fault with heating on Vaillant vuw242e hot water works perfect however when heating is called for will only work if on/off selector switch is switched off then back on again
when temp on heating is reached or hot water is used the heating will not kick back in again unless switched off/on again any ideas? had new diverter valve and both pcb's replaced 2 weeks ago

ian randall, February 2008

Hi Ian,

Sounds like possibly one of the thermisters may be faulty and allowing the boiler to fire until the reaches its hight limit and safely cuts itself out.

They are certainly much cheaper than either pcbs or diverter valves.

If these were changed to cure this problem, seems like overkill to me, as if the boiler is firing pcb is more than likely fine, and if
your heating, then turn on dhw tap and get hot water the diverter valve is working

Tony, February 2008