Major update mid-June 2016

Diesel heating in caravans and motor homes is by far the safest approach because it hugely reduces the risk of carbon monoxide poisoning. Collyn Rivers reports. Diesel heating in caravans and motor homes is relatively affordable and easy to self-install. The units are also safe, effective and efficient. Fuel is readily available and safe and easy to store. There are also LP gas versions of these units.

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This is the Webasto Dual-Top water heater unit. The Eberspacher (Dometic) unit is similar. Pic: Webasto.

The main risk of heating in a confined space is carbon monoxide poisoning. Carbon monoxide is a colourless and odourless gas. It is formed whenever any carbon-based substance (coal, LP gas etc) is burned without enough air for complete combustion. There are only minor indications: headache, nausea, fatigue – and then unconsciousness. If you were asleep, you may never wake up again. Carbon monoxide is rightly called the ‘silent killer’. It also causes brain damage at minor concentrations.

A second risk is oxygen deprivation. We breath in about a half a cubic metre of air an hour. Of that we convert about 4% into carbon dioxide. If in a confined space the exhaled carbon dioxide level rises. The remaining available oxygen level falls. It is normally 21%. Symptoms (such as fatigue) set in once below 15%. Brain damage sets in shortly after. Oxygen deprivation can be serious (even lethal) in an unventilated space: heated or otherwise.  See my (fully referenced) article on the above (Gas risk in caravans ).

Safe RV heating

Diesel or LP gas heating (as described in this article) in caravans and motor homes avoids such issues. Both draw air from outside the RV into a tiny furnace sealed from the RV’s living area. Diesel oil or LP gas is injected and ignited in this furnace. Air to be heated is blown across its hot outer skin and ducted wherever needed. The ‘burnt’ air from the furnace is expelled to atmosphere. Burning gas is totally sealed from air heated within the vehicle.

These heaters have been made since the 1930s by Germany’s Eberspacher and later by Webasto. Both brands are highly respected in Europe, the USA and Canada. They began to be promoted in Australia around 2005. Eberspacher and Webasto are similar in many ways. Some parts (such as silencers, calorifiers etc., interchangeable). The Snugger is a similar but cheaper unit – available from Diesel Heating Australia.  

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The Snugger unit. Pic: Diesel Heating Australia. 

The company’s Genesis product is also worth considering, as is the Alde Compact 3010 LP gas unit that combines space heating and water heating and can also be run 230 volts ac.

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The Genesis II provides space and water heating in one unit. Pic: Diesel Heating Australia. 

Truma also introduced similar (LP gas) units a few years ago. There are also other look-alikes – but of unknown provenance.

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The Truma LP gas space heater/ Pic: Truma

There are two main types – air heating, and air and water heating and some are made in various sizes. Personal experience showed the smallest amply heats annexes, camper trailers, small/medium sized boats, caravans and motor homes. The next size up readily heats large caravans, motor homes or coach conversions.

Diesel heating in caravans and motor homes – air heating

As both intake and exhaust are on the bottom, the basic (soup-can size) unit is best floor mounted. A separate tiny electrically-driven pump, hose and filter may be connected to a separate diesel tank. Or (with a motor home) tapped from the vehicle tank. A small electric control panel can be wherever convenient within the vehicle. The hot air is vented as desired via 50 mm flexible hose.

Diesel heating in caravans and motor homes – water heating

The combined space/water heaters have a furnace unit that heats glycol. This then flows through a calorifier heat exchange uni. This unit also stores the heated water to feeds taps and showers. It also feeds small radiators through which air is fan blow wherever required. The calorifier is also available as a tiny on-line unit that heats water as it is drawn.

Diesel heating in caravans and motor homes – the heaters in action

I used a Webasto air heater unit in a previously owned OKA in much of outback Australia. Temperatures there drop quickly after sun-down and often to below freezing. Even on its lowest heat setting, the heater kept the OKA’s interior at a comfortable (for us) 25 degrees C. It typically used a fifth of a litre of diesel an hour.

A Webasto Dual-Top air and water heating unit was installed in our TVan camper trailer. It was then used all around Australia. This too worked very well. The tiny on-line calorifier supplied ample and ongoing hot water for cooking and showering after five or so minutes of being turned on.

It is necessary, and legally required in Australia, to add a tempering valve. This automatically mixes cold and hot water to prevent it exceeding 50 degrees C. Without it valve the water can reach a scalding 80 degrees C.

Unsilenced, the exhaust is intrusive outside the vehicle and may bother neighbouring campers at night. This is reduced considerably by the now standard exhaust silencer. Noise is reduced further still by an inlet silencer. The units are not totally silent but unlikely to disturb others unless camping very close to them (in a tent) on an otherwise silent night.

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The Webasto Dual-Top water/space heater in the author’s Tvan. Pic:

Further information regarding diesel heating (and its installation in caravans and motor homes is in the author’s Caravan & Motorhome Electrics and the (2016) all new Caravan & Motorhome Book. It is also covered in the now second edition The Camper Trailer Book. These heaters are powerful enough to heat rooms in otherwise solar-powered houses. My books on solar are Solar That Really Works (for cabins and RVs) and Solar Success (for homes and property systems).

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