Installing a Diesel Heater in my Motorhome for Full-Time Living
When it comes to full-time living in a motorhome, redundancy is still one of the best fail safes you can have. It’s also about getting the most efficient value out of your resources!
One such resource is LPG. You may have already read my article on why I’m not getting rid of LPG, despite the apparent decline in places you can get LPG from (I also did a video on it if you prefer to watch rather than read).
LPG is not just used for cooking in a motorhome, but for heating too. I want to make my resources go as far as possible.
That's why I installed a diesel heater in my motorhome, not to replace my existing Truma system, but to run alongside it.
If you have absolutely no idea what I’m talking about, let me quickly explain.
What heating system is already fitted to a Motorhome?
As standard, a motorhome will come with a heating system, that includes a combi boiler, for heating your living space and heating up your onboard water.
For this quick explanation, I’ll focus on how the heat is delivered to the living space.
There are two main types. One is known as blown air heating, where a series of ducting pipes and vents around the motorhome distribute the hot air via a fan.
The other is a wet central heating system, where the heat is distributed by a series of small radiators installed around the motorhome.
They can run on gas or electric (there are new variations, particularly of the blown air system, that run on diesel and some manufacturers use diesel but for the most part, an LPG run system is the norm).
Both have advantages and disadvantages, and there is a whole separate debate on which is better. I won’t go into much more detail because that’s not relevant here.
What is a diesel heater?
In comparison, a diesel heater is pretty much what it says; a heating device that uses diesel as its primary fuel source.
Diesel is mixed with air to produce heat and a standard heater will only use a small amount of fuel to heat the vehicle.
There is the option to have a separate fuel tank to supply the diesel heater but I have chosen to plumb my fuel supply line directly into the motorhome’s main fuel tank. I don’t fancy having a separate tank of fuel on board plus there was nowhere sensible to mount one anyway.
Why add a diesel heater?
In a nutshell, because LPG is getting harder to get hold of, as I mentioned above. So I'm trying to minimise how much I use, because using LPG for the heating can use a lot of it.
Diesel is going to be readily available for many years yet so if I’m struggling to find a garage that sells LPG, I know I'm always going to be able to find a fuel station to get diesel.
By only using LPG for cooking, running my fridge, and for heating my water, I estimate I should get about five to six weeks out of two bottles. That will really stretch out my gas.
(If you’ve seen any of my electric cooking videos, you’ll know that I also now utilise solar power to cook!)
There is another bonus with a diesel heater (also called a night heater by a lot of lorry drivers), it can heat up a lot quicker than either of the other two systems. This makes it perfect for when you need heat fast!
It’s also a different kind of heat, admittedly a dryer heat, but it makes it great for drying out wet coats and clothes.
Deciding where to put the diesel heater in the Motorhome
The first thing I had to do was find somewhere to put the actual diesel heater itself in the motorhome. The original place I wanted to put it was unsuitable because the suspension and parts of the chassis were directly underneath.
The next suitable place, in the cavity underneath my sofa, meant removing my spare wheel. This might not seem like a sensible option, but to be fair, I've never used my spare wheel. And touch wood, I won't ever have to. Plus I've got a breakdown recovery service.
Drilling holes in my Motorhome
Now I had found a place to put the diesel heater, it was time to drill the big hole out for the turret (a style of mounting plate for the heater unit).
The reason I went with a turret is because it adds more protection. It adds an air gap around everything and gives more space to allow the heat to dissipate.
In typical Daz fashion, I ran into a few issues whilst drilling the hole (that's what she said!). I ended up having to go outside and start drilling from underneath.
I then came across something I didn't expect to find. For some reason, there was a sheet of aluminium, or thin steel, randomly in between the bottom of the floor and the foam.
Once I finally got through the floor, it was time to neaten up the edges because that sheet of steel I found was making a bit of a lip around hole.
I got the dremel out and sanded the edges down. It took time but I got there and then came the fun part of putting the entire diesel heater assembly (the various external pipes and feeds) together.
World’s biggest turret fanboy
As I mentioned before, the beauty of using a turret mount is it allows the heat to dissipate. However, it does make fitting the various parts a tight squeeze because you can't really get tools in and around the section in the turret you need to fit them.
I'm not one for proper tools, so I was using whatever tools I had to hand. It took some time and it was fiddly but it was worth it in the end.
