Pressure gauge waggle dance nonsense!

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benjamin_wooten

benjamin_wooten

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Hi everybody.

We had a Red Lion 6 gal. horizontal pressure tank and a Red Lion 2.5 hp jet pump... now we have a Goulds 20 gal. V60 horizontal pressure tank and Goulds jet pump.

The good: Pressure builds to 40psi and holds. Great! Tap goes on, water runs nicely. Excellent!

The bad: As pressure gets to just above 30psi, the pressure gauge needle does a freaky little freakout-waggle dance for a second, then plunges suddenly to just above 20psi thereby tripping the cut-in. It goes back up to 40psi. Wash rinse and repeat. Differential on this new tank seems to be only 10psi, as opposed to the 20psi it ought to be?

Our overall sense is that this larger pump seems to run as or more frequently than the old, smaller, Red Lion system ever did.

Before I drain the lines and check pressure etc. on the new tank, I just wanted to check and see if that crazy waggle-dance was normal somehow, or if people had encountered it before?

Thanks!
 
The pressure tank has nothing to do with the differential. That's the pressure switches job. Factory settings are always 20 psi apart. As in 20/40, 30/50 or 40/60 etc. You have too much air pressure in your tank. You said it goes to 40 psi and holds. So your pump turns on at 20 psi. Turn off the pump electrically; run a faucet until all water pressure is gone. Let tank air pressure down to 18 psi and the pressure will drain down to 20 psi slowly as you use water and the pump will kick in like it's supposed to.
 
Thanks a bunch! Understood. Everything worked out great.

As it turns out, this is supposed to be a 30-50, so I dropped the tank down to 27-28 and adjusted the pressure switch accordingly. It now cuts in at 30 and cuts out just a hair over 50.

Thanks for the guidance!
 
No matter what, the air pressure in the tank should be a couple of pounds less than the cut in of the pump.
 
Ok, my understanding is what speedbump said... the resting pressure of the dry tank should be 2-3psi lower than whatever the cut-in setting of the pump is.

The inside cover of this pump says to set cut-in at 30psi, cut-out at 50psi, so I set the resting pressure of the tank at just between 27-28psi.
 
benjamin_wooten said:
Ok, my understanding is what speedbump said... the resting pressure of the dry tank should be 2-3psi lower than whatever the cut-in setting of the pump is.
Click to expand...

Exactly... I have seen the statement about the tank pressure "always" being 2-3 PSI lower than the pressure switch cut-in, and (as a layman) was confused when I would measure anywhere from 28 to about 50 psi (depending on how full the tank was), until I realized this exact thing. The qualifying statement is that when the system is completely drained, the tank pressure should be 2-3 PSI below the switch cut-in.

That's why speedbump said to drain the system first in post #2 above.

Attached is the tag from my pressure tank. The manual states: "Setting the Tank Pressure
The tank pressure must be set 2 PSI lower than the pump cut-on pressure. Check tank pressure with a standard air gauge valve at the top of the tank as needed."

Again, neither the tag nor the manual mentions that the system must be drained, or the tank not connected at this point.

Don't want to beat a dead horse, just elaborating in case any other idiots like me are having trouble with it. :)

20160221_093201.jpg
 
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benjamin_wooten said:
Ok, my understanding is what speedbump said... the resting pressure of the dry tank should be 2-3psi lower than whatever the cut-in setting of the pump is.

The inside cover of this pump says to set cut-in at 30psi, cut-out at 50psi, so I set the resting pressure of the tank at just between 27-28psi.
Click to expand...

Yes.....that is a perfect set up.....for a submersible pump.

Jet pumps have to work harder to achieve pressure, as they suck water, and a submersible pushes. It's much easier to push water, than pull it up.

Years of working with pumps has taught me your jet pump will have an easier, longer life if you drop the pressure from 28 to 18psi. There will be no noticible pressure loss in your house.
 
Ahh, I understand what you are saying now, Matt. I can drain the system and make those adjustments, then switch the pump cut-in/cut-out to the appropriate 20/40 to match.

I do notice the pump sounds a lot louder filling up to the 50psi mark than it ever did just getting up to 40psi.

Thanks all for the thoughts and comments.
 
Years of working with pumps has taught me your jet pump will have an easier, longer life if you drop the pressure from 28 to 18psi. There will be no noticible pressure loss in your house.
Click to expand...

Matt. No disrespect, but the pump doesn't care how much air is in the tank, it will still build pressure the same as before. When you drop the pressure in a bladder, you allow the water in the tank to push the bladder up higher; in which case can with some tanks tear it loose prematurely. The WX-203 Well X Trol comes to mind. That tank set up 30/50 with a 28 lb precharge would top out at sixty some pounds. In other words the bag was totally full. Put more pressure in the tank and you are now stretching the bladder. They actually put a dome in that tank to keep it from being over extended. Most tanks will take a 30 lb differential, but not all.
 
But nobody disagrees here that my Goulds JRS5 1/2hp pump now set at 20/40, hooked up to my Goulds V60H tank with a dry tank pressure of 18psi, is an appropriate setup, yes?

::edit:: ...in spite of the fact that the inside cover of the pump's electrical box calls for a cut-in/cut-out setting of 30/50.
 
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It's just a matter of preference. If your happy with 20/40 that's fine. If you want a little better pressure, 30/50 is an improvement. The big trick with jet pumps is their max pressure. It's dependent on several things most of all the water level. As it goes down, the max pressure goes down too. So don't set the off pressure at just a few pounds below the pumps max pressure. If you do and the water table drops in the dry season, the pump might not be able to make its shut off pressure which will nuke the pump and it's plastic fittings.
 
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