CGC HKV020, Installation Operation & Maintenance

Page: 17 / 23

Hybrid Vertical Stack – Installation Operation Maintenance Manual
OPERATION ‐ DETAILED
R090303 Installation Operation Maintenance Manual is subject to change without notice Page 15
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.
4. 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.
5. Triac switched controllers – This is a commonly used switching device and all controllers
tested to date have functioned flawlessly. CGC recommends that prior to installation of
a third party supplied controller, it be checked for compatibility. CGC can confirm this.
6. Relay switched controllers – This type of controller works well with CGC devices.
SHUTDOWN OUTPUT
The CGC board has an optional input terminal strip that allows for two types of remote shutdown.
These are a) compressor shutdown and b) unit shutdown.
The advantage of these inputs is that many units can be connected in parallel and when powered
by an independent 24V AC signal one or both of these actions can be implemented. Common uses
are:
a. Duty cycling for demand control
b. Global night setback
c. Heating only mode during emergency power periods
The CGC controller is also set up so these shutdown functions can be initiated individually with on
board 24V power. This capability allows unit or compressor shutdown based on a door switch, a
light switch, or occupancy switch. A separate 24V power supply is required if two or more units are
being shutdown.
FAULT ALARM OUTPUT
The CGC board is provided with a fault alarm indication and output. The fault alarm relay
provides normally open and normally closed contacts for use in transmitting fault conditions.
NOTE: The fault alarm is energized for NORMAL, and de ‐ energized for fault. As such, if the unit
is not powered, if the board fuse is blown, or if the electronics are damaged, a fault condition
will be indicated.
The fault relay is paralleled with the Fault LED which will be ON when no fault condition exists.