+= Positive static pressure
=Negative static pressure
Fig. 4
Venting
A combustion blower is used to extract the com- bustion gases from the firebox. This causes a nega- tive pressure in the firebox and a positive pressure in the venting system as shown in fig. 4. The longer the vent pipe and more elbows used in the system, the greater the flow resistance. Because of these facts we recommend using as few elbows as possible and 15 feet or less of vent pipe. If more than 15 feet of pipe is needed, the diameter should be increased from 3" to 4" because a larger pipe causes less flow resis- tance. Be sure to use approved pellet vent pipe and wall pass through fittings.
Vent Pipe
Pellet venting pipe ( also known as PL vent ) is constructed of two layers with an air space between them. This air space acts as an insulator and reduces the outside surface temperature to allow a clearance to combustibles of only 3 inches. The sections of pipe lock together to form an air tight seal in most cases however, in some cases a perfect seal is not achieved. For this reason and the fact that the Invincible RS operates with a positive vent pressure we specify that
the joints also be sealed with clear silicone.
Outside Air
Outside air is optional except in mobile homes and where building codes require. The benefit of outside air is mainly noticed in small very tight houses.
To install outside air use 2" sch 40 plastic pipe inserted through the back of the stove. The pipe should be run outside and terminate 3 feet or more to the side or below the vent pipe outlet. Never termi- nate the outside air above the vent pipe outlet. From the stove and through the wall the PVC must be kept 3" from PL vent pipe.
HRV
When installing in a house with a Heat Reclaim- ing Ventilation System (HRV) be sure the system is balanced and is not creating a negative pressure in the house.
5
