Autoterm 4D Diesel Air Heater 4kW 12V with Digital Controller

Ten watts on low is the figure to look at, because it decides whether you wake up to a warm cab or a dead battery. At 10W a heater running eight hours uses about 80Wh, which is nothing against even your modest deep cycle setup. Compare that to a 12V fan heater pulling 150W or more, which will flatten your battery before dawn, or idling the engine, which burns litres an hour and wears your motor. That's the whole argument for a diesel air heater over the alternatives.

Four kilowatts is a lot of heat for your cabin. Most of the night you'll run it on low, which is where the 0.21 litres an hour and the 10 watt draw come from. What the 4kW ceiling buys you is the ability to warm a cold space quickly when you first get in, and to hold your temperature in genuinely cold conditions rather than running flat out and losing. Buying a heater that can only just cope means yours runs at maximum all night, which uses more fuel and wears faster.

The rough rule is space. The 4D suits a large motorhome, a dual-cab cabin, a shed, a converted container or a boat up to 15 metres. If you're heating a small camper, a troopy or a tinnie, the 2D does the job on less fuel and costs less to buy. Oversizing isn't harmful, it just means you paid for capacity you never use. Undersizing means a heater running flat out on the coldest night, which is exactly when you need headroom. Ring the store on 03 7056 6732 with the size of the space and we'll pick it with you.

You will never need a heater rated to minus forty-five in Australia. What that rating tells you is how the thing is built: the glow plug, the fuel pump and the control board are specified for conditions far beyond anything a Victorian winter or the high country will throw at them. Cheap heaters rated to -10 or -20 are the ones that throw fault codes on you on a genuinely cold morning. It is a spec you buy for the margin, not the number.

This is a full one-outlet installation kit: the heater, the digital controller and cable, the metering fuel pump and cable, the power cable with fuses, the muffler, the exhaust pipe with heat insulation, ten metres of fuel hose and a standpipe, the air intake hose and silencer, the base plate, brackets, clamps, rings and screws, plus the intake grille, vent and 1.2m of hot air ducting. You will not be chasing parts to finish your install. What isn't included is the install itself, which means drilling your floor and tapping your fuel tank.