Low Draft Voltage Adjustment - Harman XXV Installation & Operating Manual

Fig.29
Fig.1

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 igniter operation. The XXV 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 XXV is equipped with
a low draft adjustment port. Located on the control
face just to the left 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.
A simple draft test should be performed after
20
XXV Pellet Stove
Low Draft Voltage Adjustment
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.
Draft Meter
inches of water
Fig.30
completing the flue pipe installation. To record the results
for future reference:
1. Plug unit into a 120VAC, 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 2 minutes.
5. After 2 minutes, 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: The test mode alternates from high to low
draft every 60 seconds. If more time is needed
for draft adjustment, wait until the next low draft
cycle.
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.
Draft Meter bolt hole location
is just behind the left front
leg, near the top of the ash
pan area.