Loosing pressure on my combination boiler

[Melanie Birtchnell]

I have just moved into a flat with a bosch worcester combination boiler that was fitted in January 2006. I called out a service engineer as the pressure was dropping from 1.5 to 0 on a daily basis. I have been told that I have a leak, which is undetected as the pipework is housed under my concrete floor! I have injected a sealant into the system which has reduced the pressure loss to 1.5 - 0 over 5 days. Still not perfect. There is no sign of water damage anywhere, I obviously don't want to have to have my floors dug up! Any ideas on what I should do next would be gratefully received.

Regards

Melanie

[Stuart Noble]

Running new pipework above floor level is probably your best option. That's a lot of water to be losing without seeing evidence somewhere. Are you ground floor?

[John Stumbles]

dropping

[Simon Stroud]

One possible source of leakage (that affected my Eco Hometec combi boiler recently) is the pressure relief valve.

We had the boiler repaired (failed diverter valve) and after isolating the boiler from all the pipework, the repairman drained the small amount of water that lives in the boiler and its internal expansion vessel by releasing the pressure relief valve (a third of a turn on the little knob thereon). Seems a bit of crud was left on the valve seat so it did not fully close causing quite rapid pressure loss. On my boiler the PRV outlet goes to the condensate drain so there is no outside visble sign that it is leaking.

To fix it I had to release pressure a few times quite "rapidly", flushing out the valve, and it has been fine since - touch wood.

Anyway, might be worth a peep.

Regards, Simon.

[Andrew Gabriel]

Pretty sure that is a very long way from conforming to the regs, and could potentially be quite dangerous.

[Simon Stroud]

Hmmmm... well it's actually all combined by the manufacturer (MAN Heiztechnik) INSIDE the boiler, not by the installer. So hopefully it's OK!

You would be able to tell if it was actually venting, but what I mean is that looking at the slow drip of condensate in normal operation, you wouldn't be able to detect the extra extremely slight seepage of the weeping PRV. The flexible clear tube that connects to the PRV outlet inside the boiler is always all steamy inside because it is full of condensate/moist vapour, so to detect the fault I had to remove this pipe for a while so I could see the very slow drip from the valve.

Regards, Simon.

[Andrew Gabriel]

How strange. I wonder how it copes with a system which boils and ejects super heated water and steam from the PRV? Maybe they just don't consider that a possibility.

[Stuart Noble]

But an engineer has already looked at the boiler

[bof]

In message , Melanie Birtchnell writes

I've just been through a long diagnosis process with my combi boiler depressurising daily. At first I thought it was a leak in the CH, but couldn't find one, then left the CH and hot water unused for 24hours and the pressure didn't drop, eventually it appeared to be that the system was losing pressure when the hot water was run, but only if the heating wasn't being used, due to the combined heat exchanger overheating. Having descaled the boiler's DHW heat exchanger (not the CH heat exchanger) the problem has gone away.

[Logician]

Contact Worcester on 0870 5266241 and make sure your engineer is Corgi registered. Try the local paper and not yellow pages for the engineers as they are cheaper in the papers. If you can give them some technical terms on the phone, they will usually give you free advice anyway.

Trevor

- Bathroom advice and forums

[Logician]

Contact Worcester on 0870 5266241 and make sure your engineer is Corgi registered. Try the local paper and not yellow pages for the engineers as they are cheaper in the papers. If you can give them some technical terms on the phone, they will usually give you free advice anyway.

Trevor

- Bathroom advice and forums