Vaillant boiler not firing up using shower

[elmes100]

Hi, I have a vaillant boiler (TURBOmax VUW 242E, 282 E).
I had it installed about 5 years ago and it's been pucka.

In the last year or so tho it isn't firing up when I take a shower unless I put the mixer on full blast hot then as my skin comes off I gradually reduce it until just right but then the boiler goes off and then i get frostbite.

I have british gas 3 star cover and got some idiot round that ran the hot tap on full and said there you go nothing wrong, get a new showerhead.

So I have a new showerhead and have same problem that is really starting to get to me.

Even I know that switching a tap on full is not proper diagnostic as a mixer shower is like having the hot tap on half and the cold tap on half.

PS. The shower is on 3rd floor and boiler is on ground floor but as I say I have been blissfully happy for 4 odd years. I am in a hard water area.
Sometimes when it won't fire up at all I will look at the boiler and it seems to click on and off repeatedly like it is confused and other times will do nothing until I blast the hot on full.

Any ideas as to a part that could cause this (I guess there is some kind of flow valve to tell boiler that hot water is in demand). I want to next phone british gas with some armour as fed up.

Thanks peeps...

 

[Rob]

The diaphragm might be on its way out or the microswitch might need adjusting. If your lucky you might get a new diverter valve..

Get them back!!

 

[pannierstan]

Cant remember if these have the aqua sensor like the Ecomax.

Either that or the calorifier is scaled to buggery and its not transfering heat.

Stan

 

[Agile]

Think about a diverter on the right by the pump!

The boiler should switch on with a DHW flow of 3 li/min. The little white cam should operate the microswitch on the right of the diverter by 3 li/min.

If its significantly more flow to switch it on the the diverter is failed. We would always fit a complete new one but some people just change the diaphragm.

There is an adjustment screw underneath which may improve the turn on point as a very temporary repair.

Tony

 

[elmes100]

Hey thanks guys,

I will print and present this to the engineer and hopefully he won't just say 'new shower head' but will be receptive to my problem.

I'll let you know what happens.

Thanks again for very helpful quick responses...