Under counter hot water heater

Help! Local charity had one of these installed by well meaning cowboys.

Just been to take a look. It has plastic screw threaded fittings on the top in blue and red for water in and out. The guy who put it in must have got both on cross threaded first time around and then over tightened to try and stop it leaking. Several people have tried to sort it out since with no success. They have already had two biggish floods!

Someone else has put them on properly threaded and then over tightened them even more. It still leaks at a level where after an hour about 0.1L escapes. Both hot and cold sides are compromised but hot is worse. There are rust marks running down the side from the connectors.

This might be irrelevant but it is rated 2.2bar maximum pressure but I am told as originally installed it was set on 3bar (despite what the rating plate said). Will this have done any permanent damage?

I was thinking of taking it apart and putting Viton O rings around the pipes and then tightening the compression fittings again. I also have PTFE tape and circular section but I am undecided which would stand the best chance of working. Any other suggestions for how to make the thing leak proof - any magic gunks that would be worth a try. Bearing in mind that it will get hot and cold cycled so anything too rigid will fail.

I hate plumbing but I am the best chance they have of getting a repair for free - otherwise they will be buying an entire new unit (again).

Thanks for any tips or suggestions on a better way to proceed.

Reply to
Martin Brown
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If you fail with whatever washers or mechanical fixes you try, the gunk to try is LS-X

Is this a "hot" water tap, or a "boiling" water one? Just thinking what liability issues there could be if it *really* lets go and scalds someone?

Reply to
Andy Burns

Thanks for that.

Its a hot water as in hot washing up water. So at the moment they are messing around with kettles for the washing up water (not good).

The previous hot water system a decade back was a lethal uninsulated wall mounted stainless steel cylinder full of boiling water with a tap that would drip scalding water from time to time over the sink.

It was great for making tea in bulk but seriously dangerous to have bulk hot water on tap with a lot of exposed metal at ~100C.

Reply to
Martin Brown

Shocking bodge. Good luck. The o rings are worth a try - but make sure the pipe is not scored. Why do people think tightening more will fix things - it is as bad as the "Lets wrap PTFE around it brigade. In most fittings the thread provides a clamping force = not a means of sealing (pet hate)

Reply to
DerbyBorn

Is it one of those Ariston ones? My one lasted just Three years before springing a leak, it was not from the actual connector joins, (which were tricky to sort out) but one of the pipes itself had pinholed, ruined the new cupboard it was in too. Guarantee was only two years. When I replace it I will get a heatrae instead. So if it is Ariston, just chuck it and start again

Reply to
MrCheerful

Its Hyco with 15L reservoir (which isn't really enough). Its not an ideal choice since people tended to run the hot tap and exhaust it. Its predecessor same brand apparently lasted nearly a decade. Under sink cupboard doesn't look too good with the water damage and swelling but it is cosmetic rather than structural failure.

Annoyingly the thing is only 6m from the electric supply so an inline flash boiler would have been a much better solution.

I found another installation gotcha (or rather was told about it today)

- the outdoor cold tap is on the wrong side of the pressure reducer which is why they installed it at 3bar to get a decent flow rate.

Reply to
Martin Brown

What was set to 3 bar?

If the unit has a 2.2 bar max rating, and the supply pressure is higher, then you would typically need a pressure reduction valve installed before the heater.

Its not entirely clear what type of fittings are on there... if they are threaded stubs, then it sounds rather like they were intended to take tap connector style fittings. However you later mention compression fittings. These could be compression tap connectors I suppose - but in which case which joint is leaking - the compression fitting onto the pipe, or the tap connector onto the heater?

As others have said, Fernox LS-X may be the only option.

Reply to
John Rumm

there should also be a pressure relief valve plus tundish

Reply to
MrCheerful

Ah, ok that looks like a small unvented cylinder rather than an electric instantaneous heater which is what I was expecting.

These?:

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If so the install manual suggests that the PRV is only required on supplies above 4.2bar:

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The connectors are tap connectors, so as long as there is a sealing washer fitted, and they are tightened against it, they should seal. The ends of the plastic stubs can be sanded flat again if they are scored. Obviously the misthreading in the past may have hindered getting them to pull in tight enough.

Reply to
John Rumm

How does an electric heater manage only 34% efficiency?

Reply to
Andy Burns

There is a pressure relief and a thing I think is an expansion bellows in a squat red cylinder and a pressure gauge. It all looks a bit Heath Robinson but it had worked like that for a decade or so.

Reply to
Martin Brown

It is also what I would have preferred given the situation. Any recommendations for a reliable model in case it proves to be a lost cause fixing the existing broken installation?

It looks exactly like that but the rating plate definitely says 2.4bar rather than 4.2bar! I wonder which is the misprint?

Next time I'm there I will check the model number in case there is a cheap and nasty one that only works with low pressure supplies.

I haven't taken it apart yet. I wouldn't put it past them to have omitted the sealing washers in favour of over tightening it.

Reply to
Martin Brown

The pressure on the cold side going into the heater. There is an NRV, pressure reducer and expansion bellows on the feed as well as a pressure gauge. Rating plate says 2.2bar max but the manual you have found for me online seems to say 4.2bar max. Much like fig D.

Local water pressure is 4bar daytime rising to about 6bar overnight.

It looks to me like the tap connectors onto the heater. The actual configuration is a bit weird and seems to use one of every possible kind of connector including a flexible. I'll take a picture next time.

Reply to
Martin Brown

rotten insulation? Long pipework?

Reply to
charles

Unlikely given its standing loss of only 0.71kWh/day

The spec wouldn't know about that.

Reply to
Andy Burns

There should be a safety valve fitted to protect against over pressure. (May be a single unit in with the pressure reducing valve). Make sure the discharge pipe is clear.

If all else fails, take the cover off the heater, you may be able to substitute brass fittings for the knackered plastic ones. May need a bit of soldering.

Reply to
harry

Ariston have steel tanks vitreous enameled. You can't beat copper/stainless steel for this job.

Reply to
harry

There is a big difference between a Pressure Relief Valve and a Pressure reducing valve. a Pressure relief valve is mandatory, just in case the thermostat goes.

Reply to
MrCheerful

I had not realised how crap it was or I would not have installed it, the heatrae is copper outlets for sure. It was the iron inlet pipe which had pinholed.

Reply to
MrCheerful

I suspect so does the Hyco and that it isn't stainless as there are orange brown rust marks tracking down from the leaking joints.

Reply to
Martin Brown

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