut into casing sides or back
to attach any portion of return-air duct. Bypass humidifier connec­tions should be made at ductwork or coil casing sides exterior to
furnace.

E. Filter Arrangement

CAUTION: Never operate unit without a filter or with

blower access panel removed. Failure to follow this
caution wil result in intermittent unit operation or perfor­mance satisfaction.

A 3-IN. MINIMUM

COMBUSTION-AIR INTAKE

(A) ROD LOCATION

CLEARANCE TO

IS REQUIRED.

ANGLE
IRON OR
EQUIVALENT

(B)

USING DIMPLE
LOCATORS
(SEE DIMENSIONAL
DWG FOR
LOCATIONS)

(A) PREFERRED ROD LOCATION
(B) ALTERNATE ROD LOCATION

COMBUSTION-AIR

INTAKE

(B)

(A)

3

/8-IN. HEX NUT

& WASHER (4)

REQD PER ROD

3

5

⁄4″

DRAIN

(A)

(B)

13

(A)

NOTES:

(B)

1. A 1 In. clearance minimum between top of
furnace and combustible material.

2. The entire length of furnace must be
supported when furnace is used in
horizontal position to ensure proper
drainage.

3. Bottom side combustion-air entry cannot
be used when furnace is installed with
hangers as shown.

/16-IN. MAX
ALTERNATE SUPPORT
LOCATION FROM BACK

Fig. 24—Crawlspace Horizontal Application

VENT

3

⁄8-IN. ROD

ALTERNATE SUPPORT
LOCATION 4-IN. MIN
8-IN. MAX

A96209

—18—

Factory-supplied washable framed filters are shipped in blower
compartment. Determine location for filter and relocate filter
retaining wire if necessary. See Table 2 to determine correct filter
size for desired filter location. Table 2 indicates filter size,
location, and quantity shipped with this furnace. See Fig. 2 for
location and size of bottom and side return-air openings.

CAUTION: Use care when cutting support rods in filters
to protect against flying pieces and sharp rod ends. Wear
safety glasses, gloves, and appropriate protective cloth­ing. Failure to follow this caution could result in minor
personal injury.

CAUTION: Air delivery above 1800 CFM requires that
both sides, a combination of 1 side and bottom, or bottom
only of furnace be used for return air. Failure to follow
this caution will result in intermittent unit operation or
performance satisfaction.

NOTE: Side return-air openings can ONLY be used in UPFLOW
configurations. Install filter(s) as shown in Fig. 25.

Bottom return-air opening may be used with all 4 orientations.
Filter may need to be cut to fit some furnace widths. Install filter
as shown in Fig. 26.

NOTE: Remove and discard bottom closure panel when bottom
inlet is used.

F. Bottom Closure Panel

These furnaces are shipped with bottom enclosure panel installed
in bottom return-air opening. This panel MUST be in place when
side return air is used.

To remove bottom closure panel, perform following:

1. Tilt or raise furnace and remove 2 screws holding front
filler panel. (See Fig. 27.)

2. Rotate front filler panel downward to release holding tabs.

3. Remove bottom closure panel.

4. Reinstall front filler panel and screws.

CAUTION: Connect gas pipe to furnace using a backup
wrench to avoid damaging gas controls. Failure to follow
this caution will result in intermittent unit operation or
performance satisfaction.

Fig. 25—Filter Installed for Side Inlet

171⁄2-IN. WIDE
CASINGS ONLY:

INSTALL FIELD-SUPPLIED
FILTER FILLER STRIP
UNDER FILTER.

3″

1

24

/2″

1″

21-IN. WIDE
CASINGS ONLY:

SUPPORT RODS (3)
EXTEND 1/4" ON EACH
SIDE OF FILTER AND
REST ON CASING FLANGE

A00217

G. Gas Piping

Gas piping must be installed in accordance with national and local
codes. Refer to current edition of NFGC in the United States.
Canadian installations must be made in accordance with NSCNG­PIC and all authorities having jurisdiction. Gas supply line should
be a separate line running directly from meter to furnace, if
possible. Refer to Table 3 for recommended gas pipe sizing. Risers
must be used to connect to furnace and to meter. Support all gas
piping with appropriate straps, hangers, etc. Use a minimum of 1
hanger every 6 ft. Joint compound (pipe dope) should be applied
sparingly and only to male threads of joints. Pipe dope must be
resistant to propane gas.

TABLE 2—FILTER INFORMATION

FURNACE

CASING

WIDTH (IN.)

17-1/2 (1) 16 X 25 X 1† (1) 16 X 25 X 1† Cleanable

21 (1) 16 X 25 X 1 (1) 20 X 25 X 1† Cleanable

24-1/2 (1 or 2) 16 X 25 X 1 (1) 24 X 25 X 1† Cleanable

* Filters may be field modified by cutting filter material and support rods (3) in

filters. Alternate sizes can be ordered from your distributor or dealer.

† Factory-provided with furnace.

FILTER SIZE (IN.)*

Side Return Bottom Return

FILTER TYPE

FRAMED

—19—

WASHABLE
FILTER

FILTER
SUPPORT

FILTER
RETAINER

Fig. 26—Bottom Filter Arrangement

A00290

WARNING: Gas valve ON and OFF switch MUST be
facing forward or tilted upward. (See Fig. 46.) Failure to
follow this warning could result in property damage or
death.

WARNING: Never purge a gas line into a combustion
chamber. Use a commercially available soap solution
made specifically for the detection of leaks to check all
connections. A failure to follow this warning could result
in fire, explosion, personal injury, or death.

WARNING: Use proper length of pipe to avoid stress on
gas control manifold. Failure to follow this warning could
result in a gas leak resulting in fire, explosion, personal
injury, or death.

Install a sediment trap in riser leading to furnace. Trap can be
installed by connecting a tee to riser leading to furnace so
straight-through section of tee is vertical. Then connect a capped
nipple into lower end of tee. Capped nipple should extend below
level of gas controls. Place a ground joint union between gas
control manifold and manual gas shutoff valve. (See Fig. 28.)

BOTTOM
CLOSURE
PANEL

CAUTION: If a flexible connector is required or al­lowed by authority having jurisdiction, black iron pipe
shall be installed at furnace gas control valve and extend
a minimum of 2 in. outside furnace casing. Failure to
follow this caution will result in potential chaffing of
flexible gas connection.

If local codes allow the use of a flexible gas appliance connector,
always use a new listed connector. Do not use a connector which
has previously served another gas appliance.

WARNING:

FIRE OR EXPLOSION HAZARD
Failure to follow the safety warnings exactly could result
in serious injury, death or property damage.
Never test for gas leaks with an open flame. Use a
commercially available soap solution made specifically
for the detection of leaks to check all connections. A fire
or explosion may result causing property damege, per­sonal injury or loss of life.

An accessible manual shutoff valve MUST be installed external to
furnace casing and within 6 ft of furnace. A 1/8-in. NPT plugged
tapping, accessible for test gauge connection, MUST be installed
immediately upstream of gas supply connection to furnace and
downstream of manual shutoff valve.

NOTE: The gas valve inlet pressure tap connection is suitable to
use as test gauge connection providing test pressure DOES NOT
exceed maximum 0.5 psig (14-in. wc) stated on gas valve. (See
Fig. 46.)

If pressure exceeds 0.5 psig (14-in. wc), gas supply pipe must be
disconnected from furnace and capped before pressure test. If test
pressure is equal to or less than 0.5 psig (14-in. wc), turn off
electric shutoff switch located on furnace gas valve and accessible
manual shutoff valve before test.

The gas supply pressure shall be within the maximum and
minimum inlet pressures marked on the rating plate with the
furnace burners ON and OFF.

V. ELECTRICAL CONNECTIONS

See Fig. 30 for field wiring diagram showing typical field 115-v
and 24-v wiring. Check all factory and field electrical connections
for tightness.

Field-supplied wiring shall conform with the limitations of 63°F
(35°C) rise.

FRONT FILLER
PANEL

A93047

Fig. 27—Removing Bottom Closure Panel
TABLE 3—MAXIMUM CAPACITY OF PIPE

(CU FT PER HR)*

NOMINAL

IRON

PIPE
SIZE

(IN.)

1/2 0.622 175 120 97 82 73
3/4 0.824 360 250 200 170 151

1 1.049 680 465 375 320 285
1-1/4 1.380 1400 950 770 660 580
1-1/2 1.610 2100 1460 1180 990 900

* For gas pressures of 0.5 psig (14-in. wc) or less, and a pressure drop of

0.5-in. wc (based on a 0.60 specific gravity gas). Ref: Table 12.2 NFPA
54-2002.

INTERNAL
DIAMETER

(IN.)

LENGTH OF PIPE (FT)

10 20 30 40 50

—20—

GAS
SUPPLY

MANUAL
SHUTOFF
VALVE
(REQUIRED)

SEDIMENT
TRAP

UNION

Fig. 28—Typical Gas Pipe Arrangement

A93324

TABLE 4—ELECTRICAL DATA

UNIT

SIZE

024040 115—60—1 127 104 6.1 8.4 14 44 15

036040 115—60—1 127 104 7.3 10.0 14 37 15

024060 115—60—1 127 104 6.1 8.4 14 44 15

036060 115—60—1 127 104 7.1 9.8 14 38 15

048060 115—60—1 127 104 9.5 12.8 14 29 15

036080 115—60—1 127 104 7.6 10.4 14 36 15

048080 115—60—1 127 104 10.0 13.4 14 28 15

060080 115—60—1 127 104 14.1 18.4 12 31 20

048100 115—60—1 127 104 10.2 13.5 14 27 15

060100 115—60—1 127 104 14.8 19.3 12 30 20

060120 115—60—1 127 104 14.6 19.1 12 30 20

* Permissible limits of voltage range at which unit will operate satisfactorily.
† Unit ampacity = 125 percent of largest operating component’s full load amps plus 100 percent of all other potential operating components’ (EAC, humidifier, etc.) full load

amps.
‡ Length shown is as measured 1 way along wire path between unit and service panel for maximum 2 percent voltage drop.
** Time-delay type is recommended.

VOLTS—
HERTZ—

PHASE

OPERATING

VOLTAGE RANGE

Max* Min*

MAX
UNIT

AMPS

UNIT

AMPACITY†

MIN

WIRE

SIZE

MAX WIRE

LENGTH (FT)‡

MAX FUSE OR

CKT BKR AMPS**

Use a separate, fused branch electrical circuit containing a properly

WARNING: Blower access door switch opens 115-v
power to control center. No component operation can
occur. Do not bypass or close switch with panel removed.
Failure to follow this warning could result in personal
injury or death.

sized fuse or circuit breaker for this furnace. See Table 4 for wire
size and fuse specifications. A disconnecting means must be
located within sight from and readily accessible to furnace.

NOTE: Proper polarity must be maintained for 115-v wiring. If
polarity is incorrect, control center fault code indicator light will
flash rapidly and furnace will NOT operate.

CAUTION: Furnace control must be grounded for
proper operation or control will lock out. Control is
grounded through green/yellow wire routed to gas valve
and burner box screw. Failure to follow this caution will
result in intermittent unit operation.

A. 115-v Wiring

Before proceeding with electrical connections, make certain that
voltage, frequency, and phase correspond to that specified on
furnace rating plate. Also, check to be sure that service provided
by power supply is sufficient to handle load imposed by this
equipment. Refer to rating plate or Table 4 for equipment electrical
specifications.

Make all electrical connections in accordance with National
Electrical Code (NEC) ANSI/NFPA 70-2002 and any local codes
or ordinances that might apply. For Canadian installations, all
electrical connections must be made in accordance with Canadian
Electrical Code CSA C22.1 or authorities having jurisdiction.

ELECTRIC

DISCONNECT

SWITCH

COPPER

WIRE ONLY

ALUMINUM

WIRE

A93033

Fig. 29—Disconnect Switch and Furnace

CAUTION: Do not connect aluminum wire between

disconnect switch and furnace. Use only copper wire.
(See Fig. 29.) Failure to follow this caution will result in
intermittent unit operation or performance satisfaction.

WARNING: The cabinet MUST have an uninterrupted
or unbroken ground according to NEC ANSI/NFPA
70-2002 and Canadian Electrical Code CSA C22.1 or
local codes to minimize personal injury if an electrical
fault should occur. This may consist of electrical wire or
conduit approved for electrical ground when installed in
accordance with existing electrical codes. Do not use gas
piping as an electrical ground. Failure to follow this
warning could result in electrical shock, fire, or death.

