Sterling RT User Manual

INSTALLATION AND SERVICE MANUAL

J30-05380

OUTDOOR ROOFTOP GAS-FIRED DUCT FURNACE

(NATURAL OR POWER VENTED)

ATTENTION: READ THIS MANUAL AND ALL LABELS ATTACHED TO THE UNIT CAREFULLY BEFORE
ATTEMPTING TO INSTALL, OPERATE OR SERVICE THESE UNITS! CHECK UNIT DATA PLATE FOR
TYPE OF GAS AND ELECTRICAL SPECIFICATIONS AND MAKE CERTAIN THAT THESE AGREE WITH
THOSE AT POINT OF INSTALLATION. RECORD THE UNIT MODEL AND SERIAL No.(s) IN THE SPACE
PROVIDED. RETAIN FOR FUTURE REFERENCE.

Unit No. Serial No.

SA VE THIS MANUAL

FOR Y OUR SAFETY
The use and storage of gasoline or other flammable vapors and liquids in open
containers in the vicinity of this appliance is hazardous.

FOR Y OUR SAFETY

If you smell gas:

1. Don’t touch electrical switches.

2. Extinguish any open fl ame.

3. Immediately call your gas supplier.

RISM-14

Improper installation, adjustment, alteration, service or maintenance
can cause property damage, injury or death. Read the installation, operating and
maintenance instructions thoroughly before installing or servicing this equipment.

Install, operate and maintain unit in accordance with manufacturer's
instructions to avoid exposure to fuel substances or substances from incomplete
combustion which can cause death or serious illness. The state of California
has determined that these substances may cause cancer, birth defects, or other
reproductive harm.

INSTALLER'S RESPONSIBILITY

Installer Please Note: This equipment has been test fired and inspected. It has been

shipped free from defects from our factor y. However, during shipment and installation,
problems such as loose wires, leaks or loose fasteners may occur. It is the installer's

responsibility to inspect and correct any problems that may be found.

These units are certifi ed by ETL for operation on either natural or propane gas.

Read this manual and all labels attached to the unit carefully before attempting to install, operate or

service the following unit models:*

Outdoor Rooftop Duct Furnaces: QV(RT/PV)- (100, 150, 200, 250, 300, 350, 400) (H)(M)

(RT = Natural Vent; PV = Power Vent)

*Look in the direction of the unit air fl ow to determine whether the unit is right or left-hand accessible.

04/13

260 NORTH ELM ST., WESTFIELD, MA 01085

TEL: [phone] FAX: [phone]

www.mestek.com

TABLE OF CONTENTS

RECEIVING/PRE-INSTALLATION

INSTRUCTIONS ......................................................2

GENERAL SAFETY INFORMATION ....................2, 3

SPECIFICATIONS

Dimensional Data ..........................................4, 5

Performance and Specifi cation Data .................5

Performance Data Curves .............................6, 7

INSTALLATION

Location/Mounting .....................................2, 3, 8

Clearances ................................................4, 5, 8

Venting ..............................................................9

Duct and Drain Specifi cations .........................10

Gas Connections .................................10, 11, 12

Electrical Connections .....................................12

OPERATION

General Information...................................13, 14

Intermittent Pilot Ignition Parts ........................13

Controls ...........................................................14

Gas Controls ...................................................15

Air Distribution/Throughput .............................16

Lighting ......................................................17, 18

Primary Air Shutter/Pilot Adjustment ...............18

Gas Input Adjustment ......................................18

START-UP ...............................................................19

MAINTENANCE ...............................................20, 21

TROUBLESHOOTING GUIDE ..........................22-25

REPLACEMENT PARTS ........................................26

WARRANTY ...........................................................26

GAS EQUIPMENT CHECK SHEET .......................28

The following terms are used throughout this manual to
bring attention to the presence of potential hazards or
to important information concerning the product:

on the tracks, and push up into the top lip; swing and
lower the panel in place until it engages with the bottom
panel. Turn the screwhead on each latch clockwise.
The screw must turn freely one quarter turn before
resistance is felt in order for the lock to engage. If the
latch does not hold, turn the screw counter-clockwise
several turns and repeat the above procedure. Also
refer to Figures 8a, 8b and 8c for more specifi cations.

