Modine HDS, HDC User Manual

INSTALLATION AND SERVICE MANUAL

separated combustion gas-fired unit heaters

WARNING

1. Improper installation, adjustment, alteration,
service or maintenance can cause property
damage, injury or death, and could cause
exposure to substances which have been
determined by various state agencies
to cause cancer, birth defects or other
reproductive harm. Read the installation,
operating and maintenance instructions
thoroughly before installing or servicing this
equipment.

2. Do not locate ANY gas-fired units in areas
where chlorinated, halogenated, or acidic
vapors are present in the atmosphere. These
substances can cause premature heat
exchanger failure due to corrosion, which
can cause property damage, serious injury,
or death.

FOR YOUR SAFETY

WHAT TO DO IF YOU SMELL GAS:

1. Open windows.

2. Do not try to light any appliance.

3. Do not touch any electrical switch; do
not use any phone in your building.

4. Immediately call your gas supplier

 fromaneighbor’sphone.Followthegas
 supplier’sinstructions.Ifyoucannotreach

your gas supplier, call your fire department.

6-584.8

5H0800020000

September, 2015

model HDS and HDC

All models approved for use in California by the CEC and
in Massachusetts. Unit heater is certified for residential and
commercial applications.

FOR YOUR SAFETY

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

IMPORTANT

The use of this manual is specifically intended
for a qualified installation and service agency.
All installation and service of these units must
be performed by a qualified installation and
service agency.

Inspection on Arrival

1. Inspect unit upon arrival. In case of damage, report it
immediately to transportation company and your local
Modine sales representative.

2.

Check rating plate on unit to verify that power supply meets
available electric power at the point of installation.

3. Inspect unit upon arrival for conformance with description of
product ordered (including specifications where applicable).

Table of Contents

Inspection on Arrival ................................. 1

Special Precautions ................................. 2

SI (Metric) Conversion Factors......................... 3

Before you Begin ................................... 3

Unit Location....................................... 4

Combustible Material and Service Clearances ......... 4

Unit Mounting .................................. 5

Venting ....................................... 6

Gas Connections............................... 12

High Altitude Accessory Kit . . . . . . . . . . . . . . . . . . . . . . . 13

Electrical ..................................... 15

Operation..................................... 16

Unit Components .................................. 17

Dimensions....................................... 18

Service/Troubleshooting............................. 19

Unit Wiring Diagram ................................ 20

Serial/Model Number/Replacement Parts ............... 21

Commercial Warranty........................Back Cover

PLEASE BE SURE TO LEAVE IT WITH THE OWNER WHEN YOU LEAVE THE JOB.

THIS MANUAL IS THE PROPERTY OF THE OWNER.

SPECIAL PRECAUTIONS

SPECIAL PRECAUTIONS

THE INSTALLATION AND MAINTENANCE INSTRUCTIONS IN THIS
MANUAL MUST BE FOLLOWED TO PROVIDE SAFE, EFFICIENT
AND TROUBLE-FREE OPERATION. IN ADDITION, PARTICULAR
CARE MUST BE EXERCISED REGARDING THE SPECIAL
PRECAUTIONS LISTED BELOW. FAILURE TO PROPERLY ADDRESS
THESE CRITICAL AREAS COULD RESULT IN PROPERTY DAMAGE
OR LOSS, PERSONAL INJURY, OR DEATH. THESE INSTRUCTIONS
SUBJECT TO ANY MORE RESTRICTIVE LOCAL OR NATIONAL
CODES.

HAZARD INTENSITY LEVELS

1. DANGER: Indicates an imminently hazardous situation
which, if not avoided, WILL result in death or serious injury.

2. WARNING: Indicates a potentially hazardous situation
which, if not avoided, COULD result in death or serious injury.

3. CAUTION: Indicates a potentially hazardous situation which,

if not avoided, MAY result in minor or moderate injury.

4. IMPORTANT: Indicates a situation which, if not avoided,
MAY result in a potential safety concern.

DANGER

Appliances must not be installed where they may be exposed
to a potentially explosive or flammable atmosphere.

