Wasting water waiting for hot water???
While waiting for hot water to reach the faucet, I seem to waste a lot of precious water when I'm boondocking. Has anyone installed an undersink, propane, on demand hot water heater? Or some other ...
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I did something similar to smkettner, but without the extra pump.
At the galley sink (the furthest fixture from the water heater), I installed a solenoid valve that drains the hot water back into the fresh water tank (via the inlet hose of the water pump ... which just happens to be located under the galley sink). The valve is controlled by a switch that is connected to a simple timer (555) that maintains contact for a predetermined amount of time. When we want hot water, we just push the button (conveniently located right at the galley sink) and in about 20 seconds the water is hot. The timer opens the valve after about 45 seconds and the main water pump stops soon thereafter. Before a shower, we also push the button. The system can also be set to automatically run whenever the hot line temp (at the galley sink) drops below 95 degrees, but I seldom use this feature because I don't like leaving the water pump switch on...an advantage to smkettner's system.
At the galley sink (the furthest fixture from the water heater), I installed a solenoid valve that drains the hot water back into the fresh water tank (via the inlet hose of the water pump ... which just happens to be located under the galley sink). The valve is controlled by a switch that is connected to a simple timer (555) that maintains contact for a predetermined amount of time. When we want hot water, we just push the button (conveniently located right at the galley sink) and in about 20 seconds the water is hot. The timer opens the valve after about 45 seconds and the main water pump stops soon thereafter. Before a shower, we also push the button. The system can also be set to automatically run whenever the hot line temp (at the galley sink) drops below 95 degrees, but I seldom use this feature because I don't like leaving the water pump switch on...an advantage to smkettner's system.