RECEIVING INSTRUCTIONS

Inspect shipment immediately when received to
determine if any damage has occurred to the carton/
crate during shipment.

After the unit has been uncrated, check for any visible
damage to the unit. On power vented units, check
motor position and turn blower wheel by hand to
determine if damage has occurred to these critical
parts.

If any damage is found, the consignee should sign the
bill of lading indicating such damage and immediately
fi le claim for damage with the transportation company.

PRE-INSTALLATION INSTRUCTIONS

When unit is received and uncrated check data plate
on unit for type of gas and electrical specifi cations and
make certain that these agree with those at point of
installation.

Open all disconnect switches
and secure in that position before installing
the unit. Failure to do so may result in personal
injury or death from electrical shock.

Indicates an imminently hazard­ous situation which, if not avoided, will result
in death, serious injury or substantial property
damage.

Indicates an imminently hazard­ous situation which, if not avoided, could result
in death, serious injury or substantial property
damage.

Indicates an imminently hazardous
situation which, if not avoided, may result in minor
injury or property damage.

NOTICE: Used to notify of special instructions on
installation, operation or maintenance which are
important to equipment but not related to personal
injury hazards.

SERVICE ACCESS PANEL REMOVAL

To remove an access panel door, use the following
procedure: remove the two screws and two washers
from the louvered flue discharge area of the service
panel (power vent doors only). Each panel is held
in place with two “Grip” Latches. Using a slotted
head screw driver, tur n the latch screwhead counter
clockwise. Using the handle provided, pull the panel
upwards. Pull the bottom of the panel out and lower
the panel to disengage it from the top lip. To replace
an access door panel, guide the panel door upwards

NOTICE: It is the equipment owner’s responsibility
to provide any scaffolding or other apparatus
required to perform emergency service or annual/
periodic maintenance to this equipment.

RIGGING

Rig the unit using either belt or cable slings. Use spreader
bar to protect the top of the unit when it is lifted.

The furnace units are provided with two holes in the
base rail on each side of the unit. Slide pipes beneath the
unit through these holes and attach rigging to the pipes
for lifting the unit.

LOCATION

Before placing the rooftop unit in its permanent location,
make certain that the roof is capable of carrying the
additional load of this equipment. Check the shipping
weights given in Chart 2.

Refer to Figures 1, 2 and 6 and charts 1 and 2 for
adequate unit dimensions and required clearances.

MOUNTING

The units are mounted on skids and are suitable for use
on combustible fl ooring. It is recommended that the skids
be mounted either on level solid planking or steel
channels, but never on a soft tar roof where the skids
could sink and reduce the clearance between the bottom
panel and the roof.

– 2 –

A pilot burner plate is provided for access to the pilot
burner and ignition systems without removing the
burner drawer. Clearances between the external unit
and obstruction must be suffi cient for proper servicing
of pull-out drawer. See Figures 1 and 2 for this
clearance.

The outdoor units are certified for operation on either
natural or propane gas. If a unit is to be installed at an
altitude exceeding 2000 ft. (610 m) above sea level,
derate the input by 4% for each 1000 foot rise (305 m
rise) above sea level. Check all local codes.

Special orifices are required for installations above
2000 ft. (610 m). Check all local codes.

In Canada, if a unit is to be installed at altitudes of
2000 ft. (610 m) to 4500 ft. (1372 m), the unit must be
orifi ced to 90% of the normal altitude rating.

GENERAL SAFETY INFORMATION

Roofcurb kits for rooftop gas heating units are
shipped knocked down. A curb kit contains (insulated)
curb rails, hardware, sealant, self-adhering rubber
gasketing, and installation instructions. Roof insulation,
cant strips, flashing, roof felts, caulking and nails
must be furnished by the installer. See separate curb
specifi cations from manufacturer.

Failure to comply with the general
safety information may result in extensive
property damage, severe personal injury or
death!

This product must be installed by
a licensed plumber or gas fi tter when installed
within the Commonwealth of Massachusetts.

Do not alter the unit heater in
any way or damage to the unit and/or severe
personal injury or death may occur!

Never service any component
without fi rst disconnecting all electrical and gas
supplies to the unit or severe personal injury or
death may occur!

Ensure that all power sources
conform to the requirements of the unit heater or
damage to the unit will result!

