I have the truma combi e fitted in my PVC and i'm wondering if someone can confirm or otherwise if its possible to run the warm air heating when the system is drained down for the winter. I ask because of a conversation I had with a guy who said a friend of his ran his system during the winter when ever he went out in the van having drained the water system down. I have looked in the manual but it talks about heating and hot water mode or just hot water mode no mention of just heating mode so I am a tad confused. I thought as i use the van all year round a quick blast before I go out would warm the van up and not have to wait for the cab heating to reach temp