no hot water

hi need help i have a ravenheat rsf820/20 when i turn the hot water tap no hot water the micro switchs on the diverter valve click but boiler will not fire up even when ch on it turns the ch off so no flames the minute i turn the tap on turn tap off ch kicks back in

DHW stat is suspect if you are sure that both microswitches are operating

all i can say is there click when i turn the hot tap on where is the dhw and can you replace them thanks for quick reply

Sorry for not being so quick this time. Its a busy time of year for us plumbers.

There are 2 microswitches in the head of the diverter Basically one turns your CH off and the other turns your DHW on. Have a look at THIS
Click the button that appears at he bottom right when you mouse over to see it full size.
If perchance you cant get on the site; then email me for password. My addy is in my profile.

microswitch S2 is biggest suspect here btw as you say you only hear one click.
To explain the area of the problem 24V ac flows through DHW control stat then through mcroswitch S2 and then through the modulator coil when the hot tap is turned on

I dare say it is possible to replace the microswitches as they are usually just a generic microswitch that you can buy for about 2 quid. Engineers tend to replace the full diverter valve or sometimes just the head if that is available.

i will try that found a website that sells the micro switches for 5 pound noticed whilst looking that the diverter valve is also leaking right were the micro switches are so i will get that aswell thanks for the help and advice i will let you know how it goes

hi there thanks for the advice the leak had rusted the micro switch for the dhw the wire had broke off due to rusting it was thick in green cerrosion replaced the swicthes and the diverter valve i have hot water again and heating seems better than before 2 corgi registered plumbers looked at it and said unable to fix i dont give up that easy in total £55.00 to fix thanks again slugbabydotcom

Thanks for posting back with the outcome and making my efforts worthwhile.
Another happy ending ..... Nice one