J-BOX RELOCATION

1. Remove 2 screws holding auxiliary J-box. (See Fig. 31.)

2. Rotate J-box 180° and attach box to right side, using holes
provided.

CAUTION: If manual disconnect switch is to be
mounted on furnace, select a location where a drill or
fastener will not contact electrical or gas components.
Failure to follow this caution will result in intermittent
unit operation or performance satisfaction.

B. 24-v Wiring

Make field 24-v thermostat connections at 24-v terminal block on
furnace control. For proper cooling operation, Y wire from
thermostat MUST be connected to Y terminal on furnace control,
as shown in Fig. 30. The 24-v terminal block is marked for easy
connection of field wiring. (See Fig. 32.) The 24-v circuit contains
a 3-amp, automotive-type fuse located on furnace control. (See
Fig. 33.) Any electrical shorts of 24-v wiring during installation,
service, or maintenance may cause fuse to blow. If fuse replace­ment is required, use only a fuse of identical size (3 amp) and type.
The control will flash code 24 when fuse needs replacement.

NOTE: Use AWG No. 18 color-coded copper thermostat wire for
lengths up to 100 ft. For wire lengths over 100 ft, use AWG No.
16 wire.

—21—

THREE-WIRE

HEATING-ONLY

BLOWER DOOR SWITCH

BLK

WHT

115-V FIELD-

SUPPLIED

DISCONNECT

GND

BLK

WHT

AUXILIARY
J-BOX

FIVE WIRE

GND

FURNACE

NOTE 2

W

C

R

O

N
T

G

R

O

COM

L

Y

24-V

TERMINAL

BLOCK

FIELD 24-V WIRING
FIELD 115-, 208/230-, 460-V WIRING
FACTORY 24-V WIRING
FACTORY 115-V WIRING

WCR GY

NOTE 1

NOTES: Connect Y-terminal in furnace as shown for proper blower operation.

1.
Some thermostats require a "C" terminal connection as shown.

2.
If any of the original wire, as supplied, must be replaced, use

3.
same type or equivalent wire.

THERMOSTAT
TERMINALS

CONDENSING
UNIT

TWO
WIRE

FIELD-SUPPLIED
DISCONNECT

GND

208/230- OR
460-V
THREE
PHASE

208/230-V
SINGLE
PHASE

Fig. 30—Typical Heating and Cooling Application Wiring Diagram

ALTERNATE

FIELD

LOCATION

Fig. 31—Relocating J-Box

C. Accessories

1. Electronic Air Cleaner (EAC)
Two quick-connect terminals marked EAC-1 and EAC-2

are provided for EAC connection. (See Fig. 33.) These
terminals are energized with 115v (1.0-amp maximum)
during blower motor operation.

FACTORY
INSTALLED
LOCATION

A00212

A02174

2. Humidifier (HUM)
A quick-connect terminal (HUM) and screw terminal (C

OM

24v) are provided for 24-v humidifier connection. (See Fig.

26.) HUM terminal is energized with 24v (0.5-amp maxi­mum) After the inducer pre-purge period. (HK42FZoB
Control Board)

NOTE: A field-supplied, 115-v controlled relay connected to
EAC terminals may be added if humidifier operation is desired
during blower operation.

VI. VENTING

The 345MAV Furnaces require a dedicated, (one 345MAV fur­nace only) sealed vent system. All air for combustion is taken from
the area adjacent to furnace, and all flue gases are discharged to
outdoor atmosphere.

A. Removal of Existing Furnaces from
Common Venting Systems

When an existing Category I furnace is removed or replaced, the
original venting system may no longer be sized to properly vent
the remaining attached appliances. An improperly sized Category
I venting system could cause the formation of condensate in the
furnace and vent, leakage of condensate and combustion products,
spillage of combustion products into the living space, etc.

—22—

TABLE 5—APPROVED COMBUSTION-AIR AND VENT PIPE, FITTING AND CEMENT MATERIALS

ASTM SPECIFICATION

(MARKED ON MATERIAL)

D1527 ABS Pipe — — Schedule-40
D1785 PVC Pipe — — Schedule-40

D2235 For ABS — —
D2241 PVC Pipe — — SDR-21 & SDR-26

D2466 PVC — Fittings — Schedule-40
D2468 ABS — Fittings — Schedule-40

D2564 For PVC — —
D2661 ABS Pipe Fittings — DWV at Schedule-40 IPS sizes

D2665 PVC Pipe Fittings — DWV

F438 CPVC — Fittings — Schedule-40
F441 CPVC Pipe — — Schedule-40
F442 CPVC Pipe — — SDR

F493 For CPVC — —
F628 ABS Pipe — — Cellular Core DWV at Schedule-40 IPS sizes

F656 For PVC — — Primer For PVC
F891 PVC Pipe — — Cellular Core Schedule-40 & DWV

MATERIAL PIPE FITTINGS SOLVENT CEMENT AND PRIMERS DESCRIPTION

Solvent
Cement

Solvent
Cement

Solvent
Cement

For ABS

For PVC

For CPVC

WARNING:

CARBON MONOXIDE POISONING HAZARD

Failure to follow the steps outlined below for each appliance connected to the venting system being placed into operation could result
in carbon monoxide poisoning or death.
The following steps shall be followed for each appliance connected to the venting system being placed into operation, while all other
appliances connected to the venting system are not in operation:

1. Seal any unused openings in venting system.

2. Inspect the venting system for proper size and horizontal pitch, as required in the National Fuel Gas Code, ANSI Z223.1-2002/NFPA
54-2002 or the CSA B149.1, Natural Gas and Propane Installation Code and these instructions. Determine that there is no blockage
or restriction, leakage, corrosion and other deficiencies, which could cause an unsafe condition.

3. As far as practical, close all building doors and windows and all doors between the space in which the appliance(s) connected to the
venting system are located and other spaces of the building.

4. Close fireplace dampers.

5. Turn on clothes dryers and any appliance not connected to the venting system. Turn on any exhaust fans, such as range hoods and
bathroom exhausts, so they are operating at maximum speed. Do not operate a summer exhaust fan.

6. Follow the lighting instructions. Place the appliance being inspected into operation. Adjust the thermostat so appliance is operating
continuously.

7. Test for spillage from draft hood equipped appliances at the draft hood relief opening after 5 minutes of main burner operation. Use
the flame of a match or candle.

8. If improper venting is observed during any of the above tests, the venting system must be corrected in accordance with the National
Fuel Gas Code, ANSI Z223.1-2002/NFPA 54-2002 and/or CSA B149.1, Natural Gas and Propane Installation Code.

9. After it has been determined that each appliance connected to the venting system properly vents when tested as outlined above, return
doors, windows, exhaust fans, fireplace dampers and any other gas-fired appliance to their previous conditions of use.

Vent system or vent connectors may need to be resized. For any
other applicanes when resizing vent systems or vent connectors,
system or connector must be sized to approach minimum size
determined in appropriate table in NFGC or NSCNGPIC.

B. Combustion-Air and Vent Piping
C. General

WARNING: Solvent cements are combustible. Keep

away from heat, sparks, and open flame. Use only in
well-ventilated areas. Avoid breathing in vapor or allow­ing contact with skin or eyes. Failure to follow this
warning could result in fire, property damage, personal
injury, or death.

Combustion-air and vent pipe, fittings, primers, and solvents must
conform to American National Standards Institute (ANSI) stan­dards and American Society for Testing and Materials (ASTM)

standards. See Table 5 for approved materials for use in the U.S.A.
See Table 6 for maximum pipe lengths and Fig. 39, 40, and 41 for
exterior piping arrangements.

In Canada, construct all combustion-air and vent pipes for this unit
of CSA or ULC listed schedule-40 PVC, PVC-DWV or ABS­DWV pipe and pipe cement. SDR pipe is NOT approved in
Canada.

Vent pipe termination must be installed with adequate clearances
to building openings and equipment to comply with national and
local codes.

See Table 8 for required clearances.

—23—

SCHEMATIC DIAGRAM

(NAT UR AL GAS & P RO PANE)

NOTE #2

TO 115VA C FIELD DISCONNECT

L2

CAP-1

LO

EQUIPMENT GROUND

GND

L2

ILK

L1

EAC-2

IDM

BLWM

START

OL

COM

HI

MED LO

MED HI

NOTE #10

COOL

HEAT

SPARE-1

SPARE-2

HI/LO

HSIR

EAC-1

BLWR

L1

AUX

OL

M

1

3

HSI

2

1

PL3

2

1

PL2

115VAC

PR1

IDR

PL4

24VAC

TRAN

CAP - 2

2

NOTE #6

F U 1

TEST/TWIN

PRINTED CIRCIUT BOARD

LS

NOTE #3

GV

FRS

SEC-2

SEC-1

(WHEN USED)

NOTE #11

PRS

LGPS

6

2

8

PL1

R

W

HUM

C

M

4

10

GVR-1

CPU

Y

FSE

7

3

9

1

5

G

11

NOTE #5

PCB

OM

24V

C

1. If any of the original equipment wire is replaced use wire rated for 105°C.

2. Use only copper wire between the disconn e ct sw itch and the furnac e junc tion box (JB ).

3. This wire must be connected to furnace sheet metal for control to prove flame.

4. Symbols are electrical representation only .

NOTES:

optimum speed selection.

5. Solid lines inside PCB are printed circuit board conductors and are not included in legend.

6. Replace only with a 3 amp fuse.

7. Inducer (IDM) and blower (BL WM) motors contain internal auto-reset thermal overload switches (OL).

8. Neutral connections are interchangeable within the NEUTRAL connector block.

9. Blower motor speed selections are for average conditions, see installation instructions for details on

10. YELLOW lead not on all m otors.

11. Factory connected when L G P S is not u se d.

328150-101 REV. A

auto-re s et after thre e hours.

90 seconds or 5 seconds when J2 is cut.

12. Ig nition-lock out will occ ur after four consecutive unsucce ssful trials-f o r- ignition. Co ntrol will

13. Blower-on delay: gas heating 60 seconds, cooling or heat pump 2 seconds.

14. Blower-off delay: gas heating selections are 90, 120, 150 or 180 seconds, cooling or heat pump

A02271

LGPS

(WHEN USED)

NOTE #11

PRS

ORN

PCB

120

90

BLOWER OFF DELAY

150

JUMPER SELECT

J2

G

PRINTED CIRCIUT BOARD

YEL

GRN/YEL

GV

C

NOTE #3

M

BLU

FRS

RED

RED

LS

RED

ORN

BLU

180

J1

HUM

TEST/TWIN

om

Y

R

W

24V

C

FU1

NOTE #6

GRN/YEL

WHT

11

SEC-1

WHT

BLK

CAP -2

TRAN

WHT

BLU

RED

RED

RED

GRN/YEL

WHT

L2

LED 1

EAC-2

SEC-2

BRN

BRN

GRN/YEL

NOTE #8

WHT

321

PL4

YEL

WHT

12345678910

NEUTRAL

IDM

HSI

WHT

AUX

OL

M

FSE

PL1

2

1

PL3

BLK

WHT

BLK

GRN/YEL

BLK

1

PL2

2

L1

BLW

BHT/CLR BLWR

COOL

HEAT

WHT

BLK

WHT (COM)

BLK

PR1

EAC-1

BLWM

SPAR E 2

BLK (HI)

SPA RE 1

WHT

(COM )

L1

NEUTRAL

NOTE #2

FU2

FUSED OR CIRCUIT BREAKER

BLK

WHT

DISCONNECT SWITCH (WHEN REQ’D)

JB

GRN/YEL

BRN

YEL

(MED HI)

GND

TEMPERATURE SWITCH (N.C.)

OL AUTO-RESET INTERNAL MOTOR OVERLOAD

PCB PRINTED CIRCUIT BOARD CONTROL

PL1 11-CIRCU IT PCB CONNECTOR

PL2 2-CIRCUIT CONNECTOR

PL3 2-CIRCUIT HSI, CONNECTOR

ILK

BLK

WHT

CAP -1

BRN

STAR T

OL

RED (LO)

NOTE #10

BLU

(MED LO)

BHT/CLR BLOWER MOTOR SPEED CHANGE RELAY, SPDT

BLWR BLOWER MOTOR RE LAY, SPST-(N.O.)