WARNING

1. Gas fired heating equipment must be vented - do not
operate unvented.

2. A built-in power exhauster is provided - additional external
power exhausters are not required or permitted.

3. If an existing heater is being replaced, it may be necessary
to resize the venting systems. Improperly sized venting
systems can result in vent gas leakage or the formation of
condensate. Refer to the National Fuel Gas Code ANSI
Z223.1 (NFPA 54) or CSA B149.1 latest edition. Failure to
follow these instructions can result in injury or death.

4. Under no circumstances should two sections of double wall
vent pipe be joined together within one horizontal vent system
due to the inability to verify complete seal of inner pipes.

5. All field gas piping must be pressure/leak tested prior to
operation. Never use an open flame. Use a soap solution
or equivalent for testing.

6. Gas pressure to appliance controls must never exceed
14" W.C. (1/2 psi).

7. To reduce the opportunity for condensation, the minimum
sea level input to the appliance, as indicated on the serial
plate, must not be less than 5% below the rated input,
or 5% below the minimum rated input of dual rated units.

8. Disconnect power supply before making wiring connections
to prevent electrical shock and equipment damage.

9. All appliances must be wired strictly in accordance with
wiring diagram furnished with the appliance. Any wiring
different from the wiring diagram could result in a hazard to
persons and property.

10. Any original factory wiring that requires replacement must
be replaced with wiring material having a temperature
rating of at least 105°C.

11. Ensure that the supply voltage to the appliance, as indicated
on the serial plate, is not 5% greater than the rated voltage.

12. When servicing or repairing this equipment, use only
factory-approved service replacement parts. A complete
replacements parts list may be obtained by contacting
the factory. Refer to the rating plate on the appliance for
complete appliance model number, serial number, and
company address. Any substitution of parts or controls not
approved by the factory will be at the owner's risk.

CAUTION

1. All literature shipped with this unit should be kept for
future use for servicing or service diagnostics. Do not
discard any literature shipped with this unit.

2. Consult piping, electrical, and venting instructions in this
manual before final installation.

3. Do not attach ductwork, air filters, or polytubes to any
propeller unit heater.

4. Clearances to combustible materials are critical. Be sure to
follow all listed requirements.

5. Low profile heaters are designed for use in heating applica­ tions with ambient startup temperatures between -40°F and

90°F, and ambient operating temperatures between 40°F
and 90°F.

6. Do not install unit outdoors.

7. In garages or other sections of aircraft hangars such
as offices and shops that communicate with areas used for
servicing or storage, keep the bottom of the unit at least
7' above the floor unless the unit is properly guarded
to provide user protection from moving parts. In parking
garages, the unit must be installed in accordance with
the standard for parking structures ANSI/NFPA 88A latest
edition, and in repair garages the standard for repair garages

NFPA 30A - latest edition (Formerly NFPA 88B). In Canada,
installation of heaters in airplane hangars must be in
accordance with the requirements of the enforcing authority,
and in public garages in accordance with the current CSA­B149 codes.

8. In aircraft hangars, keep the bottom of the unit at least 10'
from the highest surface of the wings or engine enclosure
of the highest aircraft housed in the hangars and in
accordance with the requirements of the enforcing authority
and/or NFPA 409-latest edition.

9. Installation of units in high humidity or salt water
atmospheres will cause accelerated corrosion resulting in a
reduction of the normal life of the units.

10. Do not install units below 7' measured from the bottom of
the unit to the floor in commercial applications (unless
unit is properly guarded to provide user protection from
moving parts) and 5' measured from the bottom of the unit
to the floor in residential applications.

11. Be sure no obstructions block air intake and discharge of
unit heaters.

12. The minimum distance from combustible material is based
on the combustible material surface not exceeding 160°F.
Clearance from the top of the unit may be required to be
greater then the minimum specified if heat damage, other
than fire, may occur to materials above the unit heater at
the temperature described.

13. Allow 18" of clearance at rear (or 6" beyond end of motor at
rear of unit, whichever is greater) and access side to
provide ample air for proper operation of fan.

14. Installation must conform with local building codes or in the
absence of local codes, with the National Fuel Gas
Code, ANSI Z223.1 (NFPA 54) - latest edition. In Canada
installation must be in accordance with CSA-B149.1.

15. The concentric vent adapter box must be installed inside
of the structure or building. Do not install this box on the
exterior of a building or structure.

