Rheem MPi 551 Series Owner's Manual And Installation Instructions page 41

DIAGNOSTIC FEATURES OF THE HEAT PUMP CONTROLLER
An operating mode monitor is located on the front of the heat pump module and houses a green and a red
LED.
The green LED, marked "NORMAL", indicates the current operating mode of the heat pump water heater
and the red LED, marked "ATTENTION", indicates a fault mode.
The green LED will emit either a constant glow or a series of
flashes, with a 2 second interval between each series. A series of
long green flashes may also be emitted.
The red LED will emit a series of flashes, with a 2 second interval
between each series, only if there is a particular fault condition
with the system.
The modes are:
Flashes Operational Modes
solid green
Standby mode – water is hot
(remains on)
Call for heating received – system checks performed
1 x green
Note: unit may wait and continue flashing until compressor has cooled from its last operation
2 x green Circulator commences circulation
3 x green Heat pump operation – compressor and fan running
long green Heating unit on – ambient air temperature below 3°C to 5°C or above 45°C to 55°C
no green No power at the water heater or to the heat pump or a possible fault condition
(remains off)
Refer to notes below before calling for service
Flashes Fault Modes
1 x red Heating unit on
2 x red Heating unit off
3 x red Heating unit on
4 x red Heating unit on
5 x red Heating unit on
6 x red Heating unit on
9 x red Heating unit on
Notes:
Power must be available at the water heater and to the heat pump for the LEDs to glow or flash.
There are no 7 or 8 x red flash fault mode codes.
When power is turned on or reconnected to the water heater, the red LED will emit a solid glow for
three (3) seconds and then extinguish. This is normal operation and does not indicate a fault. The LED
display will then return to the current operational status.
If there is power to the water heater and the green LED is off or the red LED is flashing, this indicates
there may be a fault condition with the water heater. The red LED may emit up to nine flashes in each
series of flashes. Refer to
Time controlled power supply (power must be available at the water heater)
If the water heater is connected to a time controlled power supply, then during periods of no power
supply at the water heater the LEDs will be off.
This is not a fault condition, but a result of no power being available to energise the LEDs.
The green LED will recommence glowing or flashing when power is available again at the water heater.
compressor over temperature (possible circulator fault)
compressor fault condition
compressor cooling fault condition
tank thermistor fault condition
evaporator thermistor fault condition
compressor thermistor fault condition
compressor fault condition
"Possible fault condition"
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on page 42.
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