BLWM BLOWER MOTOR, PERMANENT-SPLIT-CAPACITOR

CAP 1,2 CAPACITOR

CPU MICROPROCESSOR AND CIRCUITRY

EAC-1 ELECTRONIC AI R CLE ANER CONNEC TI ON (115 VAC 1.0 AMP MAX.)

LEGEN

PL4 3-CIRCUIT IDM EXTENSION CONNECTOR

EAC-2 ELECTRONIC AIR CLEANER CONNECTION (COMMON)

D

JUNCTION

UNMARKED TERMINAL

PCB CONTROL TERMINAL

FACTOR Y WIRING (115V AC)

FACTOR Y WIRING (24V A C )

FIELD WIRING (115VAC)

FIELD WIRING (24VAC)

CONDUCTOR ON CONTROL PCB

FIELD WIRING SCREW TERMINAL

FIELD EARTH GROUND

EQUIPMENT GROUND

FIELD SPLICE

PLUG RECEPTACLE

PRS PRESSURE SWITCH, SPST-(N.O.)

TEST/TWIN COMPONENT TEST & TWIN TERMINAL

TRAN TRANSFORMER-115VAC/24VA C

(FIELD INSTALLED & SUPPLIED)

FRS FLAME ROLLOUT SW. -MANUAL RESET, SPST-(N.C.)

FSE FLAME-PROVING ELECTRODE

FU 1 FUSE, 3 AMP, AUTOMOTIVE BLADE TYPE, FACTORY INSTALLED

FU 2 FUSE OR CIRCUIT BREAKER CURRENT INTERRUPT DEVICE

GND EQUIPMENT GROUND

GV GAS VALVE-REDUNDANT

GVR 1, 2 GAS VALVE RELAY, DPST-(N.O.)

HSI HOT SURFACE IGNITER (115 VAC)

HSIR HOT SURFACE IGNITER RELAY, SPST-(N.O.)

HUM 24VAC HUMIDIFIER CONNECTION (0.5 AMP. MAX.)

IDM INDUCED DRAFT MOTOR, PSC

IDR INDUCED DRAFT MOTOR RELAY, SPST-(N.O.)

ILK BLOWER ACCESS P ANEL INTERLOCK SWITCH, SPST-(N.O.)

J1 BLOWER - OFF DEL AY JUMPER SELECTOR

J2 COOLING - OFF DELAY JUMPER

JB JUNCTION BOX

LED LIGHT-EMITTING DIODE FOR STATUS CODES - RED

LGPS LOW GAS PRESSURE SWITCH, SPST-(N.O.)

LS LIMIT SWITCH, AUTO-RESET, SPST (N.C.)

Fig. 32—Wiring Diagram

—24—

ALTITUDE (FT) UNIT SIZE

0 to 2000

ALTITUDE (FT) UNIT SIZE

2001 to 3000

ALTITUDE (FT) UNIT SIZE

3001 to 4000

See notes at end of table

024040
036040

024060
036060
048060

036080
048080
060080

048100
060100

060120

024040
036040

024060
036060
048060

036080
048080
060080

048100
060100

060120

024040
036040

024060
036060
048060

036080
048080
060080

048100
060100

060120

TABLE 6—MAXIMUM ALLOWABLE PIPE LENGTH (FT)

TERMINATION

TYPE

2 Pipe or 2-in

Concentric

2 Pipe or 2-in

Concentric

2 Pipe or 2-in

Concentric

2 Pipe or 3-in

Concentric

2 Pipe or 3-in.

Concentric

TERMINATION

TYPE

2 Pipe or 2-in

Concentric

2 Pipe or 2-in

Concentric

2 Pipe or 2-in

Concentric

2 Pipe or 3-in

Concentric

2 Pipe or 3-in.

Concentric

TERMINATION

TYPE

2 Pipe or 2-in

Concentric

2 Pipe or 2-in

Concentric

2 Pipe or 2-in

Concentric

2 Pipe or 3-in

Concentric

2 Pipe or 3-in.

Concentric

PIPE DIA

(IN.)*

1 5 NA NA NA NA NA

1-1/2 70 70 65 60 60 55

2 707070707070

1-1/2 20 15 10 5 NA NA

2 707070707070

1-1/2 10 NA NA NA NA NA

2 555035303020

2-1/2 70 70 70 70 70 70

2 5 NA NA NA NA NA

2-1/2 40 30 20 20 10 NA

3 707070707070

2-1/2 one disk 10 NA NA NA NA NA

3† 45 40 35 30 25 20

3† no disk 70 70 70 70 70 70

PIPE DIA

(IN.)*

1-1/2 67 62 57 52 52 47

2 707070707070

1–1/2 17 12 7 NA NA NA

2 706766616161

2 494430252515

2-1/2 70 70 70 70 70 70

2–1/2 35 26 16 16 6 NA

3 707070706661

3 14 9 NA NA NA NA
3† no disk 70 70 63 56 50 43
4† no disk 70 70 70 70 70 70

PIPE DIA

(IN.)*

1-1/2 64 59 54 49 48 43

2 707070707070

1–1/2 16 11 6 NA NA NA

2 686362575756

2 464128232213

2-1/2 70 70 70 70 70 70
2-1/2 33 24 15 14 5 NA

3 707070666156
3† no disk 65 58 51 44 38 31
4† no disk 70 70 70 70 70 70

123456

123456

123456

NUMBER OF 90° ELBOWS

NUMBER OF 90° ELBOWS

NUMBER OF 90° ELBOWS

COMBUSTION AIR PIPE

CAUTION: Combustion air must not be taken from
inside a structure that is frequently contaminated by
halogens, which include fluorides, chlorides, bromides,
and iodides. These elements are found in aerosols,
detergents, bleaches, cleaning solvents, salts, air freshen­ers, adhesives, paint, and other household products.
Locate combustion-air inlet as far as possible from
swimming pool and swimming pool pump house.
Excessive exposure to contaminated combustion air will
result in safety and performance related problems.

NOTE: Furnace combustion-air connections are sized for 2-in.
pipe. The combustion-air pipe will be 2-in. diameter in all
installations.

—25—

See Table 8 for required clearances.

→

Furnace combustion-air connection must be attached as shown in
Fig. 34. Combustion-air intake housing plug may need to be
relocated in some applications.

Combustion-air pipe must terminate outside of furnace casing with
1 elbow. Orient elbow so that opening faces down for upflow or
downflow applications. Orient elbow so that it faces sideways (left
or right) for horizontal left or horizontal right applications. (See
Fig. 34.) Maintain a 3-in. minimum clearance between the opening
of the combustion-air inlet pipe and any object.

NOTE: All pipe joints must be cemented except attachment of
combustion-air inlet pipe to inlet housing connection, since it may
be necessary to remove pipe for servicing.

Install combustion air inlet pipe as follows:

1. Assemble combustion-air inlet pipe.

ALTITUDE (FT) UNIT SIZE

4001 to 5000‡

ALTITUDE (FT) UNIT SIZE

5001 to 6000‡

ALTITUDE (FT) UNIT SIZE

6001 to 7000‡

ALTITUDE (FT) UNIT SIZE

7001 to 8000‡

See notes at end of table

TABLE 6—MAXIMUM ALLOWABLE PIPE LENGTH (FT) (CONTINUED)

NUMBER OF 90° ELBOWS

NUMBER OF 90° ELBOWS

NUMBER OF 90° ELBOWS

NUMBER OF 90° ELBOWS

024040
036040

024060
036060
048060

036080
048080
060080

048100
060100

060120

024040
036040

024060
036060
048060

036080
048080
060080

048100
060100

060120

024040
036040

024060
036060
048060

036080
048080
060080

048100
060100

060120

024040
036040

024060
036060
048060

036080
048080
060080

048100
060100

060120

TERMINATION

TYPE

2 Pipe or 2-in

Concentric

2 Pipe or 2-in

Concentric

2 Pipe or 2-in

Concentric

2 Pipe or 3-in

Concentric

2 Pipe or 3-in.

Concentric

TERMINATION

TYPE

2 Pipe or 2-in

Concentric

2 Pipe or 2-in

Concentric

2 Pipe or 2-in

Concentric

2 Pipe or 3-in

Concentric

2 Pipe or 3-in.

Concentric

TERMINATION

TYPE

2 Pipe or 2-in

Concentric

2 Pipe or 2-in

Concentric

2 Pipe or 2-in

Concentric

2 Pipe or 3-in

Concentric

2 Pipe or 3-in.

Concentric

TERMINATION

TYPE

2 Pipe or 2-in

Concentric

2 Pipe or 2-in

Concentric

2 Pipe or 2-in

Concentric

2 Pipe or 3-in

Concentric

2 Pipe or 3-in.

Concentric

PIPE DIA

(IN.)*

1-1/2 60 55 50 45 44 39

2 707070707070

1-1/2 15 10 5 NA NA NA

2 645958535252
2 443926212011

2-1/2 70 70 70 70 70 70
2-1/2 31 22 13 12 NA NA

3 707067625752
3† no disk 53 46 40 33 26 20
4† no disk 70 70 70 70 70 70

PIPE DIA

(IN.)*

1-1/2 57 52 47 42 40 35

2 707070707070

1-1/2 14 9 NA NA NA NA

2 605554494847

2 4136231817 8

2-1/2 70 70 70 70 70 70
2-1/2 29 21 12 11 NA NA

3 706762575247
3† no disk 42 35 29 22 15 9
4† no disk 70 70 70 70 70 70

PIPE DIA

(IN.)*

1-1/2 53 48 43 38 37 32

2 707068676664

1-1/2 13 8 NA NA NA NA

2 575250454443

2 3833211615 6

2-1/2 70 70 68 67 66 64
2-1/2 27 19 10 9 NA NA

3 686358534843
3† no disk 31 24 18 11 NA NA
4† no disk 70 70 70 70 67 62

PIPE DIA

(IN.)*

1-1/2 49 44 39 34 33 28

2 666563626059

1-1/2 12 7 NA NA NA NA

2 534846414038

2 3631191412NA

2–1/2 66 65 63 62 60 59
2–1/2 25 17 8 7 NA NA

3 635853484338
3† no disk 20 13 7 NA NA NA
4† no disk 61 56 51 46 41 36

123456

123456

123456

123456

a. Permanently install perforated disk assembly (factory-

supplied in loose parts bag) in combustion-air elbow
using RTV or by cementing. (See Fig. 35.)

For 120,000 Btuh size units only: Separate the 2 halves
of perforated disk assembly and use only the shouldered
disk half.

b. Determine length of straight portion of combustion-air

inlet pipe from table in Fig. 35.

c. Cut field-supplied 2-in diameter PVC pipe to determined

length.

d. Permanently attach elbow/perforated disk assembly to

straight portion of pipe using RTV or by cementing. (See
Fig. 35.)

—26—

TABLE 6—MAXIMUM ALLOWABLE PIPE LENGTH (FT) (CONTINUED)

ALTITUDE (FT) UNIT SIZE

024040
036040

024060
036060
048060

8001 to 9000‡

ALTITUDE (FT) UNIT SIZE

9001 to 10,000‡

Disk usage-Unless otherwise specified, use perforated disk assembly (factory-supplied in loose parts bag). If one disk is stated, separate 2 halves of perforated disk
assembly and use shouldered disk half. When using shouldered disk half, install screen side toward inlet box.
†Wide radius elbow.
‡Vent sizing for Canadian installations over 4500 ft (1370 m) above sea level are subject to acceptance by the local authorities having jurisdiction.
NA-Not Allowed; pressure switch will not make.

NOTES:

1. Do not use pipe size greater than those specified in table or incomplete combustion, flame disturbance, or flame sense lockout may occur.

2. Size both the combustion-air and vent pipe independently, then use the larger diameter for both pipes.

3. Assume two 45° elbows equal one 90° elbow. Long radius elbows are desirable and may be required in some cases.

4. Elbows and pipe sections within the furnace casing and at the vent termination should not be included in vent length or elbow count.

