Combi Boiler Playing Up -Someone HELP!

Juney

Hi All, I've just joined the discussion forum, and wondered if anyone can throw any light on our latest problem.

Yesterday we switched on our heating for the first time in a long time. When the heating is on, the hot water comes through the taps fine. When switched to hot water only, it stays cold. Also we pressurised the boiler with the loop tap as there was very little pressure in it, but then as we watched, the pressure went uo so far it blew the pressure release valve. Unlike the last valve we replaced 2 - 3 years ago, it seemed to reset itself??? Is this possible? Why is the pressure at zero until we switch on the heating - then goes up too high?

The problem still exists - the heating is really good when it's on, but no hot water when it's switched to hot water only. Can anyone help - please:j

jblack_2

Need more info make/model of boiler etc.

The PRV is designed to reset itself after it's released the excess pressure. Sounds like you added too much water to the system through the filling loop which obviously expanded when it heated up, causing the high pressure.

If you're having to top up the water pressure it indicates there maybe a leak somewhere on your system. Adding new water to the system doesn't do it any good unless your treating it with inhibitor, the oxygen in the untreated water will corrode your radiators etc.

J

YorkshireBoy

I had a very similar fault with my 13 year old Worcester 280 combi boiler recently.

Fault was traced to a burst bag in the expansion vessel. Diagnosed by checking the air pressure (should be 0.5 bar), and water came out of the schrader (tyre) valve!!

New expansion vessel from Plumb Center was around £50 inc. VAT.

EliteHeat

You have two problems.

The first is likely to be a ruptured diaphragm within the diverter valve or the DV itself.

The second is going to be a depleted expansion vessel, a blocked waterway to the expansion vessel or, again, a ruptured diaphragm.

Neither are DIY in my opinion.

trf1960

EliteHeat, and other reputable Corgi gas engineers, you must despair at the amount of people who consider and/or more importantly, will advise others, of boiler/gas repairs as DIY jobs. It would seem that no-one takes notice of the announcement at the top of this forum quoting:

Announcement: Warning! Always use a professional for gas maintenance and complex electrical repairs. Being safe is more important than MoneySaving.

andrew-b

Maybe the warning thread could have a little more info added.

I just found this http://www.trustcorgi.com/consumer/donotdiywith.htmx with regards to "don't diy with gas"

There's also a link from that page to an informative podcast (MP3 download) on DIY tips which also emphasises "if in doubt GSI (get someone in)".

Andy

YorkshireBoy

trf1960 wrote: »

EliteHeat, and other reputable Corgi gas engineers, you must despair at the amount of people who consider and/or more importantly, will advise others, of boiler/gas repairs as DIY jobs. It would seem that no-one takes notice of the announcement at the top of this forum quoting:

Announcement: Warning! Always use a professional for gas maintenance and complex electrical repairs. Being safe is more important than MoneySaving.

Earlier post modified.

trf1960

YorkshireBoy, I do apologise if you thought my reply was a personal attack, it honestly was not - but after perusing these forums for a while now it astounds me of the amount of people who do give advice who are absolutely not qualified to do so. If an individual is a very competent DIYer, makes themselves as knowledgable as possible on their task and works in a safe manner, then all credit to them. Unfortunately, most are not and do not.

I think these MSE forums are brilliant - especially on your everyday topics - but I do think these 'DIY advice' ones need to be monitored very carefully - especially where gas and electrics are concerned.

EliteHeat

To be fair, neither of these repairs involves gas or electrics but I would be astonished if they were in the province of DIYers.

Yorkshireboys diagnosis and solution are spot on though for the second part of the problem.

YorkshireBoy

trf1960 wrote: »

YorkshireBoy, I do apologise if you thought my reply was a personal attack, it honestly was not - but after perusing these forums for a while now it astounds me of the amount of people who do give advice who are absolutely not qualified to do so.

No worries. I read my post again this morning (after seeing yours) and realised that I shouldn't have suggested it was a job for a DIY'er - even though I was happy to do it myself.

I think these MSE forums are brilliant - especially on your everyday topics - but I do think these 'DIY advice' ones need to be monitored very carefully - especially where gas and electrics are concerned.

As an electrical engineer, I've previously been very vocal in my opinions on electrical DIY on this board. I don't post much now though, because baldelectrician (amongst others) does an excellent job of 'policing' the board - and I can't compete with him on the domestic side because my specialist area is industrial electrical engineering.

Juney

EliteHeat wrote: »

To be fair, neither of these repairs involves gas or electrics but I would be astonished if they were in the province of DIYers.

Yorkshireboys diagnosis and solution are spot on though for the second part of the problem.

I can see that you would all want to be responsible in your posts, but I had already said that our heating was oil, and we in no way suspected that this would be anything but a plumbing repair. It was knowing what to look for that was the problem, and we found YorkshireBoy's post and others very helpful. Please do not disuade them from offering advice, it is invaluable to people like us who are pretty capable on the DIY front, and would certainly want to attempt a repair ourselves before calling out a boiler engineer. We don't know any engineers in this area, and have seen enough programmes on "Tradesmen From Hell" to know that not all can be trusted.

Thanks to those who have given advice, I'll let you know how we get on.