Hot water only when recirc pump is running

[Grenouie]

I currently have our recirculating pump running 18hrs a day simply because if it's not on, we only get lukewarm water out of any tap. Pity the poor visiting relative who tries to take a shower at 1am.
I tried adding an aquastat, but if we were taking a shower it would turn the pump off at some point, and we would eventually get lukewarm water for a few minutes until it turned the pump back on.

My latest thought is that the issue is because there is no check valve after the pump and before it T joins (right side of the image) with the incoming cold water (which does appear to have a check valve on its side of the T).
My thinking is that with the pump off, the pressure of the incoming cold water just pushes cold water back up the hot water return and it mixes with new hot water and I just get constant lukewarm water. If I turn the pump off, it only takes a minute or two for the pipe on the pump inlet side to change from very hot to cold.
With the pump on, the cold water only goes the correct way into the water heater and everything functions as normal.

Am I maybe on the right track in trying to solve this issue?

 

[Twowaxhack]

You probably have a check valve bad.

 

[Grenouie]

You probably have a check valve bad.

Thanks for taking a look.
My understanding is that check valve stops hot water from going back into the cold line coming from the city.
We are unable to get very cold water out of the taps, so that valve failing would help explain that.

So if that's the issue and I get that valve fixed, I should be able to get hot water (not instantly) even with the pump not running, and not have to worry about another check valve to stop backflow into the pump?

 

[Twowaxhack]

Circled pumps that run all the time doesn’t need a check valve.

Based off your post, I diagnosed it as a bad check valve.


assuming the check valve is installed in the proper location. I didn’t look. I’m taking breaks between service calls and posting, not much time today

 

[TomFOhio]

Did you install this unit??

 

[Grenouie]

I did not, the house was renovated when we bought it.

Circled pumps that run all the time doesn’t need a check valve.

I am assuming the inverse of this comment si that "Pumps that don't run all the time require a check valve".
I don't want to run my pump 24/7, so I am going to look for someone who can install a valve, and potentially replace the valve on the cold water intake.

 

[Pipe Dreams]

The check valve maybe the culprit, or it could be an internal leak in a faucet or shower valve.

Any place the hot and cold connect could be the culprit. Check valve is the easiest and most likely cause.

 

[Grenouie]

The check valve maybe the culprit, or it could be an internal leak in a faucet or shower valve.

Any place the hot and cold connect could be the culprit. Check valve is the easiest and most likely cause.

That's very interesting, I haven't come across that possibility before.

We do have a guest room shower that has water coming out of the shower head even when it should only be coming out of the faucet. Had a plumber in for a few hours who tried replacing something (cartridge? valve? unfortunately I forget), and in the end said the newly installed Delta brand equipment was cheap and we would have to rip out the new tile and replace the whole thing. So we've ignored it, but maybe we do have to replace it after all.
Really starting to regret not pushing harder to get that fixed as part of the home inspection when we bought it.

 

[Pipe Dreams]

A faucet and shower valve is nothing more than a fancy mixing valve. Leaks can be inside the cartridges while not even in use and water can flow from one side to the other. It is a pressure differential thing.

*********Another possibility being as the install is new and people these days are kind of ignorant, just for fun go around and look under the sinks especially the kitchen sink, and see if you see some wierd looking octopus looking valve. They are called crossover valves, long story short, you do not need one, but may have it anyway.

I have had people live with lukewarm water for years, all having to do with ignorance.

 

[Twowaxhack]

That's very interesting, I haven't come across that possibility before.

We do have a guest room shower that has water coming out of the shower head even when it should only be coming out of the faucet. Had a plumber in for a few hours who tried replacing something (cartridge? valve? unfortunately I forget), and in the end said the newly installed Delta brand equipment was cheap and we would have to rip out the new tile and replace the whole thing. So we've ignored it, but maybe we do have to replace it after all.
Really starting to regret not pushing harder to get that fixed as part of the home inspection when we bought it.

It’s not the Delta valve, it’s probably not installed properly.

 

[Twowaxhack]

I did not, the house was renovated when we bought it.



I am assuming the inverse of this comment si that "Pumps that don't run all the time require a check valve".
I don't want to run my pump 24/7, so I am going to look for someone who can install a valve, and potentially replace the valve on the cold water intake.

Correct

 

[TomFOhio]

I did not, the house was renovated when we bought it.



I am assuming the inverse of this comment si that "Pumps that don't run all the time require a check valve".
I don't want to run my pump 24/7, so I am going to look for someone who can install a valve, and potentially replace the valve on the cold water intake.

The reason I asked who installed it is because I am trying to see in your picture if there are the hookups for you
to be able to flush this unit out every year.