16. Purging of air from gas supply line should be performed as
described in the National Fuel Gas Code, ANSI Z223.1
(NFPA 54) - latest edition, or, or in Canada in CSA-B149
codes.

17. When leak testing the gas supply piping system, the

appliance and its combination gas control must be isolated
during any pressure testing in excess of 14" W.C. (1/2 psi).

2

6-584.8

SPECIAL PRECAUTIONS / SI (METRIC) CONVERSION FACTORS

BEFORE YOU BEGIN

CAUTION

18. The unit should be isolated from the gas supply piping
system by closing its field installed manual shut-off valve.
This manual shut-off valve should be located within 6' of
the heater.

19. Turn off all gas before installing appliance.

20. Ensure that the supply voltage to the appliance, as
indicated on the serial plate, is not 5% less than the rated
voltage.

21. Check the gas inlet pressure at the unit upstream of the
combination gas control. The inlet pressure should be
6-7" W.C. on natural gas or 12-14" W.C. on propane. If
inlet pressure is too high, install an additional pressure
regulator upstream of the combination gas control.

22. Service or repair of this equipment must be performed by
a qualified service agency.

23. Do not attempt to reuse any mechanical or electronic
ignition controllers which has been wet. Replace defective
controller.

IMPORTANT

1. To prevent premature heat exchanger failure, do not locate
ANY gas-fired appliances in areas where corrosive vapors
(i.e. chlorinated, halogenated or acid) are present in the
atmosphere.

2. To prevent premature heat exchanger failure, the input to
the appliance as indicated on the serial plate, must not
exceed the rated input by more then 5%.

3. To prevent premature heat exchanger failure, observe
heat exchanger tubes. If the tubes become red while
blower and furnace are in operation, check to be sure the
blower has been set to the proper rpm for the application.
Refer to page 15 for blower adjustments.

4. Start-up and adjustment procedures must be performed
by a qualified service agency.

CAUTION

1. All literature shipped with this unit should be kept for future
use for servicing or service diagnostics. Leave manual with
the owner. Do not discard any literature shipped with this unit.

2. Consult piping, electrical, and venting instructions in this
manual before final installation.

3. Do not attach ductwork, air filters, or polytubes to any
propeller unit heater.

In the U.S., the installation of these units must comply with the
National Fuel Gas Code, ANSI Z223.1 - latest edition (NFPA

54) and other applicable local building codes. In Canada, the
installation of these units must comply with local plumbing or
waste water codes and other applicable codes and with the
current code CSA-B149.1.

1. All installation and service of these units must be
performed by a qualified installation and service agency
only as defined in ANSI Z223.1, latest edition or in
Canada by a licensed gas fitter.

2. This unit is certified with the controls furnished. For

replacements parts, please order according to the
replacement parts list on serial plate. Always know your
model and serial numbers. The right is reserved to
substitute other authorized controls as replacements.

3. Unit is balanced for correct performance. Do not alter fan

or operate motors at speeds below what is shown in this
manual.

4. Information on controls is supplied separately.

5. The same burner is used for natural and propane gas.

To check most of the possible remedies in the troubleshooting
guide listed in Table 19.1, refer to the applicable sections of the
manual.

SI (METRIC) CONVERSION FACTORS

To Convert Multiply By To Obtain

"W.C. 0.249 kPa
°F (°F-32) x 5/9 °C
Btu 1.06 kJ
Btu/ft
Btu/hr 0.000293 kW
CFH (ft
CFH (ft
CFM (ft
CFM (ft

3

37.3 kJ/m

3

/hr) 0.000472 m3/min

3

/hr) 0.00000787 m3/s

3

/min) 0.0283 m3/min

3

/min) 0.000472 m3/s

To Convert Multiply By To Obtain

feet 0.305 m
Gal/Hr. 0.00379 m
Gal/Hr. 3.79 l/hr

3

gallons 3.79 l
Horsepower 746 W
inches 25.4 mm
pound 0.454 kg
psig 6.89 kPa
psig 27.7 "W.C.

3

/hr

6-584.8

3

UNIT LOCATION

UNIT LOCATION

DANGER

Appliances must not be installed where they may be exposed
to a potentially explosive or flammable atmosphere.

