Danfoss DHP-A Service Instructions Manual page 21

Service instructions
Cause
9. Insufficient exchange surface to
transfer the heat pump's output to
the heater.(Only applies to heat
pumps with a separate heater.)
10. Heat loss in the hot water pipe.
2.4.5 Heating comfort
Problem – Too cold
Cause
1. The heat pump's control comput-
er is not set/adjusted to the custom-
er's requirements/wishes.
2. Incorrect operating mode set in
the heat pump's control computer.
3. Sensor fault, OUTDOOR/ROOM/
SUPPLY LINE/RETURN LINE.
Danfoss Heating Solutions
Domestic heat pumps
Troubleshooting
Is the exchange surface too small?
Can the heater cope with the heat pump's output?
Open the hot water tap, read off the temperature
on the outgoing hot water pipe from the heat
pump and the temperature of the hot water. The
temperature difference measured between the
heat pump and hot water indicates the tempera-
ture loss.
Examples of temperature loss causes:
▪ Long water pipes.
▪ Uninsulated hot water pipes.
▪ Hot water pipes routed through cold areas.
Other causes that can affect the hot water temper-
ature:
▪ Is a mixer valve installed in the system? Tem-
perature set too low on the mixer valve? Leak-
ing mixer valve?
▪ Water tap fault? Leaking thermostat mixer?
Troubleshooting
Check the ROOM and CURVE and MAX settings.
Check which operating mode is set.
Check what the relevant sensor shows. Is it a plau-
sible/actual value?
Measure the resistance of the sensor, check against
the ohm table, see chapter Measurement points.
Remedy
Replace with a heater with a larger ex-
change surface.
If any problems occur during troubleshoot-
ing as per the points, carry out corrective
actions.
To quickly check that the heat pump's hot
water production works as it should, drain
the hot water so that the heat pump starts
to produce the hot water. When done, read
off the temperature on the top sensor and
on the start sensor. The top sensor should
show a temperature of around 50-55°C and
the start sensor around 45-48°C. If, after
completed hot water production, these
temperatures are obtained, this means that
you have the correct temperature and vol-
ume of hot water in the water heater.
Remedy
Adjust incorrect values in the heat pump's
control computer.
ROOM = Desired indoor temperature
CURVE = Should be set so that the desired
indoor temperature (ROOM) is maintained
regardless of the outdoor temperature.
MAX = Highest set-point value on the sup-
ply line regardless of the outdoor tempera-
ture.
If the incorrect operating mode is set,
change to the desired operating mode.
If the sensor is defective, replace it.
VIGFI102
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