I like the fact that when I go into any bathroom at 2AM I get burning hot water within 2-3 seconds of turning on the faucet. There's no wait time, no ramp up time, nothing. Hot water, bam, right there.The pump runs for about 40 seconds every 20 minutes.At 30 watts I come up with 0.04kwh per day. $0.125 per month to run the pump like I do, or $1.50 per year. For my insulated piping I come up with roughly 500 btu/h loss which I come up with roughly $65 per yearSo, less than $6 a month for hot water within a few seconds any time of day and by letting things cool off more isn't going to drop that cost a whole lot.

The gravity system cools the water as it returns to the bottom of the tank.It is then heated to about +130 before leaving the top.

Also, the water that is wasted used to be hot, but that heat was lost to the basement.ChrisJ, your annual $65 heat loss is not all a waste. For 4 months it contributes to heating your house at probably the efficiency of your steam system.For me it may be 4-5 months of heating, I use that logic to justify my constant trickle flow gravity recir, which I am sure is frowned upon by some.But I have no pump or control investment initially or replacement there of.A friend in the HVAC business realized that his recir pump had failed but still had quick hot water, his system was gravity flowing thru the dead pump.He left it as is.I wonder if your system is gravity flowing between pump cycles, to give you the instant hot water. You could power it off for a couple of days to find out. Erin......I dout thenk the spelchucker feature is warking.....is that my problem or the Wall's.