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The pump starts and switches itself off again
shortly afterwards. This repeats a few times
until the system runs correctly. The same hap-
pens in the evening.
There is still too little insolation to heat up the en-
tire pipework.
Check for faults again when there is strong insolation.
The flow rate is too high (the pump is set too high). Reduce the output stage of the pump.
The switching temperature differential of the con-
troller is set too low.
Increase the switching temperature differential on the con-
troller.
The pipework is not fully insulated.
Insulate all pipes.
The cylinder and collector sensors are inter-
changed. (The problem occurs after commission-
ing).
Connect the temperature sensors to the correct sensor termi-
nals (see the control unit installation and operating instruc-
tions).
The pressure gauge indicates a drop in pres-
sure.
A pressure drop shortly after the system is filled
is quite normal, as air is still escaping from the
system. A pressure drop later on can be caused by
an air lock that has shifted. In addition, during nor-
mal operation the pressure fluctuates by 0.02-0.03
MPa depending on the system temperature. If the
pressure drops continuously, the system is leaking
somewhere.
Is the automatic air vent valve closed?
Check the fittings, the glands on shut-off gate valves and the
threaded connections. Check the soldered joints.
Check the pre-charge pressure of the expansion vessel and
ensure the diaphragm is not leaking.
Fluid loss as a result of opening the safety valve,
because the expansion vessel is not large enough,
or it is unpressurised or faulty. Collector damage
(leaking) and frost damage through insufficient
antifreeze content.
Check the vessel size. Check the antifreeze content and the
pH value.
The pump runs noisily.
Air in the pump
Vent the pump.
Inadequate system pressure
Increase the system pressure.
The system runs noisily. This is normal in the
first few days after filling. There are two pos-
sible causes if this occurs later:
The system pressure is too low. The pump draws in
air via the air vent valve.
Check whether the selected expansion vessel is large enough.
Check the pre-charge pressure of the expansion vessel. In-
crease the system pressure.
The pump rate is set too high.
Switch to a lower speed and check the flow rate at the flow
meter (with balancing valve).
The cylinder cools down over night. After the
pump has switched off, the flow and return
operate at different temperatures. At night the
collector temperature is higher than the out-
side temperature.
The gravity brake does not close.
Check the position of the adjusting screw. Check the gravity
brake for leaks. Has a swarf become jammed or are there dirt
particles on the sealing surface?
Single pipe circulation for short pipework with low
pressure drop.
Change the line routing. Never connect the solar heat
exchanger directly but draw the supply lines first in a U
downwards. The siphon assists the gravity brake. If required,
install a two-way valve that is switched simultaneously with
the pump.
Reheating does not work. The boiler runs
briefly, stops and starts again. This repeats
frequently, until the cylinder has reached its
set temperature.
There is air in the reheat heat exchanger.
Vent the reheat heat exchanger.
The heat exchanger surface area is too small.
Compare the details supplied by the boiler manufacturer with
those supplied by the cylinder manufacturer. The problem
may be resolved by selecting a higher flow temperature at
the boiler.
The cylinder cools down excessively.
The insulation is faulty or incorrectly fitted.
Check whether the insulation is intact. Insulate the cylinder
connections.
Incorrect setting of the control unit for reheating.
Check the setting on the boiler control unit.
DHW circulation runs too frequently and/or at night. Check the switching times and the interval operation.
The pump does not switch off.
Sensor faulty or incorrectly positioned.
Check the sensor position, installation and curves.
The control unit is faulty
Note: The variable speed pump does not switch off immedi-
ately but only after it reaches its lowest speed.
