All of the well known manufacturers of tankless gas water heaters provide both natural gas and propane versions of each of their models. A propane tankless water heater has the same burners as a natural gas unit, but it needs a higher gas pressure and more air for combustion. You therefore, cannot use propane to fuel a natural gas water heater, unless you use a special adaptor. Propane and natural gas water heaters have similar efficiency ratings and emissions.
Companies like Noritz, Takagi, Paloma, Rinnai, Rheem and Bosch, all make excellent propane whole house water heater models of various capacities. Some of them will serve up to as many as four hot water fixtures simultaneously in warm climates. Most of these companies provide both direct vent and power vent indoor models, as well as weatherproof outdoor models that can be used down to minus 30 degess Fahrenheit. These outdoor models are designed to be mounted on the exterior wall of your house, and serve the hot water fixtures inside. Installation is cheaper, since these exterior water heaters have no venting requirements. When purchasing a whole house water heater make sure that it will meet your peak usage hot water demand, even in the winter when the incoming water is cold.
In its bottled form, propane is used to power portable water heaters, as well as RV and marine models. Most RV hot water heaters are tank units, but PrecisionTemp has created a specialized RV propane tankless water heater. The PrecisionTemp RV-500 water heater uses about 50% less propane to heat each gallon of hot water, as compared with RV tank models, and provides an endless supply of hot water. It also has an 8 to 10 year longer lifespan than RV tank water heaters. PrecisionTemp’s more expensive TwinTemp propane RV tankless models, provide both water heating and space heating at the same time.
The Eccotemp L5 is a portable propane tankless water heater that is used outdoors wherever there is a pressurised water supply. By hanging it from a nail or a branch it can serve as a portable camping shower, or it can be used for dishwashing in campsites. At home you can use it in an outdoor shower enclosure or outdoor kitchen. It is also useful for washing your dog, your horse and even your car.
The Coleman hot water on demand portable water heater, is a tabletop propane water heater that is used on camping trips. It comes with a water pump, so water can be drawn from a river, a lake or water tank. Like the L5, it can be used as an outdoor camping shower and for dishwashing and hand washing, but it can also supply 160 degree hot water for beverages and soups.