iv got a clarke diesel heater it is........ THE BOLLOCKS! lol cost a bit but it is actually excellent!it will last 11 hours on a full tank of diesel but i only have to leave it on for litraly 5 minutes and its cooking so a full tank ends up lasting weeks and weeks. iv actually just had it on as i have done some painting and want it to bake so left the heater on and checked the temperature after 15 mins and the garage is at 45degrees c!!
i really do recomment it its one of the best things i have bought.