BULLDOG SpaceKeeper Vertical – Installation Operation Maintenance Manual
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© Copyright 2013 CGC Group Inc Installation Operation Maintenance Manual is Subject to Change without Notice- Last Revised Oct 1, 2014
The unit circuit board incorporates six relay outputs with the following uses:
K1 – Auxiliary relay for cooling valve on a two valve unit or heat valve on a
dehumidification unit.
K2 – Heating Relay
K3 – Alarm Relay
K4 – Compressor Relay
K5 – Low Fan or Fan Relay for belt drive units
K6 – High Fan or Compressor #2 on belt drive units
Each of these relays have, in parallel, a green LED indicator that lights up when the relay is energized.
The board incorporates digital inputs that are opto-coupled to a 24V AC source. These too have amber
LED indicators located near the input locations that light up when the input is closed. These inputs
include:
High Pressure Switch
Low Pressure Switch
Heat Call (W on thermostat terminal)
Cool Call (Y on thermostat terminal)
Fan Call (G on thermostat terminal)
Auxiliary (A on thermostat terminal)
Compressor shutdown (24V AC signal thru O/O).
Providing a continuous 24V potential to O/O will terminate and prevent compressor
operation. This can be used for duty cycling, or for minimizing power consumption during a power
failure while maintaining the heating function.
Unit shutdown (24V AC signal thru A/O). Providing a continuous 24V AC potential to A/O will
terminate and prevent unit operation. This can be used for a simple night shutdown. On both
arrangements a single small 24V AC can shutdown many units. ¼ VA is required per unit.
Finally, the board has four analog inputs provided via thermistors. These inputs are as follows:
Ta – Discharge Air Temperature
Tr – Refrigerant Temperature
Tw – Outgoing Water Temperature
Co – Condensate Level
Ta, Tr, And Tw are 10k Ohm NTP thermistors, while Co is a 100 Ohm NPT thermistor. These Inputs do not
have LED displays.
