gravity feed hot water retrun

Jan 4, 2022
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United States
i'm not sure if i should start here or go to plumbing, but let's start here and move this if needed.

i curious if it is worth installing a gravity feed hot water return from the furthest sink back to the water heater? it will cost me about 70$ in materials that i have got on a list now but is it really cost-effective to do? on a website that explains how to do this, they say just for the water wasted in getting the shower up to temp is like 900 showers at 1$ water cost for all those showers for the water wasted. so has anyone ever really figured this out. plus for me the water to get the kitchen sink up to temp.

for me, i waste 2 gallons of water getting the kitchen sink up to useable hot water for doing the dishes. and then more ware to get it back to temp for rinsing them. and then if we go back to do just a few extra a bit later we have to again run the hot water for a gallon or so to get it back to temp. and yes the hot water line is insulated with foam insulation.

also if i go ahead and do this job i will tap into the 1/2 hot water line just about 4' from the sink, that is about as close as i can get. the hot water line is 3/4" up to about that point and then is reduced and split to run to an outside spicket. anyway, i plan to run 3/4 pvc back to the water tank and then down to the drain valve. and about 3" from the floor i will make a horizontal run to install a flapper type check valve to act as a stop so the cold water will not back feed into the hot water line. i figure this will take some tweaking. plus they said to insulate the return line all the way back and leave about 15' uninsulated to create a section of line to cool down to create the gravity feed.

so has anyone actually done this and have it work. and then have it actually be cost-effective? thanks


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