I have one of those drop in heaters ie the picture above, Nick got it for me when I purchased my scorpian back in November!although it is 110 volts i have a 110 converter. its only rated at 1KW . since using micro splitters heat has never been an Issue, for instance I cleaned a solicitors office a few weeks ago, looked like these carpets had never been cleaned before, they were minging! oil walked in with dog muck and the customer hadn't any warm never mind hot water, I cleaned the whole lot with number 9 and rinsed out with just cold water and got a brilliant result and didn't need to spot the oil marks.
PS I have a v2 heat exchanger capable of almost steam boosted cleaning but when you get results like this why bother with heat
I have had a Recoil now for 4 years and use the heat exchanger when needed.Who would want to waste time waiting for an element to heat up to 50 liters? Plus it would add weight to a very light and manoeuvrable machine. The Scorpion looks spot on to me and at the moment would be my machine of choice when the Recoil gives up the ghost.