Gas vs Diesel Caravan Heaters

Ten years ago, this wasn’t even a debate. Gas heaters were standard equipment in Australian caravans, and diesel heaters were a niche European import. Today the picture has flipped completely. Diesel heaters dominate the aftermarket, most new off-road and touring vans come with one pre-installed, and the Facebook groups are full of travellers ripping out their gas heaters and replacing them with diesel.

But gas heaters still have their place, and they’re not as simple to dismiss as the internet suggests. This guide lays out the honest pros and cons of each so you can decide which is right for your van, your travel plans, and your budget.

How Each System Works

Gas (LPG) Heaters

Gas heaters burn LPG from your caravan’s existing gas bottles. Flued models (like the Truma range) draw combustion air from outside and exhaust fumes through a dedicated flue, making them safe for overnight use. Unflued models burn gas directly inside the living space, producing both heat and moisture (and trace carbon monoxide), which is why they should never be used while sleeping.

Modern flued gas heaters like the Truma VarioHeat and Truma Combi (which also heats water) are well-engineered, thermostatically controlled, and widely used in European caravans. They connect to the same gas supply as your cooktop and hot water system.

Diesel Heaters

Diesel heaters burn a small amount of diesel fuel in a completely sealed combustion chamber. Air from inside the van passes over a heat exchanger (never touching the combustion side) and is blown back into the van as warm, dry air. Fuel comes from either a dedicated 5-10L tank mounted under the van or tapped into the tow vehicle’s diesel supply.

They run on 12V power (10-30W) and use 0.1-0.25 litres of fuel per hour. Brands range from budget Chinese units ($200-$500) to premium European manufacturers like Autoterm, Webasto, and Eberspacher ($900-$1,800).

The Key Differences

Running Costs Compared

Let’s compare a typical winter night: 8 hours of heating, moderate settings.

Diesel (Autoterm Air 2D): Average consumption of 0.15L/hr = 1.2L per night. At $2.00/L for diesel, that’s $2.40 per night, or roughly $72 per month.

Gas (Truma VarioHeat): Average consumption of approximately 100-150g LPG per hour = 800g-1.2kg per night. A standard 9kg gas bottle costs roughly $30-$40 to refill. At 1kg per night, one bottle lasts about 9 nights, costing roughly $3.30-$4.40 per night, or $100-$130 per month.

Diesel is cheaper to run, and the gap widens over a long trip. Over a 3-month winter stint, the saving is roughly $100-$200. Not life-changing, but not nothing either.

The bigger cost factor is fuel availability. If you run out of LPG in a remote area, you might need to drive 200km to find a refill point. Diesel is at every roadhouse and servo in the country. On a big lap through remote Australia, this practical advantage matters more than the per-night cost difference.

Safety

This is the factor that’s driven the shift to diesel.

Unflued gas heaters (the cheap portable type) produce carbon monoxide as a byproduct of combustion. In a sealed caravan overnight, this is genuinely dangerous. Several deaths in Australia have been linked to unflued gas heater use in enclosed spaces. They should never be used for overnight heating in a caravan, full stop.

Flued gas heaters (Truma VarioHeat, Truma Combi) are safe for overnight use. The combustion is sealed and exhaust vents externally. However, the flue system must be maintained, and any damage or blockage creates a risk.

Diesel heaters are inherently safe for overnight use because the combustion system is completely separate from the cabin air. Premium brands include multiple safety cutoffs: over-temperature protection, flame failure shutdown, low-voltage cutoff, and overheat lockout. Even budget units include basic safety features.

Which Should You Choose?

Choose diesel if: You’re doing the big lap or extended travel. Diesel fuel is available everywhere, running costs are lower, dry heat avoids condensation problems, and the safety profile is excellent. If your tow vehicle runs on diesel, you can T-piece the heater into the vehicle’s fuel supply and never think about fuel management separately.

Choose gas (flued) if: Your caravan already has a quality flued gas heater installed (like a Truma Combi that also heats your water). Replacing a working system is hard to justify unless you’re experiencing condensation problems or LPG availability issues. The Truma Combi in particular is an excellent unit that provides both heating and hot water from a single system.

Avoid: Unflued gas heaters for overnight use. Always. No exceptions.

For most Big Lappers buying or retrofitting a heater, diesel is the clear winner. It’s cheaper to run, the fuel is universally available, it produces dry heat, and the safety case is straightforward. The only scenario where gas makes more sense is if you’ve already got a quality flued gas heater and your travel doesn’t take you far from LPG refill points.