Hot Water Coming Out Cold Water Throughout House??

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WorthFlorida

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If I recall, there several post like this over the years. On one of my post I did mention stop valves on tub/shower fixtures. Bottom line is water flows from high pressure to low pressure. I'm wondering with the pump off it has too much restriction and it lowers the pressure on the hot side and the cold water Is higher. But the check valves installed would prevent this.

 
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Jeff H Young

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I dont know the laws or practice of Alabama but in Ca we have requirements to warranty the job of cource that said when the contractor dosent repair the work the value of the warranty diminishes but at a certain point it may require hiring other contractor and good luck but the original can be held liable to pay . this is in theory, practice of getting that reimbursement can be difficult to impossible.
Im unclear still on bridge valves and dedicated return line and injection Im not familiar with.
My Moms circ pump acted up and me being outta state could not go out there. Im pretty sure the pump had quit working and the check valve at the circ line at the tank was bad. you could run water for an hour at the master bath and not get hot water it might have been just the check valve but in anycase I know the check valve was changed possibly the pump as well. problem was solved
 

John Gayewski

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This is too hard with everyone chipping in and no one being able to check things very specifically.

Both water heaters. Not the line between them that's just one water heater. Both lines leaving each water heater are they both hot during a shower where your getting cold water instead of hot?
 

John Gayewski

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Keep the shower running. Then check under every sink. See if any of the cold water lines are hot. Or hot water lines are cold.
 

aumfc

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This is too hard with everyone chipping in and no one being able to check things very specifically.

Both water heaters. Not the line between them that's just one water heater. Both lines leaving each water heater are they both hot during a shower where your getting cold water instead of hot?

I never have a problem getting cold water instead of hot. The pump works fine and does what we want it to do. Without it on, it takes forever to get hot water to the master bath. With it on, almost instant.

The only problem is hot water coming out the cold side for a few seconds to a minute-ish at most of the cold faucets, including the refrigerator water lines. I have not been able to detect a pattern in the 9 months we've lived here. Some mornings it happens, some it doesn't. But it's also very difficult to run tests given the number of drops and the family being in the house almost all day every day. I've gone days without noticing it and I've had it happen almost every time I turn on the cold water at multiple faucets.

You can see in the image how everything is connected at the water heaters. The return line is a dedicated line coming from the master bath all the way back to the heaters. There are stops on this line and the main line in.

The pipes are hot from the return line into the heaters, between the heaters, and out of the heater all the time when the pump is running.

I'll attach marked up images of the house.

First floor. Blue line is in the main line into the house to the heaters from the filtration equipment which is housed in the 1-car garage. Red line is the recirc line from the master bath back to the heaters. I didn't draw all the other lines.

Screenshot 2024-01-27 170026.png


Second floor. We added a half bath during the build so I added it in. This is only above the 3-car garage. An electronic touch faucet is up there at the bar sink. The other electronic touchless faucet is on the first floor in the kitchen.

Screenshot 2024-01-27 170457.png


Thanks.
 

John Gayewski

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I can tell you that I didn't think this was your problem. I must have skimmed when I shouldn't have.

That could be very simple. You likley have a hot and cold line ran too close together. That's what happens in my bathroom, there was only a small space to run my water lines and the hot recirc line heats the cold water in the piping. There's nothing you can do about it other than move piping. It's probably not worth doing that for such a small thing.

I'm pretty sure this is your issue. Mainly becuse you said it's intermittent. The pump running with no water running will heat the cold, but it won't happen if any child water is run and the second hand heat can't accumulate.
 

Jeff H Young

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I see the OP says the water comes out warm to very hot for 20 seconds to 3 or 4 minutes through out the house every cold
outlet including hose bibs and ice maker.
 

WorthFlorida

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. You likley have a hot and cold line ran too close together. That's what happens in my bathroom, there was only a small space to run my water lines and the hot recirc line heats the cold water in the piping.
Thought this can be true, definitely with copper, not sure if PEX can transfer that much heat between the pipes. Especially when it may last a minute before the heated water dissipates.

The symptom is like a two pipe system where the heated water returns on the coldside. I’m not sure with all of these post, has any of the tub/shower fixtures be turn off at the stop valve in the valve body, if any?
 

John Gayewski

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Thought this can be true, definitely with copper, not sure if PEX can transfer that much heat between the pipes. Especially when it may last a minute before the heated water dissipates.

The symptom is like a two pipe system where the heated water returns on the coldside. I’m not sure with all of these post, has any of the tub/shower fixtures be turn off at the stop valve in the valve body, if any?
You have no idea how much heat is being transferred.

The expansion tank is also backing up heat into the cold. Prior to the check valves the pump was backing up heat into the cold. Now he's saying 1 min. Which means it's probably got better. Now the only thing left is the pump injecting some hot back into the cold for a while and the lines being too close together.
 

