A heating system is essential for winter use or to provide hot water for a shower. Gas is the most common fuel used although some systems can operate on diesel fuel.
The simplest gas heaters require no external power supply and can be lit by a piezo electric spark. These heaters normally stand over an opening in the floor of the motorhome which provides combustion air and have a flue which exits through the roof. Some form of thermostatic control is usually provided to regulate the internal temperature. The addition of an electric fan (12V DC) allows the warm air to be distributed around the motorhome through flexible ducting concealed behind furniture or under the floor. This type of heater cannot heat water and a separate boiler will be required.
More modern heaters are electronically controlled and have a fan to supply combustion air and exhaust waste gases. A concentric flue which combines the air intake (similar to that for a domestic gas boiler) is provided which can exit through the side wall of the motorhome. A separate fan distributes warm air through ducting. The heater may incorporate a water boiler for supplying the shower and hot taps.
Where a separate water heater is provided this will normally operate on gas. An additional electric element may be provided for use when connected to mains power. Some motorhomes make use of the waste heat from the engine to heat the water. Such systems can operate in reverse and circulate hot water through the engine block to assist cold starting and reduce wear. This is most common on diesel fuelled heating systems.
The gas bottles supplying the heating may also supply other gas appliances (cooker, hob, fridge etc). Propane gas is recommended for use in cold conditions as butane does not vaporise adequately at low temperatures. The gas bottles must be stored outside of the habitation section with a vent low down to allow any leaking gas to disperse (gas is heavier than air). If the gas locker can accommodate two bottles there may be provision for easy switching from the empty bottle to the full one, ensuring continuity of supply.
Diesel powered heaters, drawing from the vehicle's fuel tank, are extremely economical to run. They cannot operate independently of an electrical supply (12V DC). A diesel heater can draw quite a large current (approx. 20A) while starting which may require an increase in the capacity of the leisure battery. A diesel heater may heat the interior by providing warm air through ducting or by providing hot water which is circulated through small radiators. This probably provides the most even form of heating although it adds to the overall weight of the vehicle.
In the same manner as a domestic heating boiler, the motorhome heating system will require periodic cleaning and maintenance whether gas or diesel powered. The entire gas system should be periodically tested for safety by a qualified technician.