A van trip is an excellent way to explore new destinations and create lasting memories. However, if the temperature drops significantly, those memories might not be particularly rosy. When the weather's cold, a campervan diesel heater is pure gold!
In our 2023 Roaming Home study, we found that of those with heaters, 68% were diesel/petrol.
In this guide we will go deep on 12V diesel heaters - including a comparison of the best diesel heater brands and an installation guide.
I'm Shane, I've been teaching people to convert campervans for years; I'm the author of Roaming Home; The Comprehensive Guide for Converting Your Van Into a Campervan,writer of The Van Conversion Newsletter, instructor of The Van Conversion Course over at Udemy. And full-time vanlifer for 4 years!
Now let's jump in and have a good look at campervan diesel heaters.
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What are the benefits of a campervan diesel heater?
Campervan diesel heaters are a popular choice because they are efficient, reliable, and cost-effective. However they (can) have a higher upfront cost than LPG or electric heaters.
The three big benefits of campervan diesel heaters overs LPG heaters are;
Diesel is more readily available at petrol stations than LPG
Diesel is a more efficient fuel source and burns at a higher BTU (heat) than LPG
Diesel is safer than LPG (doesn't ignite easily)
With that being said, one of the biggest drawbacks is how loud they can be when running compared to LPG heaters. They also don’t function as well at altitude.
It's essential to install your diesel heater properly to ensure your safety and comfort while on the road. A poorly installed diesel heater can be dangerous and cause carbon monoxide poisoning or even a fire. This is why it's crucial to follow the manufacturer's instructions and seek professional help if you're unsure about any aspect of the installation process.
The diesel heater installation is the most common job that is outsourced to professionals. If you do not feel confident in your ability to do it yourself, getting a professional would be a wise decision.
LPG heater vs. Diesel heater
Whether you choose to go for an LPG heater or a diesel heater is up to you! Here are some stats to help you make a better decision. Note that you will be using LPG anyway for other appliances in your van such as the gas stove.
Price of fuel:
LPG is cheaper than diesel
Price of installation:
A Propex LPG heater is cheaper than a Webasto diesel heater, but more expensive than a 'chinese diesel heater'
Efficiency of fuel:
LPG is more efficient than diesel (takes longer to burn same quantity of fuel)
Diesel is safer than LPG (the gas plumbing for LPG must be done perfectly + the storage of diesel is safer)
Time to warm up:
Diesel heater takes longer to warm up than LPG
LPG heaters are quieter than diesel
Diesel contains 34% more BTU than LPG (meaning it will heat a campervan more efficiently)
An LPG heater doesn't need to be cleaned as regularly as a diesel heater
LPG functions better at altitude (>1500m) than diesel
LPG heaters typically take less electricity to run than a diesel heater
How does a diesel heater work in a campervan?
A camper van diesel heater works by burning diesel fuel to heat a heat exchanger. The combustion process draws in fresh air and expels combustion gases through an exhaust. The heat exchanger, which consists of a large surface area, heats up as the diesel fuel is burned. A fan then draws in air, which is heated as it passes through the heat exchanger. The hot air is then blown into the living space of the campervan, providing warmth and comfort.
Campervan diesel heaters can be connected to the vehicle's fuel tank or to a separate, auxiliary fuel tank. This makes it possible to use the diesel heater even when the engine is turned off.
Most diesel heaters also come equipped with safety features, such as an automatic shut-off if the heater overheats or if there's a problem with the fuel supply. Some models also include a thermostat or remote control, allowing you to adjust the temperature and control the heater from a distance.
Most manufacturers of camper van diesel heaters also make a petrol equivalent.
Types of camper van diesel heater
There are three types of camper van diesel heaters;
Air and water heater
An air heater is the most common type of diesel heater. It is a ‘simple’ blow heater.
Air and water heater
An air and water heater acts as both a blow heater and a water heater, all in one! The Truma Combi is a very popular model of air & water heater.
The hydronic heater is the most modern (and complicated) type of diesel heater. When we interviewed Colby and Eric (EngineersWhoVanlife.com), they told us they had installed Eberspacher’s brand new Hydronic AquaSystem, which has automatic altitude adjustment to 3000m.
