On Tue, 19 Jun 2007 07:27:17 +0100, "Nigel"
wrote:

I've just installed a 65lt hot water tank, it has 2 heating coils and an
immersion. I haven't got around to connecting the 2 heating coils so for now
it runs on just a 1 kw immersion heater... I connected up my 1.2kw
generator ( just a cheapy from B&Q, not a marine genset) and it took 2 hours
to get warm and about 3 hours to hot.... For no very good reason I had
thought it would heat in about an hour. I have tried looking up calorific
values of water etc, but just got myself confused... anybody here shed
some light for me..

thanks
Nigel


You make it easy - specifying metric units....

65 liters = 65 kilograms
Supposing you went to 70 degC from 20 degC: that's
50 degrees X 65000 grams X 4.2 joules per calorie of energy in
joules.

If you supply energy at the rate of 1000 joules/second i.e. 1 kW
then the time needed (with no losses) is 50 X 65000 X 4.2 / 1000
seconds or 4 hours. You try not to start from cold!

Brian Whatcott Altus OK