Alde vs Diesel Air Heater: Which Is Right For You?

Alde hydronic heating and a diesel air heater both keep a caravan warm through cold country, but they go about it in completely different ways, and cost wildly different money. This guide walks through how each one heats, what you gain and give up with each, and which suits your rig and your style of travel.

The Decision in a Nutshell

This is not really a fight between two products in the same price bracket. It is a choice between two philosophies. Alde is wet hydronic heating: a boiler warms a water and glycol mix and pumps it through slim convectors run around the van, so the whole space warms gently and evenly, and the same unit heats your shower water too. A diesel air heater is the opposite approach: a compact furnace burns a trickle of diesel and blows warm air out of a vent, fast and cheap, and that is all it does.

One is the comfort end of the market, almost always fitted at the factory in a premium van. The other is the pragmatic off-grid workhorse that plenty of people retrofit into an existing van in a weekend. Knowing which camp you fall into is most of the decision, so let’s break down each option properly.

Alde Hydronic Heating

How it heats

An Alde system centres on a small boiler, currently the Compact 3020 HE, that heats roughly 8.4 litres of water and glycol. A 12V pump then circulates that warm fluid through a closed loop of pipework and low-profile convectors, typically run along the walls at skirting height and often under windows and through the floor. Heat radiates and convects off that pipework, so the warmth builds through the whole van rather than blasting from one outlet. The boiler runs on LPG, on 240V mains, or both at once for a faster warm-up, and a built-in coil heats your domestic hot water off the same unit.

The pros

The heat quality is the headline. It is gentle, even and completely silent inside, with no hot spot near a vent and no cold corner at the far end of the van. Convectors placed under windows throw up a warm-air curtain that cuts the radiant chill off cold glass and knocks back condensation, which is a genuine health and comfort win when you are living aboard through a Tasmanian or alpine winter. Warm floors are on the table too. And because one boiler does both cabin heat and hot water, you are not finding space and payload for a separate hot water service.

The cons

It is the most expensive way to heat a van, on both hardware and install, and realistically it is a factory option that adds several thousand dollars to the price of a van rather than something you buy off a shelf. It is the heaviest option by a distance once you add the boiler, the pipework, the convectors and litres of glycol, which matters if you are anywhere near your payload limit. Warm-up is slower because you are heating a body of fluid before the van, so it is background heat, not an instant blast. And there is an ongoing job: the glycol should be changed roughly every two years to keep its corrosion and bacterial protection doing its work.

Who it suits

Full-timers chasing home-like comfort in genuinely cold country, buying or optioning a premium van that offers Alde from the factory. If you want the quietest, most even heat available, warm floors, and integrated hot water, and you plan to live in the van for years, Alde earns its keep. It is overkill for a fair-weather lapper or anyone chasing the sun.

Diesel Air Heater

How it heats

A diesel air heater is a self-contained furnace, usually a 2kW unit for most vans, that burns a tiny amount of diesel in a sealed chamber and blows the resulting warm air into the van through a vent. The combustion is sealed off from your living space and the exhaust vents outside through the floor, so the air it delivers is bone dry with no fumes and no moisture. It draws diesel from a small dedicated tank or the tow vehicle, sips 12V for the fan and glow plug, and takes a freezing van to comfortable in about fifteen minutes.

The pros

It is fast and it is cheap, both to buy and to run, burning roughly 0.10 to 0.28 litres an hour. It is the off-grid champion: single fuel, no LPG bottles to chase, and once running it draws well under 1.5 amps so your solar and battery cope without complaint. It is light, adding almost nothing to your payload. And it is retrofit-friendly, which is the whole point for most owners, since a furnace, an exhaust through the floor and some ducting is a job you can do yourself over a weekend with no gas fitter involved.

The cons

The heat is less refined. Blown air warms the van quickly but unevenly, toasty near the outlet and cooler at the far end. It is not silent: there is a fan hum and a fuel-pump tick, and that tick in particular can nag at light sleepers overnight. And here is the gotcha readers routinely miss: a plain diesel air heater does not do hot water. If you want cabin heat and hot water from one unit, you need to step up to a diesel hydronic system or a Truma Combi D, not a straight air heater.

Who it suits

Off-grid, diesel-tow travellers who want efficient single-fuel warmth without the cost, weight or install headache of hydronic. It is also the obvious pick for anyone retrofitting an existing van on a budget, and for weight-critical rigs sitting close to their payload limit where a heavy hydronic loop is simply out of the question.

Side by Side: The Factors That Matter

Here is how the two approaches stack up across the things that actually shape day-to-day living.

So Which Should You Choose?

The right answer depends far more on how and where you travel than on any single spec. Match yourself to the scenario below.

Buying or optioning a premium van and chasing comfort in cold country? Go Alde. If your lap lives in Tassie, the alpine country or inland winter nights, and you want silent even heat, warm floors and integrated hot water in a van you will live in for years, this is the one. Pay for it once and enjoy it for the life of the van.

Full-time off-grid, diesel-tow, and want single fuel with no LPG? Go diesel. A plain diesel air heater is perfect if you only need cabin heat and already have hot water sorted. If you want heat and hot water from one unit, step up to a diesel hydronic system or a Truma Combi D rather than a straight air heater.

Retrofitting an existing van on a budget? Diesel air heater, comfortably. It is far cheaper and easier to fit than tearing a hydronic loop into a finished van, and for most travellers the warmth is more than good enough.

Sitting close to your payload limit? Diesel air heater again. A full hydronic system adds real weight you may not have to give, whereas a compact furnace barely registers.