PSI goes high during the night

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urdrwho

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I have my pressure gauge hooked up to the drain faucet on the hot water heater. All day long it stays at @60 PSI, all evening it stays the same, at 11PM I go to bed and it is the same.

I check it in the morning and the red needle is sitting at 140 PSI and the current PSI needle is setting at 60.

Street PSI goes up at night, that I do know. My PRV was installed in the late 1980's and it is suspect. I also removed the expansion tank and it was never pumped up past the 40 PSI. So I pumped it up to @60. When I set the hot water heater up to as high as it goes there is no spike --- so I believe the expansion tank is working.

I did set the PRV back to 60. It was showing 80 psi.

I always thought a PRV is good for a long time but the water company tells me that we are in a high pressure area (needed to pump up the big hill) and that a PRV is only good for 10 years.

So am I looking at a new PRV.
 

Reach4

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Your PRV is probably good.

You need a good thermal expansion tank. If you have a tank already, it has probably failed.

The tank would have a Schrader valve (like tire valve) to set the precharge air while there is zero PSI on the water. I would set the air pressure to about 65 PSI with your PRV. Precharge pressure should be no less than the PRV setting, and a little higher is better. For one thing, that compensates for a potential difference between the water pressure gauge and the air pressure gauge. If water comes out of the valve, your unit is bad. If you tap the tank while it is in use, it should normally sound empty.

If adding such a tank, the water heater size and water heater temperature setting and even the temperature of the incoming water comes into account. There are on-line calculators and tables.
 

urdrwho

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Thanks for the reply.

It is a Watts and there is no water coming out of the Schrader valve. Ten days ago I suspected the tank, removed it and that is how I found that the psi in the tank was @40 psi. I pumped air into it but only went to 50 > 55 psi. Today when I removed the tank I checked and the tanks was still @ 50 > 55 psi.

The reason I put more air into the tanks is because my incoming water psi was higher than the 50 > 55. I read one time that the tanks should be about 5psi less than incoming pressure but I'm not sure if that is true or not.

We'll see how it goes tonight.

The PRV itself isn't very costly. In the late 1950's and early 1960's in the summer I tagged along in the truck with my HVAC dad. I can sweat a good looking joint. I could do the PRV myself but I am getting lazy. Ha! So lazy that I can't remove the union and do what else is need to install a new PRV. So if it ends up being the PRV I have a good HVAC plumber guy and may have him do it.

Houses! In June we got a new AC plus new furnace. At this very moment we are in the process of getting all new replacement windows. So I am hoping not to spend any money on a PRV.


Your PRV is probably good.

You need a good thermal expansion tank. If you have a tank already, it has probably failed.

The tank would have a Schrader valve (like tire valve) to set the precharge air while there is zero PSI on the water. I would set the air pressure to about 65 PSI with your PRV. Precharge pressure should be no less than the PRV setting, and a little higher is better. For one thing, that compensates for a potential difference between the water pressure gauge and the air pressure gauge. If water comes out of the valve, your unit is bad. If you tap the tank while it is in use, it should normally sound empty.

If adding such a tank, the water heater size and water heater temperature setting and even the temperature of the incoming water comes into account. There are on-line calculators and tables.
 

Reach4

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The reason I put more air into the tanks is because my incoming water psi was higher than the 50 > 55. I read one time that the tanks should be about 5psi less than incoming pressure but I'm not sure if that is true or not.
Not true. The precharge should be at or above the PRV pressure. Setting it to 65 PSI with your 50 PSI PRV would be OK too. The instructions say to set the precharge at the PRV pressure, but there is some advantage to being above that. And when you measure and set the precharge pressure, you don't have to remove the tank. Just shut off the water and open a faucet to relieve the pressure.

It is possible that your expansion tank is undersized. Look at the documentation of the tank to see if it is appropriate to your water heater size and temperature. http://www.watts.com/pages/support/sizing_DET.asp

The PRV itself isn't very costly.
It could be the PRV, as you suspect.
 

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The setup at the water heater has been the same since it was new in 2011. It is a 40 gallon tank and I just looked at the expansion tank -- it says something something 5. I think because of course the label is in a place that I could barely fit my head.

So maybe the expansion tank should be larger?
 

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Probably big enough. I would try cranking your precharge up to 65.
 

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Assuming you're using water during the day and your water pressure stays stable, the ET is likely fine. They do fail eventually, and when they do that, they'll fill with water after the bladder breaks or leaks. Depending on the street pressure, some PRV's cannot handle the high differential pressures. Check the spec sheet. In some, more adverse situations, you may need two of them in series, each dropping the pressure some. You have any way to put a pressure gauge on the input side of the PRV? If it exceeds the maximum recommendation, you may need a second one, or a different model.

