Losing pressure in tank - no apparent reason


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Old 07-14-11, 11:28 AM
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Losing pressure in tank - no apparent reason

This is part of a home system, with submersible pump, older galv 42 gal tank 75 psi.

The tank is losing pressure, causing the pump to kick in. But I can't find where the pressure is going. I close the valves to the faucet line and to the sprinkler system, and the pressure still goes down to kick in level in an hour or less. I turned off the pump via the switch, and the pressure was zero the next morning.

The copper tube to the presssure gauge comes directly out of the tank. There is also an air volume controller/air release that is faulty but has not been spitting. I can't find any air noise or water dripping out anywhere.

I recently replaced the connection to the sprinkler system. After replacing, I just turned the pump back on and it filled the tank. I didn't do anything about re-pressurizing or messing with the cut-on/off setting. Everything seemed to be working at first.

Is it the check valve back at the submersible pump? Not sure what to do.

Thanks for any help. Gary
 
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Old 07-14-11, 12:45 PM
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When you pressurize the tank, how are you doing it? Are you doing it like I said in the sticky at the top of this forum? Because it is different than the way you pressurize tanks that have a bladder in them. Most of what you read on the 'net describes how to do things for a tank that has a bladder, but if you have a galvanized tank (and they are still for sale at Sears) then you have one that doesn't have a bladder. You are supposed to drain all the water out before you turn the pump on.

If you are losing pressure, then the switch ought to be kicking in and turning on the pump. Is it? I read again that it is.

First thing I would check is the new fittings you put on. Make sure you can't see any water leaking, and make sure that your paper towel has no water on it after you wipe it.

Then I would check the toilets for a slow leak. Sometimes they leak so slowly that you can't see it.
 
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Old 07-14-11, 05:07 PM
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My initial instinct is to check the tank more carefully. There are quite a few welds on those tanks and it does not take much to empty for the air to escape. Fastest way to check this is to empty the tank then splash some dish soapy water over tank as you re-pressurize, just like you do when you check gas fittings or a deflating tire.

if you do not see any bubbles forming go on to next step isolate the tank. and watch pressure reading on gauge. Lock off house, irrigation and everything els you have. If pressure is dropping down then you should just add another check valve at surface. be certain it is in freeze proof location.
 
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Old 07-25-11, 08:08 PM
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I have followed this advice. I don't find any bubbles with the soapy water. But there is a little inconsistent discharge from the air volume controller/air release (just drops a day, usually) and a little dripping from the sprinkler system piping (again just drops a day). The tank certainly is not draining, but it does go down in pressure slowly even when I isolate the tank.

When the pressure goes down and kicks in the well pump and water begins to puch into the tank, what is happening? The pressure may show 55 lbs. but when water comes in, the tank is only maybe down a tiny bit. What is happening to the water that is being pushed in? Does the pump somehow just let the water push back down to the well? If so, doesn't this damage the pump?

Should I keep the pump shut off until this is fixed, or is it ok to let it just click on every hour or so and pump when the pressure reaches the low limit?

I can't seem to find a replacement air volume controller/air release around here. If I find one and replace it, might this solve the problem?

If I fix the small dribble (just a few drops a day) coming out of the sprinkler system piping on the outside of the tank might this solve the problem?

The piping from the well comes up into the basement through a 1 1/4" PVC pipe inside a 4" plastic housing. If I need a check valve, what would I use in this application? There is only a little room between the housing and tank.

All help greatly appreciated. Gary
 
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Old 07-26-11, 05:04 AM
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As the water comes into the tank, the water compresses the air in the tank. When fully pressurized, the tank will be about one half full of water. This depends on what the pressure switch is set for. The higher the pressure, the less water will be in the tank. That is why it is important that ALL the water is removed from the tank before it is sealed up and the pump is turned on.

If the valve coming out of the tank is completely closed, the tank is isolated and you are still losing water, that means that compressed air is leaking from the top or water is leaking out the bottom to the pump.

Since it is easier to fix leaking air, you might want to remove and retape with teflon tape, the sniffer (I think you are using the correct term for sniffer - the air volume controller, but I am old fashioned) and the switch hose connector and anything else you see that screws into the tank. The soap would only look for air leaks. Water leaks, you would have to eyeball.

You are sure there are no rusty pinholes? These tanks do rust through. Put some soap on places you suspect and hang around and watch to see if the leaking air blows bubbles. Is the tank sweating? Are you confusing the sweat with a small leak?

Consider all possibilities for either air or water to leak. Look at the pipe coming into the tank. Look at the pipe leaving the tank. Anything after the last check valve and before the first valve is suspect since that is all pressurized, too.

I would hate to see you go through the trouble of changing the check valve. only to find that it does no good. That's a lot of work on old pipe that than can be a bit*** to unthread and can crack at any moment.

There should be several check valves. One is in or right above the pump -- don't worry about that one. Then, (I would have to look it up) every 75 feet or something, inside the well. Don't worry about those either. Then, some people omit the last one, but there should be one not far from the tank. If not right there at the bottom, within 10 feet or so right before or after the pipe enters the house. Could be underground.

The last one (if you have one) is what you want to concern yourself with. If you don't have one, put one in. If you have one, then it needs to be changed -- or, in a rude way of saying unworkmanlike product -- you could rig it and just add another check valve either before or after the existing one. Closer to the tank, I think would be better.

It would not be easy to add a new valve, so don't get too enthused about that option -- MUCH easier to change a valve if you have one. You would have to get to know your local plumbing or pipe supplier and have them put the threads on (a place I know of charges $1 a thread) the pipe unless you rent a hand pipe threader, which I have done, too, before I invested in a set of hand pipe threaders.

When you buy a check valve DON'T get cheap. This is not the place to cheapen out. Get a brass one that costs some money. I've had those big box store check valves be bad right out of the box.

It MIGHT be time to call in a pro. If you do, hover at his elbow and ask as many questions as you can. Call it "tuition" if you like.
 

Last edited by Vey; 07-26-11 at 05:24 AM.
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Old 07-30-11, 06:57 AM
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If the pressure tank becomes completely full of water or if you isolate the pressure tank then the pump operation will become erratic and the pressure as measured in the rest of the system will also be erratic.

Are you sure the loss of pressure is due to loss of air from the pressure tank versus loss of water from a leak anywhere in the system?
 
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Old 07-31-11, 07:48 AM
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Still Trying

This is terrific advice. Thanks so much.

This well and tank used to supply water to the inside plumbing before we connected the inside supply line to city water.

Now this tank only connects to the outside faucet line and the lawn sprinkler line. When I close both of those valves, the tank still loses pressure, according to the gauge.

I know the air volume controller/air release has had occasional dripping. I would have changed this long ago but can't seem to find one around here. I also see a tiny amount of dripping where the Sch 40 plastic piping goes out to the sprinkler system (before the shutoff valve). Other than these, the only connections to the tank are the galv well pipe in, galv bib pipe out, and small copper line to the gauge.

I will change the air volume controller/air release and the piping out to the sprinkler system and see what happens.

By the way, last week it was very humid and I noticed the sweat line on the tank was about like 80% of the height one afternoon, then had gone down about 2 inches by the evening; don't know if that means anything.

Thanks again!!

Gary
 
 

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