Hot Water On Vaillant Turbomax boiler

[rooster10]

Hi All,

I would appreciate some help with my Turbomax boiler. I can turn the hot water on full blast and the boiler is not clling for hot water? Is this a pressure switch issue? If so how can I check this?

 

[ianmcd]

which turbomax do you have there are loads of models

 

[rooster10]

It is a VUW GB 242/1 E Model

 

[ianmcd]

It is most likely the diverter valve that is faulty, a very common fault on that boiler, there is a service kit available but most prefer just to fit a complete new valve, the valve comes with a new micro-switch assembly, have you noticed any drips of water underneath the boiler ?

 

[rooster10]

No,
I had a problem with the water being luke warm about 6 weeks ago and so changed the HW Plate and this cured the fault the old plate he was severly blocked!
Now the boiler is not even asking for hot water, sometimes if I leave the tap on for a long period the 'piston' lifts breaking the microswitch but what tells this to lift?

 

[ianmcd]

the piston as you call it should make the micro-switch not break it when the HW is run, the diverter valve has a diaphragm inside which makes this happen, sometimes as a temp measure you can bend the leg on the micro switch with a pair of long nosed pliers and it will work ok for a while

 

[rooster10]

It definitely lifts off the switch??

 

[rooster10]

When there is no water it is just sat there then eventually it kicks in lifts off the switch and the boiler ignites.
Thanks for your help so far Ian! What are my next steps?

 

[Ihavenojob]

When you run a tap does the hot water demand light come on?. The pump flow switch rises when a demand is made,this is to the left of the pump,black with a red switch,is this the one you mean? If so,& you say the plate was blocked there may be some sludge in the tubes to the switch or a weak pump.

 

[rooster10]

Yeah thats the 1 I mean! so am I looking at the wrong thing?

 

[Ihavenojob]

If the demand light comes on when you run a tap the diverter valve(the brass one behind the pump)would appear to be ok.The pump should then run & lift the switch you're looking at,if it doesnt then it could be pump or blockage,or just a worn pump flow switch.Does the heating come on ok?.

 

[rooster10]

The demand light does not come on. Yes heating works fine

 

[Ihavenojob]

Then the diverter valve is at fault.The switch on it is to the right of the pump low down.When a tap is run you should see a paddle move down onto a switch,this can be adjusted to some extent as mentioned before,but is usually just delaying the inevitable-new valve.

 

[rooster10]

Found it!
Yeah can see the paddle which is coming down onto metal strip which makes switch adjusted it by pressure on strip and water does come on now. The has to be quite alot of flow though, is there anyway of adjusting the setting of the paddle??

 

[ianmcd]

no you cant adjust the paddle but you can bend the metal leg from the micro switch closer to the paddle but as we keep saying this is only temporary and you will have to change the diverter valve.