Danfoss DHP-A Service Instructions Manual page 52

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.
10.4.5 Heating comfort
Table 30. Problem – Too cold
Cause
1. The heat pump's control computer is
not set/adjusted to the customer's
requirements/wishes.
2. Incorrect operating mode set in the
heat pump's control computer.
3. Sensor fault, OUTDOOR/ROOM/SUP-
PLY LINE/RETURN LINE.
50 – Service instructions VMGFC302
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 tem-
perature on the outgoing hot water pipe
from the heat pump and the temperature
of the hot water. The temperature differ-
ence measured between the heat pump
and hot water indicates the temperature
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
temperature:
•
Is a mixer valve installed in the sys-
tem? Temperature set too low on the
mixer valve? Leaking 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 plausible/actual value?
Measure the resistance of the sensor,
check against the ohm table in Measure-
ment points.
Remedy
Replace with a heater with a larger
exchange surface.
If any problems occur during trouble-
shooting as per the points, carry out cor-
rective 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 tempera-
ture of around 50-55°C and the start sen-
sor around 45-48°C. If, after completed
hot water production, these tempera-
tures 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
supply line regardless of the outdoor
temperature.
If the incorrect operating mode is set,
change to the desired operating mode.
If the sensor is defective, replace it.