With a trip to Wales in September looming ahead, I decided to install one of the cheap Chinese diesel heaters (Eberspacher / Webasto clone). Here's how I did it...
1.
First question: where to put it? These can be mounted inside the caravan / vehicle, but I didn't want to drill too many holes inside the tub, and certainly not below the "waterline" (the exhaust exits from the bottom of the unit and
has to be outside and you want to avoid fumes coming back inside.) Any internal mounting would need at least two holes in the floor, and run the risk of damaging the bits underneath or letting spray in. My decision was to make use of the "spare" space between the tow hitch and the body, which on my portafold had once been where the gas cylinders lived, this keeps it high up, the entry hole is protected from the rain and it isn't too obtrusive.
2.
Mounting. Best height is about 9" above the chassis, this allows the hot air to enter towards the bottom of the internal floor and via a flat part of the wall, and the entry point is out of the way and not liable to let rain in. So I made up a steel bracket and fitted it to the chassis as shown:
Protection was a sheet of 1mm aluminum formed into a box, curved edges and riveted shut. A couple of lengths of 6mm rod and wing-nuts mean the cover can be removed when necessary (if I was doing it again I'd be a bit smarter about fitting it round the handbrake lever):
3.
Bring the heat inside. I bought a 90 elbow with an 80mm internal diameter which fitted over the hot air outlet and attached the heater hose to it, wrapping the join area in motorcycle exhaust wrap to give it some strength and keep the hot bits from contacting the portafold walls. A cheap set of hole-saws from an online marketplace was perfect for this and the other holes I needed inside:
On the inside, I insulated the first part of the pipe (as it's still quite warm) and boxed in the remainder, so that it doesn't get squashed when we stow things in the centre forward cubby hole:
4.
Fuel Supply. I didn't want to have smelly diesel inside the Portafold, but there isn't much space inside either. The fuel tanks that come with these heater kits aren't great quality, so I bought a 10l diesel fuel can and adapted the lid (with a 6mm hose bulkhead connector) to run a feed pipe inside (there's a hose on the other end that's weighted with a bit of brass pipe and sits on the floor of the can). A pair of quick-release sealable hose connectors mean I can remove the fuel supply and put it in the back of my tow car, nothing leaks out and no need to prime it each time to remove the air. I just loosen the tank lid to let air in when in use and close up after:
5.
Electrics and control. I've got a 12v leisure battery under the seats above the axle, so use that to power the heater. The current draw can be quite high at startup (up to 4A) so I used a relay next to the battery and kept the power lines short, with the "control" line for the relay linked back to the master switch board. The folding nature of Portafolds makes wiring a challenge, and with the cheaper version of the heaters the controller is wired (more expensive ones have a remote control). A bit of sticky-backed velcro allows us to hang the controller inside the cabin and fold it away when stowed.
So what's it like? Well, when you wake up on a cold morning it's a lovely feeling to press a button and a few minutes later feel the warm air flooding into the cabin. You can take the chill off clothes, and keep the damp out. To be honest, on anything above the lowest setting, after about 30 mins it's really rather toasty and you need a door or window open! You certainly don't need anything bigger than a 2 or 3kW machine.