Vaillant Turbomax DHW problem

[David6]

Hi there, am seeking some advice regarding a vaillant turbomax VUW GB 242E. The hotwater when turned on does not allways ignite the boiler. Hence no hotwater, It works better if the central heating is running, but is difficult to get the bolier to fire for the HW if the heating is not running.

The DHW microswitch goes down when the taps are opened but the boiler does not fire. With the heating turned off even thought the microswitch is down, sometimes it doe not even show a hot water demand light. My question is, could the problem just be the microswitch which is a cheaper fix than a diverter valve, does it mean the diverter valve is working if the microswitch goes down, in which case is the problem with the circuit board.

I am just trying to avoid replacing parts bit by bit as I will have to call out an engineer as I dont feel confident in doing the work myself on something that has the capacity to blow up. Any suggestions would be greatly appreciated.
Thanks David

 

[Mozza00]

Had similar problem. Turned out to be the small plastic armature on the bottom right-hand side of the diverter valve that hits the microswitch to call for hot water.

NB this isn't the flow switch/microswitch at the top of the diverter valve as I fist thought.

£1.50 fix off e-bay and no need to strip-out valve

 

[Mozza00]

Duplicate

 

[David6]

Thanks for that,

However the plastic arm on mine was working I could see it depress the switch. I bought a new microswitch which was 16 quid and got someone to fit it and it has fixed the problem. Even though the switch was working and making a nice click, it mustn't have been making an electrical connection.

I was worried because I had the reciepts from the last two times it was fixed and each time it had a whole new diverter valve at over 200 quid, which was what I was trying to avoid as I could watch the diverter valve moving.

One of the other vaillant post also mentioned that the microswitch is prone to failing so its worth checking

Thanks again