5. The minimum pipe length is 5 ft for all applications.

6. Use 3-in. diameter vent termination kit for installations requiring 4-in diameter pipe.

036080
048080
060080

048100
060100

060120

024040
036040

024060
036060
048060

036080
048080
060080

048100
060100

060120

TERMINATION

TYPE

2 Pipe or 2-in

Concentric

2 Pipe or 2-in

Concentric

2 Pipe or 2-in

Concentric

2 Pipe or 3-in

Concentric

2 Pipe or 3-in.

Concentric

TERMINATION

TYPE

2 Pipe or 2-in

Concentric

2 Pipe or 2-in

Concentric

2 Pipe or 2-in

Concentric

2 Pipe or 3-in

Concentric

2 Pipe or 3-in.

Concentric

PIPE DIA

(IN.)*

1-1/2 46 41 36 31 29 24

2 626058565553

1-1/2 11 6 NA NA NA NA

2 494442373534
2 3328171210NA

2-1/2 62 60 58 56 55 53
2-1/2 23 15 7 5 NA NA

3 595449443934
3† no disk 10 NA NA NA NA NA
4† no disk 35 30 25 20 15 10

PIPE DIA

(IN.)*
1-1/2 42 37 32 27 25 20

2 575553514947

2 454038333129

230251497NA

2-1/2 57 55 53 51 49 47
2-1/2 21 13 5 NA NA NA

3 544944393429
4† no disk 10 5 NA NA NA NA

123456

123456

NUMBER OF 90° ELBOWS

NUMBER OF 90° ELBOWS

2. Attach combustion-air inlet pipe.
a. Determine location of combustion-air intake pipe con-

nection to combustion-air intake housing as shown in
Fig. 34 for application.

b. Reposition combustion-air intake housing plug fitting in

appropriate unused intake housing connection.

c. Install pipe support (factory-supplied in loose parts bag)

into selected furnace casing combustion-air pipe hole.
Pipe support should be positioned at bottom of casing
hole.

d. Insert assembled combustion-air inlet pipe into intake

housing.

e. Make sure elbow is oriented in an acceptable direction

and that the minimum clearance of 3 in. is observed. (See
Fig. 34.)

f. Drill a 1/8-in. hole in 2-in. combustion-air inlet pipe

using hole in intake housing as a guide.

g. Install a field-supplied No. 6 or No. 8 sheet metal screw

into combustion-air pipe.

NOTE: Do not attach combustion-air intake pipe permanently to
combustion-air intake housing since it may be necessary to remove
pipe for service of igniter or flame sensor.

COMBUSTION-AIR INTAKE HOUSING PLUG
FITTING
The combustion-air intake plug fitting must be installed in
unused combustion-air intake housing. This fitting must be
attached by using RTV sealant, or by drilling a 1/8-in. hole
in fitting, using hole in intake housing as a guide. Install a
field-supplied No. 6 or No. 8 sheet metal screw.

NOTE: DO NOT OVERTIGHTEN SCREW. Breakage of intake
housing or fitting may cause air leakage to occur.

A plugged drain connection has been provided on this
fitting for use when moisture is found in combustion-air
intake pipe and combustion box. If use of this drain
connection is desired, drill out fitting’s tap plug with a
3/16-in. drill and connect a field-supplied 3/8-in. tube. This
tube should be routed to open condensate drain for furnace
and A/C (if used), and should be trapped. (See Fig. 36.)

VENT PIPE

NOTE: Furnace vent pipe connections are sized for 2-in. pipe.
Any vent pipe size change should be made outside furnace casing
in vertical pipe. (See Fig. 37.) This allows proper drainage of vent
condensate.
Determine vent pipe diameter and maximum pipe lengths using
Table 6.
Furnace vent pipe connection must be attached as shown in Fig.

34. Inducer housing alternate vent cap may need to be relocated in
some applications.
NOTE: Starting at furnace, slope vent pipe a minimum of 1/4 in.
per linear ft upward to termination(s) with no sags between
hangers.

—27—

TABLE 7—MAXIMUM ALLOWABLE EXPOSED VENT PIPE LENGTH (FT) WITH AND WITHOUT INSULATION IN WINTER

DESIGN TEMPERATURE AMBIENT*

FURNACE

SIZE

040

060

080

100

120

* Pipe length (ft) specified for maximum pipe lengths located in unconditioned spaces. Pipes located in unconditioned space cannot exceed total allowable pipe length as
specified in Table 7.
† Insulation thickness based on R value of 3.5 per in.

WINTER DESIGN

TEMPERATURE

(°F)

20 1.5 51 70

0 1.5 28 70

-20 1.5 16 70
20 2 45 70

0 2 22 70

-20 2 10 58
20 2 65 70

0 2 35 70

-20 2 20 70
20 2 55 55

0 2 48 55

-20 2 30 55
20 2.5 70 70

0 2.5 47 70

-20 2.5 28 70
20 2.5 40 40

0 2.5 40 40

-20 2.5 38 40
20 3 70 70

0 3 50 70

-20 3 28 70
20 3 70 70

0 3 61 70

-20 3 37 70
20 4 70 70

0 4 48 70

-20 4 23 70

MAX PIPE

DIAMETER

(IN.)

WITHOUT

INSULATION

WITH 3/8–IN. OR

THICKER INSULATION†

CAUTION: When vent pipe is exposed to temperatures

below freezing, such as when it passes through an
unheated space or when a chimney is used as a raceway,
pipe must be insulated as described in Table 7 with
Armaflex-type insulation. Failure to follow this caution
will result in intermittent unit operation.

An abandoned masonry chimney may be used as a raceway for a
properly insulated and supported vent pipe. Each furnace must
have its own vent pipe and be terminated individually, as shown in
Fig. 41.
Other gas appliances with their own venting system may also use
the abandoned chimney as a raceway providing it is permitted by
local code, the current edition of the National Fuel Gas Code and
the vent or liner manufacturer’s installation instructions. Care must
be taken to prevent the exhaust gases from one appliance from
contaminating the combustion air of other gas appliances.

WARNING: Vent pipes must be airtight and watertight.
Failure to follow this warning could result in property
damage, personal injury, or death.

NOTE: The minimum vent pipe length for these furnaces is 5 ft.
Short pipe lengths (5-8 ft) may discharge water droplets. These
droplets may be undesirable, and a 12-in. minimum offset pipe
section is recommended to reduce excessive droplets from exiting
vent pipe outlet. (See Fig. 38.)
NOTE: Do not count elbows or pipe sections in terminations or
within furnace. See shaded areas in Fig. 40.

EXAMPLE:
An 036080 size furnace located in Indianapolis, elevation
650 ft above sea level, could be installed in an application
requiring 3 elbows and 32 ft of vent pipe. Table 4 indicates
this application would allow a 2-in. diameter vent pipe. At
0-2000 ft elevation, 2-in. pipe is good for up to 35 ft with
3 elbows. If same installation were in Albuquerque, eleva­tion 5250 ft above sea level, installation would require 2-1/2
in. vent pipe. At 5001- to 6000-ft elevation, 2-in. pipe is
allowed for up to 23 ft with 3 elbows, but 2-1/2 in. pipe can
be used for up to 70 ft with 3 elbows.

Install vent pipe as follows:

1. Determine location of vent pipe connection to inducer
housing as shown in Fig. 34 for application.

2. Reposition elastomeric (rubber) inducer housing outlet cap
and clamp to appropriate unused inducer housing connec­tion. Tighten clamp.

WARNING: Inducer housing outlet cap must be in­stalled and fully seated against inducer housing. Clamp
must be tightened to prevent any condensate leakage.
Failure to follow this warning could result in electrical
shock, fire, personal injury, or death.

3. Install pipe support (factory-supplied in loose parts bag)
into selected furnace casing vent pipe hole. Pipe support
should be positioned at bottom of casing hole.

—28—

O

Y

Y

D

E

V

B

V

C

FIXED

CLOSED

OPERABLE

F

B

V

VENTTERMINAL

Item Clearance Descriptions CanadianInstallation(1)

A Clearance above grade, veranda, porch, deck,balcony, or

anticipated snow level

B Clearance to awindowordoor that may be opened 6˝ (15 cm) for appliances ≤ 10,000 BTUH (3kW),12˝ (30

C Clearance to a permanentlyclosed window

D Vertical clearance to a ventilated soffit locatedabovethe

terminal withinahorizontaldistance of 2´(61cm) from the
centerline of the terminal

E Clearance to anunventilatedsoffit

F Clearancetoanoutsidecorner

G Clearance to an inside corner

H Clearance to each sideofthecenterline extended above

electrical meterorgasservice regulator assemb ly

I Clearance to serviceregulator vent outlet 3´(91 cm)

J Clearance to non--mechanicalair supply inlet to building or

the combustion air inlettoanyotherappliance

K Clearance to amechanical air supplyinlet 6´ (1.83 m) 3´(91cm) above if within 10´(3m horizontally)
L Clearance under a veranda, porch, deck, or balcony 12˝ (30 cm) +

M Clearance to each side of the centerline extended above or

below vent terminal of the furnace to a dryer or water heater
vent, or other appliance’s direct vent intake or exhaust.

N Clearance to the vent terminal of a dryer vent, water heater

vent, or other appliances direct vent intake or exhaust.

O

Clearance from a plumbing vent stack * *

(1.) In accordancewiththecurrentCSA B149.1, Natural Gas and PropaneInstallationCode
(2.) In accordancewiththecurrentANSI Z223.1/NFPA 54, National FuelGasCode
# 18˝ (46cm)aboveroofsurface
+ Permitted onlyifveranda,porch,deck,or balcony is fullyopenonaminimum of two sides beneath the floor.
*

Forclearances not specifiedinANSIZ223.1/NFPA 54 or CSA B149.1, clearancesshallbe in accordance with localinstallation codes and the requirements of the gas supplier and the
Manufacturer’s installation instructions.

Notes:

1. Theventfor this appliance shallnotterminate
a. Over publicwalkways;or
b. Near soffit vents or crawl spaceventsor other areas where condensate or vaporcould create a nusiance or hazard or propertydamage;or
c. Wherecondensatevaporcouldcause damage or could bedetrimental to the operation of regulators, relief valves, or other equipment.

2. Whenlocatingvent terminations,consideration mustbegivento prevailingwinds,location, and otherconditions whichmaycauserecirculation of the combustiob productsofadjacentvents.
Recirculation can causepoorcombustion,inlet condensate problems, and acceleratedcorrosion of the heat exchangers.

B

X

12˝ (30cm) # 12˝ (30 cm)

cm) for appliances > 10,000Btuh (3 kW) and ≤ 100,000 Btuh
(30 kW), 36˝ (91cm)forappliances > 100,000 Btuh (30 kW)

* *

* *

* *

* *

* *

3´(91cm) within 15´(4.5 m) above the meter/regulator
assembly

6˝ (15 cm) for appliances ≤10,000BTUH(3kW), 12˝ (30
cm) for appliances > 10,000Btuh (3 kW) and ≤100,000Btuh
(30 kW), 36˝ (91 cm)forappliances> 100,000 Btuh (30 kW)

*

* *

OPERABLE

V

B

B

AIR SUPPLY INLET

B

FIXED

CLOSED

X

J

A

H

I

L

K

AREAWHERE TERMINAL IS NOT PERMITED

4˝(1.2m) below or to the sideoftheopening.1˝(30cm)
abovetheopening.

3´(91cm) within 15´(4.5 m) abovethemeter/regulator
assembly

*

4´(1.2m) below or to the sideofopening:1´(30cm) above
opening.

*

*

G

X

V

A

U.S.Installation(2)

V

M

N

25--24--65--2

→ Table 8—Other than Direct Vent Termination Clearance

—29—

A03228

WARNING: Vent pipe must be installed and fully
seated against inducer housing internal stop. Clamp must
be tightened to prevent any condensate leakage. Failure to
follow this warning could result in electrical shock, fire,
personal injury, or death.

NOTE: A 2-in. diameter pipe must be used within the furnace
casing. Make all pipe diameter transitions outside furnace casing.

4. Be certain that mating surfaces of inducer housing connec­tion, elastomeric coupling, and 2-in. diameter vent pipe are
clean and dry. Assemble the elastomeric (rubber) vent
coupling (with 2 loose clamps) onto inducer housing
connection. Insert the 2-in. diameter vent pipe through the
elastomeric (rubber) coupling and fully into inducer hous­ing connection until it bottoms on the internal stop. Tighten
both clamps to secure the pipe to inducer housing. Tighten
the clamp screws to 15 in.-lb. of torque.
VENT EXTENSION PIPE
Some furnaces are supplied with a PVC vent extension pipe
(2-in. diameter by 12-in. long). This pipe has a built-in
channel to assist vent condensate disposal. When this vent
extension pipe is supplied, it must be used to connect the
field vent pipe to furnace inducer housing on ALL upflow
and downflow applications.

