DCN: 141-00240-02 7/03
3
One stage of cooling: Y output
Fan: G output
The Fan output is selectable for normal gas heating system operation with no fan output with heat calls or for
electric heating systems which require fan output with heat calls.
The controllers connect to the HVAC systems at their standard thermostat connections and function just like a
thermostat to the system. Consult your HVAC thermostat wiring diagram for verification of compatibility with the
zone control units.
Thermal Equalizer Feature
The ZC2S version of the controllers includes the exclusive patented
THERMAL EQUALIZER
feature. This is
used in two story, forced air applications to reduce the effects of heat stratification. Heat rises naturally and
during heating cycles the upstairs zone tends to overheat. This loss of heat to the upstairs keeps the downstairs
zone cooler and calling for more heat. This process continues until the upstairs is uncomfortably hot and the
downstairs is still calling for more heat.
To balance this natural phenomena, the
THERMAL EQUALIZER
feature will monitor the length of time the heat
has been calling downstairs and after a selectable time period, will stop the heat call and recycle the overheated
upstairs air back down to the downstairs zone. This “equalizer cycle” will reduce the heat buildup upstairs and
put the heat back downstairs where it is still needed. The net effect is a more comfortable temperature in the
upstairs zone and an energy saving reuse of the excess heat in the downstairs zone.
The Thermal Equalizer feature monitors Zone 1 for heat run times and this zone must be the “downstairs zone”.
When the Thermal Equalizer cycle is on, the Zone 2 damper will be closed and the high speed fan turned on.
Zone 2 must be the “upstairs zone” when using the Thermal Equalizer feature.
Short Cycle Protection Delay
The ZC2S control unit provide a 5 minute delay between successive compressor operations for short cycle
protection. This delays one zone from calling for compressor operation shortly after another has stopped and
prevents potential damage to the compressor due to rapid off-on cycling. Most thermostats also have built-in
short cycle protection delays, so remember these compressor cycle delays are normal when trouble shooting the
system. For testing purposes, you can reset the controller’s 5 min delay by removing power from the controller.
Status Led
The status LED will flash one time every second for normal operation. During certain other modes of operation
the LED will flash differently to indication these modes. See table below.
LED Flash Modes
One Flash
Normal Operation
Two Flashes
Equalizer Cycle On
Three Flashes Short Cycle Protection Delay On. (Compressor output inhibited)