Mad Idea?

[cowboyplumber]

I been looking at thermal stores running on electric cos that is the only option available.
Tey are fookin expensive. So my thinking is why can't I just get a massive cylinder insulate it to buggery, and have twin high recovery coils in it and use them in reverse to take heat from the cylinder...
One for dhw and the other for pumped ch as a sealed system?
Would be half what a thermal store costs and no maintenance except immersions, pump and roomstat.
Must be too good to be true ?????

 

[ChrisR]

You can, in principle. You can also use an external heat exchanger for the dhw which gives higher flow rates.
I'm sure it has been discussed bofer.
But driveller wil maybe add something useful, for a change.

 

[cowboyplumber]

I await for the good doctor with bated breath...

 

[cowboyplumber]

Can anyone tell me how much heat water holds, ie how many Kw will be held per 1oo litres of water.
Cheers, cowboy

 

[cowboyplumber]

i make it 14 kw per 100 litres of water. Not sure about kw hours joules etc so would love confirmation

 

[Hooo]

From my O level Physics....
Specific heat capacity of water is 4200 J/KgC.
A litre weighs a Kg, so 100l will take 420,000J to heat it up by 1 degree C. A Watt is a Joule per second, and there are 3600 seconds in an hour, so a kWh is Joules / 1000 / 3600.
So that's 0.117kWh required to heat your 100l up by 1 degree C.
As to how much useful heat it holds, that's down to how hot you can get it, and how cold it can get and still be useful. I've got a thermal store for my hot water, it heats up to about 70C, and is useful down to about 50C. If it was 100l, that would be 2.34kWh. Doesn't sound that much does it? I've got a 280l store, and that's plenty of hot water for two people, but it wouldn't last long if I used it for heating too.

 

[holty]

4186 j/kg

 

[cowboyplumber]

Cheers guys, it doesn't appear to be feasable for it to run off economy tariffs.