Water Heater leaks at very specific time of night

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nesappa

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Hello,

I have recently replaced the pressure relief valve as well as the expansion tank.
I have attached a photo for reference.

My water pressure measured at around 60 psi, so I matched the expansion tank prior to installation.

Problem:
My new pressure relief valve leaks approximately 1/2 gallon of water every night at the same time around 3:00AM.
No other leaking at any other time during the day. High usage does not cause any leaks.
This is much better than the constant leaking prior to the new T&P and expansion tank, but I need to get this leak-free and as safe as possible.


Any ideas what could be going on here?
Thanks in advance.

thumbnail_IMG_1839.jpg
 
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Reach4

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I presume you don't have a PRV (pressure reducing valve) on the incoming water.

Thermal expansion tank is too small, or failed, or the air precharge is not set right.

Air precharge should match the pressure that the city provides. Air precharge is measured or set with the water pressure zero. However if the city pressure rises each night to 70, then set the air precharge to 70.

So if you dribble water somewhere, you should be able to knock on the tank and find it sounds empty.

See http://tools.watts.com/ETP/ is calculator for a sizing calculator.
 
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nesappa

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I presume you don't have a PRV (pressure reducing valve) on the incoming water.

Thermal expansion tank is too small, or failed, or the air precharge is not set right.

Air precharge should match the pressure that the city provides. Air precharge is measured or set with the water pressure zero. However if the city pressure rises each night to 70, then set the air precharge to 70.

So if you dribble water somewhere, you should be able to knock on the tank and find it sounds empty.

See http://tools.watts.com/ETP/ is calculator for a sizing calculator.
Thank You for the response.

Correct no PRV exists.

Expansion tank is new and of the correct size per the calculator you provided.

Based on your assessments my precharge of the tank at 60PSI may need to be increased to 70PSI. That makes sense to me too.

I assume by dribble you mean to turn the water on low at a faucet and check the expansion tank.
I did this and the tank does sound empty.

Thanks again for the information and thanks for any further information
 

Reach4

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You might want to measure the water pressure when the dribbling happens. It should be about 150 during dribbling.

Also, is somebody taking a hot 2 am shower?
 

nesappa

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*Of further note here, my pressure outside at the faucet is reading 80psi.
My pressure the day of install was reading 60psi so there is apparent fluctuation.

I suspect we are onto something here and my precharge is too low.
 

nesappa

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You might want to measure the water pressure when the dribbling happens. It should be about 150 during dribbling.

Also, is somebody taking a hot 2 am shower?
Should I measure pressure at the outside faucet, or at the water heater drain valve?

I understand the 150 measurement you reference since that is the PSI the T&P valve is set to open at so that makes sense to me.

*No showers after around 8PM. No water usage at all as a matter of fact

I am starting to wonder if I need a PRV installed?
 

Reach4

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Should I measure pressure at the outside faucet, or at the water heater drain valve?

I understand the 150 measurement you reference since that is the PSI the T&P valve is set to open at so that makes sense to me.

*No showers after around 8PM. No water usage at all as a matter of fact
Either. If there is no flow, they will read the same other than a small difference due to altitude.

I don't know how long your cellphone can take a movie, but maybe record the pressure gauge overnight. Do you have a time lapse mode maybe?
 

nesappa

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Either. If there is no flow, they will read the same other than a small difference due to altitude.

I don't know how long your cellphone can take a movie, but maybe record the pressure gauge overnight. Do you have a time lapse mode maybe?
The timing is so predictable I will wake and and observe the pressure around that 3 a.m. time frame.

I plan to increase the PSI of the expansion tank.
If that did not fix it, would a PRV be the next possible remedy?

Thanks,
 

jadnashua

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It is not unusual for your utility to temporarily raise the pressure, often at night, to refill any water towers. So, if your pressure really is peaking that high, you should probably consider a PRV to keep it down.

Many utility companies, at the Federal guidelines recommendations, are installing check valves on their customer's supply lines to help protect the system from contamination, which may be why you need an ET. Otherwise, in an open system, it is not needed, but doesn't hurt. Personally, I prefer to bump the ET size up to minimize the pressure rise due to thermal expansion.

When the ET precharge exceeds the 'normal' pressure in your home, as soon as expansion occurs, the pressure will immediately step up to the precharge level prior to the tank allowing any water in, so there's a step function there rather than a smooth transition.

Suggest you get a pressure gauge with a second, tattletale hand, and leave it attached overnight to see what your peak pressure gets to.
 

nesappa

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It is not unusual for your utility to temporarily raise the pressure, often at night, to refill any water towers. So, if your pressure really is peaking that high, you should probably consider a PRV to keep it down.

Many utility companies, at the Federal guidelines recommendations, are installing check valves on their customer's supply lines to help protect the system from contamination, which may be why you need an ET. Otherwise, in an open system, it is not needed, but doesn't hurt. Personally, I prefer to bump the ET size up to minimize the pressure rise due to thermal expansion.