A hydronic heater functions as both a blow heater and water heater. But it has one extra piece of functionality which is incredibly cool. It uses waste energy (excess heat) from the engine once the van has stopped as a fuel source. This means you get ‘free’ hot showers or heating for quite a while after you go for a drive!
Hydronic works by heating fluid (glycol), which runs through a calorifier. A heat exchanger is used for hot water, an air matrix is used for hot air.
Hydronic heating is the most efficient way to get underfloor heating in your van.
What size diesel heater should I get?
A 2kW diesel heater should be just fine for most vans. If you have a large van which you plan to use in really cold conditions, a 5kW diesel heater may be the better choice. In a house with good insulation, one sizes the heater to be about 1 kilowatt (KW) per 14 cubic metres of living space. In a campervan, we should double or triple this number.
2kW Diesel Heater
Less powerful, therefore will need to be run longer to achieve the same results as the 5kW could in a shorter length of time
In most vans, a much more comfortable temperature than the high, fast heat of the 5kW
5kW Diesel Heater
Generally only needs to run on low due to its power
You will run it on low more than the 2kW version, this means you will have to burn off the excess carbon builds up more frequently (ie. run the heater on high)
Have the option to really crank it up in sub-zero temperatures
Diesel heater carbon buildup
One of the biggest drawbacks of a campervan diesel heater versus an LPG heater is the buildup of carbon soot that can occur in the heater. This soot puts a lot of strain on the heater over time and needs to be managed carefully. The amount of soot produced by a diesel heater increases when combustion conditions are not ideal.
This typically happens when the heater is used at a higher altitude or when there is too much air restriction in the exhaust (exhaust too long, too many bends, etc).
Operation of heater to avoid carbon buildup
Avoid firing up the heater for less than 10-15 minutes
Avoid running the heater on Low for too long (especially at high altitudes)
Before shutting down the heater, "boost" it for 10 minutes (ie. turn it up to high)
The effect of altitude on a diesel heater
Altitude can have a significant effect on the performance of a camper van diesel heater. At higher altitudes (>1500m), the air becomes less dense, which can cause a reduction in the heater's ability to produce heat. This is because the heater's combustion process relies on oxygen from the air to burn the diesel fuel and create heat.
As the altitude increases, the oxygen levels in the air decrease, which can lead to incomplete combustion and reduced heat output. This can cause the heater to run less efficiently and potentially even shut off entirely - this is due to the excess carbon build up that happens at altitude.
You can sometimes buy a heater which has built-in altitude adjustment, though frequently it comes at an additional cost. Alternatively, you could purchase a high-altitude kit for your campervan diesel heater.
In some cases, manual modifications are required to adjust the fuel-to-air ratio to ensure proper operation of the diesel heater at higher elevations.
How much battery do I need for a diesel heater?
The power consumption of a diesel heater is typically measured in watts or amps, and can range from around 5 watts for a small heater to 50 watts or more for a larger heater. Most diesel heaters have a low power consumption mode for when the heater is not actively heating the space, which helps to save power and extend the life of the battery. Diesel heaters can draw 8-12A on start up.
how much diesel does a diesel heater use?
Diesel air heaters have a fuel consumption of around 0.3 litres/hour for 2kW models, and 0.5 litres/hours for 4-5kW models.
Best diesel heaters
Eberspacher Airtronic, Webasto AirTop, and Planar Autoterm are three of the most popular brands of diesel air heaters for campervans.
The Eberspacher diesel heater is known for its quiet operation, low fuel consumption, and high-quality German engineering. The Airtronic range includes models that vary in power output from 2.2 kW to 8 kW, making it easy to choose the right size for your campervan. The Airtronic also features an automatic altitude adjustment system that ensures efficient operation even at high altitudes. However, the high cost of Eberspacher heaters can be a drawback.
The Webasto diesel heater is another German brand that has been around for over 75 years. Its AirTop range includes models with power outputs ranging from 0.9 kW to 5 kW. The AirTop is known for its low noise level.