The ET is at its normal ideal position when the precharge equals your normal water pressure. The goal is to keep the pressure consistent, and if it is higher than the PRV setting, during water heating, it will jump to the precharge setting then remain stable. IF it is lower than the PRV value, it wont' hold as much, and will be stretched by the higher normal water pressure. The tank will not last as long since it will be flexing more than ideal.
 

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Yesterday I pumped up the ET to try and equal house PSI measured at the outside faucet. Everything was fine when I went to bed at midnight. This morning I found water in the bowel that I have sitting under the TP valve. The psi was way, way up. The TP had not let go in a week.

So I am thinking that maybe a bigger ET will have the extra space needed to handle the spike in pressure.

I talked with the plumbing guy at Lowe's (he is a retired plumber) and he did say that the water company has increased pressures.

My PRV is't one that has a gauge with it. If I need another PRV installed I will have a gauge coupled with the PRF.

Side issue ------

There is also an issue of our downstairs toilet (sits near the main line). When it was installed it was installed with the water supply before the PRV. It has been there for 30 years. Lately we've had a problem where fill valves prematurely die. Because the supply is installed before the PRV I'm wondering if the increased street pressure is what has been killing the fill valve.


Assuming you're using water during the day and your water pressure stays stable, the ET is likely fine. They do fail eventually, and when they do that, they'll fill with water after the bladder breaks or leaks. Depending on the street pressure, some PRV's cannot handle the high differential pressures. Check the spec sheet. In some, more adverse situations, you may need two of them in series, each dropping the pressure some. You have any way to put a pressure gauge on the input side of the PRV? If it exceeds the maximum recommendation, you may need a second one, or a different model.

The ET is at its normal ideal position when the precharge equals your normal water pressure. The goal is to keep the pressure consistent, and if it is higher than the PRV setting, during water heating, it will jump to the precharge setting then remain stable. IF it is lower than the PRV value, it wont' hold as much, and will be stretched by the higher normal water pressure. The tank will not last as long since it will be flexing more than ideal.
 
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I'm wondering if the increased street pressure is what has been killing the fill valve.
Could be.

While doing your plumbing, you could get a boiler drain installed instead of a pressure gauge. Then you could attach a pressure gauge to that, or you could use that for filling a bucket in the basement-- or whatever.

If you swap out the pressure tank, take note of the old tank. It should be as light as the new one if it is not waterlogged.
 

Jadnashua

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One of the failure modes of PRV's is that the pressure can creep up. Watts has a good ET calculation tool on their website (make sure to use the one for potable water, not hydronic heating) that should tell you the needed size. If the tank is not currently shot, it's probably not too small, as unless you have super cold water coming in, a huge water heater, and set its temperature very high, usually the smallest one they make will work. We're only talking a cup or two of water volume. A hydronic heating system tends to have more water and higher temperature swings, and often needs to be bigger. Because water does not compress, any expansion in the essentially rigid pipes, causes the pressure to spike without an ET. Yes, the hoses to things like faucets, washing machines, etc., can balloon a little, but it's not good or them.

No plumbing fixtures are designed for more than 80psi with few exceptions (yes, they have a built-in margin so they can handle 80psi continually like the WH, the T&P is set to 150psi, and the tank tested to 300 at the factory). So, yes, full street pressure where you live will tax the seal of anything fed with it.
 

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It is just odd. I pumped the ET up to 63>65 pounds. Installed it and went on an errand. Gone for two hours and return to see that at sometime the pressure hit 140. But right now the needle is @ 60. I watch and watch but it doesn't creep, it seems to spike and then go back down.

On Sunday when I first removed the ET and pumped in air I could have sworn that while pumping air and water was spitting out the 3/4 inch hole. I could not at first feel the bladder.
 

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Are you saying that that only the tattletale/lazy hand shows those high pressures, and not the hand that shows the instantaneous pressure? Tap your gauge, and you might see that that hand jumps in response to vibration.
 
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Jadnashua

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As I said earlier, you need to find out what the supply pressure is. It may exceed the capabilities of the PRV. It may leak if the city water pressure exceeds a certain value. IN some circumstances, a different PRV or using two of them in series to stair-step the pressure down is required.

The T&P valve, when working right, won't release until the pressure exceeds 150psi or the temperature exceeds 205F (some go higher). They aren't calibrated all that well, and an older one's spring could be weaker, so it could dump at 140psi, which may be why the gauge shows that limit.

If you had water out of the ET, that normally points to a failed ET. Unless the PRV leaked a lot during a pressure surge, it would not be able to fill up the ET and the pressure wouldn't be able to rise that high. IOW, something does not compute. When you're adding air to the ET, the water supply needs to be turned off and there needs to be a valve opened to relieve all pressure in the line. That valve needs to remain open while you add air so the water it pushes out can go somewhere otherwise, you're just measuring water pressure on the other side.

