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Part number 550-101-235/0903
7
GAS-FIRED WATER BOILER — Vent Supplement
Vent/air termination — through roof
(continued)
3
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 noncombustible construction,
size the vent pipe hole at least 0.4" larger than
the vent pipe diameter:
• 4" hole for 3" PVC
• 5" hole for 4" PVC
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 1, page 6.
4. Follow all local codes 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.
Termination and fittings
1. Prepare the vent termination coupling and the air
termination elbow (Figure 1, page 6) by inserting the
bird screens provided with the boiler. Bird screens
are provided for either 3-inch (Ultra-80, -105 and -
155) or 4-inch (Ultra-230 and -310) fittings.
a. If using 3-inch piping for an Ultra-230, cut the 4-
inch bird screen supplied by placing 3-inch fitting
on screen and cutting around it as a template.
2. The air piping must terminate in a down-turned 180-
degree return bend as shown in Figure 1, page 6.
Locate the air inlet pipe no further than 2 feet from
the center of the vent pipe. This placement avoids
recirculation of flue products into the combustion
air stream.
3. The vent piping must terminate in an up-turned
coupling as shown in Figure 1, page 6. 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 2 feet 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 1, page 6.
5. Do not extend exposed vent pipe outside of building
more than shown in this document. Condensate
could freeze and block vent pipe.
Multiple vent/air terminations
1. When terminating multiple Ultra boilers, terminate
each vent/air connection as described in this
supplement.
Terminate all vent pipes at the same height
and all air pipes at the same height to avoid
possibility of severe personal injury, death
or substantial property damage.
2. Place roof penetrations to obtain minimum clearance
of 12 inches between edge of air intake elbow and
adjacent vent pipe of another boiler for U. S.
installations (see Figure 2). For Canadian
installations, provide clearances required by CSA
B149.1 or B149.2 Installation Code.
3. The air inlet of an Ultra boiler is part of a direct
vent connection. It is not classified as a forced air
intake with regard to spacing from adjacent boiler
vents.
Figure 2 Through roof terminations with
multiple boilers