I have a 16Amp immersion set up. External socket on house & 24 hour timer inside house (under consumer unit).
On cold night (zero or below) I pull up & just plug in, job done!!
Van has complete frost protection (as tank acts like a giant radiator) & I get all the other benefits too, soft hoses etc. There is no difference in cleaning power IMO but it does mean my van & system are ready to go no matter what the weather.
![Wink ;)](http://www.cleanitup.co.uk/smf/Smileys/classic/wink.gif)