Plumbing: Recirc pump busted?

[dmax5705]

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 issue. recirc pump is 9 yrs old.

[JimL]

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.

[newsman]

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 motor dying.

[e-mail] wrote:

[HerHusband]

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 system?

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 the system.

If you have had the system apart, you may want to make sure the pump isn't installed backwards.

Anthony

[Not]

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 d> just wanted to check if I have diagnosed this correctly.

[dmax5705]

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 check valve

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 learning :-)

[HerHusband]

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 with expansion.

Anthony