CAUTION

1. Clearances to combustible materials are critical. Be sure to
follow all listed requirements.

2. Low profile heaters are designed for use in heating
applications with ambient startup temperatures between

-40°F and 90°F, and ambient operating temperatures
between 40°F and 90°F.

3. Do not install unit outdoors.

4. In garages or other sections of aircraft hangars such
as offices and shops that communicate with areas used for
servicing or storage, keep the bottom of the unit at least
7' above the floor unless the unit is properly guarded.
In parking garages, the unit must be installed in accordance
with the standard for parking structures ANSI/NFPA
88A-latest edition, and in repair garages the standard for
repair garages NFPA 30A - latest edition (Formerly NFPA
88B). In Canada, installation of heaters in airplane
hangars must be in accordance with the requirements
of the enforcing authority, and in public garages in
accordance with the current CSA-B149 codes.

5. In aircraft hangars, keep the bottom of the unit at least 10'

from the highest surface of the wings or engine enclosure
of the highest aircraft housed in the hangars and in
accordance with the requirements of the enforcing authority
and/or NFPA 409-latest edition.

6. Installation of units in high humidity or salt water
atmospheres will cause accelerated corrosion, resulting in
a reduction of the normal life of the units.

Table 4.1 - Clearances

Unit Side

Combustible Materials Service Clearance

Top and Bottom 1" 1"
Access Side 1" 18"
Non-Access Side 1" 1"
Rear 18" 18"
Vent Connector 4" 4"

6. Do not install units in locations where gas ignition system is
exposed to water spray, rain, or dripping water.

7. Mounting height (measured from bottom of unit) at which unit
heaters are installed is critical. Refer to mounting height and
heat throw data on page 16 of this manual. The maximum
mounting height for any unit is that height above which the
unit will not deliver heated air to the floor.

Clearance To Recommended

Turning The Unit 180° (Model sizes 30-75 only)

All units are produced at the factory with left-side controls (when
looking at the unit). If the installation requires the controls to
be on the right side, all HDS/HDC heaters - with the exception
of the 100 and 125 - can be turned-over by following the
instructions below.

• By turning the unit 180° from the way it was received from
the factory, the sides become opposite but the front and
back remain in the same relative position. The bottom
panel now becomes the top panel and vice-versa.

• Remove the access panel, turn it 180°, and re-attach it to
the unit so that all the information labels can be read.

• Remove the spring-loaded deflector blades, turn them over,
replace, and adjust so they are open and in a position to
direct the heated air down to the floor.

IMPORTANT

To prevent premature heat exchanger failure, do not locate
ANY gas-fired appliances in areas where corrosive vapors
(i.e. chlorinated, halogenated or acid) are present in the
atmosphere.

Location Recommendations

1. When locating the heater, consider general space and
heating requirements, availability of gas and electrical
supply, and proximity to vent locations.

2. When locating units, it is important to consider that the
combustion air and exhaust vent piping must be connected
to the outside atmosphere. Vent terminals should be located
adjacent to one another. Maximum equivalent vent lengths
are listed in “Section A - General Instruction - All Units” of the
venting instructions.

3. Be sure the structural support at the unit location site is
adequate to support the unit's weight. For proper operation
the unit must be installed in a level horizontal position.

4. Do not install units in locations where the flue products
can be drawn into the adjacent building openings such as
windows, fresh air intakes, etc.

5. Be sure that the minimum clearances to combustible
materials and recommended service clearances are
maintained. Units are designed for installation with the
minimum clearances as shown in Table 4.1.

4

6-584.8

UNIT MOUNTING

CAUTION

1.

Do not install units below 7' measured from the bottom of
the unit to the floor in commercial applications (unless
unit is properly guarded to provide user protection from
moving parts) and 5' measured from the bottom of the unit
to the floor in residential applications.

2. Be sure no obstructions block air intake and discharge
of unit heaters.

3. The minimum distance from combustible material is
based on the combustible material surface not exceeding
160°F. Clearance from the top of the unit may be required
to be greater than the minimum specified if heat damage,
other than fire, may occur to materials above the unit
heater at the temperature described.

4. Allow 18" clearance at rear (or 6" beyond end of motor
at rear of unit, whichever is greater) and access side to
provide ample air for proper operation of fan.

