Modine Manufacturing HD, HD30, HD45, HD60, HD75 Service Manual

INSTALLATION AND SERVICE MANUAL

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 acid
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.

6-576.5

5H74925 Rev. E

October, 2005

gas-fired unit heaters

model HD

All models approved for use in California by the CEC, in New
York city by the MEA division, 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

Unit Location. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

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

Unit Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Unit Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

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

Electrical Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Unit Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Service/Trouble Shooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Warranty. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

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

THIS MANUAL IS THE PROPERTY OF THE OWNER.

SPECIAL PRECAUTIONS/TABLE OF CONTENTS

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 you are replacing an existing heater, 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 or CSA B149.1 latest edition. Failure to follow these
instructions can result in injury or death.

4. 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.

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

6. 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.

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

8. 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.

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

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

11. 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 owners 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. Do not locate units in tightly sealed rooms or small
compartments (commonly referred to as confined spaces)
without provisions for adequate combustion air and venting.
Combustion air must have access to the confined space
through a minimum of two permanent openings in the
enclosure, at least one near the bottom. They should
provide a free area of one square inch per 1,000 BTU/Hr
input rating of the unit with a minimum of 100 square inches
for each opening, whichever is greater.

6. Low profile heaters are designed for use in heating. applica­ tions with ambient temperatures between -40°F and 90°F.

7. Do not install unit outdoors.

8. 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, and
in repair garages the standard for repair garages 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.

9. 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.

10. 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.

11. 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.

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

13. 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.

14. 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 combustion and proper operation of fan.

15. 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.

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

2

6-576.5

SPECIAL PRECAUTIONS / SI (METRIC) CONVERSION FACTORS / UNIT LOCATION

CAUTION

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).

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. Servicing or repairing of this equipment must be performed
by a qualified service agency.

23. Do not attempt to reuse any mechanical or electronic igni­ tion 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 check most of the Possible Remedies in the trouble-
shooting guide listed in Tables 17.1 and 18.1, refer to the
applicable sections of the manual.

SI (METRIC) CONVERSION FACTORS

Table 3.1

To Convert Multiply By To Obtain

"W.C. 0.249 kPa
°F (°F-32) x 5/9 °C
Btu 1.06 kJ
Btu/ft3 37.3 kJ/m
Btu/hr 0.000293 kW
CFH (ft3/hr) 0.000472 m3/min
CFH (ft3/hr) 0.00000787 m3/s
CFM (ft3/min) 0.0283 m3/min
CFM (ft3/min) 0.000472 m3/s

To Convert Multiply By To Obtain

feet 0.305 m
Gal/Hr. 0.00379 m3/hr
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.

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 (also
known as 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 reduced speed.

4. Information on controls is supplied separately.

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

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. Do not locate units in tightly sealed rooms or small
compartments (commonly referred to as confined spaces)
without provisions for adequate combustion air and
venting. Combustion air must have access to the confined
space through a minimum of two permanent openings in
the enclosure, at least one near the bottom. They should
provide a free area of one square inch per 1,000 BTU/Hr
input rating of the unit with a minimum of 100 square
inches for each opening, whichever is greater.

3. Low profile heaters are designed for use in heating applica­ tions with ambient temperatures between -40°F and 90°F.

4. Do not install unit outdoors.

5. 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,
and in repair garages the standard for repair garages 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.

6. 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 accor-
dance with the requirements of the enforcing authority
and/or NFPA 409-latest edition.

7. 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.

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 exhaust

6-576.5

vent piping must be connected to the outside atmosphere.

33

UNIT LOCATION

3. Be sure the structural support at the unit location site is
adequate to support the weight of the unit. 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.

Table 4.1 Clearances

Unit Side Clearance To Recommended
Combustilble Materials Service Clearance

Top and Bottom 1" 1"
Access Side 18" 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
information 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.

Combustion Air Requirements

The National Fuel Gas Code defines an “unconfined space” as
a space whose volume is greater than 50 cubic feet per 1,000
Btu/Hr input of the installed appliance(s). A confined space
is 50 cubic feet or less per 1,000 Btu/Hr input of the installed
appliance(s).

