I noticed today the outside drain pipe for the T&P valve was dripping water. This got me concerned because this is the third T&P valve on this AO Smith Water heater that I installed new in 2017. Is it a problem with the valve or the water heater?
Is it my water heater or T&P valve?
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GReynolds929
Active Member
Is the thermal expansion tank waterlogged? They should be precharged to house pressure when installed.
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Jeff H Young
In the Trades
x tank cant be on its side, might contribute , pressure might be high to begin with check incoming pressure and reposition tank re charge with air (if tank bladder is good) and I dont care how many times you changed t and p if its been sputtering for a long time it might not reseat. the water heater is probebly fine is the water super hot ? if not forget the water heater as being cause
Check a water pressure gauge after you stop using a lot of hot water, and then stop using water (don't flush during the test). Your cellphone can watch the gauge, maybe set to time lapse if you can. If the pressure gets to 140 or more, think tank. If the pressure stays under 140, thing T&P valve.
GReynolds929
Active Member
Expansion tanks can be installed in any orientation needed. Vertical is preferred. That little bit of plumbers tape isn't doing much, would be more effective on tank barrel.
Jeff H Young
In the Trades
Thanks John I stand corrected on side is not prohibited at least not the one I looked at it said must not be installed on side unless properly supported and I mis read
Thanks for the question and suggestion. The expansion tank was bought "pre-charged" but I did not check the house pressure. I wish the installation manual had your tip or I could have missed the "fine print". Will check the air pressure in the tank and likely recharge if not waterlogged.
With due respect what do you mean "this disaster"?
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Ok. I appreciate your response. I could have sworn that I read at least one of these expansion tank manuals that it could be either vertically downwards or sideways. I just watched this youtube video from the handyguys -
Thanks Reach4! Is the pressure of 140 measured at the outside hose bib? Also I am not sure why the time lapse is to do with the pressure gauge.
If there is not significant water flowing, the pressure is the same everywhere after the PRV, except for the effect of altitude (a little under 1/2 psi per foot of altitude). Not all hose bibs get water from after the PRV. So an indoor spigot, such as the drain for the WH, might be better.
The reason for the time lapse video is to not need somebody to watch the gauge following the hot shower. Remember, no water usage after the shower until maybe 15 or 30 minutes for the cold water in the water heater to be heated, and thus expand.
You could hurry to the gauge after turning off the water, and watch the gauge yourself. If the gauge is outdoors, throw some clothes on first.
The reason for the time lapse video is to not need somebody to watch the gauge following the hot shower. Remember, no water usage after the shower until maybe 15 or 30 minutes for the cold water in the water heater to be heated, and thus expand.
You could hurry to the gauge after turning off the water, and watch the gauge yourself. If the gauge is outdoors, throw some clothes on first.
Update: my expansion tank has zero pressure and drops of water came out when measured.
In preparing the expansion tank replacement, I bought a pressure gauge from Amazon and measured at the outside spigot and the water heater drain valve, both read 120 psi. Every place I read about the water pressure from the city main should normally be 40-80. Do I have a faulty gauge out of the box? I certainly should not charge / pump the expansion tank to 120psi, right?
When I opened a hot water tab in the nearby bathroom, however, the pressure dropped to 60. If the gauge is not to blame, how did the water pressure inside the house without water flowing get so high? Is my pressure reduce valve / regulator also shot? I need more guidance. Please help.
In preparing the expansion tank replacement, I bought a pressure gauge from Amazon and measured at the outside spigot and the water heater drain valve, both read 120 psi. Every place I read about the water pressure from the city main should normally be 40-80. Do I have a faulty gauge out of the box? I certainly should not charge / pump the expansion tank to 120psi, right?
When I opened a hot water tab in the nearby bathroom, however, the pressure dropped to 60. If the gauge is not to blame, how did the water pressure inside the house without water flowing get so high? Is my pressure reduce valve / regulator also shot? I need more guidance. Please help.
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Another update: I just went to my neighbor's house and measured their outside spigot's water pressure: 45psi. So the gauge is not at fault. Not knowing what my own is, should I use 45 to pump the replacement expansion tank?
Jeff H Young
In the Trades
im not reading back through all these postings but if water is coming out your expansion tank from the side with air in it thats a bad tank , or technically a bad rubber diphram thats inside and non replaceable You understand that right?
neighbor has 45 psi ok how much psi do you have when you open a faucet and let it run for a few minutes 45 psi ?
In any case have you removed and replaced the x tank yet
GReynolds929
Active Member
What is your pressure reducing valve set to? If you don't know, then at a hose bib open it for a brief sec, put the gauge on and open it again. That is the pressure you should set the expansion tank to.
The pressure in the house climbed to 130 when nothing was being used due to thermal expansion, and the expansion tank being waterlogged.
The pressure in the house climbed to 130 when nothing was being used due to thermal expansion, and the expansion tank being waterlogged.
Jeff H Young
In the Trades
45 psi coming to the house next door I know its a strech but Im going out on limb and wild guessing he dont need a regulator. but if water coming out the schrader valve time for an x tank
GReynolds929
Active Member
He says he has a PRV which is why I asked...
Fitter30
Well-Known Member
X tank is bad that's why the pressure is getting high.
All, thanks so much for your responses. Below is what I did and tested.
1) Replaced the xpan tank (actually twice, the first one leaking but the second one good)
2) Closed all faucets and no water usage - the water pressure gauge goes to 130, and the xpan tank air pressure out of the range of the air gauge (max 75psi)
3) Open one bath sink hot water and let it run for over a minute, the water pressure gauge comes down to 65, and the tank air pressure is almost the same.
4) The pressure reduce valve came with my ownership so I never changed so don't know what was set. See picture.
Am I still in trouble?
1) Replaced the xpan tank (actually twice, the first one leaking but the second one good)
2) Closed all faucets and no water usage - the water pressure gauge goes to 130, and the xpan tank air pressure out of the range of the air gauge (max 75psi)
3) Open one bath sink hot water and let it run for over a minute, the water pressure gauge comes down to 65, and the tank air pressure is almost the same.
4) The pressure reduce valve came with my ownership so I never changed so don't know what was set. See picture.
Am I still in trouble?
