ive been using lpg water heaters for over 4 yrs, ive never had a problem with them.
ive informed my van insurance company, with no increased premium, & they said it was ok as long as it was being used for work purposes. ??
i use the heater on every job all year round, this time of year the water is only luke warm, does it help the clean, not really, but it makes the hose nice & supple & easier to use & makes your working day less of a hassle.
summer time i turn the heat up & it does help to clean sun baked bird poo, bee spots, con roofs gutters fascias etc.
i have a refillable lpg tank ( see bottom right of photo ) and for what it costs to run £10 per week is well worth it.