We installed a diesel heater to heat the van during winter. We bought it from Camperservice Deventer and they helped us with installing it.
We chose this one because it was a lot cheaper than a Webasto for example but does exactly the same thing.
Right behind the drivers seat underneath our table we made an elevated floor so the heater could fit right underneath. with some air holes to suck air in and push hot air out.
The hose goes right into your diesel tank so not much to worry about except for an empty diesel tank during cold winter nights :-P
Truma gas water boiler. This runs on our lpg tank that we had installed underneath our van. It supplies our hot shower water and sink
water. It can heat the water up to 70 degrees celsius.