Danfoss DHP-AX Installation And Service Instructions Manual page 66

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 hea-
ting system with poor circulation
due to closed radiator valves, too
small elements or insufficient
water volume. A tight fitting sys-
tem with poor pipe dimensions
may produce the same pheno-
mena.
Problem – Connection of external AH
Cause
Incorrectly connected auxiliary
heater. Does not start when
the control computer gives the
signal.
66 – Service
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 tem-
perature.
• 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 temperature rises quickly whilst
nothing happens to the return tempera-
ture.
If this happens and the heat pump is
stopped by the hysteresis function to
later drop in temperature (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 fun-
ction in manual mode.
VMBMH302
Remedy
If the heat pump cannot cope with the
demand, replace it with one with a hig-
her output or supplement it with a hig-
her 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 con-
nected, reconnect according to the
instructions.