7
Figure 5
Combustion Air Opening
ID
Fan
Rectangular to
Round adapter
Condensate
Drain
AHU
Cabinet
4 ft. Min.
12 in. Min
Field Starkap or equal
listed Vent cap
Venting Indoor Installations
Duct furnace module must be connected to a properly designed venting system to convey flue gases
outside of the heated space. Category 1 Vent systems must be sized and installed in accordance with the National
Fuel Gas Code, ANSI Z223.1 (NFPA 54) Chapter 13 in the United States or CAN/CGA-B149 Natural and propane
gas installation code, Section 8 and Annex C, in Canada. A vent connector adaptor is available that transitions the
induced draft fan outlet (rectangular) to round vent pipe. This adaptor must be installed on the outlet of the ID fan to
provide a connection point for the vent pipe. Vent pipe connector is sized based on furnace input as listed in Table 1.
Vertically Vented Duct Furnaces
– Category I
Proper venting of the heating units is the responsibility of the installer. Venting materials are provided by others.
UL Listed Type B Vent or single wall metal pipe may be used.
If used, single wall vent pipe shall have seams and joints
sealed with pressure sensitive aluminum tape or silicone rubber sealant, rated for 480
o
F (249
o
C) or higher. Joints should be
secured with at least two corrosion resistant fasteners.
Table 1-Vent Connector Sizing
Models
Input Rating (Btuh)
Input Rating (W)
Vent Pipe Dia.
HM(D,G) 050-175; HHG050-160 50,000
– 175,000
14653
– 51287
5 in. (126 mm)
HMG200-400, HMD200; HHG200-360
200,000
– 400,000
58614
– 117228
6 in. (152 mm)
HM(A,B)150-400; HHA150-400
150,000
– 400,000
43960
– 117228
6 in. (152 mm)
HM(A,B,G)500-600; HHA500; HHG440
440,000
– 600,000
131881
– 175842
7 in. (178mm)
1. Maximize the height of the vertical run of vent pipe. A minimum of five (5) feet (1.5m) of vertical pipe is required.
The top of the vent pipe must extend at least 18 in. ( 457 mm) above the highest point on the roof. (Use Listed
Type B vent for external runs).
2. An approved weatherproof vent cap must be installed to the vent termination.
3. Horizontal runs should be pitched upward
¼” per foot (21mm/m) and should be supported at 3 foot (1m)
maximum intervals. It is best to keep horizontal runs less than 75% of vertical height to avoid possible need to
upsize vent pipe.
4. Design vent pipe runs to minimize the use of elbows. Each 90o elbow is equivalent to 5 feet (1.5m) to 7 feet
(2.13m) of straight vent pipe run depending on pipe diameter.
5. Vent pipe should not be run through unheated spaces. If such runs cannot be avoided, insulate vent pipe to
prevent condensation inside vent pipe. Insulation should be a minimum of
½” (12.7mm) thick, foil faced material
suitable for temperatures up to 500
o
F (260
o
C).
6. Dampers must not be used in vent piping runs. Spillage of flue gases into the occupied space could result.
7. Vent connectors serving Category 1 heaters must not be connected into any portion of a mechanical draft
system operating under positive pressure.
Caution!
Flue gases must be directed
away from combustion air
inlets, to avoid recirculation
into combustion air supply.