NOTE: See label on vent extension pipe for proper installation.
This pipe may be shortened if an elbow is used to connect vent
extension tube to field-installed vent pipe.

BLOWER OFF-DELAY

TWINNING AND/OR
COMPONENT TEST

5. Working from furnace to outside, cut pipe to required
length(s).

6. Deburr inside and outside of pipe.

7. Chamfer outside edge of pipe for better distribution of
primer and cement.

8. Clean and dry all surfaces to be joined.

9. Check dry fit of pipe and mark insertion depth on pipe.

NOTE: It is recommended that all pipes be cut, prepared, and
preassembled before permanently cementing any joint.

10. After pipes have been cut and preassembled, apply gener­ous layer of cement primer to pipe fitting socket and end of
pipe to insertion mark. Quickly apply approved cement to
end of pipe and fitting socket (over primer). Apply cement
in a light, uniform coat on inside of socket to prevent
buildup of excess cement. Apply second coat.

11. While cement is still wet, twist pipe into socket with 1/4
turn. Be sure pipe is fully inserted into fitting socket.

12. Wipe excess cement from joint. A continuous bead of
cement will be visible around perimeter of a properly made
joint.

13. Handle pipe joints carefully until cement sets.

14. Support vent piping a minimum of every 5 ft (3 ft for
SDR-21 or -26 PVC) using perforated metal hanging strap.

15. Slope vent pipe downward toward furnace a minimum of
1/4 in. per linear ft with no sags between hangers.

TERMINAL

J2 JUMPER

24-V THERMOST AT

TERMINALS

3-AMP FUSE

LED OPERATION &

DIAGNOSTIC LIGHT

115-VAC(L2)NEUTRAL

CONNECTIONS

COOL

HEAT

BLOWER SPEED

SELECTION TERMINALS

G Com W Y R

24V

STATUS CODE LED

NUETRAL

BLW

COOL HEAT

SPARE-1

SPARE-2

BLOWER OFF-DELAY

J2

TEST/TWIN

0.5 AMP@24VAC

FUSE 3-AMP

SEC-2 SEC-1

EAC-2 L2

SPARE-1 SPARE-2

90 150

120 180

PLT

HUM

PLT 1

1-AMP@

EAC-1

115VAC

EAC-1 TERMINAL

(115-VAC 1.0 AMP MAX.)

L1

PR-1

PL2 1

115 VAC (L1) LINE

VOLTAGE CONNECTION

HUMIDIFIER TERMINAL

(24-VAC 0.5 AMP MAX.)

TRANSFORMER 24-VAC

CONNECTIONS

PL1-LOW VOLTA GE MAIN
HARNESS CONNECTOR

PL2-HOT SURFACE

IGNITER & INDUCER

MOTOR CONNECTOR

Fig. 33—Control Center

—30—

A02100

16. Use appropriate methods to seal openings where vent pipe
passes through roof or sidewall.

NOTE: Select 1 vent pipe connection and

Select 1 vent pipe connection and
1 combustion-air pipe connection.

AIR

COMBUSTION­AIR

VENT

AIR

FLOW

HORIZONTAL-LEFT DISCHARGE HORIZONTAL-RIGHT DISCHARGE

FLOW

COMBUSTION-

UPFLOW DOWNFLOW

COMBUSTION-

AIR

VENT

VENT

AIR

NOTE:

1 combustion-air pipe connection.

VENT

COMBUSTION-

COMBUSTION-

AIR

AIR

AIR

FLOW

VENT

VENT

COMBUSTION-

AIR

AIR

FLOW

A96188

CAUTION: Make sure there is adequate clearance (3-in.
minimum) to any fixed or loose objects in order to ensure
an adequate combustion-air supply. Failure to follow this
caution will result in intermittent unit operation or per­formance satisfaction.

Fig. 34—Combustion-Air and Vent Pipe Connections

FIELD-SUPPLIED
2-IN. DIAMETER
PVC 90° ELBOW

FIELD-SUPPLIED
2-IN. DIAMETER
PVC PIPE

3/8

3/16

DRILL

TRAP

HOUSING

″ ID TUBE

″

TO OPEN

DRAIN

PLUG

MIN

4″

COMBUSTION–AIR
INTAKE HOUSING

BURNER
BOX

COMBUSTION–
AIR PIPE

A96190

Fig. 36—Air Intake Housing Plug Fitting Drain

D. Extended Exposed Sidewall Pipes

Sidewall vent pipe termination may be extended beyond area
shown in Fig. 40 and in outside ambient by insulating pipe as
indicated in Table 7.

1. Determine vent pipe diameter, as stated above, using total
pipe length and number of elbows.

2. Find appropriate temperature for your application and
furnace model using winter design temperature (used in
load calculations).

3. Determine required insulation thickness for exposed pipe
lengths.

NOTE: Pipe length (ft) specified for maximum pipe lengths
located in unconditioned spaces cannot exceed total allowable pipe
length as specified in Table 6.

E. Vent Termination

Vent pipe must terminate either through roof or sidewall. See
Table 8 for required clearances. See Fig. 39, 40, and 41 for exterior
piping arrangements.

F. Multiventing

When 2 or more 345MAV Furnaces are vented near each other,
each furnace must be individually vented. NEVER common vent
or breach vent 345MAV furnaces.

VII. CONDENSATE DRAIN
A. General

Condensate trap is shipped installed in the blower shelf and factory
connected for UPFLOW applications. Condensate trap must be
RELOCATED for use in DOWNFLOW and HORIZONTAL
applications.

A

COMBUSTION-AIR DISC
(FACTORY-SUPPLIED IN
LOOSE PARTS BAG)

LENGTH OF STRAIGHT PIPE PORTION OF

COMBUSTION-AIR INLET PIPE ASSEMBLY (IN.)

CASING WIDTH A

17-1/2 8-1/2 ± 1/2

21 10-1/2 ± 1/2

24-1/2 12 ± 1/2

Fig. 35—Combustion-Air Inlet Pipe Assembly

A96211

FURNACE

NOT IN
HORIZONTAL
SECTION

PIPE DIAMETER

TRANSITION IN

VERTICAL SECTION

A93034

Fig. 37—Vent Pipe Diameter Transition Location and

Elbow Configuration

—31—

12″ MIN

12″ MIN

VENT PIPE

HORIZONTAL TO ROOF HORIZONTAL TO SIDEWALL

12″ MIN

NOTE: A 12-In. minimum offset pipe section is recommended with

short (5 to 8 ft) vent systems. This recommendation is to reduce
excessive condensate droplets from exiting the vent pipe.

Fig. 38—Short Vent (5 to 8 Ft) System

Condensate trap MUST be used for all applications.
An external trap is not required when connecting the field drain to

this condensate trap.
The field drain connection (condensate trap or drain tube coupling)

is sized for 1/2-in. CPVC, 1/2-in. PVC, or 5/8-in. ID tube
connection.

Drain pipe and fittings must conform to ANSI standards and
ASTM D1785, D2466 or D2846. CPVC or PVC cement must
conform to ASTM D2564 or F493. Primer must conform to ASTM
F656. In Canada, use CSA or ULC listed schedule 40 CPVC or
PVC drain pipe, fittings, and cement.
When a condensate pump is required, select a pump which is
approved for condensing furnace applications. To avoid conden­sate spillage, select a pump with an overflow switch.

VENT PIPE

VENT PIPE

12″ MIN

VENT PIPE

VERTICAL TO SIDEWALLVERTICAL TO ROOF

A96189

CAUTION: Unit must not be installed, operated, and
then turned off and left in an unconditioned structure
during cold weather when temperature drops to 32
degrees F and below unless drain trap and drain line have
adequate freeze protection. See Service and Maintenance
Instructions for winterizing procedures. (See Fig. 15.)
Failure to follow this caution will result in intermittent
unit operation.

OVERHANG OR ROOF

MAINTAIN 12-IN. MINIMUM

CLEARANCE ABOVE HIGHEST

ANTICIPATED SNOW LEVEL.

MAXIMUM OF 24 IN. ABOVE ROOF.

Fig. 39—Roof Termination (Preferred)

VENT

ROOF

A96191

—32—

12″ MINIMUM

VENT

90°

MAINTAIN 12-IN.
CLEARANCE
ABOVE HIGHEST
ANTICIPATED SNOW
LEVEL OR GRADE,
WHICHEVER IS
GREATER.

Fig. 40—Sidewall Termination with 2 Elbows (Preferred)

A96192

Furnace condensate is mildly acidic, typically in the pH range of

3.2 to 4.5. Due to corrosive nature of unneutralized condensate, a
condensate pH neutralizing filter may be desired. Check with local
authorities to determine if a pH neutralizer is required.

B. Application

The furnace, A/C, and humidifier drains may be combined and
drained together. The A/C drain must have an external, field­supplied trap prior to the furnace drain connection. All drain
connections (furnace, A/C, or humidifier) must be terminated into
an open or vented drain as close to the respective equipment as
possible to prevent siphoning of the equipment’s drain.

See Fig. 42 for example of possible field drain attachment using
1/2-in. CPVC or PVC tee for vent and A/C or humidifier drain
connection.

Outdoor draining of the furnace is permissible if allowed by local
codes. Caution should be taken when freezing ambient may freeze
drain pipe and prohibit draining.

WARNING: Caution should be taken to prevent drain­ing where slippery conditions may cause personal inju­ries. Excessive condensate draining may cause saturated
soil conditions which may result in damage to plants.

C. Condensate Drain Protection

Freezing condensate left in condensate trap and drain line may
cause cracks, and possible water damage may occur. If freeze
protection is required, use condensate freeze protection accessory
or equivalent 3 to 6 watt per ft at 120v and 40°F self-regulating,
shielded, and waterproof heat tape. See Installation Instructions
supplied with accessory or heat tape manufacturer’s recommenda­tions.

1. Fold heat tape in half and wrap on itself 3 times.

2. Locate heat tape between sides of condensate trap back.
(See Fig. 43.)

3. Use wire ties to secure heat tape in place. Wire ties can be
positioned in notches of condensate trap sides. (See Fig.

43.)

4. Wrap field drain pipe with remaining heat tape, approxi­mately 1 wrap per ft.

5. When using field-supplied heat tape, follow heat tape
manufacturer’s instructions for all other installation guide­lines.

OVERHANG OR ROOF

START-UP, ADJUSTMENTS AND SAFETY CHECK

I. GENERAL

1. Furnace must have a 115-v power supply properly con­nected and grounded. Proper polarity must be maintained
for correct operation.

NOTE: Proper polarity must be maintained for 115-v wiring. If
polarity is incorrect, control center fault indicator light will flash
rapidly and furnace will not operate.

2. Thermostat wire connections at terminals R, W, G, and Y
must be made at 24-v terminal block on furnace control
center.

3. Natural gas service pressure must not exceed 0.5 psig
(14-in. wc), but must be no less than 0.16 psig (4.5-in. wc).

4. Blower access panel must be in place to complete 115-v
electrical circuit to furnace.

OPEN STAND

PIPE FOR

A/C OR

HUMIDIFIER

DRAIN

TEE

TO OPEN
DRAIN

A94054

Fig. 42—Example of Field Drain Attachment

12″ MINIMUM

VENT

6-IN. MINIMUM
CLEARANCE BETWEEN
WALL AND END OF VENT
PIPE.
10-IN. MAXIMUM PIPE LENGTH

MAINTAIN 12-IN.
CLEARANCE
ABOVE HIGHEST
ANTICIPATED SNOW
LEVEL OR GRADE,
WHICHEVER IS
GREATER.

Fig. 41—Sidewall Termination with Straight Pipe

A96210

—33—

CONDENSATE TRAP

WIRE TIE(S)

(3 WRAPS MINIMUM)

HEAT TAPE

Fig. 43—Condensate Trap Heat Tape

A93036

CAUTION: These furnaces are equipped with a manual
reset limit switch in burner box. This switch will open
and shut off power to gas valve if an overheat condition
(flame rollout) occurs in burner enclosure. Correct inad­equate combustion-air supply or improper venting condi­tion and reset switch. DO NOT jumper this switch.
Failure to follow this caution will result in minor unit
operation or performance satisfaction.

Before operating furnace, check flame rollout manual reset switch
for continuity. If necessary, press button to reset switch.