Jeff H Young

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I too was wondering about heat transfer on plastic . it should have every inch insulated of hot and recirc my opinion and the pipes should never touch ? also some question in my mind how expansion tank makes a differance with the 2 check valves ( D and E) that are on the cold hot water from circ shouldnt pass to the cold with a working check valve ? \
aumfc, You have a big house this cant be a cheap shack . The Contractor needs to perform if that means 4 000 dollars in repair work so be it . 4 minutes of hbot water when you got the cold turned on is bullshit who care how much trouble or expence it is? I d ont want them to needlessly have damage or costs but its thier job to figure out . at same time any and all of us wants to help
 

John Gayewski

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I too was wondering about heat transfer on plastic . it should have every inch insulated of hot and recirc my opinion and the pipes should never touch ? also some question in my mind how expansion tank makes a differance with the 2 check valves ( D and E) that are on the cold hot water from circ shouldnt pass to the cold with a working check valve ? \
aumfc, You have a big house this cant be a cheap shack . The Contractor needs to perform if that means 4 000 dollars in repair work so be it . 4 minutes of hbot water when you got the cold turned on is bullshit who care how much trouble or expence it is? I d ont want them to needlessly have damage or costs but its thier job to figure out . at same time any and all of us wants to help
The pump on the hot is injecting into the expansion tank and was injecting into the cold line, until they put the check valves in. Now it's just injecting into the expansion tank and the cold before the check valves.


He still hasn't verified that the checks are in the correct way.


If pex didn't transfer with pex they wouldn't use it to transfer heat for heating. All that has to happen is the hot and a decent portion of the cold supply line are in the same small space together. They don't have to touch at all. The heat will move to the cold like a magnet.

My wall has a stud pocket with both running together. That entire stud pocket is warm to the touch and my cold water going to my bathroom is hot. Until the cold water is used and refreshed. Hence the intermittent effect.
 

Jeff H Young

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The pump on the hot is injecting into the expansion tank and was injecting into the cold line, until they put the check valves in. Now it's just injecting into the expansion tank and the cold before the check valves.


He still hasn't verified that the checks are in the correct way.


If pex didn't transfer with pex they wouldn't use it to transfer heat for heating. All that has to happen is the hot and a decent portion of the cold supply line are in the same small space together. They don't have to touch at all. The heat will move to the cold like a magnet.

My wall has a stud pocket with both running together. That entire stud pocket is warm to the touch and my cold water going to my bathroom is hot. Until the cold water is used and refreshed. Hence the intermittent effect.
not much other theory seems plausable John .
 

Bannerman

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The pump causes water to circulate by creating a pressure differential between the inlet and outlet.

The current placement of the recirculation pump is causing the hot water supply circuit to be slightly boosted to higher pressure to push HW through the pipes, and cause it to circulate back to the WH in a loop. Although the intended return path is through the dedicated return line (DRL), water will always take the path of least resistance.

Because the return line is equipped with check valve(s) and possible balancing valves which will act as flow restrictions, any other less restrictive path such as the normally open hot and cold inlet connections on the electronically controlled faucets, will allow the slightly higher pressure hot water to cross over to the lower pressure cold supply, resulting in the cold supply piping often becoming the recirculation return path instead of the more restrictive DRL.

If the pump had been installed directly within the DRL, just before the water returns to the WH, then the pressure differential between the HW supply and DRL would have assisted the check valve(s) to open, thereby allowing reliable flow from the hot water supply into the DRL. The pump in this position will also not create lower pressure in the cold water supply piping.

To further reduce the potential for the pump to interfere with the WH cold water supply, the usual preferred location for the circulation return loop is to enter directly into the bottom of the WH tank, away from the cold water supply piping. When a WH is not pre-equipped with a dedicated return connection, one maybe easily added using a nipple and Tee installed directly behind the tank's drain valve, causing the drain valve to be moved further outward.

I suspect both WH's thermostats are set identically, so with the plumbing in the current series configuration, the tank on the right, will be heating almost all of the hot water consumed, and the left tank's heater will only operate when the right tank can't keep up, thereby allowing cooler water to enter the left tank.

If both WHs had been plumbed in parallel, then each would operate equally to heat 1/2 of all hot water utilized. With both operating at the same time, that will significantly improve HW recovery time, likely close to 1/2 of the current recovery time.

With the tanks plumbed in parallel, then the return loop should be Tee'd to enter the bottom of both tanks.
 
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aumfc

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The pump causes water to circulate by creating a pressure differential between the inlet and outlet.

