STIEBEL ELTRON SOL 25 PLUS - Manual (Page 66)

66 | SOL 25 PLUS WWW.STIEBEL-ELTRON-USA.COM
Fault Cause Remedy
The pump is running, but no flow rate is discernible
at the flow meter with balancing valve. The flow and
return temperatures are identical or the tank
temperature does not rise or rises only slowly.
There is air in the pipework.
System pressure too low.
System contaminated.
Check the system pressure. Operate the pump in intervals
at maximum pump rate. Open the air-vent valves at the
collector, at the pump, and at the solar tank and vent
these items. Should this fail to provide any improvement:
• Flush the system in both directions; clean fittings, such
as flow meters, with balancing valve and dirt traps.
• Check the line routing; in case of “up and down”, e.g.
at balcony protrusions or around water pipes, change
the line routing, if required or insert additional air vent
valves.
• Check the function of the automatic air vent valve.
For this, remove the protective cap and check the float
movement with a blunt needle. If necessary, replace the
air vent valve.
The pump is running, but no flow rate is discernible at
the flow meter with balancing valve.
Flow meter with balancing valve stuck or faulty.
Clog in system.
Shut-off valve closed.
Check the function of the flow meter with balancing
valve. A jammed ring can block the display in the sight
glass, even if the flow rate is correctly adjusted. Start
the pump in manual mode; the pump piston movement
should be discernible. Release the piston through
tapping it lightly; in emergencies, replace the flow meter
with balancing valve.
Open the shut-off valve.
Pump appears to start late and stop early. The temperature differential between the collector
and the tank is too large. Check for faults again when there is strong solar
irradiation.
The pump starts and switches itself off again shortly
afterwards (“short cycling”). This is repeated a few
times until the system runs correctly. The same
happens in the evening.
The solar irradiation is insufficient to heat up the
entire pipework.
The flow rate is excessive (pump set too high).
The switching temperature differential of the
controller is set too low.
Pipework not fully insulated.
The tank and collector sensor wiring is reversed
(problem occurs after commissioning). Check for faults again when there is strong solar
irradiation.
Reduce the pump rate.
Increase the switching temperature differential at the
controller.
Insulate the pipework.
Connect the temperature sensors to the correct sensor
terminals (see the control unit installation and operating
instructions).
The pressure gauge indicates a loss of pressure.
A drop in pressure seen shortly after the system is
filled is normal, as air is still being vented from the
system. A subsequent pressure drop can be caused
by an air pocket that has shifted later on. In standard
operation, the pressure can fluctuate by 3 to 4 psi,
subject to system temperature.
If the pressure falls continuously, a leak exists at
some point in the system.
Fluid loss occurs via operation of the safety valve. The
expansion vessel is too small and/or without pressure
or is faulty.
Collectors have been damaged by icing/frost as a result
of insufficient frost protection and have developed leaks.
Check to be sure that the automatic shut-off valve is
closed.
• First check the fittings, glands at shut-off valves and all
threaded connections, then all solder fittings.
• Check the expansion vessel inlet pressure and the
diaphragm for leaks.
• Check the vessel size and precharge pressure.
• Check the antifreeze level and the pH value.
The pump runs noisily. Air in the pump.
Insufficient system pressure causes voids and cavitation. Vent the pump.
Increase the system pressure.
System is noisy.
This is normal in the first few days after filling the
system. If this occurs later, two possible causes:
System pressure too low. The pump draws in air via
the air vent valve.
The pump rate is set too high. Increase the system pressure.
Change to a lower pump rate and check the flow rate at
the flow meter with balancing valve.