Water pump on/off every 3 seconds

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On Wed, 10 Nov 2004 11:19:34 -0500, willshak wrote:

I'm no plumber either, but have researched quite a bit on wells and their maintenance so I could do whatever necessary plumbing-wise to get water from the well to the house - the driller just drilled, installed the pump and checked it. I built the wellhouse, installed the pressure switch, tank, filter (to make sure no sand gets to the house) and the line from the wellhouse to inside the house where the plumber took over (new construction). As you may can tell, I like to take a hands-on approach <G>.
Having the proper precharge pressure (and a large enough tank for your standard usage) just keeps pump starts to a minimum, prolonging life. All recommendations I've seen say that the precharge pressure should be 2-3 psi below the pump cut-on pressure. Since pressure switches come with a preset of 30/50 (there's a 20/40 and a high/low adjustable also IIRC), 30 psi precharge would be close to right. Your plumber, when installing the system, may have lowered the pressure in the tank a couple of psi or he could have adjusted the pressure switch to a little higher than 30 cut-on pressure - just a matter of turning a nut clockwise on the switch I have. Then again, he may have done nothing but install the equipment - it appears to have served you well no matter what the situation.

Unless you're having one of the problems below, I'd just replace the gauge and let it be.
Frequent pump cycling - Turn off water where pipe enters house, then check pressure to see if it stays steady for at least 30 minutes. Turning off water within the house eliminates pressure drops from leaky toilet valves and dripping faucets.
Yes pressure drops - Could be a leak in the pipes somewhere or water is flowing back into well when pump is off. Turn off shutoff near pump and check pressure again after a minimum of 30 minutes. If it holds steady, there's probably a leak between the wellhouse and the house (think you'd probably know if it's inside the house). If the pressure drops, the valve that your system uses to keep water from flowing back into the well is not working properly - mine is a deep well submersible pump with foot valve.
No pressure stays steady - probably hole in tank bladder - replace tank
Low pressure - check filter, screens in faucets, holes in faucet aerators and shower heads. If you have galvanized pipe and the system is old (probably is if you have galvanized), the pipes may be filled with rust and need replacing.
Replacing the pressure gauge should be a simple fix if you can operate a crescent wrench and a pair of pliers. They're available at Home Depot and Lowes pretty cheap. Just cut off the water and let off the pressure. Then use the wrench to unscrew the original gauge while holding the pipe it's screwed onto stationary with the pliers and screw on the new. Turn the water back on and you're in business. Might want to put some plumbers putty or teflon tape on the threads of the pipe the gauge screws onto.
If the pipe the gauge screws onto needs replacing also (might be full of rust), they're available at HD and Lowes too.
Later, Mike (substitute strickland in the obvious location to reply directly) ----------------------------------- snipped-for-privacy@att.net
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As a FYI, another "odd" pump cycling cause: the tubing from the line to the pressure switch gets plugged with crud.
You'll think the pressure switch or pump was defective, because sometimes the pump fires up, and sometimes it doesn't.
--
Chris Lewis, Una confibula non set est
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On Wed, 10 Nov 2004 15:54:44 GMT, "Michael Strickland"

Yes, the pump cuts on at 42 PSI, according to the gauge in the water line. If I put my tire gauge on the air at the top of the tank, it shows 46PSI. Should I lower that to 40?
So what I need to know is if the precharge pressure should be measured with the tank empty or with water in it (assuming that the bladder has burst). If I pump it up to 40PSI w/o water, the air pressure is going to be very high after water is pumped in.
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I wouldn't worry about it. The difference is probably due to inaccuracies in the gauges.

Empty. That's what is meant by precharge pressure.

No, it won't. The control switch will shut off the pump when the pressure reaches the set point of 58 psi.
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On Wed, 10 Nov 2004 13:15:41 -0500, Jud McCranie

Without water.. The cut-on doesn't care if its 46PSI of air or 46PSI of water... That's the whole point of having the air in there, it can compress to come up with the upper limit.. so you don't short cycle like you were before.
As for the shower pressure, do you have the water valve to the house fully open? Sounds like a blockage between tank and house. You'll have plenty of pressure as long as you use practically no volume.. with a valve partially open..
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Yes, it is fully open.

