Micro switch on Valiant combi, how do i replace it ?

by **speedtbird** » Wed Jul 22, 2009 9:35 am

Hi, i have been told i need a new micro switch for my Valiant combi boiler (as i am not getting hot water on demand, the heating still works, and if i put the heating on, then i can get hot water) as this is replacing a part rather than having to fix something, i feel this is something i will be able to do myself, once i have been told what to do that is, can you explain to me what i need to do ? Also it has been recommended to me, that if the micro swotch goes, i also need to replace some valves, can you clarify this for me also ? Many thanks in anticipation of your help.

Michael.

by **htg engineer** » Sun Jul 26, 2009 2:16 pm

'i feel this is something i will be able to do myself'

You will first have to work out where and what the microswitch is.

Why is it the mocroswitch ? what was the multimeter reading ? what part of the sequence does the boiler stop at ?

It's more likely the diverter isn't operating the microswitch,

htg

by **speedtbird** » Sun Jul 26, 2009 5:00 pm

"i feel this is something i will be able to do myself, once i have been told what to do that is" is what i said. regrettably i don`t know what a micro switch is or where it is located, if i did i would have replaced it, providing it is something i can do, which is why i have asked for help on here, if it is a fairly straight forward job then i am confident with guidance it is well within my capabilities, if it requires a qualified engineer with or wothout special tools then i will get a qualified engineer to do the job, in your opinion is replacing a micro switch a relatively easy job to do?

by **htg engineer** » Sun Jul 26, 2009 6:31 pm

Why is it the microswitch ? what was the multimeter reading ? what part of the sequence does the boiler stop at ?

I will need a little more info if possible to offer anymore advice.

'i have been told i need a new micro switch for my Valiant combi boiler' Did they go anywhere near the boiler ? or is it a guess.

To change a microswitch is normally one screw (if that) and pulling apart and reconnecting a plug containing two wires, relatively simple process.

You will firstly need to locate it on the boiler, remove the boiler front cover and see how many components and wires there are.

htg

by **speedtbird** » Sun Jul 26, 2009 7:04 pm

As I do not know where the micro switch located I was wondering if someone would know!! I had a plumber here fitting a new shower, i explained to him the problems i was having with my boiler, he had a look at it, he told me it was the micro switch and that it needed replacing, but for now he could re-set it, he said it might last for a couple of days or it might last for a few months, it lasted just under 3 weeks, this is why i believe it to be the micro switch, i have no idea what the multi meter reading is\was, when i turn on the hot water tap nothing happens, if i put the heating on then i can get hot water from the tap, i think that is all your questions answered, i'm still not sure what i am doing, but in a roundabout way you eventually got round to answering one of my questions, thank you for that, i now know i can do it, all i need now is for somebody to tell me how to replace this?

by **htg engineer** » Mon Jul 27, 2009 4:10 pm

For precise info we will need the boiler model, eg Turbomax, Ecotec etc...

Like I say it's normally only one screw and undo and push together a electrical connection.

If you can find the diverter valve, opening the hot tap you should see a spindle or a fulcrum arm move, this moves to make contact with the microswitch.

You may find the the diverter isn't connecting with the microswitch, if that's the case you will need to drain down the system and renew the diaphragm - with the boiler model, you should be able to get more help.

htg