Travelling when and where you want; everybody desires this kind of freedom nowadays. When the cold weather sets in, there’s nothing like a heating system which provides a cosy warmth and operates quickly and powerfully.

How air heaters work

Air for the heater's internal combustion is drawn from an intake outside the motorhome and passed into the heater's combustion chamber. It’s mixed with fuel (diesel or LPG) and automatically ignited to heat up the large surface area of a heat-exchanger. The combustion exhaust air is kept totally separate from the inside cabin air and is blown back outside through an exhaust pipe. Cool inside cabin air is sucked into the heater, past the heat exchanger (where it warms up) and then blown back into the cabin again. It is more efficient to re-circulate cabin air rather drawing in cold air from outside.

The main differences between air heaters is the fuel type which they run on.

LPG heaters

LPG heaters cost much less than diesel heaters however like a car there are 2 prices you pay, the price of the heater and the price of running it. With the current LPG price, the running cost is about 60% more than an equivalent diesel heater.

LPG limitations when it’s cold. ‘LPG’ from service stations was originally just Propane. Propane is much better equipped to deal with the cold weather. Nowadays it is more commonly a 50/50 mix of Propane and Butane. In order to be usable, the liquid in the gas cylinder needs to turn into a gas. In the case of Propane, this will happen at -42 degC, whereas Butane will only become gas at -2 degC. In the real world, it's not so clear cut. When some of the liquid turns into gas, the remaining liquid cools down and can drop several degrees below the ambient temperature. This can easily prevent Butane from becoming a 'useful gas supply' when the outside ambient temperature is even several degrees above 0 degC. In cool temperatures, all the Propane in the bottle can be burned off leaving just liquid Butane – which is not useful. If you go the fuel station to refill your gas bottle...and your LPG cylinder is not completely emptied, the situation can over time get worse.

Diesel heaters

Diesel heaters are more expensive initially but are the most quiet and economical in terms of fuel and power consumption. LPG gas bottles last up to ten times longer when they are not used for heating. Diesel air heaters can be used while travelling too. This is a huge benefit in many bus conversions if the main heating for the dashboard has been removed. Ducting your heater to the dashboard is helpful for windscreen demisting not to mention driving comfort.

Main features of each model:

Propex HS2000 heater
Fuel type: LPG
Heat output: 1.9 kW
Cheapest heater. 12V only. Kitset with 1 outlet
1 year warranty

Propex HS2800 heater
Fuel type: LPG
Heat output: 2.8kW
12V only. Kitset with 1 outlet
1 year warranty

Truma E2400 heater
Fuel type: LPG
Heat output: 2.4kW
Quieter than the Propex. 12V only. Compact with flexible mounting options; exhaust through floor or wall. Kitset with 1 outlet.
1 year warranty
Large network of service agents around NZ
Truma manual

Eberspacher D2 heater
Fuel type: Diesel
Heat output: 2.2kw
12V or 24V. Digital controller. Kitset with 1 outlet
2 year warranty
Large network of service agents around NZ

Eberspacher D4 heater
Fuel type: Diesel
Heat output: 4kw
12V or 24V (24V option is more expensive). Digital controller. Kitset with 1 outlet
2 year warranty
Large network of service agents around NZ

Webasto AT2000 heater
Fuel type: Diesel
Heat output: 2kw
12V or 24V. Ducting purchased to suit installation
2 year warranty

Webasto EVO3900 heater
Fuel type: Diesel
Heat output: 3.9kw
12V or 24V. Ducting purchased to suit installation
2 year warranty

Webasto EVO5500 heater
Fuel type: Diesel
Heat output: 5.5kw
12V or 24V. Ducting purchased to suit installation
2 year warranty

You can compare each heater’s technical attributes against each other in the Air Heater section.
Compare fuel consumption, power consumption, dimensions, voltage options and much more.