036-21521-001-A-0103
Unitary Products Group
11
circulating fan will cycle on and off with the compressor.
If desired, the air circulating fan can be run continu-
ously.
The units have a lock out relay that will prevent the unit
from cycling on the low pressure cut out or the high
pressure cut out. If either of these safety devices open,
the compressor will not restart when the safety device
resets. To restart the compressor after a safety lock
out, it will be necessary to interrupt the power to the
control circuit. This can be done at the thermostat or at
the disconnect switch.
START-UP
1. Set the thermostat to the highest setting.
2. Set the fan switch to the 'AUTO' position, and the
thermostat system switch to 'COOL'.
3. Reduce the thermostat setting to approximately 5
degrees below room temperature.
4. The compressor, and the supply air blower, will
start. Simultaneously the reversing valve will be
energized.
5. After five minutes, verify cooling mode operation by
checking for cool air discharge at the supply air
outlet.
6. Set the thermostat system switch to the 'OFF' posi-
tion. The unit will stop running, and the reversing
valve will de-energize.
7. Allow approximately five minutes to allow for sys-
tem pressures to equalize.
8. Set the thermostat to its lowest temperature set-
ting.
9. Move the thermostat system switch to 'HEAT'.
10. Increase the thermostat setting approximately 5
degrees above room temperature.
11. After five minutes, verify heating mode operation
by checking for warm air discharge at the supply
air outlet.
12. Adjust the thermostat to maintain the desired
space temperature.
13. Check the unit for unusual vibrations, noises,
leaks, etc.
WATER REGULATING VALVE - ADJUSTMENT
The water regulating valve needs to be adjusted to
maintain a condensing pressure of 170 to 220 PSIG.
The valve is adjusted by turning the ¼ inch square
shaft on top of the spring housing. Turning the adjust-
ing screw counter clockwise will raise the opening
pressure and raise the condensing pressure being
maintained. Turning the adjusting screw clockwise will
lower the opening point and lower the condensing
pressure being maintained. If mains water is being
used, make sure the valve closes soon after the com-
pressor stops. If the flow does not stop after a few min-
utes, raise the opening pressure by turning the
adjusting shaft counter clockwise until the flow stops.
If the unit is running on mains water, we recommend
adjusting the water regulating valve to give 100ºF leav-
ing water temperature or 220 PSIG condensing tem-
perature. This will give the best compromise between
low water flow and high operating efficiency. If the con-
denser water is being re-circulated through a cooling
tower or a chilled water system, it is recommended that
the water regulating valve be set for a lower condens-
ing temperature. This will provide higher efficiency,
lower operating cost and a lower sound level. The min-
imum condensing pressure required for satisfactory
expansion valve operation is 170 PSIG.
MAINTENANCE
The air circulating fan motor has bearings that are fac-
tory lubricated and sealed for long life. No further lubri-
cation is required. The compressor is part of a sealed
refrigeration system that does not require any addi-
tional lubrication.
Filter changes are required at regular intervals. It is
suggested that the filter be checked at 60-day intervals
for the first year of operation, until field experience is
acquired. If light cannot be seen through the filter, it
should be changed. Always replace the filter with the
same size of 1-inch thick disposable type of fiberglass
filter. (See General Data for listing of required filter
sizes.)
The condensate drain pan should be checked annually,
and cleaned and flushed as required.
Recording of reference operating parameters is recom-
mended (volts, amp draw, water temperature differ-
ences, etc.). A comparison of logged data with start-up
and annual data is useful as an indicator of general
equipment condition.
