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