Hot Water Only Flows When Recirculating Pump Is On

cd0603

Hi Everyone! I've been dealing with this issue for several months, called out two plumbers, and the only thing that's been accomplished was a 10 foot hole in my dry wall that I had to repair on my own dime. I'm now hesitant, after spending quite a bit of money for nothing to be done other than my house being torn up, to call anyone else out.

We moved into a brand new home in September 2019. The Rheem tank water heater we have has a water recirculating pump on it. When we moved in, there was a tag on the recirculating pump stating that it could malfunction and if it did and the pump stayed on for longer than 6 hours, it could ruin the plumbing and the installer would not be liable. So the day we moved in we turned it off and never used it. We're in a ranch home and don't mind waiting two minutes for the hot water to come out vs. ruining our plumbing.

Having the pump turned off caused no issues from September 2019 to October 2022. In October of 2022, we suddenly stopped getting hot water. We checked the pipes at the top of the tank and they were warm. So we switched on the recirculating pump and that allowed us to get hot water in the house. However, that is now the only way we can get hot water. If the pump is off, you can get semi-lukewarm water to come out but no hot water anywhere in the house.

We've spoken with and had two plumbers come out. The first created the huge hole in the wall and the second wanted to make more holes in the wall which we politely declined since he admitted he really didn't know what the issue was and we didn't want any further damage done without someone having an idea of what they were looking for.

Does anyone know what could be causing a 3.5 year old hot water heater to stop providing hot water without a recirculating pump pushing the hot water through the lines? We called Rheem since we are still in warranty with them until 2025 but they said the hot water recirculator is broken not the hot water heater and refuse to send out one of their warranty techs. This doesn't make sence to me because the recirculator is the only thing working that gets us hot water. Shouldn't we still be able to get hot water, just having to wait longer, without the recirculator being on unless there is something wrong with the tank?

Any insight on this issue would be greatly appreciated because I have spoken with countless people who keep blaming the issue on things that don't make sense to me. The hole that was put in our wall was due to the plumber swearing that the hot and cold lines were crossed. I told him that didn't make sense to me because if the lines were crossed wouldn't we have noticed that for the first 3 years we lived here. I let him do it because he was the professional and seemed very confident he knew what he was talking about. The second plumber wanted to cut more holes in the walls because he said we had a missing valve, which I told him I would not allow. If we had a missing valve wouldn't that have caused hot water issues during the first three years we lived here?

Maybe I'm the idiot here but I'm already out hundreds of dollars and don't want to keep throwing money out the window when it seems no one really knows how to diagnose this issue. I'm ready to just buy a brand new tank and have it installed without the recirculating pump at this point to avoid wasting anymore money. Please help!

hot_rod

Is there a thermostatic mixing valve on the tank?

dko

When the recirc pump is off and you have no hot water coming out of the faucets- is the water heater still firing? (Full blown flame vs a small pilot light)

If so, had a similar issue with a water heater call last week where the pipe would feel warm (it should feel HOT) right above the tank but no one was getting hot water. Happened to be that a tenant in another apartment was on vacation and left the hot water running on one of the faucets.

so the tank was always firing and never getting to temp due to cold water always refilling.

In your case it may be a hot water leak somewhere but the recirc is diverting some of that hot water and allowing tank to maintain some temperature. 

Larry Weingarten

Hi @cd0603 , This sounds to me like a crossover between hot and cold in the plumbing. Could you do a test? Shut off cold supply to the tank and open a hot tap. Does water stop flowing pretty quickly? Also Hot Rod asked about a mixing valve. A photo of the tank and nearby plumbing would help us determine if you have that valve or possibly other issues.

Yours, Larry

cd0603

hot_rod: I'm not sure. I've attached several photos which may help answer that?

dko: I'm not sure about the flame/pilot light. This is an electric heater so I don't think we have that.

Larry: We can do a test this weekend. However, if the lines were crossed, wouldn't that have caused an issue from the time we moved in? We didn't start having the issue until 3 years after moving in and no plumbing work was done. I've attached photos which may help.

Let me know if you need better or different photos.

Larry Weingarten

Hi, I see a swing check valve in the recirculating line. This sort of valve can fail open, which would allow cold water to flow backwards through the line, so you get varying temperatures and never really hot. I see a shutoff valve under the pump. With pump off, close that valve and see if you now can get hot water. Let us know what happens 🤠

Yours, Larry

cd0603

@Larry Weingarten Weingarten Shutting of the valve under the pump worked! You are a Godsend!!!! Thank you so much for helping with this! Do you know if it is okay to just leave that shut off indefinitely or should I still call a plumber?

hot_rod

Replace the check with a low pop pressure spring check, low lead
Leave the pump off, power and valve
Let the pump run 24/7

The trade off with recirc is how long you run the distant faucet to get hot water? A few gallons each time?
Vs running the pump 24/7. It's a tiny pump, 30- 40 W? Is all the piping insulated?
Running the pump give you instant hot, at the cost of the pump wattage and the heat loss from the piping.