Installation must be made in accordance with local
codes, or in absence of local codes, with the latest
edition of ANSI Standard Z223.1 (NFPA No. 54)
National Fuel Gas Code. All of the ANSI and NFPA
Standards referred to in these installation instructions
are those that were applicable at the time the design
of the appliance was certified. The ANSI Standards
are available from the American National Standards
Institute, Inc., 11 West 42nd Street, New York, NY,
10036 or www.ansi.org. The NFPA Standards are
available from the National Fire Protection Association,
Batterymarch Park, Quincy, MA 02269.

If installed in Canada, the installation must conform
with local building codes, or in absence of local building
codes, with current CSA-B149.1 “Installation Codes
for Natural Gas Burning Appliance and Equipment”
or CSA-B149.2 “Installation Codes for Propane Gas
Burning Appliances and Equipment”. These outdoor
duct furnaces have been designed for and certifi ed to
comply with CSA 2.8.

These units have been designed and certified for
outdoor use only, and may be located on the roof of
the building or at any convenient location external of
the building to be heated. The input range is 100,000
BTU/HR. (29.3 kW) to 400,000 BTU/HR. (117.1 kW) in
50,000 BTU/HR. (14.6 kW) increments.

The venting is an integral part of the unit and must not
be altered in the field. The Natural Vented units are
equipped with a vent cap which is designed for gravity
venting. Air for combustion enters at the base of the
vent through a protective grille, and the design of the
vent cap is such that the products of combustion are
discharged at the upper section of the cap. This cap
is shipped in a separate carton. It should be fastened
in position as shown in Figure 7 and should not be
altered in any way.

The Power Vented unit has a power venting system
with the inlet and discharge grille located in the upper
section of the side access panel. This balanced flue
design also preforms well under all wind conditions.

All internal parts of the standard unit are fabricated
from aluminized steel. Standard burners are pressed
aluminized steel and have a stainless steel bur ner
port protector and air shutters. All internal and external
jacket parts are fabricated from galvanized steel.
Stainless steel heat exchangers, burners and flue
collectors are optional. An optional 321 or 409 stainless
steel heat exchanger is highly recommended for the
following applications:

1) When the entering air temperature is below
40°F (4.4°C),

2) When the furnace is installed downstream of a
cooling coil section.

A pilot burner plate is provided for access to the pilot
burner and ignition systems without removing the
burner drawer. Clearances between the exter nal unit
and obstruction must be suffi cient for proper servicing
of pull-out drawer. See Figures 1 and 2 for this
clearance.

The outdoor units are certified for operation on either
natural or propane gas. If a unit is to be installed at an
altitude exceeding 2000 ft. (610 m) above sea level,
derate the input by 4% for each 1000 foot rise (305 m
rise) above sea level. Check all local codes.

Special orifices are required for installations above
2000 ft. (610 m). Check all local codes.

In Canada, if a unit is to be installed at altitudes of
2000 ft. (610 m) to 4500 ft. (1372 m), the unit must be
orifi ced to 90% of the normal altitude rating.

Unless otherwise specifi ed, the following conversions
may be used for calculating SI unit measurements:
1 inch = 25.4 mm
1 foot = 0.305 m
1 gallon = 3.785 L
1 pound = 0.454 kg
1 psig = 6.894 kPa
1 cubic foot = 0.028 m

1000 Btu/Cu. Ft. = 37.5 MJ/m
1000 Btu per hour = 0.293 kW
1 inch water column = 0.249 kPa
liter/second = CFM x 0.472
meter/second = FPM ÷ 196.8

3

3

– 3 –

SPECIFICATIONS

DFR3541A
TFR3779 A

4" (102)

1" (25)

Typ.

5-1/16"

(129)

Electrical
Connections

5/8" (16) Typ.
Anchor Hole
Location

A

10-1/8"

(257)

B

Opening Typ.

13/16" (21) Typ.
Anchor Hole
Location

Gas
Connection

8-3/4"

(222)

*

F

26"

(660)

31-1/4"

(794)

C

L

39"

(991)

19"

(483)

Opening

K

1-1/8" (29)

Typ. Duct

Flange

Flue
Product
Outlet

Combustion
Air Inlet

DFR3538A
TFR3779A

4" (102)

1" (25)

Typ.