Did you notice any water from the Schrader valve when you added air? If so, that's another indication the ET is shot. Make sure it rings if you tap it, and doesn't 'thud' or sound full of water.
 

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Yes, my tattletale needle shows how high the pressure rose at some point in time.

Are you saying that that only the tattletale/lazy hand shows those high pressures, and not the hand that shows the instantaneous pressure? Tap your gauge, and you might see that that hand jumps in response to vibration.
 

urdrwho

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I have no idea what the pressure is for the street but if memory serves me I can go and look in the outside pit. I think there is a gauge down in that pit. I think their manhole cover is unlocked and I'll check today.

The ET is removed when I fill with air.

No water at the valve.

The water that came out was on top of the bladder.

Everything is starting to point to the PRV.

There may even be another PRV in the pit down by the street for the main coming into the house. If I remember, 30 years ago a plumber used a crows foot wrench on a long extension to dial back pressure. I could be wrong....heck these days I can't even remember what I had for breakfast. :)

The TP went off last night and the telltale needle was sitting at 150. So sometime during the night pressure went high enough to pop the new TP.

So I have the PRV dial out so far that the water pressure is low when you turn on the faucets. Close faucets and then I watch it creep up to 100 psi on the gauge.

I've called my plumber to come look and probably install a new PRV.

As I said earlier, you need to find out what the supply pressure is. It may exceed the capabilities of the PRV. It may leak if the city water pressure exceeds a certain value. IN some circumstances, a different PRV or using two of them in series to stair-step the pressure down is required.

The T&P valve, when working right, won't release until the pressure exceeds 150psi or the temperature exceeds 205F (some go higher). They aren't calibrated all that well, and an older one's spring could be weaker, so it could dump at 140psi, which may be why the gauge shows that limit.

If you had water out of the ET, that normally points to a failed ET. Unless the PRV leaked a lot during a pressure surge, it would not be able to fill up the ET and the pressure wouldn't be able to rise that high. IOW, something does not compute. When you're adding air to the ET, the water supply needs to be turned off and there needs to be a valve opened to relieve all pressure in the line. That valve needs to remain open while you add air so the water it pushes out can go somewhere otherwise, you're just measuring water pressure on the other side.

Did you notice any water from the Schrader valve when you added air? If so, that's another indication the ET is shot. Make sure it rings if you tap it, and doesn't 'thud' or sound full of water.
 
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Reach4

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The TP went off last night and the telltale needle was sitting at 150. So sometime during the night pressure went high enough to pop the new TP.
Here is an idea for experiment you could try: after taking showers for the day, turn off the hot water heater heat, or at least put it into vacation mode. Open a faucet for a bit. Reset the tattletale needle. Go to bed.

Check for signs in the morning. If the pressure rise has been due to the PRV only, there would be signs of high pressure. While a mix of PRV leak and insufficient expansion tank might not be detected that way, a T+P leak and tattletale would damn the PRV. Then turn the WH back on.
 

urdrwho

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I was planning on doing what you say but no time now because I called my plumber.

Earlier in the morning I turned off the water heater, closed off the inlet line to the water heater and attached the gauge to an outside faucet. The needle slowly moved and after a half an hour it went from 60 to almost 100.

With such pressure issues, I don't want to stress out our appliances and copper pipes so it is time for the plumber.


Here is an idea for experiment you could try: after taking showers for the day, turn off the hot water heater heat, or at least put it into vacation mode. Open a faucet for a bit. Reset the tattletale needle. Go to bed.

Check for signs in the morning. If the pressure rise has been due to the PRV only, there would be signs of high pressure. While a mix of PRV leak and insufficient expansion tank might not be detected that way, a T+P leak and tattletale would damn the PRV. Then turn the WH back on.
 

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Good move. While he is at it, are you going to have the plumber install a gauge, a boiler drain, or at least a plugged tee for later use?
 

urdrwho

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Errrr!!! So I am downstairs closing off stuff and someone flushes the commode and I hear dripping. Hm....wax ring is bad. Oh and of course it has been leaking for how long....? The new furnace that was installed in May 2015 is a mess on the back, some duct work looks just yuck. Black pipe has rust started on it.

Can I just move to the shed and not have any worries? :(



I would like to but it will depend on how much time he has today. He is going to squeeze me in at the end of the day.

Good move. While he is at it, are you going to have the plumber install a gauge, a boiler drain, or at least a plugged tee for later use?
 
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urdrwho

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It was at the end of the day and he didn't have time to do all that. It was the PRV and now everything is solid.

He asked what I had in the ET and I said about 62. He set the new Watts PRV to 70.

Good move. While he is at it, are you going to have the plumber install a gauge, a boiler drain, or at least a plugged tee for later use?
 
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