WARNING: Solvent cements are flammable and must
be used in well-ventilated areas only. Keep them away
from heat, sparks and open flames (including pilots).
Do not breathe vapors and avoid contact with skin and
eyes.
6. All joints must be made to provide a permanent, air-tight,
water-tight seal.
7. Support the combustion air and vent piping such that it is
angled 1/4" per linear foot so that condensate will flow back
toward the furnace. Piping should be supported with pipe
hangers to prevent sagging. Maximum spacing between
hangers is five (5) feet, except SDR-PVC piping, where
maximum spacing is three (3) feet.
8. Seal around the openings where the combustion air and
vent piping pass through the roof of side wall.
CAUTION: Vent piping must be insulated with 1/2"
Armaflex insulation if it will be subjected to freezing
temperatures such as routing through unheated ar-
eas or through an unused chimney.
CAUTION: When combustion air pipe is installed
above a suspended ceiling, the pipe must be insulated
with 1/2" Armaflex type insulation. The combustion air
pipe should also be insulated when it passes through
a warm, humid space.
This type installation will use combustion air from within the
space surrounding the furnace. This may be from within the
space in a non-confined location or it may be brought into the
furnace area from outdoors. It is not directly ducted into the
furnace. A single, properly sized pipe from the furnace vent
connector to the outdoors must be provided.
For upflow models combutsion air is brought into the furnace
through the unit top panel opening. It is not necessary to install a
pipe into the intake collar on top of the burner box. For details refer
to Figure 22.
For downflow/horizontal models combustion air is brought into
the furnace through the unit side panel openings.
For downflow/horizontal models, remove a minimum of two gas
piping knockouts for combustion air access. It is not necessary
to install a pipe into the intake collar on bottom of the burner
box. For details, refer to Figure 23.
MAINTAIN 12" MINIMUM
CLEARANCE ABOVE HIGHEST
ANTICIPATED SNOW LEVEL.
MAXIMUM OF 24" ABOVE ROOF
COMBUSTION AIR
VENT
12" VERTICAL SEPARATION
BETWEEN COMBUSTION
AIR AND VENT
FIGURE 19 - VERTICAL TERMINATION
VENT
COMBUSTION AIR
2"
FIGURE 20 - DOUBLE SIDEWALL TERMINATION
6"
FIGURE 21 - DOUBLE ROOFTOP TERMINATION
METHOD
TWO:
ONE
PIPE
SYSTEM
NOTE: Vent pipe must be sloped 1/4" per foot to allow conden-
sate to flow back to the furnace.
M
P
C
1
3
2
O
FF
O
N
COMBUSTION AIR
VENT PIPE
CEMENTS
INTO SOCKET JUST
UNDER TOP PANEL
FIGURE 22 - UPFLOW VENT PIPE CONNECTION
650.75-N4U
14
Unitary Products Group