Planar Autoterm is a brand that gained popularity in recent years due to its lower cost verses Webasto and Eberspacher. The Autoterm range includes models with power outputs ranging from 2 kW to 9 kW, making it suitable for larger campervans. The Autoterm is also known for its efficient operation and low fuel consumption, making it an economical choice. However, the Autoterm is relatively noisy verses it's more expensive competitors.
Chinese diesel heater (Budget option)
When it comes to buying a camper van diesel heater, you may be tempted to opt for a cheap Chinese diesel heater instead of a more reputable one like Eberspacher or Webasto. While Chinese diesel heaters can be more affordable, there are some drawbacks to consider. Chinese brands may have lower build quality and may not meet safety standards in some regions. They may also be more prone to malfunction or break down over time, which could be a serious safety hazard if you're relying on your heater to keep you warm in cold conditions. Finally, they may not have a warranty or support like the other options.
With that being said, these are incredibly popular and many people have used cheaper diesel heaters for many years without any problem.
Here’s a rough diesel heater price comparison:
Diesel heater safety and regulations
Below I have supplied some key safety information for a typical 12V diesel heater - note specifics may differ depending on manufacturer. I have also included some guidance from the BS EN 1949:2021 standards, which discuss LPG regulations (which will also be useful here).
The information provided in this guide is provided solely as a high-level resource for information - and not as a single source of truth. I am not a certified gas fitter, nor do I hold myself out to be. The information provided below is a collection of publicly available information that I have consolidated - while I have done my utmost to provide the correct information, there may be mistakes in this information.
Here are some things you should be aware of:
Heater must be installed inside the campervan.
The heater must not be used when the vehicle is in motion
The exhaust and inlet must be routed outside the van
The exhaust should be somewhere where it will not be sucked back in by the air inlet or through a window!
The exhaust needs to vent out from the edge of the van. If not vented away from the edge, carbon monoxide could collect under the van and be sucked back in the air intake.
The exhaust pipe should slope down (to prevent condensation build-up on the inside of the pipe)
The air intake pipe should also slope down (If it rains, the pipe can fill with water and the heater will fault)
Never trim the air intake / exhaust pipes.
The exhaust and air intake should be at least 50cm away from each other to prevent recirculation of bad air.
Please make sure you install a carbon monoxide alarm in your van. This is critically important.
Campervan diesel heater tips and tricks
You will need to prime the fuel pump the first time you start up your diesel heater. Follow manufacturer’s instructions for information on how to do this (normally on the control panel)
You can expect the heater to be smokey the first time you fire it up. Whether it’s burning off excess fuel from over priming or extra oxygen that was sitting in the lines, it’s completely normal
Diesel heaters are well known for the ‘ticking noise’ they produce. You can buy a silencer to reduce this noise. Install it at a 45 degree angle for maximum benefit
Being able to start your diesel heater remotely from your phone is a really handy feature. Have a warm van ready for when you get back from the hills! The ModemQstart takes a sim card and allows you to operate an Autotherm heater remotely
Running a diesel heater on a low temperature is not great for the heater, especially at high altitude. If you are running the heater on low heat, run it on high for 10 minutes before turning it off
A diesel heater should be serviced every one to two years depending on frequency of use
How to fit a diesel heater
Here is the secret to a bomber 12V diesel heater installation: Read the manual. Installation differs between models and a poor installation will only lead to headache down the road. This chapter gives an overview of the installation and is not meant to be a replacement for the instruction manual.
Step #1: Mount the camper van diesel heater
Before you start, decide on the best location for your diesel heater. This will depend on factors such as the size of your campervan, the layout of your interior, and the type of heater you have chosen. Consider mounting the heater in a location where it won't take up too much space, but also where it can provide maximum warmth to the living area. The heater should be installed in a well-ventilated area, away from flammable materials and heat-sensitive components.
A 12V diesel heater is commonly installed under the front seats, on the opposite side to the sliding door. This can reduce the noise from the heater if it's behind a bulkhead. It is also a little safer due to the separation from the back.
To mount the heater, follow the manufacturer's instructions carefully. Some diesel heaters come with a mounting plate that needs to be bolted to the floor, while others require brackets or screws to attach to the interior of the campervan. Make sure that the heater is securely fastened and positioned correctly, and leave enough space around it for proper ventilation and maintenance.
