I was thinking about a 2kw immersion for my 650l tank, think I’ll wait for the diesel heater,the immersion would take forever to heat and cost an arm and a leg in leccy
I use a 2KW in a 650L. "Proper" element that is 27" long and fixed towards the bottom below the filler hole. Have done for over 3 months having downgraded from a 3KW (so as to not fry my electrics in the house) which I used for 5 years.
A couple of points.
As a single operator I don't usually start with more than 400/500L on board.
If I want 50 degrees I would put it on at 7pm and off again at 7am so 12 hours which would cost £4.00
However I usually only heat to about 40 degrees and put it on about 10pm and off at 7 am so about £3.00
Unless I am heating for a specific job then I only heat for anti-frost, supple hoses and warmth.
If I was doing lots of cladding, gutters and soffits, conny roofs, first cleans or low frequency jobs like schools, lived by the sea or had gazillions of snail trails I would invest in a diesel or gas add on.
But for less than £100 self-fitted - it's great. I have had elements in a 400 a 200 and a 650L tank.
One thing I have thought about is having two tanks. A 400L general tank and a 250L "hot" tank. But for the extra palaver I'd just go for a hot on demand set up instead.