5-1/16"

(129)

Electrical
Connections

5/8" (16) Typ.
Anchor Hole
Location

Vent Cap
Is Shipped
In Separate
Carton

A

C (Typ.)

10-1/8"

(257)

B

Opening Typ.

13/16" (21) Typ.
Anchor Hole
Location

Gas
Connection

8-3/4"

(222)

*

F

26"

(660)

31-1/4"

(794)

C

L

D

39"

(991)

19"

(483)

Opening

K

1-1/8" (29)

Typ. Duct

Flange

Figure 1 - Standard Natural Vented Outdoor Duct Furnace

Chart 1 - Dimensional/Data

CAPACITY US CANADA GAS INLET
(CA) A B C D D *F K NAT LP

10 32-7/8 15-9/16 12 11 20-11/16 19-3/8 30-3/16 1/2 1/2
(835) (395) (305) (279) (525) (492) (767)
15 32-7/8 18-5/16 21-1/2 16 25-3/16 23-1/2 30-3/16 1/2 1/2
(835) (465) (546) (406) (640) (597) (767)
20 43-7/8 23-13/16 23-1/2 16 25-3/16 26-1/4 41-3/16 1/2 1/2
(1114) (605) (597) (406) (640) (667) (1046)
25 43-7/8 29-5/16 23-1/2 16 25-3/16 34-1/2 41-3/16 3/4 1/2 OR 3/4
(1114) (745) (597) (406) (640) (876) (1046)
30 54-7/8 34-13/16 26 17-1/2 26-11/16 37-1/4 52-3/16 3/4 1/2 OR 3/4
(1394) (884) (660) (445) (678) (946) (1326)
35 54-7/8 40-5/16 26 17-1/2 26-11/16 45-1/2 52-3/16 3/4 1/2 OR 3/4
(1394) (1024) (660) (445) (678) (1156) (1326)
40 60-3/8 45-13/16 26 17-1/2 26-11/16 51 57-11/16 3/4 1/2 OR 3/4
(1534) (1164) (660) (445) (678) (1295) (1465)

NOTE:
DIMENSIONS ARE IN INCHES, DIMENSIONS IN PARENTHESIS ARE IN MILLIMETERS.
* “F” DIMENSION IS THE RECOMMENDED CLEARANCE TO SERVICE THE BURNER DRAWER(S).
REFER TO FIGURE 6 FOR ADDITIONAL CLEARANCE REQUIREMENTS.

Figure 2 - Standard Power Vented Outdoor Duct Furnace

– 4 –

Chart 2 - Performance and Specifi cation Data

F* NG LP
INPUT OUTPUT Temp. Rise Min. Gas Gas Net Shipping
CAPACITY RATING RATING EFF. MIN. MAX. °F Static Clearance Inlet Inlet Weight Weight
MBH BTU/Hr BTU/Hr % CFM CFM (°C) in. of Water in. in. in. lb. lb.
(kW) (kW) (cu. m/s) (cu. m/s) Min. - Max. (KPa) (mm) (kg) (kg)

100 100,000 80,000 80 823 2,469 30 - 90 2 7-1/8 1/2 1/2 256 367

**

(29.3) (23.4) (0.388) (1.165) (17) - (50) (0.50) (181) (116) (166)
150 150,000 120,000 80 1,235 3,704 30 - 90 2 11-1/4 1/2 1/2 307 418
(43.9) (35.1) (0.583) (1.748) (17) - (50) (0.50) (286) (139) (190)
200 200,000 160,000 80 1,646 4,938 30 - 90 2 14 1/2 1/2 365 484
(58.6) (46.9) (0.777) (2.331) (17) - (50) (0.50) (356) (166) (220)
250 250,000 200,000 80 2,058 6,173 30 - 90 2 22-1/4 3/4 1/2 OR 3/4 405 524
(73.2) (58.6) (0.971) (2.913) (17) - (50) (0.50) (565) (184) (238)
300 300,000 240,000 80 2,469 7,407 30 - 90 2 34 3/4 1/2 OR 3/4 469 596