Step #2: Install the Fuel Line
The next step is to install the fuel pickup line. You have two options for doing so;
Option #1 - Primary tank: Drop the diesel tank down on jacks to access the lid and install the fuel line. The method of installing the fuel line differs depending on the van. The Ford Transit is relatively straightforward as it has an auxiliary fuel port pre-drilled (you can purchase a connector kit to attach to it). Other models of van may not be so straightforward and will require you to drill your own port (drain the tank first).
Option #2 - Auxiliary tank: Use a small, separate diesel container which you can install inside your van. If you're installing a separate fuel tank, make sure to choose a location that's easily accessible for filling and draining.
Fuel pump & filter: You will need to install a fuel pump to ensure that the diesel fuel reaches the heater properly. You should install the pump at an angle between 15°-35° (differs between models). Install the fuel pump as close as possible to the fuel tank. You should also install a fuel filter between the pump and the fuel source to remove any contaminants from the fuel which could break the pump or heater.
When securing the fuel pump, place a thick rubber gasket between the pump and the affixing structure. This will minimise any vibration from the fuel pump. “Quick fists” are commonly used to reduce vibration.
If you are using an auxiliary tank, you may need to drill a hole in the tank and install a quick disconnect fitting in the tank.
Step #3: Install the diesel heater exhaust pipe and air intake
Once the fuel line is installed, it's time to install the diesel heater exhaust pipe. The exhaust pipe should be routed outside the campervan (facing towards the rear of the van) to vent the exhaust gases safely. Make sure to follow the manufacturer's instructions to ensure that the exhaust pipe is properly installed and secured. Make sure not to install the exhaust beside the door or you’ll breathe in a bunch of nasty fumes.
You will need to drill through the floor to install the diesel heater exhaust pipe and air intake. You will need to attach a bi-metal holesaw to your drill. Apply some metal paint to the bottom of the van where you just drilled to prevent rusting.
NB: Use a low RPM, tapping and cutting fluid, and a pulsating action when using the holesaw. Else you risk destroying your holesaw.
The combustion intake and exhaust length should be less than 2 metres.
Don’t bend these pipes too much as it restricts air movement. The smallest bending radius is 50mm and total bend is 270°.
Install the air intake facing the opposite direction to the diesel heater exhaust pipe. It should face down slightly to prevent any rain water from getting stuck in the pipe. There should be at least a 10 cm gap between the exhaust and air intake. The end of the exhaust should not exit under the vehicle; the diesel heater exhaust pipe must end outside the vehicle edge.
You can optionally install a muffler (silencer) on the exhaust to reduce noise. Though this adds quite a bit of air restriction, so is not always installed.
Step #4: Route the diesel heater ducting
Route the diesel heater ducting around your van to evenly distribute the heat. Make sure in the inlet for cool air is not beside a heat outlet.
Step #5: Wire the 12V Heater
Wire the 12V diesel heater to your 12V batteries. You will also need to connect the heater's control panel and pump.
Step #6: Test the campervan diesel heater
After completing the installation process, it's crucial to test the campervan diesel heater to ensure that it's working correctly. Turn on the heater and check for any signs of leaks or malfunctions. You should also test the heater's thermostat and timer to ensure that they are working correctly.
If you encounter any issues, consult the manufacturer's instructions or seek advice from a professional. Some common issues include air in the fuel line, improper wiring, or a clogged exhaust pipe.
Step #7: Install a carbon monoxide alarm
Safety first! Please.
I hope you found this guide to campervan diesel heaters useful! You are well on your way to a beautiful (and warm) campervan!
Don't forget to subscribe to The Van Conversion Newsletter for everything you need to get started with your own van conversion (I'll send you a free wiring diagram when you join).
If you're looking for some guidance with your van conversion, you might be interested in Roaming Home; The Comprehensive Guide for Converting Your Van Into a Campervan. In the 380-page book (or ebook), you'll learn directly from me how to convert a van into your dream home - no prior experience needed!
Until next time,