No hot water from Combi. No CH pressure either.

[arqradeng]

I have been recently doing a lot of work on my house which involved temporary removing three out of 8 rads, two upstairs, one down. (skimming walls).

They were off for a couple of months and I have recently remounted and reconnected them.

During the period they were off I noticed the CH pressure had dropped to zero. No problem, I havn't been using it through the "summer" !!!

I followed the 'sticky, how to' yesterday to refill and repressurise the system and all seemed fine.

But, for some reason whilst I was doing this I manged to turn the filling loop fully on, rather than off !!! The pressure obviously went to 4 bar and the boiler started making a loud banging and started venting the water out of the vent pipe outside. I then noticed my mistake and turned off the filler tap, after about 10 min !! again !!

It all settled down and I thought it was fine. But now the CH pressure is back at zero and I dont seem to have any hot water. The boiler fires up initially, when you turn on the tap, but then goes off and I just get cold water out of the tap ???

If I try to bleed any rads, I just get water, no air.

Does this sound like something simple or do I need to get a engineer out ??

The boiler is a Worcester Bosch 35 CDi

Sorry I dont know its age, I would say between 5 - 10 yrs. I also don't know its service history.

Thanks in advance. Please be gentle, 'lectrics, , plumbing/CH

 

[chrishutt]

After it's rather violent operation before, the PRV (safety valve) is probably leaking. Check for drips from the discharge pipe when system is pressurised.

 

[Agile]

You must realise that your boiler needs about 1.5 Bar pressure to work properly!

If you want to use it then you must keep it pressurised!

Leaving the filling loop open like that will probably have put dirt on the seat of the pressure release valve. It might reseal it self over a few days or it may need to be replaced. Rotating the knob to make it click three times MIGHT lessen the leak. You can see the water leaking from the vent.

Tony

 

[arqradeng]

Thanks for the replies.

Yes the vent pipe is dripping or rather there is a constant stream of water coming out.

How do I fix it, if possible ??

Do I need any replacement parts or is this a straight forward fix ?

Cheers.

Tony,

How/where do I "rotate the knob" ?

 

[GeckoGas-com]

If it's stuck "open" enough to make you describe it as "stream" I would suggest that you need the PRV changed - Get a suitably qualified engineer.... Job is not much work and shouldn't cost much so long as that is the only problem.

 

[Agile]

It might reseal it self over a few days or it may need to be replaced.

"replacing" by definition, means getting a new one and fitting it in place of the leaking one.

I still suggest you try rotating it first. If you cannot work out how to do that then I think you will need someone to replace it for you.

Tony

 

[arqradeng]

It might reseal it self over a few days or it may need to be replaced.

"replacing" by definition, means getting a new one and fitting it in place of the leaking one.

I still suggest you try rotating it first. If you cannot work out how to do that then I think you will need someone to replace it for you.

Tony

Hi Tony,

I have managed to figure this out. Still no difference !!!

Can the seal be replaced, or do I need a complete new valve ? How much do these typically cost ??

I am sure with a little bit of help I can change this. I am guessing I need to vent off all the pressure, possibly drain the CH ? Or at least isolate the valve. Then its just nuts and bolts, right ???

 

[Dan Robinson]

If it is the older version of the CDi then it's a five minute job with a standard 3 bar valve.

Very cheap.

 

[gas4you]

Try rotating it loads of times in quick succession, letting it 'bang' shut each time.

You didn't drain the system with it did you?

 

[Agile]

Its very rare that clicking them a lot does not reduce the flow to just a few drips.

You have to realise that when dealing with boilers or cars you have to pay a few pounds to replace parts and cannot just bodge everything.

The PRV is a composite part costing only a few pounds. I went to one that had been bodged by a plumber and I had to replace it and that cost the owner £84 !

Tony

 

[arqradeng]

You have to realise that when dealing with boilers or cars you have to pay a few pounds to replace parts and cannot just bodge everything.

The PRV is a composite part costing only a few pounds. I went to one that had been bodged by a plumber and I had to replace it and that cost the owner £84 !

Tony

"BODGE" !!! Who me ????

Point taken. How difficult is it to change then ?? I am an engineer myself, so not a complete "spare part" when it comes to tools, etc. Although, I am an electronic/radio engineer not a CH engineer !!!!

Quick question, before I have to go and spend my hard earned.

When rotating the valve by hand, do I do this under system pressure ?? Since I have been doing it with little pressure and it is not exactly going with a 'bang' !!

 

[Dan Robinson]

How difficult is it to change then ??

What, am I Mr pheking invisible here?


Yes the system should be under pressure; but for the cost of the valve and the ease of its change just go an buy one.

 

[Softus]

What, am I Mr pheking invisible here?

Who said that?!

 

[Dan Robinson]

 

[arqradeng]

How difficult is it to change then ??

What, am I Mr pheking invisible here?


Yes the system should be under pressure; but for the cost of the valve and the ease of its change just go an buy one.

Sorry Dan !!!

So many replies.

Anyhow, I have been away for a few days and on my return the valve seems to have stopped leaking of its own accord and the system is now holding pressure.

Thanks to everyone for your replies.