II. PRIME CONDENSATE TRAP WITH WATER

CAUTION: Condensate trap must be PRIMED or

proper draining may not occur. The condensate trap has 2
internal chambers which can ONLY be primed by pour­ing water into the inducer drain side of condensate trap.
Failure to follow this caution will result in minor unit
operation or performance satisfaction.

1. Remove upper inducer housing drain connection cap. (See
Fig. 44.)

2. Connect field-supplied 1/2-in. ID tube to upper inducer
housing drain connection.

3. Insert field-supplied funnel into tube.

4. Pour 1 quart of water into funnel/tube. Water should run
through inducer housing, overfill condensate trap, and flow
into open field drain. (See Fig. 45.)

5. Remove funnel and tube from inducer housing and replace
drain connection cap and clamp.

III. PURGE GAS LINES

A99118

Fig. 44—Inducer Housing Drain Cap

WARNING: Never purge a gas line into a combustion

chamber. Never test for gas leaks with an open flame. Use
a commercially available soap solution made specifically
for the detection of leaks to check all connections. Failure
to follow this warning could result in fire, explosion,
personal injury, or death.

IV. SEQUENCE OF OPERATION

If not previously done, purge lines after all connections have been
made and check for leaks.
Using the schematic diagram in Fig. 32, follow the sequence of
operation through the different modes. Read and follow the wiring
diagram very carefully.

CAUTION: Furnace control must be grounded for
proper operation, or control will lock out. Control is
grounded throug green/yellow wire connected to gas
valve and burner box screw. Failure to follow this caution
will result in intermittent unit operation.

NOTE: If a power interruption occurs during a call for heat (W),
the control will start a 90-second blower-only ON period two
seconds after power is restored, if the thermostat is still calling for
gas heating. The red LED light will flash code 12 during the
90-second period, after which the LED will be ON continuous, as
long as no faults are detected. After the 90-second period, the
furnace will respond to the thermostat normally.
The blower door must be installed for power to be conducted
through the blower door interlock switch ILK to the furnace
control CPU, transformer TRAN, inducer motor IDM, blower
motor BLWM, hot-surface igniter HSI, and gas valve GV.

A99119

Fig. 45—Filling Condensate Trap

1. Heating

(See Fig. 30 for thermostat connections.)
The wall thermostat ″calls for heat″, closing the R to W

circuit. The furnace control performs a self-check, verifies
the pressure switch contacts PRS are open, and starts the
inducer motor IDM.

—34—

a. Inducer Prepurge Period- As the inducer motor IDM

comes up to speed, the pressure switch contacts PRS
close, 24 vac power is supplied for a field installed
humidifier at the HUM terminal and the control begins a
15-second prepurge period.

b. Igniter Warm-Up- At the end of the prepurge period,

the Hot-Surface Igniter HSI is energized for a 17-second
igniter warm-up period.

c. Trial-for-Ignition Sequence- When the igniter

warm-up period is completed, the main gas valve relay
contacts GVR close to energize the gas valve GV, the
gas valve opens. The gas valve GV permits gas flow to
the burners where it is ignited by the Hot Surface Igniter
HSI. Five seconds after the GVR closes, a 2-second
flame period begins. The HSI igniter will remain ener­gized until the flame is sensed or until the 2-second
flame proving period begins.

d. Flame-Proving- When the burner flame is proved at the

flame-proving sensor electrode FSE, the furnace control
CPU begins the blower-ON delay period and continues
to hold the gas valve GV open. If the burner flame is not
proved within two seconds, the control CPU will close
the gas valve GV, and the control CPU will repeat the
ignition sequence for up to three more Trials-For­Ignition before going to Ignition-Lockout. Lockout will
be reset automatically after three hours, by momentarily
interrupting 115 vac power to the furnace, or by inter­rupting 24 vac power at SEC1 or SEC2 to the furnace
control CPU (not at W, G, R, etc.)

If flame is proved when flame should not be present, the
furnace control CPU will lock out of Gas-Heating mode
and operate the inducer motor IDM until flame is no
longer proved.

e. Blower-On Delay- If the burner flame is proven, the

blower motor is energized on HEAT speed 66 seconds
after the gas valve GV is energized.
Simultaneously, the electronic air cleaner terminal
EAC-1 is energized and remains energized as long as the
blower motor BLWM is energized.

f. Blower-Off Delay- When the thermostat is satisfied, the

R-to-W circuit is opened, de-energizing the gas valve
GV, stopping gas flow to the burners, and de-energizing
the humidifier terminal HUM. The inducer motor IDM
will remain energized for a 15-second post-purge period.
The blower motor BLWM and air cleaner terminal
EAC-1 will remain energized for 90, 120, 150, or 180
seconds (depending on the blower-OFF delay selection).
The furnace control CPU is factory-set for a 120-second
blower-OFF delay.

2. Cooling Mode

(See Fig. 30 for thermostat connections)
The thermostat closes the R-to-G-and-Y circuits. The

R-to-Y circuit starts the outdoor unit, and the R-to-G-and-Y
circuits start the furnace blower motor BLWM on COOL
speed.
The electronic air cleaner terminal EAC-1 is energized with
115 vac when the blower motor BLWM is operating.
When the thermostat is satisfied, the R-to-G-and-Y circuits
are opened. The outdoor unit will stop, and the furnace
blower motor BLWM will continue operating on the COOL
speed for an additional 90 seconds. Cut jumper J2 to reduce
the cooling off-delay to 5 seconds. (See Fig. 33.)

3. Continuous Blower Mode

When the R-to-G circuit is closed by the thermostat, the
blower motor BLWM will operate on continuous-blower
speed (same as HEAT speed). Terminal EAC-1 is energized
as long as the blower motor BLWM is energized.
During a call for heat, the blower BLWM will stop during
igniter warm-up (17 seconds), ignition (7 seconds), and
blower-ON delay (66 seconds), allowing the furnace heat
exchangers to heat up more quickly, then restarts at the end
of the blower-ON delay period at HEAT speed.
In heating, the furnace control CPU will continue running
the blower motor BLWM at HEAT speed after the selected
blower-OFF delay period is completed.
When the thermostat ″calls for cooling″, the blower motor
BLWM will operate at COOL speed. When the thermostat
is satisfied, the blower motor BLWM will operate an
additional 90 seconds on COOL speed before reverting
back HEAT speed. Jumper J2 can be cut to reduce the
cooling off-delay to 5 seconds. (See Fig. 31.)
When the R-to-G circuit is opened, the blower motor
BLWM will continue operating for an additional 5 seconds,
if no other function requires blower motor BLWM opera­tion.

4. Heat Pump

When installed with a heat pump, the furnace control
automatically changes the timing sequence to avoid long
blower off times during demand defrost cycles. When the
R-to-W-and-Y or R-to-W-and-Y-and-G circuits are ener­gized the furnace control CPU will continue to turn on the
blower motor BLWM at HEAT speed, and begin a heating
cycle. The blower motor BLWM will remain on until the
end of the prepurge period, then shut off for 24 seconds then
come back on at HEAT speed. When the W input signal
disappears, the furnace control begins a normal inducer
post-purge period and the blower switches to COOL speed
after a 3 second delay. If the R-to-W-and-Y-and-G signals
disappear at the same time, the blower motor BLWM will
remain on for the selected blower-OFF delay period. If the
R-to-W-and-Y signals disappear, leaving the G signal, the
blower motor BLWM will continue running the blower
motor BLWM at HEAT speed after the selected blower­OFF delay period is completed.

A. Component Test
NOTE: The furnace control component test allows all compo-

nents to run for a short time; except the gas valve and humidifier
terminal HUM are not energized for safety reason. The EAC-1
terminal is energized when the blower is energized. This feature
helps diagnose a system problem in case of a component failure.
The component test feature will not operate if any thermostat
signal is present and the control and not until all time delays are
completed.

NOTE: Record the status code BEFORE opening the blower
access door and before shutting off power to the furnace. Opening
the blower access door will open the blower door switch and shut
off power within the furnace. When power to the furnace is shut
off by either method, the status code will be lost because the code
is not stored while power is removed for any reason.

To Begin Component Self-Test:

WARNING: Blower access panel door switch opens
115-v power to control center. No component operation
can occur. Caution must be taken when manually closing
this switch for service purposes. Failure to follow this
warning could result in electrical shock, personal injury,
or death.

—35—

1. Remove blower access door.

2. Disconnect the thermostat R lead from furnace control.

3. Manually close blower door switch.

4. For approximately 2 sec, short (jumper) the C

OM-24v

terminal on control to the TEST/TWIN 3/16-inch quick­connect terminal on control until the LED goes out.
Remover jumper from terminals. (See Fig. 33.)

NOTE: If TEST/TWIN and C

OM-24v terminals are jumpered

longer than 2 sec, LED will flash rapidly and ignore component
test status code retrieval request.

Component test sequence is as follows:

a. LED will display previous status code 4 times.
b. Inducer motor starts and continues to run until Step g of

component test sequence.

c. After 7 seconds the hot surface igniter is energized for 15

sec., then off.

d. Blower motor operates on Continuous-FAN speed for 10

sec.
e. Blower motor operates on HEAT speed for 10 sec.
f. Blower motor operates on COOL speed for 10 sec.
g. Inducer motor stops.

5. Reconnect R lead to furnace control, remove tape from
blower door switch, and re-install blower door.

6. Operate furnace per instruction on outer door.

EXAMPLE: (0—2000 altitude)
Heating value = 1050 Btu/cu ft
Specific gravity = 0.62
Therefore: Orifice No. 45

Manifold pressure 3.6-in. wc
* Furnace is shipped with No. 45 orifices. In this example
all main burner orifices are the correct size and do not need
to be changed to obtain the proper input rate.

Check and verify burner orifice size in furnace. NEVER ASSUME
ORIFICE SIZE; ALWAYS CHECK AND VERIFY.

2. Adjust manifold pressure to obtain input rate.

NOTE: Manifold pressure must always be measured with burner
enclosure front REMOVED. Gas meter must always be clocked
with burner enclosure front INSTALLED.

a. Remove burner enclosure front.
b. Remove cap that conceals adjustment screw for gas

valve regulator. (See Fig. 46.)

c. Jumper R and W thermostat connections on control to

start furnace operation.

d. Turn adjusting screw, counterclockwise (out) to decrease

manifold pressure or clockwise (in) to increase manifold
pressure.

NOTE: This furnace has been approved for a manifold pressure
of 3.2 in. wc to 3.8 in. wc when installed at altitudes up to 2000 ft.
For altitudes above 2000 ft, the manifold pressure can be adjusted
from 2.0 in. wc to 3.8 in. wc. If manifold pressure is outside this
range, change burner orifices to obtain pressure in this range.

7. Verify furnace shut down by lowering thermostat setting
below room temperature.

8. Verify that furnace restarts by raising thermostat setting
above room temperature.

V. ADJUSTMENTS
A. Set Gas Input Rate

Furnace gas input rate on rating plate is for installations at altitudes
up to 2000 ft. Furnace input rate must be within ±2 percent of input
on furnace rating plate.

1. Determine natural gas orifice size and manifold pressure for
correct input.

a. Obtain average gas heat value (at installed altitude) from

local gas supplier.

b. Obtain average gas specific gravity from local gas

supplier.

c. Verify furnace model. Table 9 can only be used for

model 345MAV furnaces with heating size of 120.

d. Find installation altitude in Table 9.

NOTE: For Canada altitudes of 2000 to 4500 ft, use U.S.A.
altitudes of 5001 to 6000 ft in Table 9.

e. Find closest natural gas heat value and specific gravity

on Table 9.

f. Follow heat value and specific gravity lines to point of

intersection to find orifice size and manifold pressure
settings for proper operation.

CAUTION: DO NOT bottom out gas valve regulator
adjusting screw. This can result in unregulated manifold
pressure and result in excess overfire and heat exchanger
failures.

NOTE: If orifice hole appears damaged or it is suspected to have
been redrilled, check orifice hole with a numbered drill bit of
correct size. Never redrill an orifice. A burr-free and squarely
aligned orifice hole is essential for proper flame characteristics.

e. Replace gas valve regulator adjustment screw cap.
f. Replace burner enclosure front and verify adjusted gas

input rate using method outlined in item 3.

g. Look through sight glass in burner enclosure and check

burner flame. Burner flame should be clear blue, almost
transparent. (See Fig. 48.)

h. Remove jumper from R and W.

