Danfoss DHP-AL Installation And Service Instructions Manual page 59

Cause
5. Changed conditions. Have
you increased your heating
and/or hot water demand?
Problem – Short operating times despite heating demand
Cause
ROOM and/or CURVE set too
high in combination with a
heating system with poor cir-
culation due to closed radiator
valves, too small elements or
insufficient water volume. A
tight fitting system with poor
pipe dimensions may produce
the same phenomena.
Problem – Connection of external AH
Cause
Incorrectly connected auxiliary
heater. Does not start when
the control computer gives the
signal.
Troubleshooting
• If the heat pump has been dimensioned for a
certain demand and this demand is increased,
the heat pump might not be able to maintain the
desired room temperature.
• If hot water consumption increases, a larger
proportion of time is used to produce hot water,
which means less time for heat production (only
applies to VL-systems).
Troubleshooting
Check if the heat pumps starts, if the supply tem-
perature rises quickly whilst nothing happens to
the return temperature.
If this happens and the heat pump is stopped by
the hysteresis function to later drop in tempera-
ture (supply) as quickly to start again, but cannot
due to time conditions in regulation, this means
that the heat pump cannot transport the heat
away from the condenser as it should.
In such a case, hysteresis starts and stops the heat
pump often.
Troubleshooting
Check the connection against the instructions/
wiring diagram. Test the function in manual
mode.
Remedy
If the heat pump cannot cope with the demand,
replace it with one with a higher output or supple-
ment it with a higher output auxiliary heater.
Remedy
Adjust ROOM and CURVE if necessary, ensure that
there is sufficient flow over the condenser and the
heating circuit.
Remedy
If the auxiliary heater is incorrectly connected,
reconnect according to the instructions.
VMBME102
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