[Tom White]

I've got my pumps on a bit of ply; I can unplug them from the wires going to the battery in 1 second and undo the pipe leading to the tank in under 30 seconds.  I can store them somewhere frost free.

My RO is not in my van; I RO to IBC and transfer pump it into the van.  It was fine during the freezing temps we had earlier this year.

[AuRavelling79]

Where are you guys buying your electricity? Goldplated land?

OK let's say 15p per KW hour x 3 for 3kw = 45p per hour.

Put on for four hours, night before = about £2.80 per night.

Lets say November 3 nights per week x 4 = 12 nights x £2.80 = £33,60
December 4 nights per week (Xmas off) x 3 = 12 nights = £33.60
January 4 nights pw x 4 = 16 nights x £2.80 = £44.80
February same as November = £33.60

Plus the odd night in March = £150 to keep your van frost free, hoses supple and water tepid all day for winter.

You only need to go out longer, work quicker etc for the equiv of less than one man's day of work and you're quids in.

Hot water on demand is fine but you would still need it to "click in" on a thermostat overnight to keep the frost at bay.