with the greatest respect to all alternetive hot water systems, i have a heat wave with a built in frost stat ,i know they are alot more expensive than cheaper versions (lp5 heaters) but the heat wave is alot less hassle, plumbed in to your fuel tank (no dangerous gas bottles) ext exhaust system comes from underneath the van (small tube) .all i do is take poles out then put frost stat on at night (no heaters ,boarding,insulation etc etc. JOB DONE .Some people just dont like the heatwave the only reason i can think of is that they wont pay the money £2300 it costs .money well spent in my opinon ,i have had mine 3 year now paid for itself over and over.