30
TECHNICAL ASSISTANCE CENTRE
19 TROUBLESHOOTING
FAULT
CAUSE
SOLUTION
Temperature in the collectors
is higher than in the storage
cylinder, and the pump is
working too, but heat transfer is
poor
Air in the circuit
-Bleed the circuit
The pump has not got enough
head to push the water column
up to the collectors
-Check the specifications of the pump and
change the pump if necessary
The flow rate through the circuit
is too low
-Adjust the flow rate through the solar collector
circuit to a value between 0.4 and 0.6 litres a
minute per square metre of collector area
The collector sensor is not
reading the correct temperature
-Make sure that the temperature sensor is in
the right position and that the connection
cable has not been laid near any power
cables
The heat transfer liquid is too
dense
-Check the density of the water-glycol anti-
freeze mix. If the mix is too dense, drain the
circuit and flush out any sludge that might
have formed in the collectors
The pump is working (and is very
hot), but there is no transfer of
heat from the collectors to the
storage cylinder
Air in the circuit
-Bleed the circuit
The collector circuit is blocked
by sludge or by an excessively
dense water-glycol mix
-Flush out and re-fill the circuit
The pump cycles on and off,
staying on for only a short time
The temperature differential set
between the collectors and the
storage cylinder is inadequate
-Make sure that the temperature differential
between the collector and the storage
cylinder is greater than 6 °C
The storage cylinder temperature
sensor has been installed in the
return line
-Make sure that the sensor is in the right
position. Make sure that the hot water outlet
is from the left of the collector field
The pump gets switched on very
late and stops soon afterwards,
giving no time for proper heat
transfer
The temperature differential set
between the collectors and the
storage cylinder is excessive
-Make sure that the temperature differential
between the collector and the storage
cylinder is less than 10 °C
The pump does not switch on
even if the temperature in the
collectors is significantly higher
than that in the storage cylinder
The storage cylinder has reached
its maximum temperature setting
-Make sure that maximum temperature is set
between 60 and 80 °C
The collector has reached its
maximum temperature setting
-Make sure that maximum temperature is set
between 120 and 140 °C
The pump is in manual mode
-Make sure that all controller settings are
correct
-Δt ON between 6 and 10 °C
-Δt OFF between 2 and 4 °C
-min. coll. temp. between 15 and 20 °C
-max. coll. temp. between 120 and 140 °C
-max. stor. cyl. temp. between 60 and 80 °C
-functioning mode: auto
The pump on signal is not being
received
-Make sure that the pump is not seized or
faulty
The temperature controller has
blown a fuse
-Check the fuse
The storage cylinder loses a lot
of heat overnight
The solar heating circuit pump
works overnight
-Check that the controller settings are correct
(the cooling function must be OFF if present)
Temperature in the collectors is
higher than night-time outdoor
temperature
-Check that the non-return valve used as
gravity brake is in the correct position
The domestic hot water
recirculation pump stays on
-Adjust the recirculation pump functioning
times
There is heat loss from the
domestic hot water circuit
-Make sure that there is no natural circulation
through the domestic hot water circuit to
remove heat from the storage cylinder. Fit a
siphon to the boiler’s hot water outlet
