which pressure to use

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  #1  
Old 09-21-17, 12:01 PM
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which pressure to use

I have a well 425' from 1977 with a 220 volt Gould 5SE10 submersible pump from 1988 and an A O Smith Aqua Air V100 pressure tank. I am trying to set the charge pressure in the tank and adjust the cut in and cut out pressure points. I set the pressure tank to 38# empty. The cut in is 43#. The cut out is 61# at the pressure gauge at the bottom of the air pressure tank inlet-outlet T. This pressure gauge was replaced about 8 years ago and is not water logged.

I spoke with a well person who installed the pump. He said not to trust this pressure gauge and to just measure the water pressures at the top of the air pressure tank with a tire gauge. This is the same place used to regulate the charge pressure of 38#. The pump cut in shows 38# and the cut out is 52#. So you can see the two sets of measurements do not coincide. Does this mean I should change the well pump pressure switch to show 40-60# at the top of the pressure tank and ignore the pressure gauge at the bottom of the pressure tank inlet-outlet T?

Please advise.
 
  #2  
Old 09-21-17, 12:26 PM
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You need an accurate gauge on the water system and an accurate air pressure gauge. With all the water pressure bled out of the system the air pressure in the tank should be 2-3 psi less than your pump's cut in (turn on) pressure.
 
  #3  
Old 09-21-17, 12:35 PM
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Thanks for your reply. It was my understanding the water pressure gauge at the inlet-outlet T was an accurate one. I purchased it based on a previous thread here regarding which gauge to buy. The tire pressure gauge I use is an accurate one.

I realize I was not clear with my original question. What I want to know is IF I have accurate gauges would the water pressure gauge at the inlet-outlet T and the air pressure gauge at the top of the pressure tank both read the same? Meaning that if I get 40# at the inlet-outlet T water pressure gauge as the cut in pressure should I also expect to see 40# at the air pressure gauge from the top of the pressure tank? And, similarly would both read 60# as the cut out pressure?
 
  #4  
Old 09-21-17, 06:21 PM
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Don't sweat it too much. If you get it wrong in one direction you'll have slightly less tidal volume in the tank and will never notice. Get it wrong in the other direction and you'll have a very brief pressure drop when running water and the pump cycles on. So, if you're showering and the water stops for a fraction of a second bleed a bit of air out of the tank.
 
 

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