Harman Stove Company XXV Installation & Operating Manual page 7

iMPOrtant nOtice
Pellet Vent Pipe or PL Vent Pipe Must Be Used
unless the unit is being installed with the optional
top 6" Flue Adapter.
If using 6" Flue Adapter, it is recommended to
use a sealed seam 6" flue pipe (snaplock seam
is not recommended) and seal the joints with high
temperature silicone.
In some cases it may be necessary to use a liner
in the existing chimney to obtain proper draft.
cautiOn
do not connect to any air distribution duct
or system.
+
= Positive Static Pressure
-
= Negative Static Pressure
Fig. 6
Venting
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. 6. 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 " 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-
ing) is constructed of two layers with air space
between the layers. This air space is an insulator
which reduces the surface temperature and allows
a clearance to combustibles of  inches or less. 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 XXV 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
1 ft. or more from the outlet of the stove.
When using the top vent option, 6 inch single
wall pipe must be connected with at least three ()
screws. Also, the joints must be sealed with high
temperature silicone.
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.
7
XXV Pellet Stove