Vaillant Boiler - Why is it playing up like this now?

[shawtj2]

Hi my boiler is 10 years old, no fault code but sometimes when the warmstart operation starts the water is cold and boiler does not light, then when you leave it its ok later. sometimes water goes cold in middle of a shower. Now I know its not the divertor valve as that was replaced last year and show different symptoms.
My heating I have not put on yet at all until it gets really cold as I like to save gas but the boiler struggles to light when turning the tap on, then later its ok.

No fault code is displayed and the water pressure I have checked and is 1.5 bar. I know this boiler quite well and always check the instruction book for faults.

It was serviced last year, what does it need doing to stop it failing to light.
Someone said to me it could be HE or something???

 

[mickyg]

does the heating ever come on with the hot water? It could be the diverter valve, very common fault if its the original diverter valve fitted.

 

[shawtj2]

does the heating ever come on with the hot water? It could be the diverter valve, very common fault if its the original diverter valve fitted.

the divertor valve was replaced for the third time last year so its pretty new.

I have the heating off altogether at the moment. Its when I turn the shower or hot tap on, occasionally it wont light, just green light, no flashing amber light. then try again and it works.
Its just an intermitten fault at moment.

 

[picasso]

Might be the aquasensor playing up, you could try clearing the impellers.

 

[Beerlover]

Look at the back right of the boiler - What colour is the APS? If it is black get it changed.

 

[Bunnyman]

You r the man beerlover it's classic symptoms if the air pressure switch is black not grey then change it..

Untitled

• Bunnyman
• 26 Mar 2010
• 499

 

[shawtj2]

You r the man beerlover it's classic symptoms if the air pressure switch is black not grey then change it..

Untitled

• Bunnyman
• 26 Mar 2010
• 499

How do i get into the boiler then. its got two plastic screws on the cover but they wont come off witha screwdriver.

Air pressure switch??

 

[shawtj2]

Managed to get into it here is a pic of the inside. which is the black switch for air pressure? If its that how much will it be?

 

[shawtj2]

Green light is flashing, temp down to 17 deg. enough water in. tried switching off then on. then reset it, wont light.

code showing is S23. I try the warmstart operation too with the water dial and it tries to fire up but nothing. its been working part of the day. it lets the radiators go down to cold for an hour.
Its due to come on automatically at six will see what happens. Its very strange symptoms.

 

[shawtj2]

Might be the aquasensor playing up, you could try clearing the impellers.

whats an impeller look like and where is it?
When it was serviced they took the top cover off and hoovered it??
Can you show me a photo of where they would be?

 

[shawtj2]

Anyone?????????????