Bob wrote:
This is my first visit to this group, so the question may be a repeat.
I am thinking about installing a return pipe on my hot water feed to the
kitchen to reduce the amount of cold water that is wasted before the hot
water has reached the sink.
Where is the best place to make the connection close to the hot water
tank? It takes nearly four litres of cold water to run through the pipes
before the hot water arrives. I have lots of pipe and connections left
over from different projects and I might as well use them for this. My
ceiling is easy to access. My problem is knowing where to connect near
the tank.
I have also read that some people have installed a "U" near the tank to
reduce the loss of heat when hot water is not being drawn for use.
Anyone have any details about this idea?
Many thanks for your ideas.

Bob

You can create a thermosyphon by bringing a return back from the hot
water line near the faucet and connecting it to the bottom of the water
heater through a "swing check valve". That valve will prevent cold water
from moving towards the faucet.

But keep in mind that unless you insulate the piping you'll be
constantly leaking quite a bit of thermal energy from the system which
will have to be replaced by using additional electric or gas.

You can use a amall circulating pump controlled by a timer or proximity
switch and also a temperature sensor so that it only runs when the water
near the faucet is below a preset temperature and when you expect to be
in the kitchen (timer) or when you are actually in it and moving around
(proximity sensor). Again, insulation of the piping will avoid wasting
too much energy.

There are some systems which use a small pump under the sink controlled
by a similar temperature sensor and timer or proximity switch which push
the water from the hot water line back down the cold water line. These
do work, but if you want to draw a glass of cold water, you have to
waste water while you drain off the warm water in the cold water pipe.
Again, insulation of at least the hot water pipe will help save energy.

All in all, I'd suggest you do the math and try and calculate how much
the water you are wasting will actually cost, and compare that with the
added energy you use and the amortization and maintenance costs of
whatever "immediate hot water" recirculating system you decide to use.

Chances are a "local" point of use instant electric water heater will
end up costing you less in the long run, and won't "waste" any water.

Jeff

Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."