Boiler won’t fire on H/W

[stratplus]

Vaillant Turbomax VUW 242E.
Fires fine on heating, turn on hot tap and burner goes out.
So it’s recognising there’s s call for h/w.
Could this be the diverter valve or more likely the micro switch?
Hot water is achieved with heating on apparently. Anyway to check the diverter on this boiler?

 

[stratplus]

Vaillant Turbomax VUW 242E.
Fires fine on heating, turn on hot tap and burner goes out.
So it’s recognising there’s s call for h/w.
Could this be the diverter valve or more likely the micro switch?
Hot water is achieved with heating on apparently. Anyway to check the diverter on this boiler?

Anyone?

 

[ShaunCorbs]

No heating on turn the hot water on does it start ?

 

[stratplus]

No heating on turn the hot water on does it start ?

Nope, dosen’t even attempt to start.

 

[ShaunCorbs]

I would say flow sensor if it has one

 

[stratplus]

I would say flow sensor if it has one

Not sure this boiler has one. MI’s mention micro switch not being activated? Strange that when heating is on a call for hot water cuts out the burner. Yet on h/w only nothing happens. Can’t call tech until tomorrow.

 

[ShaunCorbs]

So it's like the mains /baxi pin comes out ?

You manually pressed the micro switch with a hot tap open ?

 

[ShaunCorbs]

@king of pipes Your a vaillint man arnt you ?

 

[stratplus]

So it's like the mains /baxi pin comes out ?

You manually pressed the micro switch with a hot tap open ?

Not sure Shaun, just about to print the manual to have a good look. Diaphragm diverter by the look of it.
Gets h/w when heating has been on....or has done up until recently apparently. Had this problem for a while.

 

[Last Plumber]

Diverter valve

 

[Last Plumber]

You can still buy the water section for it and replace it. You will be able to see the diverter valve lift when you open a tap. It s on the right hand side and it has a micro switch to the right of that

 

[heliotrope]

I would say diaphragm problem.

The micro switch is sits on the side of diverter valve.

You should be able to push the switch with a small screwdriver
and see if the burner fires.

 

[king of pipes]

Diaphragm would be my first thing to check.

 

[stratplus]

Diaphragm would be my first thing to check.

As in change replace the diverter.

 

[king of pipes]

As the guys have said a service kit is available for the diverter valve part number 140352 tricky to do if you havent done one and swap the hot water thermister part number 252805 at the same time . best of luck kop

 

[stratplus]

As the guys have said a service kit is available for the diverter valve part number 140352 tricky to do if you havent done one and swap the hot water thermister part number 252805 at the same time . best of luck kop

Thank you KOP. Really helpful. Much appreciated.