NA TURAL VENT

(87.8) (70.3) (1.165) (3.496) (17) - (50) (0.50) (864) (213) (270)
350 350,000 280,000 80 2,881 8,642 30 - 90 2 33-1/4 3/4 1/2 OR 3/4 510 637
(102.5) (82.0) (1.360) (4.079) (17) - (50) (0.50) (845) (231) (289)
400 400,000 320,000 80 3,292 9,876 30 - 90 2 38 3/4 3/4 1/2 OR 3/4 558 690
(117.1) (93.7) (1.554) (4.661) (17) - (50) (0.50) (984) (253) (313)

100 100,000 80,000 80 823 2,469 30 - 90 2 7-1/8 1/2 1/2 262 373

**

(29.3) (23.4) (0.388) (1.165) (17) - (50) (0.50) (181) (119) (169)
150 150,000 120,000 80 1,235 3,704 30 - 90 2 11-1/4 1/2 1/2 298 409
(43.9) (35.1) (0.583) (1.748) (17) - (50) (0.50) (286) (135) (186)
200 200,000 160,000 80 1,646 4,938 30 - 90 2 14 1/2 1/2 356 475
(58.6) (46.9) (0.777) (2.331) (17) - (50) (0.50) (356) (161) (215)
250 250,000 200,000 80 2,058 6,173 30 - 90 2 22-1/4 3/4 1/2 OR 3/4 395 514

POWER VENT

(73.2) (58.6) (0.971) (2.913) (17) - (50) (0.50) (565) (179) (233)
350 325,000 260,000 80 2,675 8,025 30 - 90 2 33-1/4 3/4 1/2 OR 3/4 495 622
(95.2) (76.2) (1.263) (3.789) (17) - (50) (0.50) (845) (225) (282)
400 400,000 320,000 80 3,292 9,876 30 - 90 2 38-3/4 3/4 1/2 OR 3/4 543 675
(117.1) (93.7) (1.554) (4.661) (17) - (50) (0.50) (984) (246) (306)

100 100,000 80,000 80 1,235 3,704 20 - 60 2 7 1/8 1/2 1/2 253 364

***

(29.3) (23.4) (0.583) (1.748) (11) - (33) (0.50) (181) (115) (165)
150 150,000 120,000 80 1,852 5,556 20 - 60 2 11-1/4 1/2 1/2 304 415
(43.9) (35.1) (0.874) (2.622) (11) - (33) (0.50) (286) (138) (188)
200 200,000 160,000 80 2,469 7,407 20 - 60 2 14 1/2 1/2 362 481
(58.6) (46.9) (1.165) (3.496) (11) - (33) (0.50) (356) (164) (218)
250 250,000 200,000 80 3,086 9,259 20 - 60 2 22-1/4 3/4 1/2 OR 3/4 402 521
(73.2) (58.6) (1.457) (4.370) (11) - (33) (0.50) (565) (182) (236)
300 300,000 240,000 80 3,704 11,111 20 - 60 2 34 3/4 1/2 OR 3/4 466 593

NA TURAL VENT

(87.8) (70.3) (1.748) (5.244) (11) - (33) (0.50) (864) (211) (269)
350 350,000 280,000 80 4,321 12,963 20 - 60 2 33-1/4 3/4 1/2 OR 3/4 507 634
(102.5) (82.0) (2.040) (6.119) (11) - (33) (0.50) (845) (230) (288)
400 400,000 320,000 80 4,938 14,815 20 - 60 2 38-3/4 3/4 1/2 OR 3/4 555 687
(117.1) (93.7) (2.331) (6.993) (11) - (33) (0.50) (984) (252) (312)

100 100,000 80,000 80 1,235 3,704 20 - 60 2 7-1/8 1/2 1/2 259 370

***

(29.3) (23.4) (0.583) (1.748) (11) - (33) (0.50) (181) (117) (168)
150 150,000 120,000 80 1,852 5,556 20 - 60 2 11-1/4 1/2 1/2 295 406
(43.9) (35.1) (0.874) (2.622) (11) - (33) (0.50) (286) (134) (184)
200 200,000 160,000 80 2,469 7,407 20 - 60 2 14 1/2 1/2 353 472
(58.6) (46.9) (1.165) (3.496) (11) - (33) (0.50) (356) (160) (214)
250 250,000 200,000 80 3,086 9,269 20 - 60 2 22-1/4 3/4 1/2 OR 3/4 392 511
(73.2) (58.6) (1.457) (4.375) (11) - (33) (0.50) (565) (178) (232)
300 300,000 240,000 80 3,704 11,111 20 - 60 2 34 3/4 1/2 OR 3/4 452 579

