Tanks cool down at night
Collector circuit pump
runs in the night?
no
yes
Check controller
Collector temperature is
at night higher than the
outdoor temperature
no
yes
Check the check valve in
the flow and the return
pipe with regard to the
functional efficiency.
Sufficient tank insulation?
yes
no
Increase insulation.
Insulation close enough
to the tank?
yes
no
Replace insulation or in-
crease it.
Are the tank connections
insulated?
yes
no
Insulate the connections.
Warm water outflow
upwards?
no
yes
Change connection and
let the water flow hori-
zontally or through a si-
phon (downwards); less
tank losses now ?
Does the warm water
circulation run for a very
long time?
no
yes
Use the circulation pump
with timer and switch-off
thermostat (energy effici-
ent circulation).
The solar circuit pump does not work, although the coll-
ector is considerably warmer than the tank.
Is the control lamp (LED)
illuminated?
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
difference for starting the
pump is to high; choose a
value which makes more
sense.
no
Is the pump current
enabled by the control-
ler?
yes
Is the pump stuck?
Turn the pump shaft using
a screwdriver; now pas-
sable?
Pump is defective - re-
place it
Are the controller fuses
o.k.?
Controller might be de-
fective - replace it.
no
yes
no
no
yes
Replace fuses.
Circulation pump and
blocking valve should be
switched off for 1 night;
less tank losses?
yes
no
Check whether the pumps
of the backup heating cir-
cuit run at night; check
whether the non-return
valve is defective; problem
solved?
no
no
yes
o.k.
Control the non-return
valve in warm water cir-
culation - o.k.
yes
no
Further pumps which are
connected to the solar
tank must also be che-
cked.
The thermosiphoning in
the circulation line is to
strong; insert a stronger
valve in the non-return val-
ve or an electrical 2-port
valve behind the circulati-
on pump; the 2-port valve
is open when the pump is
activated, otherwise it is
closed; connect pump and
Clean or replace it
2-port valve electrically in
parallel; activate the circu-
lation again
a
a
b
b
D e lt a S o l
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