Electric combi style boiler?

[balls]

In my third floor flat we have a huge hot water tank ~350L which was put in by the previous owners. As there is no gas to the property its heated by two immersion heaters and it's costing an absolute fortune and takes up a large amount of space.

There's no central heating, so it's only used for the bath / shower / bathroom basin and kitchen sink.

I've seen small electric water heaters that are suitable to replace individual hot water supplies, is there something that can act as a single tankless water heater that would be able to supply enough hot water for all of those?

thanks

 

[blueboy2001]

Instantaneous water heating takes a huge amount of energy for a decent flow rate so is usually impractical with electricity. A typical gas combi boiler has a 24Kw output which would need 100 Amps at 240v on electric - some dwellings supply fuses are only 60 or 80A. You can get electric boilers, but they're designed for central heating so wouldn't be suitable.

350L is enormous for a flat - my house tank is 210L and thats to service 3 bathrooms. That said, it shouldn't cost you that much to run if the tank is well insulated.

When I lived in a flat it had a 180L unvented cylinder with immersion heaters and I heated it overnight on Economy 7 with a half hour boost early evening and it didn't cost much to run. The electric bill including heating and cooking etc was only about £60 a month.

It may be worth looking at upgrading to an unvented cylinder and heating the water at night on Economy 7 to reduce costs.

 

[balls]

The water tank is huge, the cupboard it's in takes a load of room in the kitchen. The flat is being used as an AirBnB place, so is only really used during the weekends and occasional few days mid week. The electricity bill is larger than the gas/electricity for my 4 bed house!

 

[Orionaut]

Also, instant hot water will use peak electricity. The huge tank is so that all the days hot water can be provided using economy 7 (Or similar)

 

[balls]

Also, instant hot water will use peak electricity. The huge tank is so that all the days hot water can be provided using economy 7 (Or similar)

It probably could, however as its not used constantly it seems a very inefficient way of water heating.
One option is an electric shower in the bathroom as well as two other instant hot water systems in the kitchen /bathroom sink but I'd prefer a single unit to do all 3 if possible to avoid replumbing it all

 

[Dave M]

The little heaters are usually for single outlets (e.g. under the sink) , but really you don't want it - if the tank is no more than 5 years old it will be very very well insulated.

I had the immersion on once a day, and a hot shower 24 hours later (e.g. just before the timer kicked in) was fine. An older tank I had in another place was awful in comparison.

 

[b0rn2sk8]

We have a megaflow type cylinder and I can also agree they are very well insulated. The water was still warm in ours after a week of being switched off.

The cylinder will have a spec of how much heat it loses over 24 hours, that’s how much it costs to maintain its temp, it really will not be a lot of it’s modern. The size of the cylinder will effect this but not greatly.

You can so get jackets for them to insulate them further if you want.

As you are running an air bnb the quickest way of ensuring you don’t get any repeat business to use tankless heaters and electric showers... the flow rates are garbage and frankly a rubbish experience.

I would suggest it’s costing a lot because people don’t tend to be frugal with their electric and water usage when they are in a hotel.