Heat Pump Dthp4-2; Operation - Zonex DigiTract 4-2 Installation Manual

The System Controller will initially run in the mode requested by the first
calling zone thermostat.
Cool mode – When running in the cool mode, the System Controller
energizes the compressor(s), indoor blower and energizes the
reversing valve (O/B made to R) if the reversing valve selection jumper
is in the O position. This is indicated by the corresponding Y, G and O/B
(if jumper in O position) LEDs illuminating. Also, the dampers for the
zones not calling for cool are closed and the dampers for the zones
calling for cool are left open. This is indicated by the DPR LEDs. If the
DPR LED is illuminated, the damper terminal strip and damper
terminal board, the corresponding damper is closed. The system will
continue to run in the cool mode until all calls are satisfied or
changeover occurs. When all calls are satisfied or prior to
changeover, the system will go into a purge mode.
Heat mode – When running in the heat mode, the System Controller
energizes the compressor(s), indoor blower and energizes the
reversing valve if the reversing valve selection jumper is in the B
position. This is indicated by the corresponding Y, G and O/B (if
jumper in B position) LEDs illuminating. Also, the dampers for the
zones not calling for heat are closed and the dampers for the zones
calling for heat are left open. This is indicated by the DPR LEDs. If the
DPR LED is on the damper terminal strip and damper terminal board,
the corresponding damper is closed. After running in heat mode for 8
minutes, the System Controller will energize the auxiliary heat if the coil
leaving air temperature drops below 88 degrees and will deenergize
when the coil leaving air temperature rises above 97 degrees. The W2
LED is on when the auxiliary heat is energized. The system will continue
to run in the heat mode until all calls are satisfied or changeover
occurs. When all calls are satisfied or prior to changeover, the system
will go into a purge mode.
Changeover
– While the system is operating in one mode, if the
System Controller receives a call for the opposite mode, the System
Controller will continue to run in the current mode for 15 minutes or
until all current calls are satisfied. Then the System Controller will go
into a purge mode for 3 minutes, then change over to the new mode.
SYSTEM CONTROLLER – HEAT PUMP DTHP4-2

OPERATION

Purge mode – When all calls are satisfied or before changing modes,
the System Controller will go into a 3-minute purge cycle. During this
mode the compressor and indoor blower will deenergize. This is
indicated by the Y and G LEDs cycling off. If the reversing valve is
energized, it will deenergize. This is indicated by the O/B LED turning
off. The damper of the last calling zone will remain open and all other
dampers will be closed. This provides a 3-minute time delay to prevent
equipment short cycling. The DPR LEDs indicate which dampers are
open and which are closed. If the DPR LED is on, the damper is closed.
If the DPR LED is off, the damper is open.
Auxiliary heat – 8 minutes after the System Controller has run in heat
mode, if the coil leaving air temperature is below 88 degrees, the
auxiliary heat is energized and the W2 LED illuminates. When the coil
leaving air temperature rises above 97 degrees, the auxiliary heat is
deenergized and the W2 LED cycles off.
Ventilation – When no zones are calling, all zone dampers are open.
During this time, if any thermostat has the fan switch ON then the
indoor blower is energized and the G LED is on. This provides
ventilation to all zones.
Emergency heat – Emergency heat mode is controlled by STAT1 only.
To make an emergency heat call, STAT1 must be in Emergency Heat
mode and making a heat call. When the System Controller receives an
emergency heat call from STAT 1, it will lock-out the compressors and
energize the auxiliary heat strips and fan unless the system is already
running in heat or cool mode. If the system is running, the unit's
auxiliary heat will be energized based on leaving air temperature. Zones
not calling for heat will close their dampers. When all zone temperatures
are satisfied, the System Controller removes the auxiliary heat call and
monitors all zones for the next call.
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