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SpaceKeeper Console (SKC) – Installation Operation Maintenance Manual
© Copyright 2013 CGC Group Inc. Installation Operation Maintenance Manual is Subject to Change without Notice Last Revised Nov 15, 2019
been put into operation. If a cooling call is in place, it must be disengaged before the cause of the
last alarm shutdown can be identified.
OPERATION ALGORITHM
There are several control algorithms to prevent cycling and problematic operation. These are:
1.
Double Call – If thermostat connections or set up is incorrect resulting in a simultaneous
call for both heating and cooling, the unit will not operate. This condition can be
observed on the thermostat connection LEDs. (Note: A heat pump thermostat will
present this scenario)
2.
Reverse Cycle Call – Poorly located automatic changeover thermostats (i.e. thermostats
mounted on a wall opposite a discharge grill, or a thermostat in a doorway to outside)
can trigger heating and cooling mode changes many times an hour. The CGC controller
has a 10-minute anti-mode change timer for both heating and cooling mode changes.
The controller will not accept a change in mode until 10 minutes have elapsed since
termination of the opposite call.
THERMOSTAT CONNECTIONS
The CGC control board has been designed to operate with most standard 24V AC thermostats.
These are powered from the CGC board with 24V AC and simply switch power ON to each of the
Heat (W), Cool (Y), Fan (G) or Aux (A). While most present day thermostats operate in this manner
there are others that may or may not work properly. The following should be checked out for
satisfactory performance prior to installation:
1.
Heat Pump Thermostat – Some heat pump units do not have heat relays (therefore are
not compatible with standard thermostats) and require “Heat Pump Thermostats”.
These thermostats call for both heating and cooling on one of the signal wires. These
thermostats are completely incompatible with CGC’s controller.
2.
Battery powered thermostats – These thermostats were developed as replacements for
old mercury bulb thermostats that had 4 wire connections while 24V electronic
thermostats required 5 wires. These will work with a CGC board, although CGC does not
recommend them. They require periodic battery replacement, which is something that
should be avoided if possible.
3.
Power stealing thermostats – This type of thermostat is electronic and was also
developed as a replacement for old mercury bulb thermostats. These too are
problematic in that they bleed a small amount of current down the signal wires and this
may be interpreted as a signal for heat or cool.
