cooling as required by the remote thermostat/sensor. Two compressor units shall have a solid-state time delay relay and random start to prevent both compressors from starting simultaneously.
Solid State Control System (CXM):
Units shall have a solid-state control system. Units utilizing electro-mechanical control shall not be acceptable. The control system microprocessor board shall be specifically designed to protect against building electrical system noise contamination, EMI, and RFI interference. The control system shall interface with a heat pump type thermostat. The control system shall have the following features:
a.Anti-short cycle time delay on compressor operation.
b.Random start on power up mode.
c.Low voltage protection.
d.High voltage protection.
e.Unit shutdown on high or low refrigerant pressures.
f.Unit shutdown on low water temperature.
g.Condensate overflow electronic protection.
h.Option to reset unit at thermostat or disconnect.
i.Automatic intelligent reset. Unit shall automatically reset the unit 5 minutes after trip if the fault has cleared. If a fault occurs 3 times sequentially without thermostat meeting temperature, then lockout requiring manual reset will occur.
j.Ability to defeat time delays for servicing.
k.Light emitting diode (LED) on circuit board to indicate high pressure, low pressure, low voltage, high voltage, low water/air temperature cut-out, condensate overflow, and control voltage status.
l.The low-pressure switch shall not be monitored for the first 120 seconds after a compressor start command to prevent nuisance safety trips.
m.24V output to cycle a motorized water valve or other device with compressor contactor.
n.Unit Performance Sentinel (UPS). The UPS warns when the heat pump is running inefficiently.
o.Water coil low temperature sensing (selectable for water or anti-freeze).
p.Air coil low temperature sensing.
NOTE: Units not providing the 8 safety protections of anti-short cycle, low voltage, high voltage, high refrigerant pressure, low pressure (loss of charge), air coil low temperature cut-out, water coil low temperature cut-out, and condensate overflow protections will not be accepted.
Option: Enhanced solid state control system (DXM)
This control system features two stage control of cooling and two stage control of heating modes for exacting temperature and dehumidification purposes.