HTP 399M - Manual (Page 15)

VENTING
15
**IMPORTANT NOTE: All vent pipes must be glued, properly supported and the exhaust must be pitched a minimum of a
¼" per foot back to the heater (to allow drainage of condensate). Always increase pipe in vertical position. Never increase
pipe size in horizontal position.
Figure 4-1a: 4" Sidewall Vent with Tee (Intake) & Coupling (Exhaust)
DIAGRAMS FOR SIDEWALL VENTING