http://www.campingworld.com/shopping/item/eccotemp-portable-water-heater/37786

Just saw the item today at camping world. It appears to run off a couple of D batteries, and measures 11 x 14 inches by about 4 1/2 inches deep. While it's designed to run off a larger propane tank, it could be adapted to a disposable cylinder pretty easily. It also appears it's designed for a garden hose, pressurized water source, but again could be adapted to a portable pump or even the westy faucet with an adapter. The ignition comes on and off automatically with water flow. Very similar to a Coleman hot water on demand, but slightly different shape and configuration. May be useful to someone out there. If not, scroll on.

Troy