When the ET precharge exceeds the 'normal' pressure in your home, as soon as expansion occurs, the pressure will immediately step up to the precharge level prior to the tank allowing any water in, so there's a step function there rather than a smooth transition.

Suggest you get a pressure gauge with a second, tattletale hand, and leave it attached overnight to see what your peak pressure gets to.
Thanks,

Yes my gauge has the "hold" hand on it so I will be able to observe the peak PSI. I just remembered that so maybe I wont set the alarm for 3AM tonight.

Sounds like I have some research to do into PRVs.
 

Reach4

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Thanks,

Yes my gauge has the "hold" hand on it so I will be able to observe the peak PSI. I just remembered that so maybe I wont set the alarm for 3AM tonight.

Sounds like I have some research to do into PRVs.
If you want to be really sure it is not the WH expanding the water, you could turn off the WH overnight, but allow time for it to recover before showering.

One thing I got to wondering about is if there was a backwashing filter that backwashed each night and fed its water to the same place that the WH T&P feeds to, and it just looked like the water was from the WH. 1/2 gallon would be way low for a backwashing filter backwashing.
 

jadnashua

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If the pressure actually is getting to 150psi where the T&P valve opens, that will decrease the life of the ET, as it will overstretch the bladder in the thing.
 

John Gayewski

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You need a prv. Make sure you get once that can do the minimum and maximum flow rates you require. Buy a rebuild kit with it because it will someday act up. Store the kit with thr prv so it can be serviced when necessary.
 

nesappa

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**Update here morning of 01/20/2022:

-Max PSI at the outdoor faucet was 90 overnight per the hold arm on the gauge.

-I had less water discharge today. I am down to 1/4 gallon. This is the first time is has been less than that approximate 1/2 gallon from the previous 5 nights in a row. Timing is still the same around that 3:00 AM mark as we can here the discharge from our room.

Per the comments above:
*Only the T&P discharges to the bucket that I am observing each day
**I need to verify via visual inspection as to whether I have a PRV or not. I have not observed the entire line under the house so that is on the to do list. A maximum PSI of 90 might indicate there is one under there, i do not know though.

Plan as of today:
1. Check the PSI overnight again.
2. Check for existing PRV

Potential remedies as of today:
1. Increasing the expansion tank precharge to 90PSI up from the current 60PSI? I would have to verify that that is an option with this et.
2. Potential installation of a PRV that can do minimum and maximum flow rates per J Gayewski post above.
3. ?


I appreciate the feedback guys. At this point I have about $550 into the repair. I had to repair the floor, walls, and I went ahead and replaced pipe, added conduit, etc and really am working to do this right. Since I have so much into the repair Id really like to see it all the way through rather than call the pros at this point.

NOTE: I used the following connector for my expansion tank installation. I do not suspect this would cause and issue, but worth noting:

 

Reach4

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Max PSI at the outdoor faucet was 90 overnight per the hold arm on the gauge.
Certainly the T&P should not release water at 90 psi. If the WH releases water at 90 psi, it should be replaced. They are often under $20 to buy, but Rheem would probably provide one if you call their customer service.

I would retry that measurement with the gauge indoors. While it is unlikely, let's make sure that there is no PRV between the outdoor water and the WH. Still, how about putting the gauge on the drain valve for the WH and then opening that valve.

One thing about the tattletale (peak reading) hands those gauges: they can be affected by vibration.

It would be interesting to make a movie of the gauge during the 3am event. This is a really strange occurrence.
 

nesappa

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Certainly the T&P should not release water at 90 psi. If the WH releases water at 90 psi, it should be replaced. They are often under $20 to buy, but Rheem would probably provide one if you call their customer service.

I would retry that measurement with the gauge indoors. While it is unlikely, let's make sure that there is no PRV between the outdoor water and the WH. Still, how about putting the gauge on the drain valve for the WH and then opening that valve.

One thing about the tattletale (peak reading) hands those gauges: they can be affected by vibration.

It would be interesting to make a movie of the gauge during the 3am event. This is a really strange occurrence.
Got it.

I will move the gauge in tonight. I think I will set an alarm on the phone and wake up and film one night as soon as possible as well.

I have considered a faulty T&P as well, but this one is brand new so the likelihood seems lower and I thought I would discuss this with you guys first. I will add this to the list of potential remedies.

Potential remedies as of today:
1. Increasing the expansion tank precharge to 90PSI up from the current 60PSI? I would have to verify that that is an option with this et.
2. Potential installation of a PRV that can do minimum and maximum flow rates per J Gayewski post above.
3. Faulty T&P.
4. ?

*Note 2:
Water heater temperature is set at 120 F.
 

nesappa

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Here are the PRVs I am looking into now if anyone has an opinion or suggestion for a better please share:


 
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