Vokera Combi boiler how water will not trigger?

The fulcrum arm operates a microswitch. This tells the boiler you need domestic hot water, otherwise turning on the tap only moves the diverter valve so that the pumped water goes through the DHW heat exchanger instead of the radiators. If the central heating is on anyway then the water the boiler thinks it is heating for the radiators actually goes through the DHW heat exchanger and you get some hot water, if the central heating is off you will just get cold water.

Check the microswitch operation, you should see it being operated by fulcrum arm movement. With the electricity off you could measure the switch operation with a multimeter. Or you could just replace it as it sounds likely it is broken, cut the wires about three inches from the switch and take it to a gas parts supplier for a replacement, should cost you about 12 quid, connect the new one with a chocolate block connector or with the crimped bullets supplied with the replacement.

Be aware that there are two models of 80sp with different DHW switches with different mounting positions, make sure you get the correct one.

Take care, there are lethal voltages (mains) on internal wires when it is connected to the electricity supply.

cd
March 2007

ive got exactly that problem, and i replaced the big diaphragm today, but still ii only have water hot when the heating is on.
the pin pushes out to th fulcum point but the boiler doesnt fire up, any ideas are really appreciated, were trying really hard to save up to take the little ones on holiday in the summer

derek manchester
March 2007

To expand on Mr Gas's answer (I think it's correct).
1)Download the manual (if you havent got it) from the Vokera Website.
2)Read it.
3) Turn off electricity, gas and water to boiler.
4) Remove case.
5) remove plastic grill from beneath boiler (2 self tappers)
6) remove fulcrum arm (one slot head screw)
7) remove five screws (spanner or philips screwdriver) from brass cover with fulcrum operating pin going through over domestic hot water diaphragm. (Page 33 of manual)
8) remove shot diaphragm, clean all traces of rubber from pusher plate and brass casing. (Or you will be replacing it again soon)
9) fit new diaphram, and re-assemble boiler. If there is any leak from where the actuating pin comes through when the water is back on, you need to fit a new o ring holder thingy, found in kit t0019.
10) re-light pilot and see if it has fixed it. If not suspect the microswitch that the fulcrum arm is operates. These are not too reliable.

The diaphram is replaced as a matter of routine in a proper annual service. Various other wearing bits are replaced, other bits are cleaned and pressures are checked. Well worth getting done every so often, by a corgi Vokera specialist, or a corgi someone who knows the model well. Will prevent hot cold cycling when running a bath, wild pressure variations when using central heating, improve the efficiency, etc etc.

cd
March 2007

diverter valve diaphram gone. needs replacing

mr gas
February 2007