Temperature & Pressure Relief Valve (+ shite plumber) + anode

[ryanjjones]

Hi

I'm a very keen DIYer - and when I had to replace an unvented hot water cylinder I actually paid a "professional plumber" company to install everything.

However, I wasn't actually happy with them (they deliberately made it a full days work and were very very very slow on basics. LOADS of visits to van for 20 mins....). They installed the cylinder and didn't really test the temperature/pressure relief valve in detail as they never went out the back where the outlet was.... Also - they left the tank temp on max (meaning it was reliant on the boiler stat which failed last year - oh joy!)

That was 3 years ago.

Last night, the TPR valve failed and, as designed, water came out, into the tundish, and then over the floor through the ceiling, down the walls.......

When you check the install - the first bend under the tundish is too close (as per the documented minimum in the manual) and the pipe isn't perfectly vertical. Anyway - we probably dumped the entire tank (at least once!) - and fortunately most escaped down the overflow (not all).

The TPR valve is faulty - leaks on cold water and under no pressure.

ALAS - thats the history - if only we knew a good guy locally :)

So may I ask some questions?

1 - Do I have any comeback on the plumber - or am I likely to be told its tough luck; out of guarentee period; no proof; no "professional service"? (I'm not expecting any!)

2 - Do TPR valves fail normally? Should they be replaced regularly?

3 - Where can I get TPR valves from? Its a reliance valve. TPR15. 95mm probe. 7 bar. 90-95'C DN15-DR - 15mm outlet, 1/2" male inlet. Google hasn't found any supplier

4 - The tank is an Ariston contract cylinder and has ProTech anti- corrosion system a "magnesium anti-corossion anode". It has a red error light on - assume annode is duff and may need replacing - though the troubleshooting guide suggests the PCB is duff. Any thoughts? Where can I get one from, and is it simply a case of unscrewing the old anode and putting in new?

Alas - any help welcome.

Alas #2 - guess I'm decorating over the bank holiday!

[Lobster]

I wouldn't be trying to make waves over how the guy worked at the time - ie, dragging the job out, setting the stat wrong etc - far too late for that; however what you describe above is attributable to an incorrect and dangerous installation which you as a customer would not be expected to have been aware of at the time, and you should focus on that.

AIUI the whole point of the safety system and tundish, and the specifications of its installation (eg bends, bore of tube etc) is that it should be able to accept the entire contents of the tank without overflowing, which yours hasn't.

Presumably you have an invoice or something on paper proving he did the work?

You're probably aware that any plumber working on an unvented system needs a special "G3" qualification from CORGI - do you know if yours does? You should be able to find out from the cORGI website.

Either way, I would have thought that CORGI would be interested in your story and may be able to advise an appropriate course of action for you.

David

[Aidan]

Yes. If not installed as per instructions, it's negligence. Liability is 15 years or 5 years from date of discovery of the negligence, I believe; IANAL. Besides which, this is predictable & avoidable; if he'd done the relevant course (which is why you hired him) he should know this. I believe one of the commissioning tests is to run each of the two relief valves at full-bore (not simultaneously) to ensure the discharge pipework does cope.

Small claims, County Court. I'd anticipate they'll argue you've altered it since installation.

If the T&P relief valve goes, it discharges hot water. In an enclosed space you get lots of steam which condenses on the cold feed pipes. This alone can cause quite a flood; sure it's not just that?

No. You need to test them annually to ensure they haven't been cemented shut by limescale and then they often won't re-seat. If it doesn't drip, it's usually OK. If the fluid leaks, they'll operate (open at full-bore) at a lower temperature, which apparently is very unusual. RWC make most of the UK ones.

You need the right one for your water heater. Electric Water Heating Co., or something similar, is where I got the last one (Harlow, I think).

Dunno, never done one of those. RTFM. The sacrificial anode corrodes away to nothing, and the water heater starts corroding then, so it needs to be sorted out.

It's nothing to do with CORGI, CORGI do gas and nothing but gas. CORGI do training courses for associated works (Part P, water byelaws, etc..) but I don't know if they do UVWH. IoP & CITB do training courses, which are the more usual ones. The local authority should have been notified of the installation; were they? It might cause problems when you come to sell up if the relevant paperwork isn't available.

[ryanjjones]

Hi Yes I have a reciept. The company was corgi registered. I was shown no photo ID.... I assume corgi was gas only The corgi website has no knowledge of their ID - and when giving address and unvented - they do not appear. ah,

[ryanjjones]

RJ> Cheers. Oh yes. We have friends staying over, and they said "you know water is coming though the ceiling..." Like y'know it was expected! I checked cylinder and saw the water coming out (cold - hot drained) and 1/2 going in tun-dish and 1/2 missing it completely. If he did test it, he never checked the outlet pipe on the back of the house. Not worth small-claims - damage isn't as bad as it could've been - just neet to consider how to permanently fix it

RJ> Yep. I do test requently - this litterally is stuck "open" as much as a tap...

RJ> Ta - I'll hunt them down.

RJ> The installation was to replace a 15yr old (and leaking) existing cylinder - so should have been a simple replacement. (in effect it was - and not really worth an "expert" - as it was just (bascially) connecting the existing pipes to the inlets/outlets on the cylinder)

Thanks again

[Jim Alexander]

My commiserations that you have a tank with a magnesium anode. Me too, but next time it'll be stainless steel.

Doesn't happen quite as you describe. Its not true that the entire tank is dumped. First thing that happens is that the pressure driven by the pressure vessel expansion is relived, then the flow continues indefinately driven by the cold supply. Wondering if another installer shortcoming is that the probably required pressure regulator on the cold is missing or not set. Not sure what the setting for the Ariston is but with mine it's 3 bar. Another possibility which might have triggered the TPR failure is loss of pressure in the pressure vessel.

I doubt the distance to first bend is critical, the slope and length of the near horizontal section would govern the discharge. I take it the discharge pipework is large enough? Should probably be 28mm min.

Bound to say that there are annual checks which you appear to have overlooked. If you are a competent DIYer I would sort the problems out myself in accordance with the installation instructions and cite the original receipts etc as provenence if you come to sell. I think the high discharge rate may have more to do with the failure mode of the TRV. If so its bad luck.

Jim A

[Lobster]

Sorry, like the other bloke said, this would have nothing to do with CORGI - no reason that the tank should be filled from a gas-fuelled installation, for a start!

There's definitely a special qualification required (this G3 thingy) but I don't know who administers it. Maybe talk to Building Control (who should have a note of it, as the other poster also mentioned?). You can normally wander in and check their indexes to see what applications have been made for any address.

David

[Ed Sirett]

CORGI don't administer the G3 qualification which is handled by the the CITB. CORGI are only involved in that they are one of the guilds that allow self certification & notification of the installations.

[John Stumbles]

The unvented qualification is nothing to do with CORGI.

[Ron Lowe]

In addition to what others have said, bear in mind that a tundish is an inherently 'splashy' thing.

Even a correctly installed tundish with adequate drainage will splash a fair amount around it when running full-bore ( and even drips a fair amount out when running at a dribble, in spite of the downward-pointy finger thing intended to steer the drips downward. )

I was surprised how much wetness was found beside my megaflow when the tp relief vented due to the internal air volume needing replenished. Testing showed the pipework was perfectly capable of dumping the volume without backing up, but simple splashage caused a fair old mess.