Vaillant auroTHERM VFK 900, Start-Up, Maintenance And Troubleshooting Manual

Page: 55 / 69

Manual - Solar hot water systems 0020009607_02 62
8 Troubleshooting
The following tables provide information on possible
malfunctions during the operation of the solar system as
well as their cause and remedy.
All work on the Vaillant solar system (installation, main-
tenance, repairs etc.) may be performed only by appro-
ved specialists.
d
Danger!
Risk of serious injury or death!
Never try to correct faults in the solar system
yourself. Bear in mind that you risk death or se-
rious injury if the work is performed incorrectly.
Consult an approved qualified servicing compa-
ny in the event of malfunctions.
h
Note!
Only use original spare parts from Vaillant Ltd.
for the replacement of parts.
We recommend making a maintenance agree-
ment
.
Malfunction Cause Remedy
Solar pump
Pump is not running although the
collectoris warmer than the cylinder
(neither motor noises can be heard nor
vibrations felt). 1. No current available. Check the power cables and fuses.
2. Temperature difference set too high or
controller is not switching.
• Check the controller.
• Check the temperature sensor.
• Reduce the temperature difference.
3. Maximum temperature reached.
4. Pump shaft jammed by deposits in the
bearings.
Switch temporarily to max. speed or unblock the
rotor, insert a screwdriver in the notch and turn
it by hand.
5. Pump dirty. Dismantle the pump and clean it. Close the flow
rate meter and pump ball valve.
6. Pump defective. Replace the pump.
7. Flow rate set incorrectly Check the setting and adjust it if necessary.
Pump is running, but no solar fluid is
coming from the collector (pump gets
hot).
Forward- and return flow temperatures
are the same or the storage tank
temperature not increasing at all or only
slowly. Air is in the pipework. Check the system pressure. Operate the pump
intermittently at maximum power. Open the
bleeder at the pump and at the cylinder and
bleed. Bleed the back flow prohibition.
If there is no improvement, check whether there
is a “u pocket” anywhere in the piping (e. g. at
beam projections or at the bend of water pipes).
Change the pipework or install additional air
vents. If the system has already been started up
and is refilled again, check the automatic air
vent: Unscrew the protective cap and check the
floater for mobility with a blunt needle. If the
floater is jammed, replace the air vent.
Pump goes on too late and stops running
early. 1. The temperature difference between the
collector and cylinder has been set too high.
Reduce the temperature difference.
2. Collector connection pieces not insulated
(tube collector).
Insulate the collector connection pieces.
Table 8.1 Troubleshooting
8 Troubleshooting