Figure 5.2 - Unit Heater Turned 180° (30-75 units only)
(Access panel and heated air outlet change sides)

1. Be sure the means of suspension is adequate to support
the weight of the unit (see page 18 for unit weights).

2. For proper operation, the unit must be installed in a level
horizontal position.

3. Clearances to combustibles as previously specified must be
strictly maintained.

4. For model sizes 30-75, before lifting the heater for
suspension, the mounting brackets must be installed as
follows (for bracket accessory installation on model sizes
100-125, see the latest revision of literature 6-594):

• For standard (left side) control access, remove the 3

screws and mounting bracket along the top edge of both
the front and back of the unit. Install the front bracket as
shown in Figure 5.1 by aligning the screw holes on the
bracket with the screw holes on the top edge of the unit.
Repeat for the bracket on the back of the unit.

• For right side control access, remove the 3 screws and

mounting bracket along the top edge of both the front and
back of the unit. Turn the unit over and install the front
bracket as shown in Figure 5.2 by aligning the screw holes
on the bracket with the screw holes on the top edge of the
unit (originally the bottom edge). Repeat for the bracket on
the back of the unit.

5a. Suspension by screws/lag bolts: Secure the mounting

brackets to the ceiling joists or truss, using 1/4" screws with
1/2" washers. These unit mounting brackets are slotted to
accommodate joists on 16" or 24" centerlines. See page 18
for mounting bracket dimensions.

Figure 5.1 - Unit Heater in Standard Mounting
Configuration (30-75 units only)

5b. Suspension by threaded rod: The unit can also be hung

with threaded rod utilizing the same mounting brackets.
Attach the threaded rod to the unit mounting brackets,
securing with a top and bottom nut. For model sizes
100-125, the units are designed to be suspended by
threaded rod without the use of brackets. On each piece of
3/8" threaded rod used, screw a nut a distance of about 1"
onto the end of the threaded rods that will be screwed into
the unit heater. Place a washer over the end of the threaded
rod and screw the threaded rod into the unit heater weld nuts
on the top of the heater at least 5 turns, and no more than
10 turns. Tighten the nut first installed onto the threaded rod
to prevent the rod from turning.

Next, drill holes into a steel channel or angle iron at the

same centerline dimensions as those chosen for the heater
being installed. The steel channels or angle iron pieces need
to span and be fastened to appropriate structural members.
Cut the threaded rods to the preferred length, push them
through the holes in the steel channel or angle iron and
secure with washers and lock nuts, lock washers and nuts,
or a washer with double nut arrangement.
NOTE: A pipe hanger adapter kit, shown in Figure 5.3, is
available as an accessory. One kit consists of two drilled
3/4" IPS pipe caps and two 3/8" - 16 x 1-3/4" capscrews
to facilitate threaded pipe suspension. Two kits would be
required.

5c. Shelf mounted units: The unit heater can also be installed

on a shelf. The mounting brackets will need to be attached
to the heater the same manner as explained in note #4,
however, to mount on a shelf the brackets must go on the
bottom of the heater. The brackets must be affixed to the
shelf using similar screws (1/4" screw with 1/2" washer) as
overhead joist or truss mounting. Be sure all clearance to
combustible requirements are met.

Figure 5.3 - Unit Heater Suspension Methods

(Threaded Rod) (Pipe Adaptor Kit)

6-584.8

5

INSTALLATION - VENTING

WARNING

1. Gas fired heating equipment must be vented - do not
operate unvented.

2. A built-in power exhauster is provided - additional external

power exhausters are not required or permitted.

3. If an existing heater is being replaced, it may be necessary
to resize the venting systems. Improperly sized venting
systems can result in vent gas leakage or the formation of
condensate. Refer to the National Fuel Gas Code ANSI
Z223.1 (NFPA 54) or CSA-B149.1 Installation Code - latest
edition. Failure to follow these instructions can result in
serious injury or death.

4. Under no circumstances should 2 sections of double wall

vent pipe be joined together within 1 horizontal vent system
due to the inability to verify complete seal of inner pipes.

CAUTION

Installation must conform with local building codes or in the
absence of local codes, with Part 7, Venting of Equipment, of
the National Fuel Gas Code, ANSI Z223.1 (NFPA 54) - latest
edition. In Canada installation must be in accordance with
CSA B149.1.

