Ventilation and heating

The diesel heater is going to be vented from an external source and all waste gases discharged externally. In theory, assuming no faults there shouldn’t be any reason for additional ventilation. A carbon monoxide detector compliant with BS EN 50291-2 will provide additional safeguard in the event of a fault.  The issue of using it at night is therefore more concerned with power consumption and noise than safety. Typically they draw about 6 or 7 amps on start up and then a couple of amps when running. Most leisure batteries should be able to cope OK although you’ll obviously need to charge fairly regularly and solar might not be good enough in winter. Sounds like you’ve already discovered that!

For Health & Safety purposes I understand that European standards require a set amount of fixed ventilation even when windows and doors are closed. So whether to ventilate or not is down to you, but a habitation check should reveal any problems. Personally whatever the temperature outside I always leave a roof vent at least slightly open at night to improve air quality. However, sometimes on stormy nights that isn’t always an option. 

We had a Starburst with Webasto heating and found it very efficient. Like you I also had concerns about using this off EHU. I solved this by fitting a second battery and alternating between the two each travel days and when on EHU sites. This system worked well, just required that little extra monitoring and attention but never had a problem. 

Partly agree with the above, get a 2nd battery.....but you don't need to fiddle about changing them over, just connect together and add the capacities.

the pair should be evenly matched on size and, ideally age. I don't know what size came with the van but why not get a new pair of (say) 100/120 ah batteries and perhaps an extra 100w solar panel to make things better on cloudy days?

Thanks all. I'm heading off on my own - just me and the dog - today for a couple of nights. I'm staying on a commercial site with EHU so if I need heat, I'll be fine... though I may not need any. I will be closing the roof vents though or maybe just keep one open a fraction. My dog will be pleased too as she tends to throw her blanket off half way through the night and then later regret it. Do dogs go through menopause?