Pressure and flow are low. But the gauge at the tank shows 42-57 PSI.
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Latest: today we drained the tank again and this time I pumped the pressure up higher with a tire pump that plugs into a cigarette lighter, and refilled the tank. Also, right now I'm bypassing a filter, which was clogged up. (I really should have checked that earlier, but I replaced it not too long ago.) The air pressure in the tank is 62 PSI.
At the moment the water pressure and flow is fine - just like it should be. I'm going to see how it holds over the next few days.
The pump is running for about 15 seconds each time. Should it be longer?
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Damn. I didn't consider a filter in the system. That is a common cause of low flow even when the tank is operating correctly.
15 sec is way too short of a cycle time and is very hard on the pump. You say air pressure in the tank is 62 psi. Is that with the tank empty or full? If it is empty it is way too much and the pump shouldn't even be shutting off unless an overload switch is being activated.
Now that you have a air pump, start over. Drain the tank, add air to 2 psi below cut-off and restart your system. You will then have it set correctly.
Harry K
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Too high.
Look, this isn't rocket science. Your pump control is set to come on at 42 psi, and shut off at 58. So shut off the power to the pump and drain the tank, completely. Pressurize the tank to 40 psi. Turn the pump back on.
That's all.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
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On Sun, 14 Nov 2004 18:00:13 GMT, snipped-for-privacy@milmac.com (Doug Miller) wrote:

It is working OK with that pressure. If I drain the tank and pressurize the tank to 40 PSI and then turn the pump on, the pressure will be even higher. The first time I drained the tank, I didn't pump any air in. The second time I pumped it up to 11 PSI, turned on the pump, and it compressed the air until it was at 46 PSI. The third time I drained it and pumped it up to 20 PSI, then turned on the pump and the air pressure went up to 62 PSI.
After using it for more than a day, the air pressure is still at 62 PSI when the pump cuts off. And to check to see if the gauge is wrong, I used a different one and it reads 63.5 PSI.
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(Doug Miller)

No, the pressure will NOT go higher. The control switch is set to cut off at about 62 psi. It will do that whether you have 1 psi or 40 psi for the precharge. 62 is where it will cut off. It will also start at about 40 psi no matter what your precharge is. The precharge is not what operates the system. The system operates only on the 20 psi differential that the pump adds on top of the pre-charge. The pre-charge is there to for two reasons. 1. Air bubble to compress to make the system work. 2. To control the cycle time of the pump. Anything less than the optimum (2 psi approx below cut-in) makes the pump run more often for less time. That is hard on pumps.
Trust us. I don't know about Doug but I have been running these systems since I was 16 and am now 70 still running them. Shut the pump off, drain the tank and pump the proper amount of air in.
Harry K
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On 15 Nov 2004 06:47:15 -0800, snipped-for-privacy@hotmail.com (Harry K) wrote:

Well, it did the other three times.
The first time I drained it, I let the air pressure off and didn't pump any air in. After I cut the pump back on, the air pressure in the top of the tank was around 20 PSI, but I don't remember the exact figure.
The second time I drained the tank, I pumped the air up to 11 PSI. Then I turned the pump on, and the air pressure went up to 46 PSI. After the pump went through , it maintained 46 PSI (when the pump cut off).
The third time I drained the tank, I pumped the air pressure up to 20 PSI. After turning the pump back on, the air pressure went up to 62 PSI. Three days later, when the pump cuts off, the air pressure is still around 62 PSI.
So, to summarize: air pumped in / final air pressure:
before final
0 PSI 20 PSI (approx) 11 PSI 42 PSI 20 PSI 62 PSI (63.5 according to my other gauge)
If I drain the tank, pump up the air to more than 20 PSI, and then turn the pump on, the final air pressure is going to be higher than 62 PSI. I'm willing to take bets on that.
It has twice been said that this isn't rocket science, but there is physics involved - Boyle's law. As a gas is compressed onto a smaller volume, its pressure goes up.
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Yeah, but the pump is supposed to be cutting off at a specific pressure, so boyles law or not, the upper limit should be constant. If it's not, then there's something wrong with your setup. Specifically, if you pre-pressurise the tank to or beyond what the upper cutoff is, the pump should never come on at all.
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Exactly.
He's showing erratic operation. No matter what he precharges the tank to, the peak pressure _should_ be the pressure switch cut-out pressure.
Which suggests to me that something is wrong with the pressure switch setup, and the pressure switch isn't seeing the true line pressure.
If the unit has a small hose supplying the pressure switch, take it off, and ream it (and the fittings) out with a pipe cleaner.
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Chris Lewis, Una confibula non set est
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On 15 Nov 2004 22:47:13 GMT, snipped-for-privacy@nortelnetworks.com (Chris Lewis) wrote:

