Replacing Over Pressure Relief Valve

[chillyfly]

Hi All

First post on here, hope someone on here can help!

I had a problem with a central heating pump running on, which took a while to diagnose, and after replacing the old pump (just as well as it had been running non stop for about 3 weeks!), the fault was finally traced to a sticking 2-way motorized valve for the hot water circuit, which was stuck open and obviously tripped the pump on all the time.

Anyway, it's fixed from that point of view, but during the diagnosis and pump replacement rads were bled many times, and the overpressure relief valves on both the expansion vessel and on the pipe from the boiler were tested. (I have now read that this is not a good idea as it can introduce debris that will make the valve stick open and vent or dribble.) And now the system will not hold pressure (1.5 Bar) for more than about 15-20 minutes. There are no apparent leaks anywhere, the expansion vessel is quite new so should be ok internally, but I do notice that the discharge pipe that comes off the relief valve above the boiler and goes outside to the drain is very hot and has been working overtime.

So I am guessing I have got some dirt lodged in it with my fiddling! Does this sound plausible? Under normal circumstances it shouldn't vent, should it? The rest of the system now works fine, it just won't hold pressure. If it's straight forward enough I am going to do it myself, rather than pay £200 for a £15 valve to be fitted to a water pipe. Obviously anything to do with the boiler I wouldn't go near...

Thanks in advance for your help, the rest of the forum was very helpful in fixing the initial problem!

 

[wms]

you say any thing to do with a boiler you would not go near? the pressure release valve is a critical part in the systems safety. don't belive that all companies will rip you off ask them for a price based on your findings.but be prepared that some other underlying problem could be causing the valve to release. any decent company finding that your findings are correct will stick to the price given.

ask at work and the pub for recommendations of qualified professionals.

a little knowledge can be dangerous.

 

[chillyfly]

Hi WMS, thanks for the reply, I do appreciate your concern. When I referred to the boiler, I meant the internals and workings of it I would obviously not touch, but an external valve connected to a pipe connected to the boiler I don't have a problem with. I understand (from these forums) that you don't have to be a Corgi Engineer to work on water system components that are not internal to the boiler or involve the gas installation.

Unfortunately it's a case of once bitten... You are quite correct that not everyone will rip you off, but it's a question of how many times you get ripped off before you find a good one! And it has happened several times to me. I am not a plumbing and heating engineer, but I am an engineer, and I have in the past had to re-do the work that somebody has gashed and charged me several hundred pounds for. I had an emergency plumbing insurance, and we lost our ceiling due to a cheap low quality tap on the refill loop sticking open and flooding out the over pressure relief on the expansion vessel. It was fitted by a British Gas engineer, and he had left it permanently attached to the filling loop...

When the 'emergency response' plumber came out 48 hours later (!) he took one look at the tap on the cold water filling loop and said "Sorry mate, can't touch that, it's part of your gas central heating" He wouldn't change a £5 tap connected to the cold water main! So I did it myself, it took 5 minutes and cost a tenner for a better quality gate valve. I cancelled the insurance on the spot, and ended up in a legal argument with the insurer over where the central heating system starts and the water system ends, as it is all connected ultimately. (Radiators were covered for Christ's sake!) I paid many hundreds of pounds for that 'insurance' and the so called peace of mind it didn't deliver.

Anyway, I digress. If I can call a corgi engineer in and say with at least some confidence 'I have bought an overpressure relief valve, can you fit it for me to stop the old one venting out the discharge pipe' then that will be a start and I am happy to do so to keep it legal. If however I am not doing anything illegal then I'll do it myself.

 

[ChrisR]

Nope, nothing remotely illegal here if it's just a pressure relief valve on a heating system.

 

[wms]

did not mean to imply that changing it would be illegal. but as previously explained is a critical part of the system.by how you have further explained the problems you have experienced and the fact that the call out company would not change a basic filling loop, left attached over pressurizing your system.due to a faulty filling loop , fitted by bg engineer. this would be the start of your problems,with the prv releasing and not seating correctly, so I would add the further problems to your complaint to the insures.

the job its self as you said is not a difficult one and you are already aware of the cause so should be no problem for you, do not forget when you have refilled your system and checked it out to top up the inhibitor.

48hours for an emergency response is despicable in anybodys eyes.
and I can see why you are now cautious! about being ripped off.

 

[chillyfly]

Thanks wms and Chris R - job completed today, new prv fitted and corrosion inhibitor added. System holds pressure rock steady now and the rads seem to be hotter than before. Pump is also quieter - I guess down to the additive.

So the emergency response plumber (contracted by Homeserve) was telling porkie pies when he said that he needed to be Corgi registered to change a filling loop tap then?

 

[wms]

Well now you have mentioned homeserve you do not need to say any more,

I remember home serve when they were Highway windscreens. then highway glass then highway locks and glazing and over the last couple of years I believe all vehicles changed to red ones with Homeserve on.

Originally Highway were all franchises but they shafted franchisees,and took them back. friend of mine just could not make it pay due to the royalties that had to be paid.plus all vehicles and accountancy had to be supplied by them. told him he was wasting his time taking it on.

Our company has come up against them several times even though we are cheaper on the job.they have the insurance companies locked into some sort of deal.

maybe it was a joiner from the glazing side that turned up to fix your heating.?

 

[chillyfly]

Yes Homeserve are being pushed big time by utility companies, offering free insurance for a 3 month period to get you to sign up. They send you a little diagram showing everything that's covered in your house (it shows the heating system but not the boiler) Then you get a list of example prices if things go wrong and you weren't covered. It's a low level sales pitch by an even lower level company, and I learned early on that it isn't worth the paper it's written on let alone the money it costs. As proven by my case - ceiling falling down, water spewing out at 2am. No plumber available for 2 days (!), then when he did turn up he couldn't get out of the house fast enough. When I phoned to complain the customer service agent on the phone said "If he says it's part of the gas central heating then he's the professional so we have to trust his judgement. You can get a second opinion but it will cost standard call out charge..."

Top tip, don't go near them. If you already are, I would cancel it and go elsewhere before you need them.