[Plankton]

http://m.ebay.co.uk/itm/NEW-Portable-Outdoor-LPG-GAS-SHOWER-WASHING-HANDS-ETC-12volt-Butane-Propane-BAG-/222032029200?nav=SEARCH
I've never seen these before and thought they looked good. I assume they have an internal pump which may only be 35psi so would need to be upgraded.
Has anyone used them?
http://i.ebayimg.com/00/s/MTYwMFgxMDY2/z/iDIAAOSwll1WzGkM/$_1.JPG

[Spruce]

It looks like a Kampa gas heater.

David Hinton used one to heat water for his back packs

https://www.youtube.com/watch?v=ZgmKVt4HgM0

I don't know how it worked long term. Its not meant to be in the back of a van or a similar enclosed space due to having no exhaust vent provision.

Its a very small unit - 5 kw. The specs for the Kampa say it will raise water for 30 degrees to 55 degrees at 2.5lpm.
Theoretically it should work, but in winter our water in the van is around 6 to 9 degrees. So heating water from that base by 20 degrees won't give you scolding hot water, rather just warm. By the time it gets through the hose and out to the brush head it will loose some of that temperature.

http://www.kampa.co.uk/water-heating-showers/geyser-hot-water-system

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[Plankton]

I've just noticed what I thought was a filter is actually the pump.

[Spruce]

I've just noticed what I thought was a filter is actually the pump.

The heater is being used to heat water that the heater has already heated.  So he isn't taking cold water from the tank and pumping it warm into his 25 liter barrel.

[Smurf]

That type of heater would be a total waste of time if you ask me.

[Spruce]

That type of heater would be a total waste of time if you ask me.

I would  have to agree with you Smurf.  It isn't the right tool for window cleaning. It has it place for the odd camping trip but that's about it.