There is a 3/4" pipe coming off the main pipe that goes to the pressure switch, and there is a circular pressure gauge coming off that pipe. The pump cuts on and off consistently according to that gauge. I'll have to drain the tank again to clean it out.
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When you do, precharge the tank to 2 psi below the cut-ON setting on the control. Trust me. That's how it's supposed to work.
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On Mon, 15 Nov 2004 17:07:45 -0500, " snipped-for-privacy@uri.edu"

The pump does cut off consistently at 57-58 PSI of the WATER. The AIR pressure at the top of the tank at that point depends on how much air I put in when the tank was drained. The more initial air, the higher the air pressure.

The bladder may be broken, but it is holding the air pressure.

Correct me if I'm wrong, but isn't there a diaphragm or bladder made out of rubber or something like that in the tank, with air above it and water below it? When the tank is drained, there is no water in the tank and pressurizing the air in the tank via the valve at the top pressurizes the air above the diaphragm, but not below, right? (It doesn't pressurize the whole tank, just the bladder, right?) Then the pressurized air doesn't affect the water going in until it hits the diaphragm, right?
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wrote:

O.K. I think I see why you are misunderstanding the system. The pressure in the tank is initially set by the pre-charge. The switch will be set for a specific cut-in/cut-off. The pump starts and will add about 20 psi to whatever pre-charge you put in and then cut off when system pressure reaches the cut-off (62psi). Here is a basic step-by-step.
Tank empty 20 psi pump starts and pumps 40 psi until it reaches 60 cuts off.
You now have a tank containing water and an air bubble that is now compressed to 60 psi.
you draw water. Tank empties down as the air bubble expands System pressure reaches 40 psi. Pump cuts off. At this point the air bubble has decreased only 20 psi System repeats until something fails.
Your basic misunderstanding in your post is that the water is compressed. No it is not, water cannot be compressed. The air bubble, whether separated from the water by a bladder or not is what makes the system run and is the only thing having pressure. Yes, it does compress the bladder and thus presses on whatever is in the tank, i.e, the entire tank both above and below the bladder senses the same pressure. When the tank is empty the bladder will probably be resting on the tank bottom with no water at all in the tank.
When you clean out the pipe to the pressure switch (should be a 1/8" or 1/4" pipe) then re-pressurize the tank to about 40 psi (I think you said it cuts off at 42psi). Watch the gauge. You will see it happily cranking along between 40 and 60 psi (okay, a bit higher at your settingss). Ignore testing teh pressure via the air fill valve on the top of the tank other than when adding the pre-charge. It will always be the same as the tank guage within the error range of the instruments you are using.
Erratic operation could also be caused by a sticking pressure switch.
Harry K
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On 16 Nov 2004 07:03:36 -0800, snipped-for-privacy@hotmail.com (Harry K) wrote:

I know that water can't be compressed, I said that as water filled the tank, it compressed the air at the top.

It is a 3/4" outside diameter pipe going to it, but it has a connector like this: http://www.homedepot.com/prel80/HDUS/EN_US/diy_main/pg_diy.jsp?CNTTYPE=PROD_META&CNTKEY=misc%2fsearchResults.jsp&BV_SessionID=@@@@0881397307.1100653999@@@@&BV_EngineIDdhaddddimlgjhcgelceffdfgidgjm.0&MID76
Thank you for all of your help and for being patient. It is working acceptably well right now, so I'm going to try to wait until the new year to replace the tank.
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Which is a violation of physics. In a closed vessel with liquid and/or gas components, ALL of it will be at _exactly_ the same pressure at any given moment. The presence of the diaphram can essentially be ignored (if the diaphragm is in contact with both components).
[There's a couple of teensy imperfections in this "ideal situation", but we're talking less than .25PSI in this case.]
If you're reading a different pressure for the air and the water, either your measurements are defective, or the points at which you measure the air and water do not have a free flow of _pressure_ between them. Ie: there's a plug.

Right.
Right.
Right.
Right. Once the wqater hits the diaphragm, however, the water and air pressure will be the same (within half a PSI).
So, if you're reading 68PSI on the air, and 50-ish PSI on the water when the pump kicks out, something _very_ wierd is going on. I"ll bet on the laws of physics being respected ;-)
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