Well pump comes on after only 2 gallons used???

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I measured several times and each time my water pump comes after LESS than 2gallons are used in the house.
I have:
1hp jet pump Bladder water tank Amtrol Model CM8003 (32gal, 15dia, 46high, closest similar model specs on their website) Well water is hard water.
The sweat line on outside of water tank is 1/3 of the way up the tank, and the upper 2/3 of the tank sounds hollow, so I know theres water/ air in it. Tank specs say air pressure in tank should be 30. I measured 32 with tire gage, so kinda close. Pressure switch turns on at 28psi, instantly jumps to 40 where it stays for about 10sec, quickly rises (in less than 5sec) to 58 , then shuts off and instantly drops to 50.
Im guessing maybe the stub to the water tank might be mostly clogged and that the tank is not acting like the reservoir it should be??? Opinions appreciated.
Thanks! Theodore
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millinghill wrote:

Check the small diameter line to the pressure switch...perhaps it's where the problem is.
Otherwise, sounds like classic case of the waterlogged pressure tank.
32 gal isn't real big, a small change in pressure is a good volume.
I'd drain the tank and reset the pressure and see if the symptoms improve....I'm betting they will.
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Usable size of a 32 is probably around 18 or so. If the differential between the cutoff and cuton is not very much a couple gallons might be all it takes. Why is it a problem? You use the water, the pump comes on. You want a bigger reserve before the pump comes on get a bigger tank.
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I suspect a problem because it sounds very peculiar that withdrawing only 2gallons will cause a pump cycle. If the usable capacity is around 18gallons, it sounds weird that I only actively use 10% of that. That's why I'm concerned.
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Note that the pressures measured on your gauge are psig; the relevant information is the absolute pressures in psia, which are 1 atm = about 15 psi higher.
So... cut-in of 30psig, cut-out of 50psig = 45psia and 65psia respectively.
Increasing the pressure in an empty tank from 45psia to 65psia means reducing the volume of air by (65 - 45) / 65 = 31%. 31% of a 32-gallon tank is about ten gallons.
So you're not getting anywhere near the drawdown you should.
My conclusion is that your tank is waterlogged.
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I'll check the line to the pressure switch (located on the pump). I don't follow what draining the tank will do. Can you explain?
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millinghill wrote:

That's when you need to check pressure and reset it.
If there's a pinhole leak in the bladder, that'll rezero it and the behavior will be better (for a while) until lose more air volume if it does have a leak...
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On 9/23/2010 1:26 PM, millinghill wrote:

You must release all pressure from the tank before setting the air pressure!
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Nonsense. You need to get all the water out, that's all.
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On 9/23/2010 6:54 PM, Doug Miller wrote:

Yes, I agree. I just worded it wrong.
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It'll get rid of the water that's reduced its effective capacity. When the tank is at (actually, slightly below) the cut-in pressure, there should be *no* water in it. That's not the case with your tank.
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When my pump comes on too quickly or runs a long time before shutting off after I turn water off at the sink, I usually pump some air in the bladder. Those things lose air pressure sometimes. When I put air in, I usually check to see if I'm getting a lot of water blowing out the pressure valve. If that happens, I drain all the air/water out of the bladder before bringing the air pressure up to snuff.
David
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I may be mistaken, but I'd expect that draining the tank would be: 1) turn off electricity to the pump 2) open a faucet 3) Inflate till air comes out the faucet 4) Close valve 5) Inflate to just below cut-in pressure 6) disconnect air compressor, screw the cap on the valve stem. 7) turn on the electricty to the pump
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On Sep 24, 6:14am, "Stormin Mormon"

If you are getting any water at all blowing out the pressure valve, the bladder is busted. Harry K
Harry K
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On Thu, 23 Sep 2010 09:39:32 -0700, millinghill wrote:

Water doesn't compress, air does. If the bladder was doing it's job the pressure wouldn't jump from 28 to 40 then to 58 and back down to 50 erratically and instantly. My house has had a submersible pump well for 42 years with hard water and every problem with erratic pressure has been related to insufficient air in the tank. My first tank didn't even have a bladder. Second and current tank does. It was installed in 1984. I've replaced the pump and associated PVC plumbing once.
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I measured the tank air pressure with the pump electrical cord unplugged and the enough water withdrawn to just trigger the low pressure switch to come on. I will also try to let all the water out of the tank and see what the air pressure reads. Honestly, the tank doesn't SOUND water logged. Knocking on the tank anywhere above the sweat line makes it ping like a bell. Wouldn't it thud if waterlogged?
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On 9/23/2010 11:17 PM, millinghill wrote:

Possibly, first pressurize it properly and see if that cures the problem.
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I haved never seen a case where the pressure jumped around like that. Please posst back when you find the problem.
Probably repeating (but adding a bit) to what has been said.
Drain the tank then measure the precharge. I should be 2psi below cut in OR the same as cut-in depending what outfit makes the recommendation - 2psi below seems to be the standard though. I think you said cut-in is 28 and precharge 30. That is too high.
While the tank is empty it won't hurt to pull the small riser pipe to the pressure switch. I had to ream mine out due to erratic operation.
Harry K
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On Thu, 23 Sep 2010 20:17:48 -0700 (PDT), millinghill

Here's the procedure for checking/fixing a "waterlogged" pressure tank problem:
Shut power to the pump
Drain water from the tank by opening the water drain at the bottom of the tank OR the lowest water outlet in the plumbing system. After the water finishes draining, close the valve.
Use a tire pressure gague to check the pressure of the air bladder in the tank. It should be about 2 psi ABOVE the low pressure pump turn on pressure. If it is significantly lower, then you have a "waterlogged" tank which will cause rapid pump cycling. If the air presure is too low, use a compressor to add pressure to about 2 psi about the low pressure pump turn on pressure.
Turn on pump.
If you have to add pressure more than once or twice a year, you need a new pressure tank.
--
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On Thu, 23 Sep 2010 20:17:48 -0700 (PDT), millinghill

CORRECTION: the above should read "2 psi BELOW", not "ABOVE"
sorry of the brain-jam.
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