It is not recommended to install these unit heaters into residential
confined spaces. This recommendation is due to the concern
that at some point in time, the combustion air openings provided
by the installer may become blocked or eliminated by the owner,
either intentionally or unintentionally. Despite this commendation,
if these units are installed into a residential confined space, see
National Fuel Gas Code ANSI Z223.1 or CSA B149.1 Installation
Code, latest edition, for detailed combustion air provisions. These
requirements must be adheard to.

Units installed into confined spaces in industrial/commercial
installations, must be provided with two permanent openings,
one near the top of the confined space and one near the bottom
of the confined space. Each opening should have a free area of
not less than one square inch per 1,000 Btu/Hr of the total input
rating of all units in the confined space, freely communicating
with interior areas having, in turn, adequate infiltration from the
outside.

For further details on supplying combustion or to a confined (tightly
sealed) space or unconfined space, see the National Fuel Gas
Code ANSI Z223.1 or CSA B149.1 Installation Code, latest edition.

Turning The Unit 180°

All units are produced at the factory with left-side controls, when
looking at the unit. If the installation requires that the controls be
on the right side, the unit heater can be “turned over”. In addition,
the following instructions must be followed:

• 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. This is important 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.

4

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 requited 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 combustion and proper operation
of fan.

1. Be sure the means of suspension is adequate to support
the weight of the unit (see page 16 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. Mounting bracket installation:
Before lifting the heater for suspension, the mounting
brackets must be installed. Decide if the unit will be
installed as standard; that is with left-side controls when
looking at the front of the unit or with right-side controls.

For standard (left side)remove brackets from shipping

position and remove the (3) screws along the top edge of
both the front and back of unit. Align screw holes on
mounting bracket with holes along front and back top
edges. Secure (1) mounting bracket to front of unit with
retained screws. Secure the other mounting bracket to back
of unit in a similar way.

For right-hand, the mounting brackets are attached in a

similar manner after the unit is turned over.

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 1" - angle,
mounting brackets are slotted to accommodate joists on 16"
or 24" centerlines.

5b. Suspension by threaded rod:
This heater can also be hung utilizing the same mounting
brackets and threaded rod. Attach the threaded rod to the
unit mounting brackets, securing with a top and bottom nut.

Next, drill holes into a steel channel or angle iron at the
same centerline dimensions as those chosen for the heater
that is 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 double nut arrangement like used on
the unit heater mounting brackets.

5c. Shelf mounted units:
The unit heater can also be installed on a shelf, if so
desired. The mounting brackets will need to be attached to
the heater the same manner as explained earlier, 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.

6-576.5

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 you are replacing an existing heater, 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 or CSA B149.1 latest edition. Failure to follow these
instructions can result in serious 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.

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.

Before you start use the following steps to verify that
the venting system is adequately sized:

1. Seal any unused openings in the venting system.

2. 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.

3. In so 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. Turn on clothes dryers and any
exhaust fans such as range hoods and bathroom exhausts,
so they shall operate at maximum speed. Do not operate a
summer exhaust fan. Close fireplace dampers.

4. Follow the lighting instructions. Place the appliance being
inspected in operation. Adjust thermostat so that the
appliance will operate continuously.

5. 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-burning appliance to their
previous conditions of use.

6. If improper venting is observed during any of the above
tests, the venting system must be corrected.

Table 5.1
ANSI Unit Heater Venting Requirements

Venting
Category Description Requirements

I Negative vent pressure Follow standard

Non-condensing venting requirements.
II Negative vent pressure Condensate must
Condensing be drained.
III Positive vent pressure Vent must be gas tight.
Non-condensing
IV Positive vent pressure Vent must be liquid and
Condensing gastight. Condensate
must be drained.

Note: A vent is the vertical passageway used to convey flue gases
from the unit or the vent connector to the outside atmosphere.
A vent connector is the pipe which connects the unit to a vent
or chimney. Vent connectors serving Category I appliances shall
not be connected into any portion of mechanical draft systems
operating under positive pressure.

Venting Instructions

1. All vertically vented heaters are category I venting. All
horizontally vented heaters are category I or III depending
on venting. The pipe should be galvanized steel or other
suitable corrosion resistant material (except for category III
horizontal, refer to Additional Requirements for Horizontal
Category III Venting section). 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.

