Harman Stove Company HARMAN P68 - Manual (Page 20)

20 P68 Pellet Stove 3-90-00688R24_06/13
low draft voltage adjustment
These units are pre-tested at the factory with exactly 120 VAC,
60 Hz. They are checked and adjusted for firebox tightness,
gasket leakage, motor operation and igniter operation. The
P68 is then factory set at a mid-point adjustment and in most
cases will not need any adjustments.
note: the factory low draft setting may not be correct
for the unit's permanent installation conditions.
The control board on the P68 is equipped with a low draft
adjustment port. Located on the control face just to the right
of the igniter light. This voltage adjustment is provided to allow
the unit to be adjusted for the household voltage where the
unit is going to be in permanent operation. note: the line
voltage varies from area to area and often home to home.
The low draft voltage should be adjusted to achieve the most
efficient burn on low burn or "maintenance". This voltage
adjustment allows the installer to change the low voltage set
point approximately 10 volts. This adjustment should be done
by the installer during set up because a draft meter reading
is required to insure proper set up.
If the unit is not adjusted properly, it does not cause a safety
concern. If the unit is adjusted too high, only effiency is lost.
If the unit is adjusted too low, the low draft pressure switch
will not allow the feed motor or the igniter to operate.
Combustion Motor
Speed Control
Low draft only set
point.
The small straight
screwdriver slot is
plastic; therefore, the
unit can be adjusted
while in operation.
Fig.22
Fig. 23
Draft Meter bolt hole
location
On a P68 the draft test
hole is under the left rear
corner of the firebox.
low draft voltage adjustment
A simple draft test should be performed after completing the
flue pipe installation. To record the results for future reference:
1. Plug 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 total of 1 minute.
5. After a 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 -.35 and -.45, record the reading
_____ in W.C. If the reading is higher, slowly turn the
set screw counter-clockwise until the draft lowers. If the
reading is lower, very slowly turn the set screw clockwise
until the draft increases.
note: in some cases, the draft may not go as low as
-.35 to -.45 even with the set screw completely counter-
clockwise. ideally, you should just set it as low as
possible.
If there is no change in draft reading between high and low
voltage, check for obstructions in the air intake or the outside
air connection, if installed.