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The Ductless Split System of Choice
COOLING OPERATION
The electronic circuit board of the indoor unit also has
an anti-short cycle timer (ASCT) feature designed to pro-
tect the compressor from short cycling. The ASCT is acti-
vated immediately following the off cycle of the outdoor unit.
Once the room temperature is satisfied and the outdoor unit
switches off, the ASCT will not allow the outdoor to restart
unit a three-minute time period has elapsed.
After connecting the thermostat to the unit place the
system switch in
cool
mode. Adjust the set-point tempera-
ture below the room temperature. The compressor and fan
motors will start and cooling will begin. For chilled water
systems, the coldwater valve will open allowing the flow of
water. Place the set-point temperature above the room tem-
perature. The outdoor condenser will stop (or CW valve will
close) while the indoor fan will remain on for an additional
sixty seconds.
ELECTRIC HEAT OPERATION
Place the thermostat system switch in
heat mode
.
Adjust the set-point temperature above the room tempera-
ture. The electric heat will energize along with the indoor
fan motor. Heating will continue so long as the set-point
remains above room temperature. Next place the set-point
temperature below room temperature. The electric heater
will switch off and the indoor fan will remain on for an addi-
tional sixty seconds.
HYDRONIC HEAT OPERATION
(Optional On CHP And FHP Units)
An optional hydronic heat package may be selected in
lieu of electric heat. Heating operation is essentially the
same as that of units with electric heat. With the thermo-
stat
system switch
set to
heat
and the set-point tempera-
ture above room temperature, the hydronic valve will open
allowing water to flow through the coil. The indoor fan will
also switch on and warm air will flow from the unit. Heating
will continue so long as the set-point remains above room
temperature. Place the set-point temperature below room
temperature. The hydronic valve will close and indoor fan
will switch off after the sixty-second purge time has elapsed.
COMMON TO ALL AIR HANDLERS
Continued
Units with an optional hydronic heat coil or chilled wa-
ter coil are also equipped with a freeze protection thermo-
stat. The freeze protection thermostat is designed to pro-
tect the hydronic coil or chilled water coil from freeze up
due to abnormally cold fresh air from the fresh air system or
from abnormally cold air from the evaporator coil. Should
the freeze sensor activate, the indoor fan will switch off to
eliminate the source of cold fresh air, and also the outdoor
condenser
unit will be switched off eliminating cold air from the refrig-
eration system. For units with a hydronic hot water valve
installed, the valve will be energized allowing warm water to
flow and assist in the defrost process. The system will re-
main in this state until the freeze condition is satisfied where-
by the freeze thermostat will reset.
HEAT PUMP
(Cooling Mode)
Cooling operation in a heat pump unit is described in
“Cooling operation” above. Heatpump condensers are
equipped with a reversing valve that is energized for cooling
and de-energized for heatpump mode.
OPTIONAL HEAT PUMP WITH
ELECTRIC HEAT
(2-Stage Heating)
The electronic circuit board of the indoor unit also has
an anti-short cycle timer (ASCT) feature designed to pro-
tect the compressor from short cycling. The ASCT is acti-
vated immediately following the off cycle of the outdoor unit.
Once the room temperature is satisfied and the outdoor unit
switches off, the ASCT will not allow the outdoor to restart
unit a three-minute time period has elapsed.
After connecting the thermostat to the unit place the
system switch in
heat
mode. Adjust the set-point tempera-
ture above the room temperature. The compressor and fan
motors will start and heating will begin. Depending on the
thermostat selected, electric heat will also energize when
the deviation between room temperature and set point tem-
perature is greater than two degrees. (See the thermostat
owner’s manual for this feature) Place the set-point tem-
perature below the room temperature. The outdoor condenser
and electric heat will stop while the indoor fan will remain on
for an additional sixty seconds.
