I just ran some water lines from the basement to the garage - about 75
feet or so. I ran an extra 1/2" line because I want to feed the hot
water line back to its source so that you don't have to wait five
minutes for the water to become hot.
Do I just tee off the hot water right before it goes to the fixtures
and then attach the other side of the return line to the input side of
the hot water heater? I guess this would keep both the hot water line
and the return line hot when the faucet was on but as the water starts
to cool it will return to the hot water heating in the return line
when the faucet is off.
Would putting a one-way valve in on the return to the water heater or
maybe that will cause problems with the cold side water pressure?
Hmm, Google is your friend:
"Gravity hot water recirculating loops that do not require a pump
can sometimes be installed after a house is built. They will only
work when the water heater is below the water supply lines. This
system requires that the hot water line return back to the heater
after it services the farthest fixture. The return line connects to
the bottom of the water heater at the drain valve. Natural
convection drives the system. Energy loss is a minimum if you
insulate the entire hot water loop except for the last 15 feet of
pipe as it re-enters the water heater."
More info here:
I got that much but now my concern is that the path from the heater to
the farthest point is not a constant uphill climb. It goes up then
down a little then back up around the corners then up then down. The
net change is definitely uphill.
Sorry I thought you asked where to connect the return line. The site
tells you that it might work if you connect it to the drain valve.
That will at least maximize the thermal gradient. Whether it works
for you or not depends on how much of a gravity drop you actually
have. Think about the flow and try to eliminate any thermal "hills"
especially on the return leg, turns left and right aren't much of a
concern. The damn transistors burned out on my crystal ball a few
years ago, and I haven't been able to find replacements for looking
at your set up.
The house I grew up in was done this way. The return "T's" into the drain
port, and you should have a flapper type check valve in that vertical line.
This will keep cold water from being "pulled" back towards a faucet when you
open it. Be sure to get a flapper type and not a spring loaded one. Try to
keep the return line headed down hill even if just a slight amount. Most of
the "gravity" work will be in the vertical line down the side of the tank.
Keep it a few inches from the shell of the tank to allow it to cool better.
These are great systems and very nice especially if you return it from your
clothes washer also, so it gets hot water the second it comes on.
Having a 150 foot loop of hot water pipe constantly circulating to
provide fast hot water to a garage doens't sound like a good idea to
me for energy reasons, even if it would work. I'd get one of the
small pumps you connect at the garage end with a button you can push
that then quickly pumps water from the hot pipe back into the cold
pipe until it gets hot water. Using X10, you could also rig this so
the pump goes on based on a motion sensor when anyone enters the
area, so you don't even have to push a button.
Alternatively, there are pumps that will keep it constantly hot, using
similar idea, but also offer timers, so you don't waste energy for
most of the day when you don't need it hot on demand.
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