Water Heater leaks at very specific time of night

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nesappa

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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.
Im gonna turn the WH off tonight and report back tomorrow. Good idea here.
 

Reach4

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if anyone has an opinion or suggestion for a better please share:
My opinion is that unless you see 85 psi while dribbling water from a faucet, don't add a PRV. My thinking is that the peak that you saw outside could have been due to thermal expansion-- no reason to add a PRV. But even if that doesn't sit right, then at least see 80 while dribbling water before pulling the trigger on a PRV. Also, that needle on the meter could have jumped due to a vibration or even the pressure rising suddenly from 72 to 75 and momentum carried the needle. A PRV is a maintenance item IMO.

The dribbling water bit ensures you are measuring pressure from the city, and not measuring your thermal expansion pressure rise.

If you do add a PRV, you may want to consider putting that after the tee to the outside hose spigots.

I am not a plumber. And I understand that other opinions may be better than mine.
 
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jadnashua

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If you set the precharge to 90-psi...whenever you get any expansion, the pressure will go from its 'normal' level and jump immediately to 90-psi before the ET can accept any water...this is not a good thing! The whole goal with using an ET is to limit the pressure changes. The larger the ET, the less pressure rise you'll get.

Code says the nominal pressure should not exceed 80-psi.

Your water pressure gauge may not be accurate. To get an idea, if you have a decent air pressure gauge, the air pressure on the ET fill valve should equal the water pressure when in the system as long as you don't have the ET over pressurized in the first place. They should track together.

The T&P valve is designed to open under two circumstances by itself:
- the water pressure exceeds 150-psi
- the water temperature exceeds 210-F

If it was releasing because of temperature, it would be easier to tell.
 

nesappa

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My opinion is that unless you see 85 psi while dribbling water from a faucet, don't add a PRV. My thinking is that the peak that you saw outside could have been due to thermal expansion-- no reason to add a PRV. But even if that doesn't sit right, then at least see 80 while dribbling water before pulling the trigger on a PRV. Also, that needle on the meter could have jumped due to a vibration or even the pressure rising suddenly from 72 to 75 and momentum carried the needle. A PRV is a maintenance item IMO.

The dribbling water bit ensures you are measuring pressure from the city, and not measuring your thermal expansion pressure rise.

If you do add a PRV, you may want to consider putting that after the tee to the outside hose spigots.

I am not a plumber. And I understand that other opinions may be better than mine.
When dribbling the water, should I use hot or cold, or does it matter? I assume you mean open a valve slightly at a faucet and let the water dribble out?
My bad on needing such specifics I just know enough to keep myself safe with this stuff I hope and not much more.

I will also check this weekend to ensure a PVR does not currently exist in the system.

I think I am jumping the gun as I am looking for anything at all I can do to eliminate the leak.
I m gonna slow it down a bit and try to figure this out.

Thanks,
 
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nesappa

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If you set the precharge to 90-psi...whenever you get any expansion, the pressure will go from its 'normal' level and jump immediately to 90-psi before the ET can accept any water...this is not a good thing! The whole goal with using an ET is to limit the pressure changes. The larger the ET, the less pressure rise you'll get.

Code says the nominal pressure should not exceed 80-psi.

Your water pressure gauge may not be accurate. To get an idea, if you have a decent air pressure gauge, the air pressure on the ET fill valve should equal the water pressure when in the system as long as you don't have the ET over pressurized in the first place. They should track together.

The T&P valve is designed to open under two circumstances by itself:
- the water pressure exceeds 150-psi
- the water temperature exceeds 210-F

If it was releasing because of temperature, it would be easier to tell.
Got it,

Like Reach4 said above, my peak pressure measurement may have been inaccurate also.

I have the ET at 60PSI, and it is looking like I see a range between 60 and 90 or so (possibly) on the pressure at the faucet. Based on your assessment it is likely best to leave it and not increase it.

