Draft Test Procedure - Harman PP38+ Installation & Operating Manual

A simple draft test should be performed before
and after completing the flue pipe installation.
To compare and to record the results for future
reference:
1. Plug the unit into a 120 VAC, 60 HZ outlet.
2. Close the hopper lid, front view door, and the
ash pan. Neither pellets or a fire are required for
this test.
3. With the mode selector in the "OFF" position,
turn the feed adjuster to "TEST".
4. Record the high draft______in W.C. (Normal
is -.50 to -.60) The control will be on the High
Draft for a minute.
5. After 1 minute, the combustion motor will go
down to low draft and the distribution blower will
go on high. Allow approximately 15 seconds to
pass for the combustion motor to slow before
checking the low draft.
6. If the low draft is between -.25 and -.35,
record the reading _____ in W.C.
If the reading is lower, check for resistance in
the venting configuration. Too many elbows, or
excessive horizontal runs will add resistance.
Also, be sure the doors and hopper lid are
properly secured.
As long as the draft reading drops when the
combustion blower goes to low speed, higher
readings are not an issue. Long vertical runs
can actually increase the readings due to the
addition of natural draft. If the draft reading does
not drop, there is likely restriction on the air
intake. Be sure the intake flapper is opening and
check for resistance in the outside air conduit if
installed.

draft test Procedure

Draft Meter bolt
hole location
On a PP38 the draft
test hole is under the
left rear corner of the
firebox.
Fig. 23
PP38+ Pellet Stove
19