Model HDS/HDC unit heaters must be vented with the proper
passageway as described in these instructions to convey
flue gases from the unit or the vent connector to the outside
atmosphere. The heaters must also have a separate combustion
air intake pipe to bring in fresh air for combustion from the
outside atmosphere.

The venting instructions are organized in sections, based on
installation type. The sections are identified as follows:

Instructions Applicable Installation Instructions
Section by Vent System Type

A General instructions for ALL installations
B VERTICAL 2-PIPE vent systems ➀
C HORIZONTAL 2-PIPE vent systems ➀
D HORIZONTAL AND VERTICAL

CONCENTRIC vent systems ➀

➀ The differences between vertical and horizontal vent systems in 2-Pipe or

concentric vent configurations will be identified in “Section A - General
Instructions – All Units”.

A4. Refer to Table 6.1 for total equivalent vent pipe lengths,

making the vent system as straight as possible. Refer to
Table 6.1 for total equivalent vent pipe lengths, making the
vent system as straight as possible.

Table 6.1 - Vent Pipe Diameters, Transitions, and
Total Equivalent Vent Pipe Lengths For Horizontal
and Vertical Venting Systems

Model

Size

30-45 3" 3' 25'

60-125 4" 3' 25'

A5. A minimum of 12" straight pipe is recommended from the

flue outlet before turns in the vent pipe.

A6. Horizontal sections of vent pipe are to be installed with a

minimum downward slope from the appliance of 1/4" per foot
and suspended securely from overhead structures at points
not greater than 3' apart.

A7. Fasten individual lengths of vent together with at least 3

corrosion-resistant sheet metal screws.

A8. Keep single wall vent pipe at least 6" from combustible

materials. For double wall vent pipe, follow the vent

pipe manufacturer’s clearances to combustibles. The

minimum distance from combustible materials is based
on the combustible material surface not exceeding 160°F.
Clearance from the vent pipe (or the top of the unit) may be
required to be greater than 6" if heat damage other than fire
could result (such as material distortion or discoloration).

A9. Avoid venting through unheated space when possible.

When venting does pass through an unheated space or
if the unit is installed in an environment that promotes
condensation, insulate runs greater than 5' to minimize
condensation. Inspect for leakage prior to insulating and use
insulation that is noncombustible with a rating of not less
than 400°F. Install a tee fitting at the low point of the vent
system and provide a drip leg with a clean out cap as shown
in Figure 8.1.

Vent Pipe

Sizes

Minimum

Eqv. Length

Maximum

Eqv. Length

Figure 6.1 - Venting Through Combustible Roof or Wall

Single Wall Vent Pipe

Flashing

Listed
Terminal

Double Wall Vent Pipe ➀

Flashing

Listed
Terminal

Section A – General Instructions – All Units

A1. If the unit heater being installed is replacing existing

equipment and using the existing vent system from that
equipment, inspect the venting system for proper size and
horizontal pitch, as required in the National Fuel Gas Code
ANSI Z223.1 or CSA B149.1 Installation Code-latest edition
and these instructions. Determine that there is no blockage
or restriction, leakage, corrosion and other deficiencies,
which could cause an unsafe condition.

A2. The combustion air pipe and vent pipe should be galvanized

steel or other suitable corrosion resistant material. Follow
the National Fuel Gas Code for minimum thickness of vent
material. The minimum thickness for connectors varies
depending on the pipe diameter. Do not vent unit with PVC
or other forms of plastic venting material.

A3. All heaters come with factory installed vent and combustion

air adapters for attaching the vent pipe to the heater. Attach
the vent pipe to the adapter with 3 corrosion resistant
screws. (Drill pilot holes through the vent pipe and adapter
prior to screwing in place). Vent pipe must not be smaller
than the connector size.

6

Listed
Thimble

Single
Wall

Single Wall Vent Pipe Terminating
with Double wall vent pipe. ➀

Clearance Specified
by Type B Vent Mfg.

Single Wall Vent Pipe

Listed
Thimble

➀ See Instruction A12 for attaching single wall pipe to double wall pipe.

6-584.8

Clearance Specified
by Type B Vent Mfg.

