Pressure Tank Empties, Pauses, Fills...

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dsk

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I've read several threads on this forum with information relating to setting the the pressure switch in relationship to the air bladder's internal pressure. But none of them come from situations similar to mine, so I'll ask the question again, from my own recent experience.

I just installed my pressure tank and pressure switch. The switch I ordered is a 40-60, and the pressure tank was "supposed" to be set at 38 psi from the factory. In fact it had lost some pressure and only contains 35 psi. But that should be ok, right? Because at 40 psi the pressure switch will cut in and the tank should fill to 60 psi before the switch cuts off.

Well in reality that's not how it's working.

After wiring up the pressure switch and hitting the power the switch closed and the tank began filling. It finally cut off, but not at 60 psi. It cut off at 55 psi. Hmmm...

So I opened the drain on the tank, wide open, and let the water flow full blast. I watched the water pressure gauge and it dropped to 40 psi, and then kept going... the switch didn't close and the pump didn't come on.

At 35 psi on the gauge the water stopped, and the pressure gauge dropped to zero, the tank had fully emptied. But still the pump didn't come on.

I didn't have the pressure switch cap off so I couldn't see when the switch actually closed, but about 5 to 10 seconds after the tank would hit zero pressure the pump would finally kick on and pressure would rise to 55 psi, then the pump would be shut off.

I did this several times and it was very repeatable. Finally I did it by emptying the tank at a more leisurely rate (not full blast), and when the pressure got down to 40, the pressure switch would kick on and the tank refill (but only to 55 psi).

So this leaves me wondering about a few things...

First, why doesn't the pressure switch kick in at 40 psi when I drain the tank fast?

Second, why does it only fill to 55 psi and not to 60?

Third, does it matter that my tanks air pressure is 35 psi and not 38?

Fourth, why is there a 5 to 10 second pause before the rpessure switch/pump turns on after the tank has completely emptied?

And fifth, what steps should I walk through to preperly set up the pressure tank/switch to operate properly (at 40 to 60 psi)?

This forum has been a tremendous wealth of information and without it I couldn't have accomplished this entire well installation. I really appreciate all the generous feedback that so many people have given, and I hope this post will serve to answer the questions of other DIY'ers in the future.

Thanks,
DSK
 

Jadnashua

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The small pipe fitting going to the pressure switch could be mostly clogged, so it takes awhile for the pressure to register.

The tank could have been filled to 40# at the factory, but you probably aren't at the same altitude or temperature, which will affect it some.

By not having the desired pressure, you will be putting a bit more water into the tank and streching it further than it needs. My guess is it would decrease the life of it a bit, maybe not much.

If you find the pipe and fittings to the pressure switch are clear, the switch may be bad. It isn't a fancy time-delay cycle on switch or something is it? This might limit the time between cycles (I'm guessing someone makes one).

If the switch functions better after checking and clearing the pipes, then the switch can be adjusted. From what I read, the bigger screw adjusts both the upper/lower settings together, keeping the same amount of offset. Adjusting the smaller one adjusts the setting differences.

Some pumps just can't manage 60 pounds. What type of pump is it and how deep is the thing in the well...how deep to the water?
 

dsk

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Thanks for responding Jim.

In this case all materials are brand, spanking new. I installed a 10 gpm submersible pump in my 96' deep well last month. It's 4 feet off the bottom with 70 feet of water above it, in a six inch diameter well. Only 24 feet of lift above water level to reach the pressure tank. I used 1" poly pipe for the drop pipe below the pitless adapter. From the pitless adapter I used more 1" poly pipe, with a couple of elbows, to reach the tank tee package I purchase from this fella:
As you can see it uses a "Square D" pressure switch, so no voodoo there. I assembled the package and screwed it into the bottom of a 36 gallon pressure tank that I purchased from Lowes. So everything seems to be put together correctly, no bends in the pipe, and all the fittings were clean when I put them together.

At this point my only suspicions revolve around the two or three variables:
1 - the pressure tank probably needs 3 more pounds of pressure to get it up to 38 psi,
2 - the pressure switch might need to be adjusted upward to achieve a turn on at 40psi and turn off at 60 psi, and
3 - draining the tank at full blast might have an impact on how the system responds.

So until I can get back up to the farm and make these adjustments I'll keep my eyes peeled for other ideas that the kind readers of this board might have.

Thanks Jim.
DSK
 
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Speedbump

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Your gauge could be wrong. Usually Square D switches are pretty much on the money. The ten second delay thing has got me. Jim's idea of the tubing to the switch being clogged is very possible, but it sounds like this is a new system.

We need you to take the cover off the switch and tell us if the points close when they are supposed to at 35 psi. (This is where it should close the points if the shut off is 55 and you haven't messed with the little spring yet).

bob...
 

Jadnashua

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If you got overzealous with pipe dope or Teflon tape, you could have an obstruction in the tube to the pressure switch and or gage. You might want to check anyways.
 

dsk

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The pipe dope angle might be a possibility. I was using the teflon from a squeeze tube and that stuff can get away from you, quick. I'll also take the cover off and watch what's happening in the pressure switch, as Bob suggests. To this point I haven't made any adjustments to the system. First thing I plan on doing is bringing the air bladder's pressure up to 38 psi. Then I'll test it all again and see if there are any changes.

Thanks for the ideas and I'll report back on my findings.

DSK
 
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