VCW242E - Central Heating not firing up

[plimsol]

Hi,

my Vaillant VCW242E has not been firing up it's CH. HW works fine, but CH never triggers the ignition. All the other sounds seem normal like the pump, just doesn't do the 'click' and ignition.

I've had a guy come round and he checked the divertor valve but he doesn't think that's at fault. He had a good look around, including the switches at the front of the boiler but no joy. He managed to get the CH to fire up but only by switching the main switch on the boiler off then on, which seems to do the trick. But if it stops for any reason it won't start again without the off/on trick, so if the HW triggers and stops, CH won't make it back.

He plans to speak to Vaillant technical as he isn't sure where else the problem could lie. Anyone have any clues?

Thanks

 

[ollski]

The spindle on the dhw valve has a slight leak on it, this corrodes the pushrod above it which overrides the spring tension on the servo valve to close it when the water demand ceases. The boiler therefore remains in hot water demand which has priority over heating therefore the heating will not run. Easy way to prove is that the boiler will fire up every few minutes for a second or two with no demand on.

 

[Agile]

Hi,

He plans to speak to Vaillant technical as he isn't sure where else the problem could lie. Anyone have any clues?

Thanks

That gives me the clue that this "guy" is not competent enough to diagnose boiler faults!

Did he quote to replace the boiler?

Tony

 

[plimsol]

thank you both.

Ollski, I have no idea what you're talking about but that's because I don't know much about boilers! What I can say is that I've never seen the boiler fire up without demand - currently it only fires up for HW and never fires up for CH, regardless of whether HW has been triggered or not.

The 'guy' who came in never got back to me, so I'm moving on. I'm planning to go through the list of installers on the Vaillant site. I thought of using Vaillant themselves, they do a fixed fee of 270 (all in) for any work they carry out, only thing is that if they can't diagnose or don't carry the part they will still charge 87 callout. Also, no idea what their BER value is for my model. Can't say they filled me with confidence - I'm thinking I'll leave them as a last resort!

 

[Agile]

Be aware that those listed are installers!

Installers are not always ( often ) very good at repairing boilers. Thats a problem with these manufacturers sites, they are promoting selling new boilers as its not in their interest to get older boilers repaired.

If you sit beside your boiler for an hour without opening any taps then does it fire up every 15 minutes or so?

Tony

 

[plimsol]

I shall check - I'm assuming you mean I should have the CH switched on during this time!

Any other diagnostics I can supply? The only other possibly relevant information I can think of is that I've had to repeatedly bleed some of my radiators a few times over the winter. I may have done this a couple of times whilst the heating was on - my bad, I know

cheers

 

[plimsol]

Hi Tony,

so no firing up of the boiler at any point with CH on and none of the hot water taps switched on. shame

anything else I can try out?

Would it help to get a manufacturers manual and trying to understand what parts I am looking at when I examine? I'm having a hard time finding an engineer with experience of these old Vaillant boilers

 

[Bunnyman]

This Is probably a fault with the economiser on the middle pcb the clue is that when u turn off the power an then back on again it discharges the time delay an starts again then when it reaches temp an goes off into time delay it won't automatically come back on

Untitled

• Bunnyman
• 26 Mar 2010
• 499

 

[plimsol]

the trick with the power switch initially worked a few times when the engineer tried it but then stopped working. when he did it I was surprised as I had tried the same thing and no joy

 

[plimsol]

Fixed

Managed to find an ex-Vaillant chap who diagnosed the problem quickly. Looks like it was the diverter in the end - just the diaphragm.

Thanks for the input guys - I took on board the thing about installers not necessarily meaning expertise at fixing. That knowledge of the older models makes all the difference

 

[Agile]

There is a myth that there is some special feature of each model and only a very few engineers can understand them.

The reality is that your boiler is a common model and any competent engineer who repairs boilers will be familiar with them and able to repair them.

The difficulty is that there are many less able people putting themselves forward as boiler repairers who can only fix a very obvious fault like a fan or pump not working and most use their inability to repair boilers to give a quotation to fit a new one.

No-fix No-fee is something to look for before calling an engineer for a repair.

Tony