I have a gravity fed hot water recirculation system in my house that has given us great, fast hot water. 75G Bradford-white hot water heater; 2 storey house with hw heater in basement.
However, we've discovered that hot showers can turn lukewarm pretty fast with the return line open -- especially for the person who is second in line for the shower.
With the return valve closed, we don't have this problem -- hot water is plentiful. But we have the "3 minutes to hot water" problem, which is why a return appealled to us in the first place.
It is weird, the 1st hour rating on this 75G water heater is great, so it is hard to imagine that we could be out of hot water in 10 minutes of showering (primary shower head is not a 2.5 gpm head, but shhhhh, don't tell anyone...).
I wonder if the balancing valve in the shower is somehow mixing hot water with cold and sending the mixture down to the hot water heater?
So diagnosing help would be great.
But, I'm also wondering if I can kill this problem at the hot water heater, since I know that with the valve off there I enjoy long hot showers. Could I install a valve on the return line that would shut off the return when the water fell BELOW a certain temperature, yet stayed open when the water was pretty hot? All the thermostatic valves I've seen work the other way around.
Thanks for any help in diagnosing and fixing this problem!
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