I know I sound like a right fanboy with these turrets, and you probably don't want to read the word turret anymore. Thankfully you won't have to because at this point, the assembly was finished and it was time to secure the heater unit to the floor.
This was literally a case of threading all of the pipes and feeds I’ve just fitted, through the hole in the floor and then screwing the unit to the floor.
Fitting the fuel pump for the diesel heater
That was the inside part of the installation virtually done. Now was the fun part of getting underneath the motorhome to sort all the cables and fit the important part, the fuel pump. The heater wont run without it.
If you’ve never seen one, a night heater fuel pump is quite small, so it’s easy to find a space for it. I made sure the pump was at a 45 degree angle and utilised the existing chassis bolt holes to secure everything with cable ties.
The last thing that had to be done inside was to make a vent hole where the heat is going to come out from and into the living area. I decided on putting the heater vent in the centre of the panel under my sofa, so that it flows straight into the middle of the motorhome.
I opted for that central location as opposed to trying to route the heat through the existing Truma vent, because there wasn’t enough space to run a heating pipe around the inside of the cavity and to the existing vent.
It also means the heat will flow straight down the centre of the motorhome, nice and toasty!
Temporary jerry can
I fitted the control panel for the heater on the wall of the motorhome, this was simple enough by running the cable from the heater unit around the edge of the cabinet where it's fitted. They supply enough cable so that the control panel doesn’t have to be next to where your installation is if it's more convenient to have it somewhere else.
The only job left now was to run the fuel line into the main fuel tank. I had to wait for some extra kit, a longer fuel line and the bits for plumbing into the main tank, to arrive for that so I had to temporarily run the heater from a jerry can.
Fitting the fuel line for the diesel heater to the main diesel tank
My mate John was helping me with this bit of the installation. We couldn't get the whole fuel sender unit out because one, it was full of diesel, so diesel could potentially go everywhere. And two, access to remove the fuel sender unit is restricted because normally, people would remove the fuel tank. I didn’t have that option so we worked around it.
I held the sender unit up in mid air and then held some tissue underneath the hole that we were about to drill. That was to make sure no debris got into the fuel tank.
Then, we screwed in the fuel pick up pipe. The hole was quite tight (that's what she said! I know I’ve done that already but these opportunities cannot be missed) but it was fairly easy. It just screwed all the way in, then did up on the back.
My fuel sender unit is a pressurised one so after connecting the internal fuel line pipe, we pressed the unit down into place, put the retaining ring back on and bolted the sender unit back in.
Then we fitted the fuel line that runs from the pick up on top of the sender unit to the diesel heater. I started the engine after to make sure there were no fuel leaks and to ensure the fuel gauge still read correctly.
Connecting the fuel line to the diesel heater assembly
Now it was time attach that fuel line to the rest of the diesel heater assembly. I routed it down beside the fuel tank and John pulled it through from underneath the motorhome.
We then cable tied it to the chassis, all the way to the back of the vehicle, making sure to keep it away from the exhaust pipe.
I could then attach the fuel line to the fuel pump I fitted earlier, adding in the fuel filter at the same time.
Priming the diesel heater (or trying to)
Priming a new diesel heater is the process of pulling the fuel through the fuel line and up to the diesel heater unit. This is an important process when it's brand new, because the fuel line will be dry.
I had trouble priming my diesel heater. I looked at many different videos on YouTube about it but I couldn't get my heater to go into prime mode.
Eventually, what I had to do was keep turning it on and wait for it to try and fire up. It kept giving me an error and wouldn’t turn on. I did this 8 to 10 times and finally, it started working.
Whilst doing this, John had the idea to open the fuel tank at the filler cap to allow a free flow of diesel through the new fuel line.
I’ve since learnt that this priming process should be done using a vacuum pump. That way you’re not running the fuel pump dry. However, I didn’t have one at the time so I had to improvise.
A working diesel heater in my motorhome
And that completes the installation. I have a fully working diesel heater in my motorhome, plumbed into the main fuel tank. It's been operating absolutely fine since fitting and I am happy to report I have one very toasty motorhome.
I really appreciate John helping me out with it, because there was no way I was doing that on my own. I was a bit out of my depth there but it went well and I’m chuffed I had a part in fitting it myself.