I stopped by the local SuperMegaUltraCamping World on the weekend and spotted this guy, the Coleman Hot Water on Demand machine. Designed to provide instant hot water for camping trips it’s quite a nifty gadget. It uses a 16 oz propane gas cylinder to heat the water and has a built-in 6V rechargeable lead-acid battery which powers the water pump.
On the warm setting it will increase the water temperature by 50°F, the hot setting will increase it by 100°F up to a maximum of 160°F and within 5 seconds of turning the knob. There’s also a shower attachment and an adapter to plug it into a 9kg gas bottle. It will make about 152 L (40 gallons) from one 16 oz bottle of gas and a full battery charge. The battery can be recharged via the wall or a car cigarette lighter socket.
If it was really clever the waste heat from the burner would power a Stirling engine to recharge the battery. Then it would be truly awesome instead of just nifty. US$249.99 from Coleman.
Heats cold water to over 100°F in less than five seconds / Full size faucet folds into handle / Heat up to 40 gallons of water with one compact Coleman® 16.4 oz propane cylinder (Propane sold separately) / Rechargeable 6 volt battery pumps the water