Electric water heaters + showers question

Hello - I've been racking my brains to see whether an electric water heater could take the place of my ageing Main Medway gas heater. Thinking electri c because there's very little room on outside walls for a combi boiler. My flat is a modest 2 bedroom and there's just the kitchen sink, bathroom sink , bath and shower. In Europe many domestic homes have 3 phase wiring and 40

0v electric heaters, but good luck if you could have this fitted in Kensing ton, London.

The 230v tankless options seem largely to go up to around 10Kw which should be OK for kitchen sink and a rather puny but serviceable shower e.g. Mira. Main problem is Winter when the water gets cold. But I have seen some larg er more expensive Bosch and other models which may be more efficient.

Going back to basics, to fill a bath you probably need a tank with electric heating. But rather than the tank being on all the time, just switch over to the tank when you want a bath, and leave it off most of the time for tan kless operation. Also, the tank would not need to be the full 80 litres of an average bath - could be just enough to get the water hot and top up with tankless operation. Maybe 50 litres or less. Also the tank has to be heate d to over 50* to kill bacteria.

Is there any way I could get away with electric heating? What are my option s?

Reply to
Eusebius
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The Main instant water heaters are around 20-25kW output IIRC. You can't run a single appliance of that power from a normal domestic electricity supply.

Max UK single-phase domestic supply is 100A, but in a small house or flat, you might have only a 60A or 80A supply. You can have a 2 or 3- phase supply, but you'll have to pay for it to be installed (can be very expensive if there isn't 3-phase nearby). There's no limit to

3-phase current you can have, but again, installation cost will depend how far they have to run the supply cables to reach a point which can supply your load. There may be 3-phase coming in to the block of flats, which could make it an easy option. You can get [single phase] electric showers a little above 10kW, but that's about it.

The Main appliances hang from the through-the-wall flue terminal. For something like 40 years, Main designed each new model to hang from all the previous models' flues, which made fitting the current models in place of an old one quite easy. (The pipework doesn't line up, so you will need to get that adjusted to fit.) I don't know if that's still the case. (Only the room-sealed models without any electricity supply, not the fanned-flue electric models.)

One issue is the room-sealed models are permenent pilot, and that costs you around 250W gas energy continuously lost out the flue, which is more significant in costs that it was when these systems were designed. For a little used water heater, it's easily more than the heater uses heating the water averaged over a period of time.

If you want to get rid of the instant gas water heating, your options are really a combi, or stored hot water heated electrically if you don't want gas. Yes, you can just heat the tank when you need it if you are sufficiently organised. (I now do that even with a gas boiler heating the tank.)

Reply to
Andrew Gabriel

Where does your existing heater have its flue? Any reason not to replace it with a new multipoint gas water heater?

Tim

Reply to
Tim+

The 2 possible locations are both on an inner wall giving into a well. And only 2 wall spaces since the rest is windows. Only two options for gas:

  1. Where the existing Main is, which will be a bedroom. so that excludes a combi. Is the Main legal in a bedroom anyway? If so it could be replaced wi th a newer one, but these types are obsolescent and anyway they develop fau lts and it's £250 minimum to call a plumber to service it. Like Andrew sa ys, the pilot light is always on as well.
  2. In the kitchen next to the bedroom. This would be for a combi, but it's where the cooker is and I don't want to put the cooker on another wall, sin ce the kitchen is small and works the way it is. I could fit a combi on the back wall and run about 14ft of pipe around the walls and out above the co oker..... not perfect.

Andrew - thanks for a REALLY informative and helpful post.

Reply to
Eusebius

Room-sealed boilers are legal in bedrooms, AIUI.

What is your existing heating system?

Peak rate electricity costs are about 3x the price of gas. Also depending on the age and specification of your flats you may have as low as a 40 amp supply.

Owain

Reply to
spuorgelgoog

How deep is the well (or rather, how far are you from the top)

Some boilers allow quite long flues.

Andy

Reply to
Vir Campestris

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