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

That was 3 years ago.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?

Answer:

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.

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