Weil-McLain WM97+70 Manual page 32

WM97+ -
gas fired water boiler
DIRECT VENT —
Prepare roof penetrations
1. Air pipe penetration:
a. Cut a hole for the air pipe. Size the air pipe hole as close as
desired to the air pipe outside diameter.
2. Vent pipe penetration:
a. Cut a hole for the vent pipe. For either combustible or non-
combustible construction, size the vent pipe hole at least 0.4"
larger than the vent pipe diameter.
b. Insert a galvanized metal thimble in the vent pipe hole.
3. Space the air and vent holes to provide the minimum spacings
shown in Figure 25, page 27.
4. Follow all local codes and vent pipe manufacturer's instructions
for isolation of vent pipe when passing through floors, ceilings
and roofs.
5. Provide flashing and sealing boots sized for the vent pipe and air
pipe. Follow all vent pipe manufacturer's instructions.
Termination and fittings
1. Prepare the vent termination elbow and the air termination elbow
(Figure 31, page 31) by inserting bird screens. Bird screens must be
purchased separately. See the parts list at the end of this manual
for part numbers.
2. The air piping must terminate in a down-turned 180-degree re-
turn bend as shown in Figure 31, page 31. Locate the air inlet pipe
no further than 12 inches from the center of the vent pipe. This
placement avoids recirculation of flue products into the combus-
tion air stream.
3. The vent piping must terminate in an up-turned coupling as shown
in Figure 31, page 31. The top of the coupling must be at least 1
foot above the air intake. The air inlet pipe and vent pipe can be
located in any desired position on the roof, but must always be no
further than 12 inches apart and with the vent termination at least
1 foot above the air intake.
4. Maintain the required dimensions of the finished termination
piping as shown in Figure 31, page 31.
5. Do not extend exposed vent pipe outside of building more than
shown in this document. Condensate could freeze and block vent
pipe.
– 32 –
— Boiler Manual
Vertical with separate pipes
See notices on previous page.
Terminations for multiple boilers
Figure 32
Also maintain maximum distances between
the vent and air pipes for each boiler as shown
in Figure 25, page 27.
(continued)
Part number 550-142-085/0712