46
FURNACE
PIPE DIAMETER
TRANSITION IN
VERTICAL SECTION
NOT IN
HORIZONTAL
SECTION
A93034
Fig. 42 -- Combustion Air and Vent Pipe Diameter Transition Location and Elbow Configuration
The Maximum Vent Length for the vent and combustion air pipe
(when used) is determined from the Maximum Equivalent Vent
Length in Table 16 minus the number of fittings multiplied by the
deduction for each type of fitting used from Table 17.
OPTIONAL CONFIGURATION FOR COMBUSTION
AIR INLET PIPE
In applications where there is a risk of excessive moisture
entering the combustion air inlet pipe, a moisture trap may be
added to the inlet pipe to help prevent moisture from entering
the furnace from the combustion air inlet pipe. See Fig. 44.
When sizing venting systems, the equivalent length of the
optional moisture trap (15 feet/5 M) must be taken into
account.
NOTICE
EXAMPLE FOR
UPFLOW INSTALLATIONS.
MAY BE APPLIED TO
OTHER CONFIGURATIONS.
A12220
Fig. 43 -- Sample Inlet Air Pipe Connection for Polypropylene
Venting Systems
