9
P68 Pellet Stove
A combustion blower is used to extract the combustion
gases from the rebox. This causes a negative pressure
in the rebox and a positive pressure in the venting
system as shown in Fig. 7. The longer the vent pipe and
more elbows used in the system, the greater the ow
resistance. Because of these facts we recommend using
as few elbows as possible and 15 feet or less of vent
pipe. The maximum horizontal run should not exceed
48". If more than 15 feet of pipe is needed, the interior
diameter should be increased from 3" to 4" because
a larger pipe causes less ow resistance.
Approved 3" or 4" Pellet Vent Pipe Such As,
Type "PL", Must Be Used.
Fig. 7
Pellet venting pipe (known as PL vent) is constructed
of two layers with air space between the layers.
This air space acts as an insulator and reduces the
outside surface temperature to allow a clearance to
combustibles of 1 to 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 P68 operates with a
positive vent pressure
Aluminum
tape can also be used for any joint that is 1ft. or more
from the outlet of the stove.
T
without exhaust blower
operation. Negative pressure in the house will resist this
natural draft if not accounted for in the pellet appliance
installation.
Heat rises in the house and leaks out at upper levels.
This air must be replaced with cold air from outdoors,
which ows into lower levels of the house. Vents and
chimneys into basements and lower levels of the house
can become the conduit for air supply, and reverse
under these conditions.
= Positive Static Pressure
= Negative Static Pressure
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