3. Verify natural gas input rate by clocking gas meter.

NOTE: Be sure all pressure tubing, combustion-air and vent
pipes, and burner enclosure front are in place when checking input
by clocking gas meter.

a. Calculate high-altitude adjustment

UNITED STATES
At altitudes above 2000 ft, this furnace has been ap­proved for a 2% derate for each 1000 ft above sea level.
See Table 11 for derate multiplier factor.

EXAMPLE: 100,000 BTUH INPUT FURNACE INSTALLED AT

4300 FT.

Furnace Input Rate

at Sea Level

100,000 X 0.91 = 91,000

X

Derate

Multiplier

Factor

Furnace Input Rate

=

at Installation

Altitude

—36—

TABLE 9—MODEL 345MAV ORIFICE SIZE AND MANIFOLD PRESSURE FOR CORRECT INPUT

(TABULATED DATA BASED ON 20,000 BTUH PER BURNER, DERATED 2% FOR EACH 1000 FT ABOVE SEA LEVEL) *

ALTITUDE

RANGE

(FT)

0 925 44 3.5 44 3.7 44 3.8 43 3.4 43 3.5

to 975 44 3.2 44 3.3 44 3.4 44 3.5 44 3.6

2000 1025 45 3.5 45 3.6 45 3.7 44 3.2 44 3.3

U.S.A. and Canada

0% 1075 45 3.2 45 3.3 45 3.4 45 3.5 45 3.6

derate 1100 47 3.6 47 3.7 45 3.2 45 3.4 45 3.5

ALTITUDE

RANGE

(FT)

U.S.A. 775 43 3.8 42 3.2 42 3.3 42 3.4 42 3.5

Altitudes 800 43 3.5 43 3.7 43 3.8 42 3.2 42 3.3

2001 to 825 44 3.8 43 3.4 43 3.6 43 3.7 43 3.8

3000 850 44 3.6 44 3.7 44 3.8 43 3.5 43 3.6

or 875 44 3.4 44 3.5 44 3.6 44 3.7 43 3.4

Canada 900 44 3.2 44 3.3 44 3.4 44 3.5 44 3.6

Altitudes 925 45 3.7 45 3.8 44 3.2 44 3.3 44 3.4

2001 to 950 45 3.5 45 3.6 45 3.7 45 3.8 44 3.3

U.S.A. and Canada

4000 975 45 3.3 45 3.4 45 3.5 45 3.6 45 3.8

5% 1000 45 3.1 45 3.2 45 3.4 45 3.5 45 3.6

derate 1025 45 3.0 45 3.1 45 3.2 45 3.3 45 3.4

ALTITUDE

RANGE

(FT)

3001 825 44 3.5 44 3.6 44 3.8 43 3.4 43 3.5

to 875 45 3.8 44 3.2 44 3.3 44 3.5 44 3.6

U.S.A. Only

4000 925 45 3.4 45 3.5 45 3.6 45 3.7 44 3.2

7% 975 45 3.0 45 3.2 45 3.3 45 3.4 45 3.5

derate 1000 45 2.9 45 3.0 45 3.1 45 3.2 45 3.3

* Orifice numbers 45 are factory installed.
Percents of derate are based on midpoints of U.S. altitude ranges.

AVG GAS
HEAT VALUE
AT ALTITUDE

(BTU/CU FT)

850 43 3.7 43 3.8 42 3.2 42 3.3 42 3.4
875 43 3.5 43 3.6 43 3.7 43 3.8 42 3.2
900 44 3.7 43 3.4 43 3.5 43 3.6 43 3.7

950 44 3.4 44 3.5 44 3.6 44 3.7 44 3.8

1000 45 3.7 45 3.8 44 3.2 44 3.4 44 3.5

1050 45 3.3 45 3.4 45 3.6 45 3.7 45 3.8

AVG GAS
HEAT VALUE
AT ALTITUDE

(BTU/CU FT)

AVG GAS
HEAT VALUE
AT ALTITUDE

(BTU/CU FT)

750 43 3.7 43 3.8 42 3.3 42 3.4 42 3.5
775 43 3.5 43 3.6 43 3.7 43 3.8 42 3.2
800 44 3.7 43 3.4 43 3.5 43 3.6 43 3.7

850 44 3.3 44 3.4 44 3.5 44 3.7 44 3.8

900 45 3.6 45 3.7 45 3.8 44 3.3 44 3.4

950 45 3.2 45 3.3 45 3.4 45 3.5 45 3.7

0.58 0.60 0.62 0.64 0.66

Orifice

No.

Orifice

No.

Orifice

No.

Manifold

Pressure

0.58 0.60 0.62 0.64 0.66

Manifold

Pressure

0.58 0.60 0.62 0.64 0.66

Manifold

Pressure

Orifice

No.

Orifice

No.

Orifice

No.

SPECIFIC GRAVITY OF NATURAL GAS

Manifold

Pressure

SPECIFIC GRAVITY OF NATURAL GAS

Manifold

Pressure

SPECIFIC GRAVITY OF NATURAL GAS

Manifold

Pressure

Orifice

No.

Orifice

No.

Orifice

No.

Manifold

Pressure

Manifold

Pressure

Manifold

Pressure

Orifice

No.

Orifice

No.

Orifice

No.

Manifold

Pressure

Manifold

Pressure

Manifold

Pressure

Orifice

No.

Orifice

No.

Orifice

No.

Manifold

Pressure

Manifold

Pressure

Manifold

Pressure

—37—

TABLE 9—MODEL 345MAV ORIFICE SIZE AND MANIFOLD PRESSURE FOR CORRECT INPUT Continued

(TABULATED DATA BASED ON 20,000 BTUH PER BURNER, DERATED 2% FOR EACH 1000 FT ABOVE SEA LEVEL) *

ALTITUDE

RANGE

(FT)

4001 800 44 3.5 44 3.6 44 3.7 44 3.8 43 3.4

to 850 45 3.7 45 3.8 44 3.3 44 3.4 44 3.5

U.S.A. Only

5000 900 45 3.3 45 3.4 45 3.5 45 3.6 45 3.8

9% 925 45 3.1 45 3.2 45 3.3 45 3.4 45 3.6

derate 950 45 3.0 45 3.1 45 3.2 45 3.3 45 3.4

ALTITUDE

RANGE

(FT)

5001 800 44 3.2 44 3.3 44 3.4 44 3.5 44 3.6

to 850 45 3.4 45 3.5 45 3.6 45 3.8 44 3.2

U.S.A. Only

6000 900 45 3.0 45 3.1 45 3.3 45 3.4 45 3.5

11% 950 45 2.7 45 2.8 45 2.9 45 3.0 45 3.1

derate 975 45 2.6 45 2.7 45 2.8 45 2.9 45 2.9

ALTITUDE

RANGE

(FT)

6001 725 44 3.6 44 3.7 44 3.8 43 3.4 43 3.5

to 775 45 3.8 44 3.2 44 3.3 44 3.4 44 3.5

U.S.A. Only

7000 825 45 3.3 45 3.4 45 3.6 45 3.7 45 3.8

13% 850 45 3.1 45 3.2 45 3.4 45 3.5 45 3.6

derate 875 45 3.0 45 3.1 45 3.2 45 3.3 45 3.4

* Orifice numbers 45 are factory installed.
Percents of derate are based on midpoints of U.S. altitude ranges.

AVG GAS
HEAT VALUE
AT ALTITUDE

(BTU/CU FT)

725 43 3.7 43 3.8 42 3.2 42 3.3 42 3.4
750 43 3.4 43 3.5 43 3.7 43 3.8 42 3.2
775 44 3.7 44 3.8 43 3.4 43 3.5 43 3.7

825 44 3.2 44 3.4 44 3.5 44 3.6 44 3.7

875 45 3.5 45 3.6 45 3.7 44 3.2 44 3.3

AVG GAS
HEAT VALUE
AT ALTITUDE

(BTU/CU FT)

700 43 3.6 43 3.7 42 3.2 42 3.3 42 3.4
725 43 3.4 43 3.5 43 3.6 43 3.7 43 3.8
750 44 3.6 44 3.7 43 3.4 43 3.5 43 3.6
775 44 3.4 44 3.5 44 3.6 44 3.7 43 3.4

825 45 3.6 45 3.7 44 3.2 44 3.3 44 3.4

875 45 3.2 45 3.3 45 3.4 45 3.6 45 3.7

925 45 2.9 45 3.0 45 3.1 45 3.2 45 3.3

1000 45 2.5 45 2.5 45 2.6 45 2.7 45 2.8

AVG GAS
HEAT VALUE
AT ALTITUDE

(BTU/CU FT)

650 42 3.2 42 3.3 42 3.4 42 3.5 42 3.6
675 43 3.6 43 3.7 43 3.8 42 3.2 42 3.3
700 44 3.8 43 3.4 43 3.6 43 3.7 43 3.8

750 44 3.3 44 3.4 44 3.6 44 3.7 44 3.8

800 45 3.5 45 3.7 45 3.8 44 3.2 44 3.3

0.58 0.60 0.62 0.64 0.66

Orifice

No.

Orifice

No.

Orifice

No.

Manifold

Pressure

0.58 0.60 0.62 0.64 0.66

Manifold

Pressure

0.58 0.60 0.62 0.64 0.66

Manifold

Pressure

Orifice

No.

Orifice

No.

Orifice

No.

SPECIFIC GRAVITY OF NATURAL GAS

Manifold

Pressure

SPECIFIC GRAVITY OF NATURAL GAS

Manifold

Pressure

SPECIFIC GRAVITY OF NATURAL GAS

Manifold

Pressure

Orifice

No.

Orifice

No.

Orifice

No.

Manifold

Pressure

Manifold

Pressure

Manifold

Pressure

Orifice

No.

Orifice

No.

Orifice

No.

Manifold

Pressure

Manifold

Pressure

Manifold

Pressure

Orifice

No.

Orifice

No.

Orifice

No.

Manifold

Pressure

Manifold

Pressure

Manifold

Pressure

—38—

TABLE 9—MODEL 345MAV ORIFICE SIZE AND MANIFOLD PRESSURE FOR CORRECT INPUT Continued

(TABULATED DATA BASED ON 20,000 BTUH PER BURNER, DERATED 2% FOR EACH 1000 FT ABOVE SEA LEVEL) *

ALTITUDE

RANGE

(FT)

7001 700 44 3.5 44 3.6 44 3.8 43 3.4 43 3.5

to 750 45 3.7 45 3.8 44 3.3 44 3.4 44 3.5

U.S.A. Only

8000 800 45 3.3 45 3.4 45 3.5 45 3.6 45 3.7

15% 825 45 3.1 45 3.2 45 3.3 45 3.4 45 3.5

derate 850 45 2.9 45 3.0 45 3.1 45 3.2 45 3.3

ALTITUDE

RANGE

(FT)

8001 650 44 3.7 43 3.4 43 3.5 43 3.6 43 3.7

to 700 44 3.2 44 3.3 44 3.4 44 3.6 44 3.7

U.S.A. Only

9000 750 45 3.4 45 3.5 45 3.6 45 3.8 44 3.2

17% 775 45 3.2 45 3.3 45 3.4 45 3.5 45 3.6

derate 800 45 3.0 45 3.1 45 3.2 45 3.3 45 3.4

ALTITUDE

RANGE

(FT)

9001 625 44 3.7 44 3.8 43 3.5 43 3.6 43 3.7

to 675 45 3.8 44 3.3 44 3.4 44 3.5 44 3.6

U.S.A. Only

10,000 725 45 3.3 45 3.4 45 3.6 45 3.7 45 3.8

19% 750 45 3.1 45 3.2 45 3.3 45 3.4 45 3.5

derate 775 45 2.9 45 3.0 45 3.1 45 3.2 45 3.3

* Orifice numbers 45 are factory installed.
Percents of derate are based on midpoints of U.S. altitude ranges.

