New pressure switch not turning on pump

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imacdad

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I have a submersible pump on 220v with a large diaphragm tank on a 30/50 system. I put in the large tank to reduce pump usage. This past weekend I replaced the pressure switch because the old one was sticking open. The new switch works intermittantly. Works fine for a few days and then when the shower is running, will not kick the pump on when the pressure drops down. The new switch has the cut-off feature built in for low pressure. I noticed yesterday that when the shower is on that the pressure drops down slowly until it gets to about 30psi. Then it drops off like a rock. I believe this is what is causing my switch to not work right, but what causes the sudden drop in pressure? Shouldn't it be more gradual to the cut in pressure of 28psi?
 

Valveman

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You have too much air in the pressure tank. The point where the pressure drops like a rock tells you how much air is in the tank. If you only have 25 PSI air in the tank, then it will drop from 25 to 0 instantly. You just dont want the bladder to hit bottom and the presure drop like a rock until the pressure switch gets the pump running.
 

Valveman

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No two gauges ever read the same. You need to give yourself a little cushion, especially with a low pressure cut off switch. I would go with 20 to 25 PSI air in the tank.
 

lando

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not sure how to make a new thread i have been seen you comments on some but im not finding anyone who has my problem. i can shut off power to pump and drain faucet and pressure gauge goes to zero but when i check with tire gauge it acts like little to no air? when pumps on i have great water pressure in the house. the tank fills empty it isnt water logged and the top sound hollow and the bottom full? no water comes out when checking the pressure i cant figure out what my problem is. Thanks in advance.
 

Valveman

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Blue box in top right corner says "post new thread".

I have had some air gauges that were not made right and would not connect with the Schrader valve to see the air pressure. You can check it another way. Turn off power to the pump. Open a faucet and watch the gauge. The pressure will drop slowly as the water is released. At some point the gauge will drop to zero instantly. If the gauge slowly drops to say 25 then falls to zero, you have 25 PSI air in the tank.
 

Reach4

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not sure how to make a new thread i have been seen you comments on some but im not finding anyone who has my problem.
To make that "Post New Thread" blue box appear, click on the forum name or go to https://terrylove.com/forums/index.php?forums/pumps-and-tanks-well-forum-blog-water-is-life.4/

i can shut off power to pump and drain faucet and pressure gauge goes to zero but when i check with tire gauge it acts like little to no air?
A valve extender may compensate for a stubby Schrader valve. https://www.walmart.com/ip/Slime-20...-Hard-to-Reach-Valve-Stems-4-6-Pack/120929650 With the cheap plastic one, you have to hold the gauge.

I use a metal one with threads to attach a gauge setup I have used on my tank. I got it an an auto parts store.
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These things don't have a valve in them, but instead the pin in the extender presses the pin in the Schrader valve.
 
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