Electric on demand water heater advice

[John Williamson]

I'm in the process of buying a property which needs a complete bathroom overhaul. The current bathroom has an electrically powered hot water tank feeding a bath, shower and sink.

I would really like to remove the water tank to save valuable space (and probably energy usage too) and so wondering if an option might be an on demand electric water heater and if so what kind of kwh I would be looking at (or even if this is the right measure to look at in terms of providing a decent flow of hot water).

Things which guide my decision are:

• The house has no gas/LPG supply and getting a supply is not an option
• We love showers. The stronger the better
• Must be capable of running a bath, a shower and a hand basin but NOT at the same time
• The electricity supply is single phase, so the 3 phase units I have seen are not an option
• There are 4 people in my family and generally two of us shower in the morning and two in the evening
• This is a holiday home so likely to be used in the weekends mostly but could be for weeks at a time in the holidays
• The water heater will be for this bathroom only, will not need to supply any other heating or sinks other than this room

I was thinking along the lines of

Trianco Aztec Water Heater | 4052 | Electric

Buy Trianco Aztec Instant Water Heater 12Kw - White today. Trianco Part No: 4052. Free UK delivery in approx 2 working days.

www.heatandplumb.com

but wondering if something like this might work better?

Ariston Velis Water Heater | 3626307 | Unvented | Electric

Buy Ariston Velis 45L Evo WIFI Unvented Electric Water Heater with Kit 3Kw today. Ariston Part No: 3626307. Free UK delivery in approx 3 working days.

www.heatandplumb.com

 

[SimonG]

Instantaneous electric water heaters are crap. Just look at electric showers.
If pressures and flow allow then I would look at a direct unvented cylinder.

 

[steadyon]

1. The laws of physics are against you.
2. To heat 100 litres of water from 20 to 50 degrees (Celsius) in an hour uses about 3.5 KW of power for the whole 60 minutes. To heat the same amount in 10 minutes would require 21 kW. That amount of power at 230 volts requires over 90 amps.
3. The maximum amperage available to domestic property is 100, and sometimes only 80. You could not run a heater to heat the water unless:
3a. You have a 100 amp supply. AND
3b. You could find such a water heater. AND
3c. You could guarantee no other appliances were ever used at the same time.

 

[Ben-gee]

I’m with Simon g , look at getting a direct unvented cylinder- provided you have enough pressure and flow that will provide what you’re looking for.
Need at least 2 bar and hopefully 20lpm then you’re good to go.

 

[John-sjw]

One is instant, they are the biggest you can fit in a domestic house. 5 litre/min. Not too bright. At 12kW that is approx 19 amps. You could pipe two in parallel drawing 38 Amps well within a 100A domestic home. But then over £500. Check with maker. Check electrical diversity as well. That gives a respectable 10 litre/min. Probably more when mixed hot and cold. Will fill a 100 litres bath in 10 mins or less if mixed hot and cold. Many new baths are 80 litre capacity.

The second, a 45 litre 3kW storage unvented cylinder. It will give a decent quick shower. 45 litres in a bath that will be half full. You will get more in a bath when mixed hot & cold, but no full bath.

 

[Murdoch]

How is the hot water in the kitchen heated?

 

[king of pipes]

A joule direct unvented cylinder would be my choice negotiate a economy 7 tariff minimum with your energy provider if possible . Kop