I am going to measure pressure from inside at the water heater drain valve tonight and report back.
I will also check the pressure in the ET to see if they track. (I assume they should as I filled originally to 60PSI so hopefully that was not over fill)
 

John Gayewski

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Don't lose sight of the fact that the relief should not open unless it gets to 150psi. If it does then it's bad, simple as that.
 

Reach4

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When dribbling the water, should I use hot or cold, or does it matter?
It does not matter, but cold is cheaper.
I have the ET at 60PSI, and it is looking like I see a range between 60 and 90 or so (possibly) on the pressure at the faucet. Based on your assessment it is likely best to leave it and not increase it.
Let's see what your studies show.
 

jadnashua

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In a closed system, the pressure WILL rise when you heat (expand) water. How much all depends on how much water the ET needs to accept (based on the volume of water heated and the delta T). The characteristics of that expansion are well known and quantifiable. The bigger the air volume and the lower the percentage you are compressing, the less the pressure will rise, thus, the bigger the ET you use, the less the pressure rises. IMHO, it's easy to select one large enough to keep the pressure below 80-psi. The ET manufacturer's calculators often will NOT keep it below 80-psi...they want you to end up buying a new one, and as long as it keeps the T&P from dumping water, IMHO, they feel everything is just fine. Yes, it will work, but you'll be putting more stress on things along the way. ETs are cheap, a bigger one ends up being cheaper in the long run.

But, unless you have a closed system you don't 'need' one, but likely will, as most public systems either have or will be making their customers' systems closed to help protect the supply system from being contaminated in case a hiccup occurs and pushes potentially contaminated material back into the system.
 

nesappa

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*Update 01/21/2022. I set my alarm for 3AM and observed the following measured at the WH drain valve:
**Note 3: Manufacture date of WH: 24Jun2016


1. Photo taken before dribbling water. 150 psi had been reached and a small discharge of water occurred out of T&P
2. Photo taken after dribbling water. Water discharge stopped after this release of pressure. Dribbling occurred directly behind WH at the bath tub.
3. Small quantity of water discharge. There will likely be no discharge during the day at high usage (has been this way consistently for 7 days or so. 0 discharge at all except around 3AM every night).

Potential remedies in my mind as of today:
1. Bigger ET per jadnashua post above?
2. Discard this water heater and purchase new?
3. ?
4. ?


thumbnail_IMG_1847.jpg
thumbnail_IMG_1848.jpg
thumbnail_IMG_1849.jpg
 

nesappa

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*Note 4 & 5:
-Same size ET was installed prior. Prior to recent severe leaking that led to repair, no leaking occured in 3 years.
-I travel for work 5 months out of the year to Colorado. I shut off the water to the home for those 5 months. Just fyi in case this could lead to deterioration of the WH in any way.


See below installation photos of ET in case this is useful:
thumbnail_IMG_1850.jpg
thumbnail_IMG_1851.jpg
thumbnail_IMG_1852.jpg
 

wwhitney

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Are you able to determine if there is a check valve between the outdoor hose bib where you saw 90 psi two nights ago, and the water heater, where you saw 150 psi last night?

If there is such a check valve, then your results are consistent with getting 150 psi at the water heater every night and the T&P valve working properly. In which case the problem is either with the expansion tank (too small, defective, blocked from the water supply so it's not able to do its job, etc) or with the water heater (somehow overheating overnight?).

If there isn't such a check valve, the data is confusing, as the night that you saw only 90 psi, the T&P valve should not have discharged.

Cheers, Wayne
 

John Gayewski

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My guess is the meter has a check in it or there is a prv. The prv is bad or needs set to a lower pressure.

In any case you need a prv or rebuild kit for the current one, but you do need a prv.

The water heater and expansion tank should be ok once the pressure is regulated.
 

