In my van, I have 2 ways of heating during colder days.
During my build, I did install underfloor heating foil below the vinyl top layer of my floor. This is only on the parts where you can walk, so it can expose its heat. Under the cabinets and in the garage there is no floor heating (since this doesn’t make sense).
The floor heating is a thin (<1mm or so) heating foil. I’ve sourced this directly from AliExpress. In total, its around 400 watt of heating power. Not enough to be as primairy heating, but it will give you a nice heated floor and warm feets. Depending on the outside temperature, it might be enough to keep the van on its temperature during the night.
Main advantage of this: It’s comfortable and silent.
Disadvantage is its current draw: Around 400 watt. So its likely I’m only able to use it when connected to an external power source. I have connected it to a regular power plug, so if I want, I can connect it to my inverter and run on the batterie, but by default its only working when connected to outside power.
Another heating source will be a diesel powered heater.
When I bought my van, it included a Webasto Airtop 2000 diesel heater, which was installed under the passenger seat. It was connected to the main fuel tank, so no need to have a seperate fuel tank for heating.
During my build, I’ve relocated this Webasto to the back, in the garage below the bed. The outlet is in one of the benches, directing towards the front. Since my front cabin is seperated from the living space in the back, I had to relocated it. Since there is a gap between the bed and the rear doors, this will force air circulation. The heater draws its cool air from the back, thus behind the bed. Hot air is directed towards the front. Since hot air rises, I expect it to circulate through the hole van, giving me a nice evenly distributed heat.
Only part which was missing were the controls of the Webasto: The previous owner had it connect to a switch on the dashboard, so it would run either on (full power) or off. For my van, I wanted it to run also on low power, so I had to install some kind of thermostat. Most basic option was the Webasto Rheostat, which came with these models.
Unfortunately, they are very expensive: 70 euro or so ($80), which I wasn’t willing to pay for such a simple device (It only exists of a 2.2kOhm potentionmeter with switch and a LED), so I have build my own. In the manuals of the Webasto heaters is the schematic, they only lack the resistor value, but for the Rheostat this is a 2.2kOhm one.
The Rheostat doesn’t have a temperature sensor, it just relies on the temperature of the air reaching the input of the heater. So it’s not fully a thermostate, but it will do the job. If needed, I might relocate the temperature sensor.
I’ve bought a potentiometer with integrated on-off switch, so it will act just as the original Rheostat. This is included in my control panel in the upper cabinet.
The heater is now installed in the back. Exhaust is pointed towards the back. I also extended the fuel lines and cables, since it’s now in the back. All cables are routed underneath the van. For additional protection I’ve put them in a protective sleeve (Looks like some kind of thick heatshrink, which I had as leftover when it was a service van, I did recover these to be used later).
By default, the heaters are kinda noisy. After adding an exhaust muffler and an air intake filter it was much more silent (Especially the exhaust muffler made a huge difference). I used these parts from the cheap Chinese diesel heaters, so not genuine (expensive) Webasto parts. But if they fail, they are easilly to replace anyway.