Harman Stove Company P43 - Manual (Page 8)

8 P43 Pellet Stove
venting
A combustion blower is used to extract the
combustion gases from the firebox. This causes a
negative pressure in the firebox and a positive pres-
sure in the venting system as shown in Fig. 7. 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. 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 flow resistance. be sure
to use approved pellet vent pipe wall and ceiling
pass-through fittings to go through combustible
walls and ceilings. The use of a starting collar is
not always necessary. The first piece of pipe should
be fastened securely with at least fasteners to the
flue collar of the stove. If a starting collar is used to
attach the venting system to the stove, the starting
collar must be sealed to the stove with high temp
silicone caulking.
vent Pipe
Pellet venting pipe (known as L or 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 P43 operates with a positive vent
pressure we specify that the joints also be sealed
with silicone. Aluminum tape can also be used for
any joint that is 1ft. or more from the outlet of the
stove.
We cannot emphasize enough, the importance
of sealing every seam and joint in the venting system
which is inside the home. Even the smallest pin hole
can leak and when it does you will smell wood smoke
or a creosote smell in the room. If this occurs check
for leaks. Leaks are easiest to see during start-up.
Alternatively you can use a smoke pellet to leak test
the venting before lighting your first fire.
venting
iMPOrtant nOtice
Approved Pellet Vent Pipe Such As, Type "L"
Or "PL", Must Be Used.
= Positive Static Pressure
= Negative Static Pressure
+
+
-
+
-
Fig. 7