Double
Wall

Listed
Terminal

Single
Wall

Listed
Terminal

INSTALLATION - VENTING

A10. When the vent passes through a combustible INTERIOR

wall or floor, a metal thimble 4" greater than the vent
diameter is necessary. If there is 6' or more of vent pipe in
the open space between the appliance and where the vent
pipe passes through the wall or floor, the thimble need only
be 2" greater than the diameter of the vent pipe. If a thimble
is not used, all combustible material must be cut away
to provide 6" of clearance. Where authorities have
jurisdiction type B vent may be used for the last section
of vent pipe to maintain clearance to combustibles while
passing through wall or floor (see Figure 6.1). Any material
used to close the opening must be noncombustible.

A11. All seams and joints of the single wall pipe must be sealed

with metallic tape or silastic suitable for temperatures up to
400°F. Wrap the tape 2 full turns around the vent pipe. One
continuous section of double wall vent pipe may be used
within the vent system to pass through the wall to a listed
vent cap. Refer to instruction A12 in “Section A – General
Instructions – All Units” for attaching double wall pipe to
single wall pipe.

A12. The following are general instructions for double wall (type

B) terminal pipe installation:

How to attach a single wall vent terminal to double wall
(type B) vent pipe:

1. Look for the “flow” arrow on the vent pipe.

2. Slide the vent terminal inside the exhaust end of the
double wall vent pipe.

3. Drill 3 holes through the pipe and the vent terminal.
Using 3/4" long sheet metal screws, attach the cap to
the pipe. Do not overtighten.

How to connect a single wall vent system to a double
wall (type B) vent pipe:

1. Slide the single wall pipe inside the inner wall of the
double wall pipe.

2. Drill 3 holes through both walls of the single and double
wall vent pipes. Using 3/4" sheet metal screws, attach
the 2 pieces of pipe. Do not overtighten.

3. The gap between the single and double wall pipe must
be sealed but it is not necessary to fill the full volume
of the annular area. To seal, run a large bead of 400°F
silastic around the gap.

A13. Vent termination clearances must be maintained:

Table 7.1 - Vent Termination Clearances

Minimum Clearances for
Structure Vent Terminal Location

Forced air inlet within 10 feet 3 feet above
Combustion air inlet of another

appliance 6 feet all directions
Door, window, gravity air inlet, 4 feet horizontal and below

or any building opening 1 foot above
Electric meter, gas meter, gas 4 feet horizontal (U.S.)

regulator, and relief equipment ➀ 6 feet horizontal (Canada)
Gas regulator ➀ 3 feet horizontal (U.S.)

6 feet horizontal (Canada)
Adjoining building or parapet wall 6 feet all directions
Adjacent public walkways 7 feet all directions
Grade (ground level) 3 feet above

➀

Do not terminate the vent directly above a gas meter or regulator.

A14. Do NOT vent this appliance into a masonry chimney.
A15. Do NOT use dampers or other devices in the vent or

combustion air pipes.

A16.

The venting system must be exclusive to a single
appliance, and no other appliance is allowed to be vented
into it.

A17. Precautions must be taken to prevent degradation of

building materials by flue products.

A18. Single wall vent pipe must not pass through any

unoccupied attic, inside wall, concealed space, or floor.

A19. Uninsulated single wall vent pipe must not be used

outdoors for venting appliances in regions where the 99%
winter design temperature is below 32°F.A19. Long runs
of horizontal or vertical combustion air pipes may require
insulation in very cold climates to prevent the buildup of
condensation on the outside of the pipe where the pipe
passes through conditioned spaces.

A20. Vertical combustion air pipes should be fitted with a tee

with a drip leg and a clean out cap to prevent against the
possibility of any moisture in the combustion air pipe from
entering the unit. The drip leg should be inspected and
cleaned out periodically during the heating season.

A21. The vent terminal must be:

Table 7.2 - Vent Terminals (two pipe)

Model Size Modine PN Other Listed Terminals

30-45 5H0722850005 Gary Steel 1092

60-75 5H0722850001 Gary Steel 1092

100-125 5H0722850001 Gary Steel 1092

A22. In addition to following these general instructions, specific

instructions for vertical and horizontal vent systems in
2-Pipe or concentric vent configurations must also be
followed. The following outlines the differences:

Vertical Category III Vent System Determination

• Vertical vent systems terminate vertically (up) (an example is
shown in Figure 8.1).

