Instantaneous water header - advice please ?

[Adrian]

HI All

In my soon-to-be-completed shed / stained-glass studio I'm going to need hot water for hand-washing, cleaning up completed glass panels etc.

A cold (pressurised) water supply is easy - the alkathene pipe from the deep-bore well runs along the side of the new studio. Hot water fed from the house might be a bit of a pain to arrange, as it would involve digging up concrete paths & so on...

So - I though about some kind of electric 'instantaneous' heater. Never had one of these before - so looking for advice on the subject. Enormous flows are not required - it's just to avoid having to wash twenty or thirty pieces of stained glass in water at 5c straight out of the well !

And - before anybody suggests it - NO thank you - I don't want an air-to-water heat pump, or a windmill, or a solar furnace ...!

Are there units like showers, which would provide a flow of 'warm' (mixed) water from the one tap - or are they 'hot or off' ??

Thanks in advance for your suggestions / recommendations ... Adrian

[DIY]

[Harry Bloomfield]

Adrian expressed precisely :

You can buy instant water heaters of about 2 or 3Kw which provide an adjustable output flow, flow speed is inversely proportional to temperature. Not much output if hot, but it might be what you are looking for.

[Andrew Gabriel]

Yes there are. I've seen them in 3kW versions for running off a FCU and 7kW versions for running from a dedicated circuit like a shower, but that will need a juicey wire from the house. I think temperature is more usually set by adjusting the flow rate. Another option might be a gas multi-point water heater, depending how easily you can run another gas pipe from your meter to the shed. These do come up for sale second-hand for peanuts from time to time. (Don't buy an ancient open-flued one though.)

[meow2222]

Its ironic that this is one situation where the right type of simple alt energy heater would be cheaper to put in than an electric heater, and could give better performance.

NT

[Cicero]

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[Adrian]

I've seen them, but never installed one. Mains won't be a problem (need a hefty 240v feed for kilns etc) - so perhaps one of these is the way to go...

Don't need 'gallons' of hot water - just a trickle would be fine !

Thanks Adrian

[Adrian]

Don't think I'll need the 7kw one ! - 3k will do just fine..... OK on the temperature vs flow thing - what I really want is a lowish flow of warmish water (technical, eh !?) - and I guess what a non-mixing unit will provide is a trickle of hot water or a gush of tepid......?

I could always fill a sink with water of the right temperature, but, when you're trying to get the corrosive flux off a piece of stained glass work the last thing you want to do is soak it in diluted flux !

- hence the requirement for a trickle of water to take away the 'stuff'...

Good thought - but it's rather a long way from here to the nearest gas meter ! We're way out in the far south-west of Ireland.... gas round these parts comes in bottles

Thanks again Adrian

[Adrian]

Hmm - do you think so ??

Thing is, I could put in a little solar water setup - but the house is south of the studio and not very far from it - so the panels would need to be somehow elevated and remote in order for them to see the sun. The requirement for warm water isn't 'daily' - so I'd be afraid that I'd lose more heat than I used, if storing warm water....

Putting on my 'lateral thinking' hat - I wonder what's the smallest 'immersion'-style hot water tank you could get - we have no end of wind round here (not speaking personally !) - and a little wind turbine hooked up to an immersion heater might make sense..?

I could just bite the bullet and arrange a suitable pipe from the house dhw tank, which will have been heated by our groud-to-air heat pump. There's a need to run pipework to the dhw cylinder from the new heatpump (probably in some kind of conduit up the back wall of the house) - so I might find room in said conduit for a feed back from the tank to the studio.....

....might be simplest in the long run....... and cheapest in terms of running costs........

Thanks for the suggestions

Adrian

[SJP]

[Peter Parry]

Local company I know has a few 3kW Heatray Sadia instant heaters as handwash units and the things are almost completely useless producing a trickle of tepid water at best.

would probably be better off with a small stored water oversink unit such as which would at least give you the option of 5 or 6 litres of really hot water before reverting to tepid until it reheated.

[John Rumm]

I have seen two types that would probably do what you want. The small above sink type that include a spout and tap and serve in place of a hot tap, and the under sink type that are plumbed in to supply a hot tap and work as a in line on demand heater. Some have small tanks included to allow higher flows of hot water for a while (although these are more suited to hand washing and other non continuous uses).

[David Hansen]

On Sat, 24 Feb 2007 11:30:12 +0000 someone who may be Adrian wrote this:-

A 3kW heater will provide a suitable flow. Fine for washing hands and things gently, but they take many minutes to fill a basin. A 7kW would probably be too much.

Undersink versions are available, some of which work with ordinary taps. Alternatively oversink versions have everything in one box.

[Adrian]

Sounds like a 3kw heater will do the job then.... unless, as I mused further up the thread, I decide to plumb the studio into the house dhw system ....

Thanks again Adrian

[Owain]

According to Dimplex catalogue:

Unvented cylinders - 80 to 305 litres (bigger ones have two heaters)

Unvented undersink - 7 to 15 litres

Unvented mid-range (wall hung) 30 to 75 litres

Bear in mind that if the main purpose is rinsing stuff, fitting a water-reducing spray head will mean that a smaller storage capacity will last a lot longer before running cold.

As Peter Parry says, the 3kW instantaneous ones are disappointing.

Owain

[David Hansen]

On Sat, 24 Feb 2007 15:40:23 +0000 someone who may be Adrian wrote this:-

Generally not a good idea. Hot water is best generated close to where it is used. In domestic circumstances beyond around say more than 5-10m it is generally best generated locally.

[Adrian]

I've not measured, but it'll be about a far from the dhw tank to the sink in the studio as it currently is from the dhw tank to the sink in the downstairs bathroom.

I agreee, it'd be ideal to generate the hot water 'at the tap' - but, against that, it'd be generated by peak-rate electricity....

All depends on how difficult the hot water pipe run turns out to be...

I guess, for the amount of hot water I'll be using - maybe a gallon or so every other day - I might as well go the electric route....

Studi may well have a 'home-brewing corner' - so on-demand hot water could be helpful there....

Many thanks Adrian

[Adrian]

Ah - thanks for finding that out for me - appreciated....

True....

Thing is - with the ground-based heat pump installed, it seems a bit daft to spend lots of money on expensive electricity with an instantaneous system.

I suppose a possible way of doing it (need to check with heatpump man) would be to put an additional indirect hot tank in the studio and run the dhw heating circuit from the heat pump through the studio tank on the way back from the house dhw tank.

Means two pipes from the heatpump to the studio - but that's a fairly small distance - then you've got the hot water available at the point of use (as per David's post)...

Lots of choices / decisions....!

Thanks Adrian

[Cicero]

=============================== If you're going to be using so little ("...... maybe a gallon or so

Alternatively, if you want to heat it in the shed use an ordinary kettle to heat it and pour into a container of cold water.

Cic.

[Lurch]

On Sat, 24 Feb 2007 17:40:25 +0000, Adrian mused:

But running it outside would ean that to get water outside as hot as it is inside you'd have to start of with it hotter and run it for longer. By the time you got a sink of hot water in the studio you'd have used a tank full of hot water inside!