Could this be a thermocouple problem?

[mickybannon]

Ravenheat 820/80T combi, working fine until yesterday when no DHW. The pilot remains lit but the boiler doesn't fire when hot tap turned on. Same problem when central heating turned on, ie DHW stays cold and boiler does not fire for CH either.
If I turn off the pilot and then relight it, the problem disappears only to re-appear about 1/2hr later.
If I hold the ignition for 20 secs (when pilot already on), the pilot goes out. (I did this as it was part of the Ravenheat troubleshooting algorithm- and it suggested it might be thermocouple or overheat thermostat of the gas valve.

No other problems,Pilot lights easily, CH pressure fine, no leaks, the pilot flame envelops the t/c.

On this model the thermocouple/overheatstat come as one so I was thinking about replacing this and if the problems is not solved I will call a CORGI engineer.

Any advice?

I know the wiser of you will suggest calling an engineer now rather than later but it is so difficult to get someone quickly and the main problem is working long hours and difficullty being there to let them in. Hence the logic of my suggestion to try fitting the relatively cheap t/c in the first instance.

Thanks in advance

Michael

 

[gas4you]

If the pilot remains on after you light it and release the grey knob then the thermocouple/overgeat seems ok.

Does pump run? Is fan spinning? could be aps, could be gas valve.

 

[Agile]

Does the boiler make any noise at all when a hot tap is turned on or CH is selected?

No point in changing the thermocouple if the pilot remains lit as its clearly OK.

Tony

 

[mickybannon]

Wow thank you both for lightning fast responses!

When I turn the hot tap on there is a click from the boiler but no lighting of burner.

When CH put on the pump and fan definitely both run.

Thanks

Michael

 

[undercover]

Probably a faulty/sticking gas valve or APS

 

[mickybannon]

thanks, I will call an engineer

Michael

 

[werewolf]

Make sure after relighting pilot that the knob comes all the way back.Sometimes they stick.You get all the "clicks "but the boiler doesn`t fire.
If ok then possibly faulty dhw limit stat top rhs of heat excahnger.

Paul

 

[mickybannon]

That knob has been a bit sticky ( although not used for months before the recent problem) Do you think this is serviceable by me or is it considered part of the gas train?

Many thanks for your advice

Michael

 

[ChrisR]

Deffo part of the gas train. But if it's what I'm thinking of, if you gently pull the knob with a wiggle, it'll come out and the thing will work then.

Where are you? A few of us Londoners do silly hours. I mean if there's nothing on telly why not watch a Ravenheat?

 

[mickybannon]

Thanks Chris, I have wiggled it, now need to see if it keeps happening or not.

I'm in Lewisham.

I would welcome an evening visit if anyone wants to fix it, will post again if still problematic.

Thanks

M

 

[mickybannon]

Despite my making sure the knob fully retracts after relighting pilot- the same problem as above still persists.

So far no local engineers I have tried can make it- they either have too much on or don't get back to me.

Anyone up for a bit of moonlighting? (!)

I can still use it, just have to keep putting out and relighting the pilot. My only worry is that it will eventually fail completely.

Michael