49
end of pipe and fitting socket (over primer). Apply cement
in a light, uniform coat on inside of socket to prevent
buildup of excess cement. Apply second coat. DO NOT
CEMENT POLYPROPYLENE FITTINGS.
13. While cement is still wet, twist pipe into socket with 1/4--in.
turn. Be sure pipe is fully inserted into fitting socket.
14. Wipe excess cement from joint. A continuous bead of ce-
ment will be visible around perimeter of a properly made
joint.
15. Handle pipe joints carefully until cement sets.
16. Horizontal portions of the venting system shall be
supported to prevent sagging. Space combustion air piping
and vent piping hangars as shown in Table 11. Support
pipes using perforated metal hanging strap or commercially
available hangars or straps designed to support plastic pipe.
17. Slope the vent and combustion air piping downward
towards furnace. A minimum slope of at least 1/4-in. (6
mm) per linear ft.(1-in (25 mm) per 4 ft.(1.2 M)) with no
sags between hangers is required. See Caution Box below.
FURNACE RELIABILITY HAZARD
Failure to follow this caution may result in nuisance short
cycling, frozen vent termination, and/or no heat.
Slope the vent and combustion air piping downward towards
furnace a minimum of 1/4--in. (6 mm) per linear ft. of pipe.
CAUTION
!
18. Complete the vent and combustion air pipe installation by
connecting the concentric vent or by installing the required
termination elbows as shown in Fig. 53, 54 and 56.
For Ventilated Combustion Air Termination, See Fig. 57.
19. Use appropriate methods to seal openings where combus-
tion air pipe and vent pipe pass through roof or sidewall.
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in personal injury
or death.
DO NOT
use cement to join polypropylene venting systems.
Follow the polypropylene venting system manufacturer’s
instructions for installing polypropylene venting systems.
!
WARNING
Table 11 – Hanger Spacing
Diameter
Material
PVC Sch 40
SDR 21 & 26
ABS
CPVC
Polypropylene
1 1/2--in.
3--ft.
2 1/2--ft.
3--ft.
3--ft.
3.25--ft.
38--mm
914--mm
762--mm
914--mm
914--mm
1000 mm
2--in.
3--ft.
3--ft.
3--ft.
3--ft.
3.25--ft.
51--mm
914--mm
914--mm
914--mm
914--mm
1000 mm
2 1/2--in.
3 1/2--ft.
3--ft.
3 1/2--ft.
3 1/2--ft.
3.25--ft.
64--mm
1067--mm
914--mm
1067--mm
1067--mm
1000 mm
3--in.
3 1/2--ft.
3--ft.
3 1/2--ft.
3 1/2--ft.
3.25--ft.
76--mm
1067--mm
914--mm
1067--mm
1067--mm
1000 mm
4--in.
4--ft.
3 1/2--ft.
4--ft.
4--ft.
3.25--ft.
