Instructions / Assembly

6
6-583.8
Model HD/HDB 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 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 Category I vent systems ➀
C HORIZONTAL Category III vent systems ➀
➀ The difference between Vertical Category I and Horizontal Category III will be
identified in "Section A - General Instructions - All Units".
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 (NFPA 54) 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 vent pipe should be galvanized steel or other suitable
corrosion resistant material (except for Horizontal Category
III vent systems, which will be covered in “Section C –
Horizontal, Category III Vent System Installation”). 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 a factory installed 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).
A4. Refer to Table 6.1 for total equivalent vent pipe lengths,
making the vent system as straight as possible. The
equivalent length of a 3" elbow is 1' and for a 4" elbow is 5'.
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 inch
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.
A10. When the vent passes through a combustible INTERIOR
wall or floor, a metal thimble 4" greater than the vent
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 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 the National Fuel Gas Code,
ANSI Z223.1 (NFPA 54) - latest edition. In Canada, installation
must be in accordance with CSA B149.1.
Figure 6.1 - Venting Through Combustible Roof
or Wall
Listed
Terminal
Flashing
Listed
Thimble
Listed
Terminal
Flashing
Clearance Specified
by Type B Vent Mfg.
Listed
Thimble
Single Wall Vent Pipe
Double Wall Vent Pipe ➀
Non-Residential Single Wall Vent
Pipe Terminating with Double Wall
Vent Pipe ➀
Agency Approved Vent
Kit or Single Wall Vent
Pipe
➀ See Instruction A10 for attaching single wall pipe to double wall pipe
Double
Wall
Single
Wall
Listed
Terminal
Clearance Specified
by Type B Vent Mfg.
Single
Wall
Listed
Terminal
Table 6.1 - Vent Pipe Diameters and Total Equivalent
Vent Pipe Lengths For Horizontal Venting Systems
Model Size Vent Pipe Diameter
Minimum
Eqv. Length
Maximum
Eqv. Length
30-75 3" 3' 30'
100-125 4" 3' 30'