just wanted to check if I have diagnosed this correctly.
When hot water is being drawn used in the house
(like in a shower) the inlet to the recirc pump, which is
next to the water heater in the garage, starts to run very
cold. I assume this is not normal and must mean that the
recirc pump is broken in some way?
my issue is that when taking a hot shower in a bathroom that
is closest to the water heater, the water turns very cold in parts
of the house that are further from the water heater (but closer
to the return pipe for the recirc pump). i.e. water in one shower
is nice and hot while water in the other shower is very cold
when both are running. the "cold" shower returns to nice and
hot when it is on by itself. I replace valves that could be causing
mixing and/or turned off secondary shutoffs and nothing worked.
Only thing I notice now is that the return pipe going to the recirc
pump gets very cold when I have both showers on and then one
of the showers run cold.
is there anything else i should try to make sure its the recirc
pump or not? My water heater is less than 2 years old and since
I get steaming hot water during this problem I assume its not the
recirc pump is 9 yrs old.
On 6 Jul 2006 09:05:00 -0700, email@example.com wrote:
Assuming that you are very wealthy and want to keep the energy
wasting recirc pump, then hire a plumber to check it out.
I'd guess that either you have a restriction in your lines (calcium
buildup), or you bought a way too small water heater.
The recirc pump should shut off when you are taking a shower and
using hot water. Most new installations I see either have a on/off
buttion near the sink/shower or a timer.
And you probably need more than one recirc pump, or better yet,
insulate and increase the size of your hot water line.
You need to describe your recirc system a little better. Is it one
where you have two sets of hot water pipes with the water moving in a
circuit through the two sets (and is the pump controlled by a
thermostat?); or is it one that uses the cold water pipes as part of the
hot water recirc system? If it's the former, is the pump pulling from
one hot water line and pushing the water into the water heater drain
pipe at the bottom of the tank? Are the hot and cold pipes connected to
the correct stubs at the top of the water heater? BTW, if you can hear
the pump motor running, odds are very high (but not certain) that the
pump rotor is turning. Usually when recirc pumps fail, it's due to the
My first guess would be you have air in the recirculating line and the pump
isn't pumping water. Have you tried bleeding the air bubbles out of the
Also, it sounds like your system may be missing a check valve on the
recirculation line. Cold water shouldn't be able to work backwards through
If you have had the system apart, you may want to make sure the pump isn't
I have a circulating system that works without a pump, so I'll not say
anything about the pump, other than that I assume it is plumbed to the
bottom of the water heater. Incidentally, the two plumbers I have had
work on my system, while licensed, didn't know anything about how the
system worked, and one even installed the check valve backward.
My guess is that you don't have a functioning check valve, so when you
turn on the hot water, you draw both hot water from the top of the
heater, and cold water from the bottom. That would explain why the line
near the pump is cold. I would suspect the shower that is nearest the
line drawing hot water from the top of the tank would get mostly hot
water, while the shower that is nearest the return line drawing cold
water would get more cold than hot water. Its possible that when using
only one shower, you get enough hot (even when mixed with some cold)
that it feels hot, while when using both showers you are drawing more
water, and get the imbalance you describe. I know my system worked
without a check valve, but I got hotter water after I added the check
valve, and got the plumber to point the arrow the right way.
Incidentally, when he came back to redo the check valve, he said he had
been talking about my system with some of the other plumbers, and they
weren't certain it would work, so at least some of them knew about it.
Mine works without a pump because I have an old house with about a
fifteen foot vertical rise from the heater in the basement to the
upstairs bath, and I insulated that rise, while leaving the return
uninsulated. Thanks to gravity, the hotter water rises naturally and
the system works.
thanks for all the replies. I do think the first suspect is the
check valve as cold water appears to be going back thru the
check valve, thru the recirc pump and then making the shower/faucets
cold that are nearest to the recirc pipe. I have a WATTS WVC type
can it be disassembled to find out if its the problem
or do i just need to replace and see what happens? also
there are screws on the inlet and outlet of the recirc pump piping...
would those by chance stop the flow of water? if so, i could do that
as a test to isolate my problem.
btw, my recirc pump is next to the water heater in the garage
and it plumbs in to the cold water supply going to the water heater.
the new water heater is the same size as old one.
house--recirc pipe ---check valve----cold water inlet--water
heater--hot water outlet--house
again, thanks for all the replies. I am a plumbing novice but am
I don't know what kind of check valve yours is, but mine is a simple
flapper (I think it's called a "swing type". When I take it out, I can
easily look through and see if the flapper is swinging. If it swings OK,
and the seat looks clean with no pitting or anything, it's probably OK. I
think the swing type valves partially rely on gravity, so the valve has to
installed upright to work properly. And, of course, it has to be oriented
properly with the flow of water.
They are probably the built-in shut-off valves for the pump. So yes, they
should stop the flow of water.
My recirculating setup is like yours. Because my water heater sits down in
a drip pan in a tight alcove, I couldn't connect to the drain line of the
tank. Instead, I have a "Tee" in the cold water line coming in the top of
the hot water tank. Just off the Tee is my check valve, then a shutoff
valve, a tee to a drain valve, then the pump, then my recirculating line.
The check valve should ONLY be on the recirculating line. You do not want a
check valve on the cold or hot water lines as this could cause problems
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