First steps in solving boiler problem (zero pressure)?

[SamuraiJack]

Came back from holiday to find my boiler (Sime Friendly Format 80E) with 0 pressure. Hot water still works and when I try to repressurise the system (using single valve on filling loop) some radiators become very warm (some don't) but the pressure will drop from 1 bar to 0 in less than an hour. There are no obvious leaks at boiler or any of the rads.

Before I went on holiday system was making strange noises which from reading other posts I think indicates air in the system but all rads were very warm.

To get the system repressurised and stay pressurised, do I need to bleed the radiators then do the repressurisation?

Cheers,

Neil

 

[hi-spec plumbing heating]

>but the pressure will drop from 1 bar to 0 in less than an hour


you have a leak

>To get the system repressurised and stay pressurised, do I need to bleed the radiators

find the leak

 

[Blasphemous]

PRV?

I note that you say there are no obvious leaks at the boiler or the rads but have you checked outside? Look on the outside wall near to where the boiler is mounted. You should be able to see a short copper pipe protruding from the wall and probably pointing down the wall. This is the 'Blow Off' pipe. Is there any water dripping from this pipe when you pressurise the system?

The boiler has a valve called a Pressure Relief Valve (PRV). It is designed to protect the system from over pressure by venting water from the system if the pressure gets too high. However, sometimes the PRV can get bits of grit, debris etc on the valve seat and this prevents the valve from closing thus water slowly leaks from the system via the PRV and to outside via the Blow Off pipe.

Check for this. If there is water coming from the Blow Off pipe then the PRV is suspect (possibly Expansion Vessel). Phone a Corgi and explain the symptoms to him. If water is leaking from the Blow Off then tell him this and tell him you suspect the PRV needs replacing.

Hope that helps.

 

[SamuraiJack]

Thanks for the replies, I'll check for the copper pipe outside first and take it from there.

Cheers,

Neil

 

[SamuraiJack]

Thanks Blasphemous - I think you've got it spot on!

I put 0.5 bar back into the system and then watched the blow-off pipe on the outside wall, a constant dripping every couple of seconds came from it (and is still coming it from some hours later).

I'll get an engineer out to look at it in the next few days.

Cheers,

Neil