[jimbo2012]

Herv, ok to refocus found this

How Much Energy is Wasted?

The systems vary in how much energy is wasted. The ones that run a pump 24/7 obviously waste more heat and electricity. The ones that work off a timer or thermostat would save some of this waste, but not nearly all of it.

The "demand" systems would be much more efficient, since they only circulate water when its actually needed.

I estimated the energy waste for recirculation by measuring the amount of energy my gas water heater uses with and without the recirculation loop enabled. With the recirculation system on, the gas burner comes on every 1.25 hours for 5.1 minutes. With the recirculation system off, the burner comes on every 5 hours for 5.1 minutes. All of these measurements were taken over the night period when no hot water was being used. If you go through the math on this, it comes out to 200 gallons of extra propane wasted per year to support the recirculation system. Or about $400yr.

I know we don't use propane but elec cost must be close.

Add the cost of the install ( I saw $700) and possible failure of valves etc.

Now how much a gallon is water at TV?

A shower uses 7 GPM, with a water saver head you can bring that to about 2.5 GPM.

How many minutes does the shower take to get hot?

Or how many quarters?


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