Specifications
CONTROLS — SYSTEMS USING CEILING-SUSPENDED OR CASSETTE FAN COILS (cont)
Defrost — The DFB energizes the RVS (reversing valve sole-
noid), and the reversing valve switches to the cooling position.
The K1 relay on the DFB opens and the outdoor fan stops. The
W2 contact on the DFB is also energized, which in turn ener-
gizes the defrost relay on the fan coil relay board, turns off the
electric heater and stops the indoor fan.
The DFB logic checks the 10-minute defrost timer and the DFT.
If the DFT opens in less than 10 minutes, the DFB switches the
unit back to normal heating operation. If the DFT remains
closed, the DFB switches the unit back to heating operation
after 10 minutes. When the DFB changes back to heating mode,
the RVR (reversing valve relay) is deenergized and the revers-
ing valve switches back to heating operation. Both the outdoor
and indoor fans come back on, and if necessary, the electric
heater also turns on.
System Safeties — The system is equipped with the following
safety devices to protect system components:
A. Indoor coil freeze protection thermostat (cooling cycle only)
— If a coil temperature of 28 F or lower is sensed, the com-
pressor and outdoor fan will be shut down until the coil tem-
perature exceeds 28 F. The indoor fan will continue to run.
B. Condensate float switch (units equipped with accessory con-
densate pump, cooling cycle only) — If the level of conden-
sate in the drain pan rises too high, the condensate float
switch will turn off the compressor and outdoor fan until the
condensate level returns to normal. The indoor fan will con-
tinue to run.
C. Outdoor Unit Safeties — These units are protected by the
following devices:
• high-pressure switch
• loss of charge switch (condensing units only)
• compressor internal overloads
• outdoor-fan motor internal overload
NOTE: Outdoor units with scroll compressors are also pro-
tected by a high discharge gas temperature sensor and a
2-minute timer to prevent possible reverse rotation of the
compressor.
Should any of these devices trip after the compressor is ener-
gized, the Cycle LOC™ protection device will lock out the out-
door unit (turn if off) to prevent cycling on a safety device.
Special Operation, Heating — Outdoor cooling units can be
matched with heat pump ceiling-suspended or cassette fan coil
units to provide supplemental electric heat. All other operation is
the same as a cooling-only system, except these units have
heating capability as follows:
When the room thermostat initiates a call for heating, the elec-
tric heater is turned on. The indoor unit fan will start at the same
time if it was not already running.
When the heating requirement is satisfied, the room thermostat
will open, and the heater will turn off.
Use cooling-only thermostat --HH--07ZE-010 for these
applications.
Heat Pump Thermostats — These thermostats are for heat
pump applications when both cooling and heating set points are
required. They can also be used for systems with a cooling-only
outdoor unit and heat pump indoor unit. When set in AUTO
mode the space conditions are maintained by calling for either
cooling or heating and maintaining at least a 2 degree differen-
tial between them. Indoor fan will operate in all instances either
in auto mode or in a pre-selected manual mode. Automatic
mode operation is as follows:
Auto Cooling mode:
Y contact closed
O contact closed
H1 contact open
Auto Heating mode:
Y contact closed
O contact open
H1 contact closed
For heat pump systems, Y contact provides mechanical heating
(H1 contact remains closed). If control logic calls for auxiliary
heat, it is activated through contact H2 and the center (orange)
LED is lit. When the system is in emergency heat mode, only H2
and the fan are activated.
Other thermostat operating features include the following:
• Center (orange) LED is for AUX heat.
• Right-hand (red) LED indicates a fault — compressor lockout
when wired.
• Filter indicator on display screen becomes activated at
250 hrs of run time. To reset, hold fan button in for 5 seconds.
• Terminal block RS1, RS2, RS+V can be used for a remote in-
door sensor so that the thermostat can be located elsewhere
(secure room).
81