Low Draft Voltage Adjustment - Harman Home Heating PC 45 Installation & Operating Manual

Corn/pellet/grain stove
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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.

low draft voltage Adjustment

These units are pre-tested at the factory with exactly
120 Volts A.C., 60 Hz. They are checked and adjusted
for firebox tightness, gasket leakage, motor operation
and ignitor operation. The PC 45 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 PC45 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 feeder motor or
.
the igniter to operate
A simple draft test should be performed after
completing the flue pipe installation. To record the results
for future reference:
20
PC 45 Corn/Pellet Stove
low draft voltage Adjustment
Fig. 27
draft meter bolt
hole location
On a PC 45 the draft
hole is under the left
rear corner of the
firebox.
Fig. 28
draft Test Instructions
1. Attach a draft meter capable of reading up to a
minimum of 0.5 inches of water column (W.C.).
2. Plug the unit's power cord into a 120VAC, 60 HZ
grounded outlet.
3. Close the hopper lid, front view door, and the ash
pan access door. Neither fuel or a fire are required for
this test.
4. With the mode selector in the "OFF" position, turn the
feed adjuster to "TEST".
5. Record the high draft_____in W.C. (Normal is
-.35 to -.55) The control will be on the High Draft for a
minute.
6. After 1 minute is up, 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.
7. If the low draft is between -.25 and -.35, 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 -.25 to -.35 even with the set screw completely
counter-clockwise. This is not a problem. vertical
runs of venting may add natural draft.
If the draft reading does not drop at all when the test
mode switches from high to low, be sure to check
for restrictions in the appliance air intake.

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