Is there any company that sells gas heaters that are installed by them,I thought I read somewhere once that Calor now do one. My diesel heater is good and has been since I got it but it plays havoc with the battery's even when there properly split charged they drain a hell of a lot of power. I mains charged 1 the other day it was reading 14 volts before I turned the van off and then within 10 minutes using the heater dropped it to 11.4 and then it powered off due to lack of battery power,thing is with gas it only requires ignition after that your only powering a 12volt pump just working cold my battery never dropped below 12.5 Volts.