POWER VENT

(87.8) (70.3) (1.748) (5.244) (11) - (33) (0.50) (864) (205) (263)
350 350,000 280,000 80 4,321 12,963 20 - 60 2 33-1/4 3/4 1/2 OR 3/4 492 619
(102.5) (82.0) (2.040) (6.119) (11) - (33) (0.50) (845) (223) (281)
400 400,000 320,000 80 4,938 14,815 20 - 60 2 38-3/4 3/4 1/2 OR 3/4 540 672
(117.1) (93.7) (2.331) (6.993) (11) - (33) (0.50) (984) (245) (305)

*

See fi gures 1 and 2. ** Indicates high temperature rise furnaces. *** Indicates standard temperature rise furnaces.

The clearances dimensions shown in chart #2 are the absolute minimum clearances for servicing the burner drawer. However, the clearances
shown in chart #1 are the recommended clearances for ease of servicing the unit.

– 5 –

PERFORMANCE DATA CURVES

Figure 3 - High Temperature Rise Duct Furnaces — 30-90°F (17-50°C)

Pressure drop through the heat exchanger is based on
the CFM throughput. The desired data is obtained in
the following manner:

1. Select heater size based on heat loss of the building
to be heated.

2. Select temperature rise desired.

3. Based on temperature rise, the horizontal line inter­sects heater temperature vs. CFM curve.

Figure 4 - Standard Temperature Rise Duct Furnaces — 20-60°F (11-33°C)

4. Follow vertical line down to select CFM.

5. For pressure drop selection, follow vertical CFM line
until it intersects the selected heater performance
curve vs. pressure drop.

6. Follow the horizontal pressure drop line to the left,
and read pressure drop of the selected heater.

– 6 –

BYPASS SIZING INFORMATION

(BUILT ON THE JOB – NOT FURNISHED BY
FACTORY)

On occassion when a duct furnace is incorporated in an
air handling system, it may be desirable to handle a total
of more CFM than the duct furnace will pass at a given
static pressure drop and temperature rise. Therefore, it
is necessary to arrange to bypass the additional CFM
required. The size of the bypass duct can be determined
by referring to the chart. This permits the static pressure
drop through the bypass to balance off the drop through
the heat exchanger. The bypass duct is not factory
furnished and must be built on the job by the installer and
a damper placed therin if required.

Figure 5 - By-Pass Curve

USE OF BYPASS CURVES

The width of the by-pass for CFM in excess of that
provided through the heater may be found in the
following manner:

1. Determine the CFM and pressure drop through
the heater based on the heating requirement
specifi cations.

2. Determine the additional CFM desired, over and
above the CFM for the heating requirements.

3. Using the pressure drop which was determined from
performance curves above, for the heating load,
locate this pressure drop on the by-pass curves.
Follow this curve until it intersects the vertical CFM
line for the excess CFM desired.

4. Follow horizontal line to left to obtain width of b y-pass
duct.

– 7 –

INSTALLATION

D3589A

18"

(457)

5/16"

(8)

Ductwork

Natural

(or Power)

Vent

Furnace

Air Flow

5/16"

(8)

18"

(457)

18"

(457)

36"

(914)

36"

(914)

Clearance

For Drawer

Pul-out

18"

(457)

5/16" (8) Typ.

Open all disconnect switches
and secure in that position before installing
unit. Failure to do so may result in personal
injury or death from electrical shock.

Installation must conform with local building codes,
or in the absence of local codes, with the latest
edition of the National Fuel Gas Code ANSI Z223.1
(NFPA 54).

A heat loss study and a complete layout of the system
should be made fi rst.

When locating the unit in its permanent location, make
certain that the roof is capable of carrying the additional
load of the equipment. Check the net weights from the

engineering data.

Make certain that clearances are provided for service,
minimum clearance to combustible material and to
venting cap. See below for this infor mation. Service
clearance information is given in the engineering data
in Figures 1, 2 and 6. Clearances around secondary air
must be unobstructed.