AVG GAS
HEAT VALUE
AT ALTITUDE

(BTU/CU FT)

625 43 3.8 42 3.3 42 3.4 42 3.5 42 3.6
650 43 3.5 43 3.7 43 3.8 42 3.2 42 3.3
675 44 3.8 43 3.4 43 3.5 43 3.6 43 3.7

725 44 3.3 44 3.4 44 3.5 44 3.6 44 3.7

775 45 3.5 45 3.6 45 3.7 45 3.8 44 3.3

AVG GAS
HEAT VALUE
AT ALTITUDE

(BTU/CU FT)

600 43 3.8 42 3.3 42 3.4 42 3.5 42 3.6
625 43 3.5 43 3.6 43 3.8 42 3.2 42 3.3

675 44 3.5 44 3.6 44 3.7 44 3.8 43 3.4

725 45 3.6 45 3.8 44 3.2 44 3.3 44 3.4

AVG GAS
HEAT VALUE
AT ALTITUDE

(BTU/CU FT)

575 43 3.8 42 3.2 42 3.3 42 3.5 42 3.6
600 43 3.5 43 3.6 43 3.7 42 3.2 42 3.3

650 44 3.4 44 3.5 44 3.7 44 3.8 43 3.4

700 45 3.6 45 3.7 45 3.8 44 3.3 44 3.4

0.58 0.60 0.62 0.64 0.66

Orifice

No.

Orifice

No.

Orifice

No.

Manifold

Pressure

0.58 0.60 0.62 0.64 0.66

Manifold

Pressure

0.58 0.60 0.62 0.64 0.66

Manifold

Pressure

Orifice

No.

Orifice

No.

Orifice

No.

SPECIFIC GRAVITY OF NATURAL GAS

Manifold

Pressure

SPECIFIC GRAVITY OF NATURAL GAS

Manifold

Pressure

SPECIFIC GRAVITY OF NATURAL GAS

Manifold

Pressure

Orifice

No.

Orifice

No.

Orifice

No.

Manifold

Pressure

Manifold

Pressure

Manifold

Pressure

Orifice

No.

Orifice

No.

Orifice

No.

Manifold

Pressure

Manifold

Pressure

Manifold

Pressure

Orifice

No.

Orifice

No.

Orifice

No.

Manifold

Pressure

Manifold

Pressure

Manifold

Pressure

—39—

CANADA
At installation altitudes from 2000 to 4500 ft, this
furnace must be derated 5% by an authorized Gas
Conversion Station. To determine correct input rate for
altitude, see example above and use 0.95 as derate
multiplier factor.

b. Reinstall burner box cover.

NOTE: Burner box cover MUST be isntalled while clocking gas
input rate.

c. Gas valve regulator seal cap MUST be installed.
d. Turn off all other gas appliances and pilots.
e. Start furnace and let operate for 3 minutes.
f. Measure time (in sec) for gas meter test dial to complete

1 revolution.

g. Refer to Table 11 for cu ft of gas per hr.

REGULATOR
SEAL CAP

REGULATOR
ADJUSTMENT
SCREW

ON/OFF SWITCH

REGULATOR SPRING
(PROPANE - WHITE, 6 TURNS
NATURAL - SILVER, 10 TURNS)

GAS PRESSURE
REGULATOR

INLET
PRESSURE T AP

ADJUSTMENT

MANIFOLD
PRESSURE T AP

h. Multiply gas rate (cu ft/hr) X heating value (Btu/cu ft)

using natural gas heating value from local gas
utility/supplier.

EXAMPLE:
Btu heating input = Btu/cu ft X cu ft/hr Heating value of
gas = 975 Btu/cu ft
Time for 1 revolution of 2-cu ft dial = 70 sec
Gas rate = 103 cu ft/hr (from Table 11)
Btu heating input = 103 X 975 = 100,425 Btuh
In this example, the orifice size and manifold pressure
adjustment is within ±2 percent of the furnace input rate.

B. Set Temperature Rise

CAUTION: Temperature rise must be within limits

specified on unit rating plate. Recommended operation is
at midpoint of rise or slightly above. Failure to follow this
caution may result in primary and secondary heat ex­changers failure.

Determine and adjust air temperature rise as follows:

1. Place thermometers in return and supply ducts as close to
furnace as possible. Be sure thermometers do not see heat
exchanger so that radiant heat does not affect readings. This
practice is particularly important with straight-run ducts.

2. When thermometer readings stabilize, subtract return-air
temperature from supply-air temperature to determine air
temperature rise.

3. Adjust temperature rise by adjusting blower speed. Increase
blower speed to reduce temperature rise. Decrease blower
speed to increase temperature rise.

BURNER FLAME

BURNER

A03142

Fig. 46—Redundant Automatic Gas Valve

BURNER

ORIFICE

A93059

Fig. 47—Orifice Holes

CAUTION: DO NOT redrill orifices. Improper drilling

(burrs, out-of-round holes, etc.) can cause excessive
burner noise and misdirection of burner flames. This can
result in flame impingement of burners and heat exchang­ers causing failures.

MANIFOLD

A89020

Fig. 48—Burner Flame

TABLE 10—ALTITUDE DERATE MULTIPLIER FOR U.S.A.

ALTITUDE

(FT)

0—2000 0 1.00
2001—3000 4—6 0.95
3001—4000 6—8 0.93
4001—5000 8—10 0.91
5001—6000 10—12 0.89
6001—7000 12—14 0.87
7001—8000 14—16 0.85
8001—9000 16—18 0.83

9001—10,000 18—20 0.81

* Derate multiplier factor is based on midpoint altitude for altitude range.

%OF

DERATE

DERATE MULTIPLIER

FACTOR FOR U.S.A*

—40—

TABLE 11—GAS RATE (CU FT/HR)

SECONDS

FOR 1

REVOLUTION

10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49

SIZE OF TEST DIAL

1

cu ft2cu ft5cu ft

360

720

327

655

300

600

277

555

257

514

240

480

225

450

212

424

200

400

189

379

180

360

171

343

164

327

157

313

150

300

144

288

138

277

133

267

129

257

124

248

120

240

116

232

113

225

109

218

106

212

103

206

100

200

97

195

95

189

92

185

90

180

88

176

86

172

84

167

82

164

80

160

78

157

76

153

75

150

73

147

1800
1636
1500
1385
1286
1200
1125
1059
1000

947
900
857
818
783
750
720
692
667
643
621
600
581
563
545
529
514
500
486
474
462
450
439
429
419
409
400
391
383
375
367

SECONDS

FOR 1

REVOLUTION

50
51
52
53
54
55
56
57
58
59
60
62
64
66
68
70
72
74
76
78
80
82
84
86
88
90
92
94
96

98
100
102
104
106
108
110
112
116
120
124

SIZE OF TEST DIAL

1

cu ft2cu ft5cu ft

72

144

71

141

69

138

68

136

67

133

65

131

64

129

63

126

62

124

61

122

60

120

58

116

56

112

54

109

53

106

51

103

50

100

48

97

47

95

46

92

45

90

44

88

43

86

42

84

41

82

40

80

39

78

38

76

38

75

37

74

36

72

35

71

35

69

34

68

33

67

33

65

32

64

31

62

30

60

29

58

WARNING: Disconnect 115-v electrical power before
changing speed tap. Failure to follow this warning could
result in personal injury.

4. To change blower motor speed selections for heating mode,
remove blower motor lead from control center HEAT
terminal. (See Fig. 33.) Select desired blower motor speed
lead from 1 of the other motor leads and relocate it to HEAT
terminal. See Table 12 for lead color identification. Recon­nect original lead on SPARE terminal.

Follow this same procedure for proper selection of COOL
speed selection.

360
355
346
340
333
327
321
316
310
305
300
290
281
273
265
257
250
243
237
231
225
220
214
209
205
200
196
192
188
184
180
178
173
170
167
164
161
155
150
145

TABLE 13—BLOWER OFF DELAY SETUP POSITION

PINS 1 AND 2 2 AND 3 3 AND 4 4 AND 5

Time (in sec) 90 120 150 180

D. Set Thermostat Heat Anticipator

When using a nonelectronic thermostat, the thermostat heat
anticipator must be set to match amp draw of the electrical
components in R-W circuit. Accurate amp draw readings can be
obtained at thermostat subbase terminals R and W. Fig. 49
illustrates an easy method of obtaining actual amp draw. The amp
reading should be taken after blower motor has started and furnace
is heating. Connect ammeter wires as shown in Fig. 49. The
thermostat anticipator should NOT be in the circuit while measur­ing current. If thermostat has no subbase, the thermostat must be
disconnected from R and W wires during current measurement.
See thermostat manufacturer’s instructions for adjusting heat
anticipator and for varying heating cycle length.

For an electronic thermostat, set cycle rate for 3 cycles per hour.

VI. CHECK SAFETY CONTROLS

This section covers the safety controls that must be checked before
the installation is complete. The flame sensor, gas valve, and
pressure switch were all checked in the Start-up prodecure section
as part of normal operation.

A. Check Primary Limit Control

This control shuts off combustion control system and energizes
air-circulating blower motor if furnace overheats. Recommended
method of checking this limit control is to gradually block off
return air after furnace has been operating for a period of at least
5 minutes. As soon as limit control has shut off burners, return-air
opening should be unblocked to permit normal air circulation. By
using this method to check limit control, it can be established that
limit is functioning properly and operates if there is a restricted
return-air supply or motor failure. If limit control does not function
during this test, cause must be determined and corrected.

B. Check Pressure Switch

This control proves operation of draft inducer. Check switch
operation as follows:

1. Turn off 115-v power to furnace.

2. Remove main furnace door and disconnect inducer motor
lead wires from wire harness.

THERMOSTAT SUBBASE
TERMINALS WITH
THERMOSTAT REMOVED

HOOK-AROUND

VOLT/AMMETER

TABLE 12–SPEED SELECTOR

COLOR SPEED

Black High Cool

Yellow (When Present) Medium High Spare

Blue Medium Low Heat

Red Low Fan

White Common Com

FACTORY-

SHIPPED

CONNECTION

C. Blower Off Delay (Heat Mode)

The blower off delay has 4 adjustable settings from 90 sec to 180
sec. (See Table 13.) The blower off delay jumpers are located on
the furnace control board (See Fig. 33.) To change the blower off
delay setting, move the jumper from one set of pins on the control
board to the pins used for the desired blower off delay. Factory
blower off delay setting is 120 sec.

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EXAMPLE:

R Y W G

10 TURNS

FROM UNIT 24-VOLT
TERMINAL BLOCK

5.0 AMPS ON AMMETER
10 TURNS AROUND JAWS

= 0.5 AMPS FOR THERMOSTAT SETTING

Fig. 49—Amp Draw Check with Ammeter

A80201

3. Turn on 115-v power to furnace.

4. Set thermostat to "call for heat" and wait 1 minute. When
pressure switch is functioning properly, hot surface igniter
should NOT glow, and status code LED flashes a 31 fault.
If hot surface igniter glows when inducer motor is discon­nected, shut furnace down immediately. Determine reason
pressure switch did not function properly and correct
condition.

5. Turn off 115-v power to furnace.

6. Reconnect inducer motor leads, reinstall main furnace door,
and turn on 115-v power supply.

CHECKLIST

1. Put away tools and instruments. Clean up debris.

2. Verify manual flame rollout reset switch has continuity.

3. Verify that blower and main access doors are properly
installed.

4. Cycle test furnace with room thermostat.

5. Check operation of accessories per manufacturer’s instruc­tions.

6. Review User’s Guide with owner.

7. Leave literature packet near furnace.

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LOAD CALCULATION

CHECKLIST—INSTALLATION

Condensate Drain

____________ Heating Load (Btuh)

____________ Cooling Load (Btuh)

____________ Furnace Model Selection

VENT PIPING

Termination Location

________ Roof or Sidewall

________ Vent Pipe Length

________ Vent Pipe Elbow Quantity

________ Pipe Diameter Determined from Sizing Table

________ Pipe Sloped To Furnace

Pipe Insulation

________ Over Ceilings

________ Low-Ambient Exposed Pipes

________ Unit Level or Pitched Forward

________

________

________ Condensate Trap Primed before Start-Up

________ Heat Tape Installed if Required

________

________ Temperature Rise Adjusted

________ Anticipator Setting Adjusted or

________ Cycle Rate (3 Cycles per Hr) Selected

Internal Tubing Connections Free of Kinks
and Traps

External Drain Connection Leak Tight and
Sloped

CHECKLIST—START-UP

Gas Input Rate (Set Within 2 percent of
Rating Plate)

Thermostat Anticipator

Safety Controls Check Operation

________ Primary Limit

________ Pressure Switch

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© 2003 Bryant Heating & Cooling Systems 7310 W. Morris St. Indianapolis, IN 46231

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Printed in U.S.A. 345m408 Catalog No. 5334-520