i use aan l5 type one from corwood and co, never given me any problems works great, does't use a lot of gas at all and kept me working in the winter , however these things said i have now taken it out for next winter, as hose becomes two flacid and catches on everything hard to pull around corners (heat tested ionics orange hose) conecters constantly leak n the van with the mixture of temperatures and sometimes blow off with the heat, everything always needs tightning jubali clips etc.
recently to simplify everything, i purify the water at home ( removed my di vessel from the van and have taken out my heating system, leaving ... a tank a pump and a hosereal... not much stuff to go wrong.
preformance ways i have noticed on dirty conservatory roofs and first cleans, virosol seems to be more effective than heat.
the more stuff you have in your van the more stuff that goes wrong, if you use push fit connecters they dont like heat either, certain brushes dont like heat, and ez push fit taps dont like the heat. also hose which is made for heat, is really crap when its not heated