Reach4

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1. Photo taken before dribbling water. 150 psi had been reached and a small discharge of water occurred out of T&P
2. Photo taken after dribbling water. Water discharge stopped after this release of pressure. Dribbling occurred directly behind WH at the bath tub.
How much time between gauge photos? If only minutes then I think no PRV needed.
Bigger thermal expansion tank needed if the current tank is functional, but you could try increasing the air precharge to 74 psi. That only gains you a bit. So existing tank probably has a problem or is just too small.

But that 3am thing is the BIG mystery, unless you are regularly using hot water at 2:50 am. But here is another thought. I there a water heater timer or a device from the electric company that sheds loads and uses power when the electricity gets cheaper? Or do you have an Econet WiFi control for the WH? So suppose this timer turned off the WH for a while, and turns it back on at 2:50 am? That could account for the timing. And since the WH would be starting from cooler, there would be more expansion. Yes, this all sounds improbable, but I don't see a better explanation for the 3am part of this all.


rheem-water-heater-accessories-rewra631ewh-1f_100.jpg
rheem-water-heater-accessories-rewra631ewh-4f_100.jpg
 
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Weekend Handyman

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I am not a plumber. On the timing of the discharge, could it be that that at 3:00 the WH has not been used for a while and hits it max temperature / pressure and blows the valve?
 

nesappa

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How much time between gauge photos? If only minutes then I think no PRV needed.
Bigger thermal expansion tank needed if the current tank is functional, but you could try increasing the air precharge to 74 psi. That only gains you a bit. So existing tank probably has a problem or is just too small.

But that 3am thing is the BIG mystery, unless you are regularly using hot water at 2:50 am. But here is another thought. I there a water heater timer or a device from the electric company that sheds loads and uses power when the electricity gets cheaper? Or do you have an Econet WiFi control for the WH? So suppose this timer turned off the WH for a while, and turns it back on at 2:50 am? That could account for the timing. And since the WH would be starting from cooler, there would be more expansion. Yes, this all sounds improbable, but I don't see a better explanation for the 3am part of this all.


rheem-water-heater-accessories-rewra631ewh-1f_100.jpg
rheem-water-heater-accessories-rewra631ewh-4f_100.jpg
-Less than 1 minute time between the two photos of the gauge readings.
-No Wi-Fi control on this WH.
-No water usage at all typically after 8PM or so we get to bed early.
-No device from the electric company that I am aware of.

I appreciate the feedback guys. This is the kind of weird problems I seem to face regularly I dont know what it is about me to attract these kind of problems but I am used to it and exhausted quite frankly lol.

70 PSI at the time of this post measured at the WH drain valve.
Not a drip of water discharge since 3AM last night.

Goodness.
 

nesappa

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I am not a plumber. On the timing of the discharge, could it be that that at 3:00 the WH has not been used for a while and hits it max temperature / pressure and blows the valve?
I have considered this as well if one of the guys has a thought here.

Dribbling for literally less than 10 seconds or so dramatically decreased the pressure and the pressure from 150 down to 70PSI or so and has maintained around 70 PSI since then. The duration of the dribbling was likely less than 1 minute total. The location of the dribbling was directly next to the WH.
 

John Gayewski

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The time is related to the pumping by the municipality. You need to regulate the incoming pressure.

That's my theory.
 

nesappa

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The time is related to the pumping by the municipality. You need to regulate the incoming pressure.

That's my theory.
My initial though on the timing was something along these lines as well.

I will verify the existence of PRV tomorrow. If it is there the 150 reading last night would prove it is failing.
 

Reach4

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I would still up the air precharge to 73 or 73. You saw 73 on your gauge while dribbling. And is that their max?

Consider talking to the water department about how much pressure they deliver to you. The technical people will like talking about their product.
 

nesappa

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*Note 6: Water district is Tennessee American Water per the link below. I am unaware of how they operate and could not comment on the existence of water towers, etc. I am within 5 miles of the Tennessee river. Water is plentiful in this area.

 
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