I have had the Watts system, purchased from Costco, for about a year and
am pleased with it. It saves me time and water by not having to run
cold water doen the drain while waiting for hot water. By setting the
timer to run only when I need it, the additional energy usage is
trivial. The only drawback is some water hammer because of the sensor
valve between the hot and cold lines.
The Watts system places the recirculating pump at the water heater and
the sensor valve at the fixture at the end of the line. Other brands
combine the pump and the sensor valve. One deciding factor is at which
location an electrical outlet is available.
Complex and innefficient.
Best way to have "instant" hot water is to have a small water heater
at the point of use which supplies hot water immediately on demand,
untill the cold water has come through the pipes. You get HOT water
right away, then the temperature drops a little bit if you use more
than the capacity of the small heater as the cold bollus comes
through, then back to hot.
Except the small heater will inevitably be electric, which cost significantly
more to run than gas. Pumping a little cold water back to the heater costs next
to nothing, and saves water over running the water.
Plus, the extra heater is one more to fail/replace regularly.
Another energy wasting idea from the fuel companies.
What you need is a small 6 gallon point of use tank under the sink.
Gives you instant hot water and uses little energy. If you use enough
hot water the hot water from the main tank reheats the point of use tank
so it doesn't even need to heat the water.
Have you ever checked to see how much power is required to keep a well
insulated 5 gallon water heater hot?????? Likely about as much as to
run a circulating pump. And it's a lot easier to retrofit to an
You can also put a SWITCH on it, or a TIMER so you only have hot water
in reserve when you are likely to want it.
But most of the systems are NOT push-button on-demand circulators.
And the non-push-button-on-demand systems not only draw constant power
running the circulating pump, they also lose heat from the entire
circulation loop constantly, meaning the water heater needs to run
They are definitely a convenience, but they most certainly are NOT an
The push button type? Yes. But the complexity of the required plumbing
for a retrofit is significant. The aditional small volume heater is a
simple install, and NOT a huge energy waste. - and CAN be set up to
run on a timer so you have hot water at , say, bath time.
Yes it works. There are several different ways of doing it.
However how much if any energy that might be saved is questionable.
I have seen versions that constently circulate the water and
some that only circulate it when called on (meaning it still takes a
I have not bothered. I do have an instant hot water supply in
my kitchen however. Convenient.
I think pumping the tepid water into the cold water supply line means
you won't have cold water, assuming the pump is in working order.
I like keeping the cold and hot water supply lines separate. When I was
remodeling the bathroom, and had easy access to the lines, I added a
return line from the far end of the hot water supply line back to the
water heater, forming a supply loop. I put a check valve in the return
line so when flow is high, the return line is disabled. I insulated the
original supply line, and left the return line uninsulated. Through the
magic of gravity (more reliable than a pump, and cheaper) there is a
constant flow of hot water through the loop, so when we crack the
faucet, we get instant hot water. There is no cost for electricity, and
no pump to break. I do use a little more gas for the heater, as there
is a heat loss from the return line, but that is welcome heat into the
house during the cold months.
Installation is not hard if you can get access to the supply lines and a
space for the return line. Operating costs are low, and the system will
run until congress repeals the law of gravity.
I think putting hot water into the cold
pipe is not good. Just think, you
get up at 3AM and want a drink of water.
You get warm water or you
then must run the cold to purge out the
warm. I would prefer a real loop.
In my new house, everything seems to be
connected with 3/4" PEX. The
faucets are all lower flow than I'm used
to. But, they have made up for
the flow with better aerators. Anyway,
my kitchen sink it right above the
water heater (in the basement). Low
flow, coupled with larger pipes and
a kitchen faucet that has a pull out
hose end, makes for a long wait for hot
water. Also, the bathrooms take
forever. Unfortunately, they are at
opposite ends from the water heater. I
was thinking of gravity loops, but
I know they don't always work well. I
might need 2 pumps to accomplish
this ... or one, with some flow
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