At its most basic level, hydronic heating systems use tubing to run hot liquid into heat exchangers that disperse heated air. It is not unlike how a residential boiler heating system works. For hot water, coils with potable water running through them wrap around the boiler to transport hot water to faucets and appliances. The innovative use of liquids and tubing in the hydronic heating process results in moist, comfortable heat that can be evenly spread through the living space and bay areas of an RV; steady, continuous hot water in bathrooms and kitchens; and the option for engine pre-heating*. A variety of heat sources can be used depending on the type of hydronic heating system installed, but all use some combination of the vehicle’s own surplus engine heat, on-board fuel (gas, diesel, or propane), and/or AC shore power.