Troubleshooting; Alarm; Measurement Points - Danfoss DHP-A Service Instructions Manual

Service instructions
2

Troubleshooting

2.1

Alarm

In event of alarm this is indicated in the display with the text ALARM and an alarm message, see following table. For alarms that are not
reset automatically acknowledgement is required. Acknowledge the alarm by setting the heat pump to operating mode OFF and then
back to the desired operating mode.
Tripped high pressure switch. Compressor stop-
HIGH PRES-
ped.
SURE ERROR
Tripped low pressure switch. Compressor stop-
LOW PRES-
ped.
SURE ERROR
Deployed overload relay (overcurrent relay) com-
MOTOR P ER-
ROR pressor, deployed overload relay for outdoor unit
fan. On certain models alarms from the brine
pump or soft starter can also occur. Compressor
stopped.
BRINE OUT Brine out is less than the set minimum tempera-
ture. Compressor stopped. No hot water produc-
tion.
Flow sensor not active during last start. Compres-
LOW BRINE-
sor stopped. No hot water production.
FLOW
Overheating protection deployed. No auxiliary
AUX. HEATER
heater.
ERROR
Fault in outside sensor. When the control system
OUTDOOR
calculates the heat demand, zero degrees is used.
SENSOR
Supply line sensor error. Everything stops except
SUPPLY LINE
the heating system's circulation pump.
SENSOR
In event of alarm the heat pump will, if possible, supply heating to the house. Primarily with the compressor, secondarily with the auxili-
ary heater. Hot water will stop to indicate that something noteworthy has occurred.
2.2

Measurement points

1. Disconnect the relevant sensor from I/O-card/terminal block.
2. Measure the resistance for the sensor and any extension cables.
3. Then measure the sensor only.
Caution When reading the resistance of the sensors, the sensor leads must first be disconnected from the control
equipment.
To ensure the sensor value the actual temperature must be checked against the measured resistance.
N
Measurement checking sensors during fault tracing
°C ohm, Ω outdoor and defrost sensors
-30 1884
-25 1443
-20 1115
Danfoss Heating Solutions
Domestic heat pumps
RETURN LINE
SENSOR
HOT WATER
SENSOR
DEFR SEN-
SOR
COOLING
TEMP
ERR PHASE
SEQ.
HIGH RE-
TURN
RVV PASSIVE
COOLING
FLOW SEN-
SOR
1000 ohm, Ω
Return sensor fault. Return temperature = Supply
line -5 is used. Calculated supply temperature
limited to maximum 45°C.
Fault on sensor for start temperature. No hot wa-
ter production.
Defrost sensor fault. Heating and hot water pro-
duction is controlled from the outdoor sensor's
value instead (applies to the DHP-A models).
Sensor fault. Cooling function stops.
Alarm that indicates that there is an incorrect
phase sequence to the compressor. Only display
and only the first 10 minutes.
Alarm that indicates that high return temperature
prevents the compressor's operation.
Error detected on exchange valve at start up. Ap-
plies to DHP-C models.
Error detected on flow switch. Applies to DHP-C
models.
kilo ohm, kΩ other sensors
VIGFI102
7