Instantaneous electric water heating

[marinaaquamarina]

Hi, I'm buying a flat which has no gas. Currently has storage heaters which is fine.
The water is heated in a copper tank by immersion on economy 7 overnight.

I'm used to gas combi boilers but willing/have to change.

I really like baths and showers and I'm worried that if we have showers in the morning there will be no hot water left in the tank for a bath in the evening so we'll have to heat the tank at full rate electricity.

Also, once the tank is gone there'll be no hot water for washing up and so on.

It's not so much the cost of the electricity that concerns me but the time spent waiting for the water to heat up - don't want to be boiling kettles to wash up and so on.

My mum had an instant over sink electric water heater when I was a kid and I was hoping there might be something like that available now. Surprised to see that electric heating stuff seems to have changed a lot!

Has anybody used one of these things:

www.heatraesadia.com/Multipoint_Instantaneous.htm

OR

www.cnmonline.co.uk/Stiebel-Eltron-Combined-Instantaneous-Water-Heater-pr-35892.html

Are these worth buying? They seem like possible solutions on paper. Would they do away with the need for an electric shower?

Any advice appreciated - thanks.

instant electric heaters, in an ordinary UK domestic house, are very weedy. The second one you show is 3-phase so not domestic. The first one will supply less hot water than an electric shower - it says about a gallon a minute.

If you still have a copper tank, you could upgrade to a more modern one. If your cold water supply to the flat is good (fill a bucket at the kitchen sink, time it, calculate litres per minute) then you could get a Megaflo or similar, which is a superior sort of cylinder; usually bigger, very well insulated, and, being pressurised, delivers hot water at the same pressure and flow rate as your kitchen tap.

You will continue to heat it by immersion heater, it will usually have one at the bottom on a timer, to heat the whole cylinder at overnight cheap rate, and one at the top, manually switched if necessary, to heat a couple of gallons at peak rate for a top-up if you run out. It will normally be sized to hold enough hot water for a bath and a shower and some washing-up.

If you incoming flow is poor, just get a bigger, well-insulated cylinder with two immersion heaters as described above. You will not get such a good shower though.

Flats often have a small cold water tank perched on top of the cylinder.

Thanks - the water system is as you describewith a copper tank at floor level and a smaller cold water tank sitting on a shelf over. Fairly poor water flow I think but I'm not sure about the age of the tank and system generally.

I didn't realise a gallon a minute was bad!

Would the expensive heater - the one you say is 3 phase - not be allowed in a domestic setting?

If it could be put in a flat would it be better than the electric shower/new immersion set up?

Or is it just impossible to do?

Sorry, another question! Has anybody used these two either?

www.cnmonline.co.uk/Stiebel-Eltron-Instantaneous-Water-Heater-9.6kW-pr-37806.html

OR

www.cnmonline.co.uk/Zip-Inline-DEX-18-27-KW-water-heater-pr-39163.html

Could I run a standard electric shower off the cold main and then (further down the water pipe) have the instant heater powering the bath and kitchen hot taps, using one of the above devices?

At the moment the bath has a hand mixer/shower mixer tap.

You can't use a 3-phase heater in an ordinary house because it does not have a 3-phase (415 volt) electricity supply.

If you have an electric shower and a instant heater, it will draw more electricity than your flat's main fuse and incoming cable (probably) can supply. It will also annoy tenants in other flats when their lights go dim.

Ha ha - I didn't mean to use them both at the same time - ha ha - Dr Frankenstein is in his laboratory draining the power.

I see - so the big heaters are 'illegal' in the home.

Thank you - your information is excellent help.

I think I would like to put in an electric shower so that I don't empty the copper tank in the morning and then can still have a bath in the evening.

Do you think the use of an instant electric heater like the small Heatrae has any value over a traditional immersion?
Would it be worth installing it for the kitchen sink?
Or for the bath - to save the cost of heating more water than I need and letting it go off in the tank?
Or would it be too slow, but bearing in mind it never runs out of water, unlike the copper tank.

I feel that I may heat a big copper tank of water at economy 7 prices but only for it to go cold over the day and so losing me the benefit when I have to top up at normal full price.

It is imprecise science, I know, but what would your opinion be?

I suppose you could, if you wanted, have a cylinder, heated overnight at cheap rate, plus an electric shower at peak rate to use if/when you had emptied the cylinder. An electric shower doesn't deliver anywhere near enough water for a decent shower.

A Megaflo or similar is available in 250litre size. A bath uses about 100 litres of hot water, less if you are fat, and some cold.

A wel insulated modern cylinder will stay hot for more than 24 hours.

Thank you again PigletJohn - invaluable.

Am I correct in think that my system: electric with copper tank with cold water tank sitting above is called an 'unvented' system?

From what you say, if I was to get a very modern new copper tank system, I should be able to fill two baths in the evening (although the incoming cold water would dilute the existing hot and need reheating) and I could use the weak electric shoer in the morning.

I am at a loss to understand how to select the correct water tank!

There are so many with integrated cold sections or separate cold sections. Can you suggest a good website or advise on the best type/brand of cylinder for maximum efficiency and reasonable cost.

How much would you know, would it cost to install such a tank?

Also, on top of the purchase price, how much is usual to install an electric shower?

I appreciate your advise greatly.

3-phase heaters are not illegal in the home, if you were willing to pay the electricity company a substantial amount, they would install a 415v supply. However it is generally not worthwhile, unless you have your own gold-smelting furnace in the shed, 240v is enough for all normal domestic purposes.

415v is more dangerous, though, in the event of an electric shock it is much more often fatal.

We have 3 phase supply into our house, not quite sure why.

A system with a cold tank on top of the cylinder "Combination Cylinder" (often called a Fortic - trade mark) is vented. Usually hold in the region of 100 litres. Usually copper, but stainless ones now available. Always factory insulated now.

A system with no cold tank, fed directly from the watermain, and running at (about) mains pressure is unvented. Due to the pressure it has to be installed and serviced by a qualified plumber or heating engineer with a G3 ticket which authorises him to work on systems up to 500litres. Often called a Megaflo (trade mark) and often quite big. Well insulated under the external casing, the cylinder itself is stainless steel. quite expensive to buy

Birds

Did you formerly work in the Brinks-MAT warehouse at Heathrow?

"Did you formerly work in the Brinks-MAT warehouse at Heathrow?"

:-)

If I was smelting gold I wouldn't be living in an ex-council house in the midlands.

installation costs: maybe about 2 days for a pressurised cylinder. Fitting a new (bigger) fortic to replace the old one, about a day.

electric shower, needs a qualified electrician to run a new circuit, test and certify as well as having the shower plumbed in, so might take two people or one multiskilled, maybe about a day.

You will have to make enquiries locally to get recommendations for good people. Tradesmen with good reputations don't need to advertise. Web pages of "recommended people" are usually paid for by the people whose advertisements recommendations they carry.

For some reason Parish Magazines are a good source.

Thank you PigletJohn - the Fortic cylinders are essentially the existing arrangement fused into one (2-part) tank which certainly looks better too.

I shall look them up for prices and sizes.

I've eased off on the gold-smelting lately - it's very drying - but if the Fortic doesn't work out - who knows!