• Determine the venting configuration as follows:

> For two building penetrations through the wall or roof (one

for the combustion air inlet pipe and one for the vent pipe),
proceed to “Section B - Vertical 2-Pipe Venting”.

> For a single larger building penetration through the wall or

roof, through which both the combustion air inlet and vent
pipes will pass, proceed to “Section D - Horizontal and
Vertical Concentric Venting”.

> For all other cases, proceed to the next section for

Horizontal Vent System Determination.

Horizontal Category III Vent System Determination

• Horizontal vent systems terminate horizontally (sideways)
(an example is shown in Figure 9.1).

• Determine the venting configuration as follows:

> For two building penetrations through the wall or roof (one

for the combustion air inlet pipe and one for the vent pipe),
proceed to “Section C - Horizontal 2-Pipe Venting”.

> For a single larger building penetration through the wall or

roof, through which both the combustion air inlet and vent
pipes will pass, proceed to “Section D - Horizontal and
Vertical Concentric Venting”.

6-584.8

7

INSTALLATION - VENTING

Section B – Vertical 2-Pipe Vent System
Installation

B1. This section applies to vertically vented 2-pipe (one

combustion air inlet pipe and one vent pipe) vent systems
and is in addition to “Section A – General Instructions – All

Units”.
B2. Vertical vent systems terminate vertically (up).
B3. It is recommended to install a tee with drip leg and clean out

cap as shown in Figure 8.1.
B4. The combustion air and vent pipes must be terminated with

2 listed vent caps.
B5. Vertical vents must terminate a minimum horizontal and

vertical distance from roof lines and adjacent walls or

obstructions. These minimum distances are outlined in

Figure 8.1 and Table 8.1.
B6. The vent must terminate at least 1' above and 6" horizontally

from the combustion air inlet.

Figure 8.1 - Vertical 2-Pipe Vent System - Sloped Roof

Table 8.1 - Minimum Height from Roof to Lowest
Discharge Opening

Rise X (in) Roof Pitch Min Height H (ft) ➀
0-6 Flat to 6/12 1.00
6-7 6/12 to 7/12 1.25
7-8 7/12 to 8/12 1.50
8-9 8/12 to 9/12 2.00
9-10 9/12 to 10/12 2.50
10-11 10/12 to 11/12 3.25
11-12 11/12 to 12/12 4.00
12-14 12/12 to 14/12 5.00
14-16 14/12 to 16/12 6.00
16-18 16/12 to 18/12 7.00
18-20 18/12 to 20/12 7.50
20-21 20/12 to 21/12 8.00

➀ Size according to expected snow depth.

Figure 8.2 - Vertical 2-Pipe Vent System - Flat Roof

TO WALL OR ADJOINING BUILDING

MINIMUM DISTANCE TO ADJOINING WALL
OR BUILDING IS 2 FEET.

REFER TO TABLE 8.1 FOR "H" DIMENSION.

ROOF FLASHING

"H" MIN*

(SEE TABLE 8.1)

USE LISTED THIMBLES
THROUGH CEILING
AND ROOF

X

ROOF PITCH IS:

X / 12

12

USE LISTED THIMBLE
THROUGH ROOF AND
CEILING

"H" MIN*

(SEE TABLE 8.1)

EXHAUST

COMBUSTION AIR

"H" MIN*

LISTED
TERMINAL

TEE WITH DRIP LEG
AND CLEANOUT CAP

(SEE TABLE 8.1)

LISTED
TERMINAL

"H" MIN*

ROOF FLASHING

2' MIN

LISTED
TERMINAL

6" MIN

LISTED
TERMINAL

12" MIN

USE THIMBLE
THROUGH
CELLING

12" MIN*

Exhaust

ROOF FLASHING

* SIZE ACCORNING
TO EXPECTED

Combustion Air

SNOW DEPTH.

TEE WITH DRIP LEG
AND CLEANOUT CAP

B9. Once venting is complete, proceed section titled “Installation

– Gas Connections”.

BACK VIEW

4" MIN

EXHAUST

COMBUSTION AIR

12" MIN

RECOMMENDED

8

TEE WITH DRIP LEG
AND CLEANOUT CAP

(SLOPE 1/4" PER
FOOT DOWNWARD
TOWARD DRIP LEG)

6-584.8