035-17468-001 Rev. A (801)
14
Unitary Products Group
COMBUSTION AIR AND VENT SYSTEM
1.
Two-pipe with a sealed combustion intake/vent system
using outdoor combustion air.
2.
Single pipe vent system using combustion air from the
area surrounding the furnace.
3.
Two-pipe intake/vent system using combustion air from a
ventilated attic space and a vent pipe to the outside.
Be sure to follow the appropriate venting section details,
related information and limitations for your type of installation.
METHOD ONE: TWO PIPE SEALED
COMBUSTION AIR & VENT SYSTEM
COMBUSTION AIR INTAKE/VENT CONNECTIONS
This type installation requires outdoor combustion air. Two
separate, properly-sized pipes must be used. One bringing
air from the outdoors to the furnace combustion air intake col-
lar on the burner box, and a second pipe from the furnace
vent connection (top right of unit) back to the outdoors. Refer
to Figure 16 or 17.
The intake/vent should be located either through the wall
(horizontal or side vent) or through the roof (vertical vent).
Care should be taken to locate side vented systems where
trees or shrubs will not block or restrict supply air from enter-
ing or combustion products from leaving the terminal.
Also, the terminal assembly should be located as far as pos-
sible from a swimming pool or a location where swimming
pool chemicals might be stored. Be sure the terminal assem-
bly follows the outdoor clearances listed in Table 3 for U.S.
installations: In Canada, refer to CAN/CGA-B149.1 or .2
Installation Code (latest edition-Venting Systems and Air
Supply).
COMBUSTION AIR/VENT PIPE SIZING
To select the proper size piping for combustion air intake and
venting refer to Table 6 on Page 19. The size will be deter-
mined by a combination of furnace model, total length of run,
and the number of elbows required. The following rules must
also be observed.
This furnace is certified to be installed with one of
three possible intake/vent configurations.
Furnace Intake / Vent Connection Size (All Models)
60 - 100 MBH
120 MBH
Intake
2”
3"
Vent
2”
2"
1
1.
Vent must be increased to 3" on this model.
Note 1:Any vent pipe size change must be made outside
furnace casing in a vertical pipe section to allow proper
drainage of condensate.
Note 2: An offset using two 45 degree elbows will be required
for plenum clearance when the vent is increased to 3”.
FIGURE 16 :
Air Intake and Vent Locations - Upflow
FIGURE 17 :
Air Intake and Vent Locations -
Downflow/Horizontal
VENT PIPE
CEMENTS
INTO SOCKET
JUST UNDER
TOP PANEL
COMBUSTION AIR
PIPE PASSES
THROUGH TOP PANEL
CONNECTS TO
COLLAR ON TOP
OF BURNER BOX
OPTIONAL
LEFT SIDE
COMBUSTION
AIR PIPE
ROUTING
COMBUSTION
AIR PIPE
CONNECTS TO
COLLAR ON
BOTTOM OF
BURNER BOX
VENT PIPE PASSES
THROUGH TOP PANEL