So it comes down to which is more important for you? If the wait for hot water isn't a big problem, leave everything off.

Is there a thermal expansion tank near the water heater? That is code now. If that check decides to work again , you need to have an expansion device.

Larry Weingarten

Hi @cd0603 , Glad things are working! To add to what @hot_rod said, you might look into demand controls for the pump. That gives you the best of both worlds, efficiency and fast hot water. A problem I've seen with running the pump all the time is it can triple the energy used for heating water. Demand controls are available from the originator of the idea at gothotwater.com, or Taco and Grundfos, who are pump manufacturers. There are also time and temperature controls available, but they don't perform nearly as well as demand controls.

Yours, Larry

mattmia2

Would it be unreasonable to send the plumber that looked at the same piping that we looked at with the same symptoms a bill for repairing the hole in the wall? i also suspected the check valve and was looking to see if there was a valve in series with the recirculating pump to turn off to test if it was bypassing through the pump.

DJDrew

mattmia2 said:

Would it be unreasonable to send the plumber that looked at the same piping that we looked at with the same symptoms a bill for repairing the hole in the wall? i also suspected the check valve and was looking to see if there was a valve in series with the recirculating pump to turn off to test if it was bypassing through the pump.

Best to just never give them your business again.

Jon_blaney

Sad when two plumbers failed to find this problem. I thought it might be a check valve issue when I read this and I am an accountant. Are we doomed?

Larry Weingarten

Hi, Troubleshooting is part science, part art, and is seldom taught in a classroom. The best teacher of it is experience, which demands your time and attention. If our attention spans get any shorter, we just might be doomed, but when we see problems as interesting challenges, the problems do get solved. So let’s just have more fun doing plumbing 🎉🤩

Yours, Larry

rick in Alaska

That pump has a timer on the side that you can set so it only comes on at pre-programmed times so the pump doesn't have to run all the time.
Set the actual current time, and then set the times you want it to run. Depending on the control, you can set it for multiple on and off times. You probably want it off at night, then come on just before you get up, and if you are going to be out of the house all day, maybe have it come back on just before you get home.
You will just have to figure out what works best for you.
Rick

BENKRU

Larry, can I post some pictures of my water heater which is a NG 75 gallon Bradford White. I kind of have the same situation as CD0603 and after you look at it would you recommend the same action for me? I know I have hot water in the tank, and it worked fine prior to the circulating pump going out. Now I can get hot water but it's not as hot as it should be like before with the pump working.

I also had the gas temp valve replaced today, it was under warranty so no issues there. The gas temp valve went out first ( to get hot water for a short time I had to unplug from wall, turn GTV to lower setting and GTV to off then turn it all back on in reverse order and set the temp control very hot setting ).

A day later the circulating pump went out, pump was installed in 2008 & tank was installed this past March of 2023.

Any help wold be most appreciated.

Larry Weingarten

Hi and welcome @BENKRU , Please do post photos of the whole arrangement and close-ups as needed. As a quick test, before any hot water has been used, feel the pipes. See what's hot, warm or cool. Now have someone run hot water while you feel the pipes again. What changes? Let us know.

Yours, Larry

BENKRU

@Larry Weingarten please note above post

The one picture is the part that was replaced, no cost to me. The other picture with the round brass thing with the red top, the valve right beside it is what I turned to the off position, and doin that I now have hot water throughout the house. The other picture close to the floor shows a valve that is on the same run as the pump which is a Laing brand. All pictures are on the same run of copper that the circulating pump is on. The only issue we now have is the upstairs guest bath takes about a minuet to get hot water when it's turned on, which I don't think is that big of an issue overall. The circulating pump is unplugged at this time. When I tried to plug it in earlier before getting the part replaced, it was tripping the GFI switch. My question is, I can go through life as it's currently set up with no issues correct?

hot_rod

Looks like a small magnetic drive recirc pump. It may just have something stuck inside. Should be a large brass ring that unscrews to pull it apart. Water pressure drained off and pump un plugged first😏

BENKRU

hot_rod, the plug is unplugged at this time, earlier when I plugged it into the wall outlet it would trip the GFI switch. Could that also come from something being stuck in it by chance? Thanks for the advice from both you and Larry, appreciate it very much.