Stores cool down at night.
Collector circuit pump runs during
the night?
no yes
Check the controller.
Collector temperature at night is
higher than the outdoor temper-
ature.
no yes
Check the non-return valves in
the flow and the return pipe for
functional efficiency.
Sufficient store insulation?
yes no
Increase insulation.
Insulation close enough to the
store?
yes no
Replace insulation or increase it.
Are the store connections insu-
lated?
yes no
Insulate the connections.
Warm water outflow upwards?
no yes
Change connection and let the water
flow sidewards or through a siphon
(downwards); less store losses now?
Does the DHW circulation run for
a very long time?
no yes
Use the circulation pump with
timer and switch-off thermostat
(energy-efficient circulation).
Circulation pump and blocking valve
should be switched off for 1 night;
less store losses?
yes no
Check whether the pumps of the
after-heating circuit run at night;
check whether the non-return
valve is defective; problem solved?
no
no yes
o.k.
Check the non-return valve in warm
water circulation - o.k.
yes no
Further pumps which are connect-
ed to the solar store must also be
checked.
The gravitation circulation in the
circulation line is too strong; insert
a stronger valve in the non-return
valve or an electrical 2-port valve
behind the circulation pump; the
2-port valve is open when the pump
Clean or replace it.
is activated, otherwise it is closed;
connect pump and 2-port valve
electrically in parallel; activate the
circulation again. Deactivate pump
speed control!
The solar circuit pump does not work, although the collector is considerably
warmer than the store.
Is the display working?
yes no
Does the pump start up in manual
operation?
yes
There is no current; check fuses /
replace them and check power
supply.
The adjusted temperature differ-
ence for starting the pump is to
high; choose a value which makes
more sense.
no
Is the pump current enabled by the
controller?
yes
Is the pump stuck?
Turn the pump shaft using a screw-
driver; now passable?
Pump is defective - replace it.
Controller fuse ok?
Controller might be defective -
replace it.
no
yes
no
no yes
Replace fuse
a
a
b
b