If the unit is installed downstream of refrigeration coils,
condensate will form and collect in the bottom of the
heater. Drain connections are provided to dispose of
this condensate from the unit. Connect drain pipes to
dispose of this condensate where necessary.

Ducts connected to duct furnaces shall have removable
access panels on both upstream and downstream sides
of the unit. These openings shall be accessible when
the unit is installed in service, and shall be of such size
that smoke or refl ected light may be observed inside the
casing to indicate the presence of leaks in the heating
element. The covers for the openings shall be attached
in such a manner as to prevent leaks.

If a duct furnace is connected
to a return air duct or any other inlet air
restriction, the appliance shall be installed on
the positive pressure side of the air-circulating
blower.

Atmospheres containing solvents or chlorinated
hydrocarbons will produce corrosive acids when
coming in contact with the flames. This will greatly
reduce the life of the gas duct furnace and may void
the warranty. Avoid such areas.

CLEARANCES

Minimum clearances are shown in Figures 1, 2 & 6
and charts 1 & 2. It is important that clearances be
maintained for servicing the unit (refer to Figures 1
& 2 for clearances necessary to pull out the burner
drawer for servicing), and that minimum clearances are
provided from combustible material and from the venting
cap/top of unit. Clearances around the outside air hood
must be unobstructed.

Ducts which are outdoors must
be insulated and sealed to prevent water from
entering either furnace or building through duct

combustibles to prevent injury or death from
fi re.

(see section on duct and drain specifi cations).

Figure 6 - Minimum Clearances to Combustible Material or Obstructions

D3589

*See fi gures 1 & 2 and charts 1 & 2.

– 8 –

Provide adequate clearance from

Power Vent Units required 36"
clearance above top of unit.

VENTING

2

1

4

3

FRONT

REAR

LEFT

RIGHT

TOP VIEW

Neoprene Washers

Screws

All venting installations shall be in accordance with the
latest edition of “Par t 7, Venting of Equipment of the
National Fuel Gas Code, ANSI Z223.1 (NFPA 54), or
applicable provisions of local building codes”.

Natural venting models are equipped with a vent cap
designed for natural venting. Air for combustion enters
at the base of the vent through a protective grille, and
the design of the vent cap is such that the products of
combustion are discharged at the upper section of the
cap. The cap is shipped in a separate carton. It should
be fastened in position as shown in Figure 7 and
should not be altered in any way.

The venting is an integral part of
the unit and must not be altered in the field. If
altered, excessive carbon monoxide could be
produced.

Figure 7 - Vent Cap Assembly
(Natural Vented Furnaces Only)

Power vented models are designed with combustion
air inlet and fl ue products outlet located in the louvered
side access panel. Never locate these units in an
area where the flue products outlet may be directed
at any fresh air vents.See Figures 8a 8b, and 8c for
installation and servicing requirements.

Figure 8a - Power Venter Discharge Location

*These Surfaces (indicated with an asterisk in fi gures 8a & 8b)
MUST be flush and sealed at all times to ensure the proper
discharge of fl ue products from the unit.

These discharge fl anges are equipped with special gasketing,
which must create an air tight seal connection around the
louvers of the access panel.

Secure in place the access door to the discharge adaptor using
the two screws and neoprene washers, then tighten
the grip latches (see service access panel removal
section).

D3505

D3591

FIELD INSTALLATION INSTRUCTIONS

1. Remove “Side Access Panel”.

2. Insert Vent Sleeve of “Vent Cap Assembly” (Item 1)
thru “Top Panel Assembly” (Item 2), and over Vent
Collar of “Flue Collector Assembly” (Item 3).

3. Align “Vent Cap Assembly” so it is square to “Top
Panel Assembly”.

4. Fasten with “Drill Screw” or “Sheet Metal Scre w” (Item

4) by reaching between “Flue Collector Assembly”
(Item 3) & “Top Panel Assembly” (Item 2), and drilling
through vent sleev e of “Vent Cap Assemb ly” into vent
collar of “Flue Collector Assembly”.

5. Replace “Side Access Panel”.

NOTICE: If your unit is to be equipped with the
optional extended vent cap assembly, see the
special instructions supplied with the vent cap.

Figure 8b

D3725

Figure 8c

D4596

– 9 –