Vailant Turbomax 282E - Intermittent Hot Water

Hi
Just looking for some advice please.

I have the above make of central heating boiler.
When the hot water is called for sometimes it produces hot sometimes it doesn't.

The system is on contract with british gas. I had this same problem about 18 months ago and BG were called out. The engineer said that there was nothing wrong with the boiler and that the fault was more likely a faulty mixer tap and that cold water was getting into the hot water circuit. Literally over night the fault cleared and has been fine ever since.

The fault has just returned and I feel reluctant to call BG out again (or should i?). I just wondered if any experienced boiler engineers had any thoughts (I'm an electrician by trade so no boiler experience as such).

I understand that I could isolate the cold water/mixer valves circuit to prove it, but it is a bit of a pain getting under the floor.
I read somewhere on a forum that the Vailant Diverter valve, microswitch or diaphragm can cause such a fault?
Would appreciate any ideas??
Thanks
Peter

If your paying for a service get them out to have a look

What you read is correct, tell the BG engineer that and he will think that you know more than him

You need to ecplain what the fault symptoms actually are!

Does the boiler fire up when you turn on a hot tap?

If its the diverter valve the switch can be seen not to be making and the boiler will not fire up.

Tony

Thanks Guys for the replies...

Working from home today, so looked at this in more detail..

Although I have these very same symptoms before..I have recently had a new kitchen fitted and I've got a feeling that the builder may have the water connections the wrong way around..(ie incoming Water mains supply connected to the DHW out)..Difficult to tell because after the stop cock, the pipes go up and over the ceiling before supplying the boiler. So cant trace the pipes visually..

I might get chance to swap them around on Sunday, but then away with work...the week after.

Will keep you posted
Thanks
Peter

Quick Update:
Managed to get under the floor today; the pipes were crossed. All working well now.

Thanks for all replies; much appreciated.

Regards
Peter

PS - I work in IT now and if anyone moans to me that plumbers charge too much; I'll explain how it feels lying in two inches of water, I wouldn't do that again for £100/Hour!