Northern Heatpump NorthStar RD-WE-096 Installation & Operating Instructions Manual - page 26
08/19/2014
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NI701
Operation Indicators
External Monitor Lights
The two monitor lights indicate control power and/or fault indicator.
ICM Board – The ICM board performs the functions controlling the compressor operation: system lockout,
compressor anti-short cycle, and a five minute delay after power is applied.
The control will begin the 5-minute time delay upon a Y call from the thermostat. After the time delay expires,
the compressor contactor will be energized as long as the high and low pressure switches are closed. If either
switch is open after the delay expires, the compressor will not energize. If either switch opens while the
compressor is energized, it will de-energize immediately and begin the anti-short cycle delay. The compressor
will not be allowed to turn on again until the anti-short cycle delay expires and both pressure switches are
closed. The flow switch will have a 30-second bypass timer in which the control will ignore an open flow
switch for the first 30 seconds. If the flow switch remains open after the 30-second bypass timer expires, the
unit will de-energize the compressor and begin the anti-short cycle delay. If the control experiences three high
pressure, low pressure, or flow switch faults in a 60-minute period, it will lock out the compressor and energize
the fault output. A manual reset of power will be required to reset the lockout condition.
Problems that could cause a lockout situation include:
1.
Water flow problems
2.
Freeze sensor (RD-WE series)
3.
Internal heat pump operation problems
4.
Cold ambient air temperature conditions
The control has a status LED to indicate which type of fault or lockout has occurred. If a high pressure fault or
lockout occurs, the status LED will blink once. If a low pressure fault or lockout occurs, the status LED will
blink twice. If a flow switch fault occurs, the status LED will blink three times.
ICM Fault Code LED
1 blink = high pressure cutout
2 blink = low pressure cutout
3 blink = Flow switch open
The anti-short cycle function puts a time-out period of 5 fixed ±20% minutes on the compressor before re-
starting. This function protects the compressor from repeated on/off operation in the event of a loose wire or
faulty controller.
DO NOT reset the system more than once.
Repeated resetting of the lockout can cause serious damage. If same lockout occurs contact your service
dealer immediately.
High and Low Pressure Switches – The heat pump is equipped with both high and low pressure switches that
shut the unit off if the refrigerant pressure exceeds 550 PSI or goes below 40 PSI. Do not reset a well water
system in the heating mode without first verifying water flow.
Pressure Switch Settings
Low
Pressure
Switch
High
Pressure
Switch
Fault Code LED
Cut-out pressure
40 PSI
550 PSI
1 blink = high pressure cutout
Cut-in pressure
65 PSI
420 PSI
2 blink = low pressure cutout
RD-WE Series, Freeze Protection – this heat pump is equipped with freeze protection temperature sensors
used to monitor source side entering water temperature and load side leaving water temperature. The sensors
are connected to a circuit board located in the control box and is wired in series with the low pressure cutout
switch. If one of these sensors drops below the set point, the low pressure circuit is opened on the ICM control