Under sink heaters - recommendations

[R D S]

As subject, anyone experirence of such things?

Ta.

[Tricky Dicky]

Daughter had one in a house they rented temporarily and it was forever breaking down with the inevitable long wait to get spares. I cannot remember the make but to me it seemed more trouble than it was worth.

Richard

[R D S]

There is a gas pipe nearby. I suppose we could whack a boiler in. It's for hot water upstairs at work, I was under the impression that the under sink affairs were quicker and more economical...

[Chris Green]

We have two of the smallest, cheapest ones from Screwfix:-

They are pretty easy to install and seem to 'just work', no issues with them at all and the older one has been in use for more than two years now.

[charles]

preesumably you don't live in a hard water area.

[Algernon Goss-Custard]

charles [e-mail]> posted

We fitted an Elson 10/15L Unvented Water Heater nearly five years ago, and it has worked perfectly without any maintenance since. However our water is the softest you can get; I can imagine there'd be problems in a hard water area.

We run it at a fairly low level, with a timer so that it's only on when it's likely to be needed, and only heating the water to about 45 degrees.

[Roger Mills]

How much hot water, and *how* hot?

We have a Quooker in our kitchen which heats 7 litres of water under pressure to over 100 degC and stores it in an insulated container. It has two outlets - one to a boiling water tap for making tea and coffee and the other, blended with cold to provide 60 degC or so (adjustable) to the kitchen tap.

Not cheap, and may be an overkill for what you need.

[Hot water for bathing and showering is heated by a gas boiler and stored in a vented cylinder in the airing cupboard. But this is a very long way from the kitchen - resulting in a long wait for the tap to run hot, and wasting lots of water.]

I installed the Quooker myself several years ago, and we haven't had any issues with it despite being in a fairly hard water area.

[Chris Green]

Our water is moderately hard, South Suffolk, the lime scale does tend to be crumbly though and doesn't seem to build up in heavy deposits.

[R D S]

Just handwashing.

Keep thinking about these for home, for the reasons you mention.

[Jeff Layman]

When we moved in nearly 8 years ago there was an Ariston under the sink in the garage. As soon as I turned it on it tripped the RCD.

I didn't need stored hot water, so had it replaced by an over-the-sink Triton instant water heater. That worked well off a 13A supply for hand cleaning after work in the garage, gardening, etc, and I have had absolutely no problems with it in over 7 years. Do you really need the store of hot water, or would an instant heater do?

[Martin Brown]

Don't unless you have no other choice. We have them in our village hall.

Tedious to install properly, need a vent to the outside and possibly a pressure reducer, non-return valve and expansion tank to do it properly. They cannot supply very much hot water at once. They are just about acceptable in a seldom used toilet but pretty well useless in a kitchen.

The inline flash boiler ones with a decent power feed are better.

Either sort fail expensively in hard water areas unless you put in a water softener (more space and plumbing complication) and even then they seem to have a lifetime of about 5 years before the heating element insulation fails and they take out the mains RCD when switched on.

The thermal insulation on them isn't great either so they tend to warm the cupboard and run up the electricity bill if they get left on. (Not massively but ISTR an average of 50W 24/7 for each one there is.)

[Brian Gaff (Sofa)]

We used to all use Ascots inthe 1950s mounted on the wall above the sink and burst into life when you turned the tap on, crude I know... Brian

[Chris Green]

They don't all need a vent, the one I recommended (from Screwfix) doesn't (there is an emergency excess pressure release valve). Nor do they need any of the other things you suggest unless the water pressure is over 5 bar (I think that's the limit). The only requirement is a minumum length of feed pipe with no taps/valves.

If the mains pressure is too high then they work perfectly well with 'tank in the roof space' pressure, that's how I feed both of mine.

[Martin Brown]

The units here are rated for 2.4bar or maybe 3bar. I forget. Local mains water pressure here is much higher than that.

The catch is that late at night you find water pressure rises a lot when there is no demand. 5bar isn't the safety margin you might think.

If fed directly off mains water without suitable precautions they are quite likely to leak drips of water overnight every night.

[Chris Green]

So do as I did? I suppose not everybody has a tank in the loft now though.

[Cynic]

I installed one of the Ariston units from Screwfix in our memorial hall kitchen about two years ago. It does the job! If it fails it'll get a like for like replacement. Not worth buggering around with parts and labour by comparison with a new unit price.

[R D S]

I'm getting a bit fancy in my old age Brian, I don't want to see it.

I've changed!

[R D S]

I don't think we need a store , for the one in the WC at least, are the instant ones instant enough?

[R D S]

The instant ones get shocking reviews until you are up in high KW territory.

The beauty of the storage ones seems to be that the water will be hotter, quicker, better flow and doable on a 13A. Just need to consider the inefficiency of the water being kept warm, I presume they are well insulated.

[T i m]

A mate has put an instant (Triton T30i, 13A) one in his shop, replacing the storage type that had gone wrong (and was taking up valuable space) and seems very happy with it? I think part of the appeal was not only the space saving but the fact they would never run out of hot water, no matter how often they drew water from it?

He and the other staff are particularly aware of their need for regular hand washing and having constant hot water seems to be serviced by said instant heater very well. Also handy for washing up tea cups and plates and still having hot water straight after for post customer equipment contact (PC's etc) hand washing.

I was going to fit one here because of the long delay with hot water coming though from our multipoint water heater but as it's got milder it's ok to use cold water and soap for the hand washing.

For us it would mean usable hot water for comfortable hand washing in ~6 seconds rather than ~30.

I do get the storage type but concerned how suitable they might be for regular usage (like wanting to wash your hands after running a bowel of water for washing up (with the smallest capacity storage units especially))?

Cheers, T i m