2. Vertically vented (horizontal run does not exceed 75% of
vertical rise and vent terminates no less than 5’ above the
vent connector) units may be vented with single or double
wall vent pipe. Horizontally vented units must use single wall
vent pipe (category III residential may vary) although one
continuous section of double wall vent pipe may be used
with the vent system.

3. Using Table 5.1, determine the venting requirements for
the category determined above. A category III heater must
conform to the venting requirements called out in Table

5.1, which are detailed in the following sections, as well as
additional requirements also detailed in following sections.

4. A minimum of 12" straight pipe is recommended from the
flue outlet before turns in the vent pipe. For vertical venting,
it is recommended to install a tee with drip leg and clean out
cap to the flue outlet followed by a 90° elbow.

5. All heaters come with a factory installed 3” vent adapter for
attaching the vent pipe to the heater. Attach the vent pipe
to the adapter with 3 non-corrosive screws. (Drill pilot holes
through the vent pipe and adapter prior to screwing in place)

6. Install the vent pipes with a minimum downward slope from
the appliance of 1/4 inch per foot and suspend securely
from overhead structures at no points greater than 3' apart.
Fasten individual lengths of vent together with at least three
corrosion resistant sheet metal screws.

7. Keep single wall vent pipe at least 6" from combustible
materials. Follow the double wall 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 (such as material distortion or
discoloration) could result.

8. 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 350°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 Figures 6.2 and

6.3.

9. 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.

6-576.5

55

INSTALLATION

10. Do NOT use dampers or other devices in the vent or
combustion air pipes.

11. Precautions must be taken to prevent degradation of building
materials by flue products.

12. Single wall vent pipe must not pass through any unoccupied
attic, inside wall, concealed space, or floor.

13. All vertically vented heaters that are category I must be
connected to a factory built chimney or vent complying with
a recognized standard, or a masonry (or concrete) lined
chimney with a material acceptable to the authority having
jurisdiction. Venting into an unlined masonry chimney is not
permitted. Refer to the National Fuel Gas Code for common
venting.

14. The outlet of the vent should extend as shown in Figure

6.3 and Table 6.1 if the following conditions are met: Vent
diameter is less than 12", vent is of double wall construction
and is a listed product, and the vent does not terminate
within 8’ of a vertical wall or similar obstruction. For vents that
have a diameter of 12" or larger, constructed of single wall, or
terminate within 8' of a vertical wall or similar obstruction, the
vent pipe shall extend at least 2' higher than any portion of
a building within a horizontal distance of 10’ (refer to Figure

6.2).

15. The vent system exhaust shall terminate at least 3’ above
any forced air inlet located within 10’, and at least 4’ below, 4’
horizontally from, or 1’ above any door, window, or gravity air
inlet into any building and 2’ from wall or adjoining building.
The bottom of the vent terminal shall be located above the
snow line or at least 1’ above grade; whichever is greater.
When located adjacent to public walkways the vent system
shall terminate not less than 7’ above grade.

16. A minimum of 4’ horizontal terminal clearance (6’ for
Canada) from gas and electric meters, regulators, and relief
equipment is required. The vent terminal shall not terminate
closer than 2’ to adjacent buildings.

17. Use an approved vent terminal to reduce down drafts and
moisture in the vent.

Figure 6.1
Venting Through Combustible Wall or Roof

Single Wall Vent Pipe

Listed
Terminal

Double Wall Vent Pipe ➀

Listed
Terminal

Table 6.1
Minimum Height from Roof to
Lowest Discharge Opening

Rise Roof Pitch Min Height
X (in) 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 6.2
Vertical Venting Through Flat Roof

8' Min

Listed Terminal

2' Min

5' Min

4" Min

Downward

Drip Leg

Slope 1/4" towards drip leg.

12" Min

Figure 6.3
Vertical Venting Through Sloped Roof

Flashing

Clearance Specified
by Type B Vent Mfg.

Double
Wall

Single
Wall

Listed
Thimble

Single
Wall

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

Clearance Specified
by Type B Vent Mfg.

Single Wall Vent Pipe

Listed
Thimble

Flashing

➀ See Instructions for attaching single wall pipe to double wall pipe (page 6)

6

Specified

Terminal

Specified

Terminal

Drip Leg

6-576.5

Listed
Terminal

Downward
Slope 1/4" towards drip leg.

4" Min

12" Min

X

H

12

Roof Pitch is

x/12