The complete guide to diesel heating

Whether you’re going to buy an RV with diesel heating from the factory, or you intend to install a system yourself, this is the complete guide to diesel heating

TYPES OF HEATING

When you look at adding an aftermarket heating solution to your RV, there are three main categories to consider: 240V electricity, LPG gas or diesel.

240V Electricity

If you know you’re going to spend every night in a caravan park where you’re already paying for the 240V power supply, a reverse-cycle air-conditioning unit isn’t a bad way to go.

However, they’re expensive to purchase (and have installed), and if you already have an air-conditioner for cooling only, then a changeover will be costly. A small portable heater is an alternative – but they can be a nuisance and a trip hazard. If you decide to free camp, your only option is to travel with a generator. Keep in mind that the significant power heating draws means the generator will need to be a large unit.

LPG Gas

While most caravans and other RVs use gas for cooking, gas is also used for heating water and operating absorption-style fridges that are fitted with burners when away from 240V electricity. So adding a gas-style ducted heating solution, given you already have a fuel supply in place is an advantage. In addition, the units run relatively quietly, and the fuel is clean-burning. On the flipside, these units need to be installed by a certified gas installer; regulations dictate how and where they can be located; and you’ll need adequate 12V capacity to run the unit. And with an increase in demand on your LPG gas supplies, finding LPG when travelling remotely can be difficult.

Diesel Heating

With diesel fuel readily available throughout Australia, this solution for heating is a good option especially as it doesn’t diminish LPG supplies. However, it does require some 12V capacity to run. As RV owners add diesel heating as a retrofit, suppliers now offer installation kits for the competent DIYers, which can save you a considerable amount of money.

WHY DIESEL?

In colder climes, such as Europe, diesel-fuelled engines require a form of pre-heating when in sub-zero temperatures. This concept of using a heat exchanger with diesel fuel has been modified, improved, and applied to motorhomes for a suitable heating solution (as many motorhomes were diesel-fuelled).

The natural progression for this type of heating for motorhomes soon extended to boats, caravans and camper-trailers. The rapid demand has brought competition into this sector, and there’s a range of products available as OE for aftermarket fitment.

WHAT’S IN A KIT?

Let’s look at what components make up the Dometic Eberspächer diesel heater kit, and we’ll walk through the process of how they all work together.

Diesel fuel – while diesel motorhomes have an onboard diesel storage tank that you can simply tap into, you’ll need to install some form of diesel storage tank for a caravan or camper.

Hosing – is used to direct the diesel from the tank through a pump and then to the heater unit.

Pump – is designed to deliver the right amount of fuel and is installed between the diesel tank and the heater unit.

Heater unit – where all the heat is produced. The design characteristics vary among brands.

Intake air and exhaust gases – both are managed via ducting filters and mufflers.

Ducting and outlets – are used to direct the atmospheric air inside the RV to appropriate locations.

Wiring harnesses – contain the fusing circuits and connections to direct the onboard 12V power to all the components in the set-up.

Electronic control board – uses microcircuit processors to control all the functions; from metering the diesel pump, to the combustion process and fan speeds in the heater unit, along with start-up and shut-down procedures and fault-finding diagnostics.

HOW IT WORKS

The RV’s cold ambient air is directed via an intake duct so it passes over a hot cylindrical metal surface, thus heating the air as it does so. Ducting then directs the fan-assisted air to an outlet, where the warm air is pushed out of the duct into the RV. This process is repeated over and over, resulting in heated air throughout the RV’s interior.

WHAT TO PURCHASE

We spoke with John Lewis from Plenty River Plumbing who has been in the caravan industry for 40 years. John’s advice when purchasing a diesel-heating solution is to look for units that have quality parts and come with a muffler – otherwise, they may be noisy and costly to operate. John also says to check that the warranty covers you Australia-wide and service agents are available in all states.

KEY INSTALLATION POINTS

While reputable diesel heating brands come with very good installation instructions, RVs are all different in terms of design, dimensions and materials. These are just a few points worthy of consideration before making that purchase. Discuss these with sales staff who have the experience and knowledge to answer – so you can buy with confidence and know your chosen unit will work for your RV.

Where to mount the heater unit, because it needs adequate clearance around it.
What is the distance between the fuel tank and heater unit? The closer, the better – and use gravity to your advantage.
Consider protection under your RV (i.e. for flying stones) to avoid any damage.
The wiring to the 12V supply needs to be fused and the cable size adequate – all wiring also needs to be protected and well insulated.
Consider the location of the control switch and thermostat for the best operating efficiency.
Consider where to mount the air intake in relation to the heated outlet air, to maximise air circulation in your RV.
Think about whether you would like zones, multiple ducts and outlets; and how will these be installed.
Consider what direction the combustion exhaust fumes and outlet will face in relation to neighbours, vents and window openings.
Take the time to work out how to keep dust out of the exhaust when you’re travelling on dirt roads.

OTHER PURCHASING CONSIDERATIONS

Determine where the diesel tank can be safely installed on your RV, prior to purchase.
Do you have adequate payload allowance to add the weight of the diesel heater and a full tank of diesel?
Consider buying your kit from a specialist who has a proven track record. Look for a unit that comes with warranty and has service agents right throughout Australia.
Kits can be installed by a competent DIYer, but it’s recommended to have yours fitted by a professional if you lack the knowledge and experience (particularly with the electrics).
Investigate how many Amps the unit will draw from your house batteries, as not all units are the same.

MYTHS AND MISCONCEPTIONS

You only need to sit around with others to hear all sorts of comments and opinions about diesel heating. So let John Lewis set the record straight, with some Q&As.

Is diesel heating noisy?

Diesel heaters that make a ticking noise and sound like jet engines taking off can often be traced back to poor installation and cheaper-end kits. The fuel pump needs to be installed with rubber mounts and insulated to prevent drumming through the chassis rail. The better kits come with intake silencers on the fresh air intake, and how these are positioned is important for noise.

As a DIY project, is there any risk I can cause a fire if I install it incorrectly?

Fitting a diesel heater can be achieved by a competent DIYer who also has a good understanding of electrics. Ensure you follow all installation instructions, paying particular attention to the exhaust pipe and muffler. Secure the exhaust pipe well clear of all plastics and appliances such as the hot water service, and avoid placing the muffler outlet too close to open windows.

Should diesel heating smell?

Not inside the RV, unless windows are left open and the wind picks up. As a combustible fuel, the smell can be greater outside upon start-up but reduces once running – similar to a generator.