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.
3-90-08422R33_06/13

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
18