Thermo Pride CMA4-50D36N, Installation And Service Manual, Page: 29 / 66

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gas flame. Should acid compounds form in your furnace, it may reduce the
life of the furnace.
H. Direct Venting Through a Sidewall
1. Vent And Combustion Air Pipes
Vent and combustion air pipes may pass through a maximum wall thickness
of 18 inches. The minimum wall thickness is 2 inches. Referring to Figure
7, the maximum distance from the outer wall to the center of the elbow is 12
inches.
Figure 7: Proper Direct Vent Terminations (RH & LH views) and Vent
Termination Only w/o Outside Combustion Air Intake (RH view)
NOTICE: If exterior sidewall building materials are subject to degradation
from contact with flue gases or moisture, a minimum 24-inch diameter shield
shall be fabricated from stainless steel or UV-resistant plastic sheet. The
protective shield shall be installed around the vent pipe on the outside wall.
2. Exhaust Vent Termination Elbow
The exhaust vent termination elbow shall be installed in accordance with
these instructions and any applicable local codes. Refer to Figures 7 and 8 for
typical examples of proper terminations.
a. The exhaust vent termination must be installed in the same
atmospheric pressure zone (i.e. on the same wall) as the air intake
termination.