Keeping Warm in the Van: What Actually Works

Our first proper cold snap on the road was at Wilpena Pound, and I'd packed like a bloke who reckoned "outback" only ever meant hot. Woke up to frost on the awning, a flat feeling in the bones and a wife who wasn't much interested in conversation. Six winters of laps later, I've sorted out what actually keeps you warm in a van and what's just money you handed over for the privilege of a good yarn.

The cold isn't your real problem. The damp is.

Two people breathing overnight put roughly a litre of water into the air of a small van. Add a pot of pasta on the stove and a kettle, and you're closer to two. All that moisture goes looking for the coldest surface it can find, which in most vans is the single-glazed windows and the aluminium frames around them. By morning it's running down the glass and soaking into the curtains, and a wet van feels colder than a dry one at the same temperature.

The fix isn't sealing yourself in tighter. It's the opposite. I crack a roof vent on the downwind side and pop a window a finger's width, even when it's freezing, so the wet air has somewhere to go. Feels wrong the first time you do it. It works. A little 12V fan pointed at the window glass helps too. If you wake up and wipe a cupful of water off the sills, that water was going to end up in your bedding sooner or later.

Diesel heaters: the honest verdict

A diesel air heater is the single biggest comfort upgrade we ever made, and I'll happily say the cheap ones work. The budget 2kW and 5kW units you see everywhere (the ones people call "Chinese diesel heaters") land somewhere around $150 to $400 depending on the week and where you buy. The name-brand Webasto and Eberspacher units do the same job with better build and cost several times that. For a van that lives in the weather months at a time, I'd not talk anyone out of the branded one. For a first trip, the budget unit is a fair place to start.

Here's my mildly unpopular take: most people buy the 5kW and then spend every night cooking themselves out of the van and cracking a window to cool down, which wastes fuel and dries your throat to sandpaper. In a small to mid caravan a 2kW unit run steadily beats a 5kW run in short savage bursts. The 5kW cycles hard, sooting up its burner, and short-cycling is what kills these things early. Set it low, let it tick over, sleep like a baby.

Running costs are modest. Ours sips somewhere in the range of 0.1 to 0.25 litres of diesel an hour once it's up to temperature, so a tank in a jerry can lasts a good while. On power it draws a big gulp on the glow-plug start, then settles to roughly an amp. That's easy overnight if your battery bank is halfway decent, and it's worth reading up on lithium vs AGM battery setups before you assume your old cranking battery will cope with a heater and a fridge together.

Insulate the bits you forget

You lose a surprising amount of heat straight down into the mattress. Your body squashes the foam flat underneath you, there's no loft left to trap air, and the cold from the bed base wicks it away all night. A cheap closed-cell foam underlay or even a couple of the interlocking gym mats under the mattress makes a bigger difference than most people believe. Same story on the floor. Rug down the walkway. Bare vinyl at 3am is a cruel thing.

Windows are the other leak. Reflective window covers (the concertina-fold ones cut to size) knock back a lot of radiant loss and double as privacy and condensation control. We keep the front ones up all night in the cold country. If you're heading somewhere genuinely alpine like the Victorian High Country around Wonnangatta, or doing the desert legs where the nights bite hard on the Red Centre loop, that reflective layer earns its cupboard space.

Thermals beat a bigger heater

The best money I've spent on staying warm wasn't a heater at all. It was a set of merino base layers each. Wool keeps working when it's a bit damp, doesn't hold a stink the way synthetics do, and a thin merino top plus a beanie in bed means you can run the heater lower and still be toasty. A hot water bottle at your feet is old-fashioned and unbeatable, and it costs nothing to run but the last of the kettle water you'd have tipped out anyway. Grandmothers were right about a lot of things, and keeping warm cheaply was one of them.

For the bedding itself, a decent sleeping bag rated a good five degrees colder than you expect to need, thrown over the doona, sorts most nights. The rating on the bag is a survival number, not a comfort one, so don't trust it to the letter. Same goes for the kids: layers they can add and shed beat one thick jumper, because a child who's overheated at 8pm kicks everything off and wakes cold at 2am. Wool socks and a beanie do more than a doubled blanket, since most of what you lose goes out the head and the feet.

A warm camp starts before you stop

Half of staying warm is where you park, and it costs nothing. Cold air runs downhill and pools in the low ground, so a creek bed or a gully that looks sheltered is often the coldest spot for miles by 4am. I aim for a rise, or at least the side of one, with a windbreak of scrub or a bank between me and the prevailing wind. Wind strips heat off a van faster than still cold ever will, and a diesel heater fighting a gale through single glazing works twice as hard for half the comfort.

The other trick is sun. Park so the morning sun hits the side of the van you sit against and the windows you'll open first, and the van warms itself for free while you're still under the doona. In the desert country the swing between a frosty dawn and a warm mid-morning is huge, and a bit of thought about which way the nose points turns that swing in your favour. I also drop the awning down and peg it tight on the windy side to make a still-air pocket against the van wall, which cuts the wind-chill on the coldest face. None of this is high-tech. It's just reading the ground before you unhitch, and it's the sort of habit that separates a comfortable winter camp from a miserable one.

What I'd skip

Unflued gas heaters that burn inside the van make me nervous, and they should make you nervous too. They dump water vapour and carbon monoxide straight into your living space, which is a double insult: wetter and dangerous. If you use any combustion heater, a battery carbon monoxide alarm is not optional. We have two.

Electric fan heaters are grand on a powered site and useless everywhere else, since they'll flatten a battery bank in an hour. Handy to carry for caravan parks in the cold months, not a free-camp solution. If you're planning your nights around cheap or free stops, my notes on what a lap actually costs cover how the powered-site nights add up.

Warm camping isn't about one hero gadget. It's a dry van, an insulated bed, wool on your skin and a small heater run gently. Get those four right and you'll be the ones sitting out with a cuppa watching the frost while the neighbours defrost their windows.