The current placement of the recirculation pump is causing the hot water supply circuit to be slightly boosted to higher pressure to push HW through the pipes, and cause it to circulate back to the WH in a loop. Although the intended return path is through the dedicated return line (DRL), water will always take the path of least resistance.

Because the return line is equipped with check valve(s) and possible balancing valves which will act as flow restrictions, any other less restrictive path such as the normally open hot and cold inlet connections on the electronically controlled faucets, will allow the slightly higher pressure hot water to cross over to the lower pressure cold supply, resulting in the cold supply piping often becoming the recirculation return path instead of the more restrictive DRL.

If the pump had been installed directly within the DRL, just before the water returns to the WH, then the pressure differential between the HW supply and DRL would have assisted the check valve(s) to open, thereby allowing reliable flow from the hot water supply into the DRL. The pump in this position will also not create lower pressure in the cold water supply piping.

To further reduce the potential for the pump to interfere with the WH cold water supply, the usual preferred location for the circulation return loop is to enter directly into the bottom of the WH tank, away from the cold water supply piping. When a WH is not pre-equipped with a dedicated return connection, one maybe easily added using a nipple and Tee installed directly behind the tank's drain valve, causing the drain valve to be moved further outward.

I suspect both WH's thermostats are set identically, so with the plumbing in the current series configuration, the tank on the right, will be heating almost all of the hot water consumed, and the left tank's heater will only operate when the right tank can't keep up, thereby allowing cooler water to enter the left tank.

If both WHs had been plumbed in parallel, then each would operate equally to heat 1/2 of all hot water utilized. With both operating at the same time, that will significantly improve HW recovery time, likely close to 1/2 of the current recovery time.

With the tanks plumbed in parallel, then the return loop should be Tee'd to enter the bottom of both tanks.

Without redoing all the plumbing at the heaters, could they just move the pump to make things better? Looking at the photo with labels I posted, where should the pump be to make it work correctly?
 

aumfc

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The pump on the hot is injecting into the expansion tank and was injecting into the cold line, until they put the check valves in. Now it's just injecting into the expansion tank and the cold before the check valves.


He still hasn't verified that the checks are in the correct way.


If pex didn't transfer with pex they wouldn't use it to transfer heat for heating. All that has to happen is the hot and a decent portion of the cold supply line are in the same small space together. They don't have to touch at all. The heat will move to the cold like a magnet.

My wall has a stud pocket with both running together. That entire stud pocket is warm to the touch and my cold water going to my bathroom is hot. Until the cold water is used and refreshed. Hence the intermittent effect.

One of the valves I found the arrow pointing to the heaters. The other one, I looked with mirrors and my phone for 10 minutes and never saw an arrow, but given the orientation of the letters, I'm fairly certain it's also in the right configuration. I don't know how else I can verify it.
 

aumfc

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I just went back to the kitchen sink. The hot water supply is still cut off to it and the bar sink upstairs.

The water was initially room temp. After 10 seconds or so, it got up to 88 degrees. Stayed there a couple of seconds, then dropped back into the mid-60s. Note: This is much different than a week ago where the water from the cold side was HOT for up to 30-60 seconds before cooling off.

No water has been used in the house since 830am this morning and the pump has been running all morning.

I also went into the attic before the test. We have spray foam so the air temp up there is 72, or so right now. I felt all the lines and hot was hot and cold was room temp. I checked and all of the cold and hot lines are a few inches away from each other. There is one run where the recirc line comes back from the master bath and is run close to the cold line going out. However, all 3 lines, hot supply, cold supply, and hot return, are insulated. So they are within 1/2 an inch of each other but they have the black pipe wrap tubes around them.

I'm thinking that the main issue may have been solved, which was bleed over at the electronic faucets. I haven't experienced that anywhere in almost a week. And this warm water bleed over may be due to the pressure as mentioned above.
 

Bgard

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Instead of putting bandaids on a obviously poorly designed system, why not re-plumb it the way I suggested in post 16 and take full advantage of having two tanks to draw from and nearly double you draw down and recovery,and save some energy by putting the pump on a thermostat also. 6000 sq ft house would imagine it is pretty high end, whey skimp on something you will use every day you live in it.
 

WorthFlorida

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It's sure a long post but only little mention of the expansion tank. Has it's pre-charge pressure been checked? The pressure tanks appears to be only for a 50 gallon tank. However, the second WH should have a heat trap on the cold inlet, thereby, expanding water in the second tank goes into the hot piping. For a100 gallon tank, the expansion tanks needs to be larger, double in size. The way the problem seems not to be consistent, cold water inlet pressure is usually not consistent.. It can vary over night and the static pressure gets too high. A pressure gauge should be used.

 

aumfc

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Thanks everyone. Check valves on the cold water supply to the electronic faucets have solved the problem.
 
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