VAILLANT 20/1 T3 W WON’T SWITCH OFF

[gorselands]

Hoping that Bunnyman and The831Bunny can help me again.

(Nice to know you got it sorted Mike. If there's anything in the future, just shout me or Bunnyman.)

The boiler "WE" fixed together is working fine after replacing water valve and flow switch. But now the other boiler is playing up - did I say I had two side by side? Big old house.

Yesterday, after putting on my washing the boiler lit as usual but noticed the flames stayed on low after wash had finished. Same when switching on and off hot tap. Switched off at boiler (timer also off) then switched back on and boiler fired up again accompanied by 'machine gunning'. No dripping taps. No heating on. (Switched off and decided to call the experts. I suspect the pin in the water valve is stuck. What say you? All help much appreciated.

Mike

 

[Agile]

I agree, most likely to be the pin is jammed up in the top of the water section. Usually needs new gland.

Easiest to see by opening the die cast box housing the PCB where its easily viewed at the bottom.

Tony

 

[The831Bunny]

Indeed it sounds like the water section gland is stuck. To 100% confirm: run the hot tap for 30secs or so, press the heating switch in at the bottom (lhs), press the pre-heat switch in at the bottom (rhs), leaving only the main switch (centre) on. If the boiler still fires (and external controls are wired correctly...) then the water section spindle is stuck in the gland. As Tony says, inspect in the control box.

The'machine gunning' indicates the microswitch on the DC solenoid needs replacing. Thats the red one visible in the centre of the boiler above the red and green push buttons. A standard microswitch from maplins will fit BUT the NC & NO connections usually need to be reversed. Check your new switch!

 

[gorselands]

Thanks so much for getting back.

Ran HT for 30 secs, turned it off - boiler still on. Put heating switch to off and boiler stopped firing and gunning. Pre heat switch on/off makes no difference.

Mike

 

[Agile]

Sounds like a rogue demand for heating!

Do you have a frost stat?

Tony

 

[gorselands]

Hi Tony,

No frost stat or external stats fitted - only TRV,s

Mike

 

[The831Bunny]

Did you not have a duff Randell 103 clock?? Have a read through the old thread. All the info is there to test about heating demand to boiler.

Its too nice to sit in front of a PC today, now back from my calls, and I'm off to the beach. Today may be Summer! lol

 

[The831Bunny]

One more thing cosset my mind... Have you got the pump mode wire in terminal II? With a duff solenoid microswitch the boiler may fire. Check in the terminal box cover where the mains wiring connects. The pump mode wire is a black wire at the top of the terminal box. Choices are: I, II or III, connect the wire to I if not already there. Oh, and change the microswitch.

Now wheres that disposable BBQ...

 

[gorselands]

will check all that - enjoy the beach.

Mike

 

[gorselands]

Thanks The831Bunny and Tony.

Did as instructed - changed wire to T1, changed micro switch - no change. This morning took out and overhauled water valve and now all working again.

So a big, big thank you.

All the best ('till next time).

Mike

 

[D_Hailsham]

Yesterday, after putting on my washing the boiler lit as usual

So you have a hot and cold fill to the washing machine. Get a Y converter and change it to cold-fill only. I was advised to do this by the Bosch Engineer who repaired my washing machine a few years ago.

He explained that, as the hot water temperature is unknown, the system will fill, for most washes, with cold water and then heat it up to the correct temperature. The only time the incoming hot is used is for high temperature (95C) washes. As modern detergents are designed for use with low temperatures, the number of times you need a 95C wash is negligible.

 

[gorselands]

Thanks for the info. I can't remember the last time I used 95 deg. wash - 60 degs. is generally my max. As I'm re-doing kitchen I will certainly look into that.

Mike