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Air over water tank and well pump cycle plus pressure loss

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Hankhill11

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Discussion starter · #1 ·
Hi all. to start, I have a Pentair Pro Source AW42T 'air-over-water' pressure tank that was here when we bought the place and looks like it was installed in 2017. It also looks like it had a 5 year warranty and is discontinued. late last week we lost all pressure to the house, and the tank pressure dropped to zero or near zero. After resetting the well pump via the breaker, it filled back up slowly and pressurized but the condensation line showed the tank was nearly full of water. I understand it should probably have a lot more air in it. Under heavy use, it drops to unusable pressure again. Under normal use, I can see it cycling pretty rapidly, more than I'd expect.

So, I have had a really hard time finding out how to diagnose or fix this issue, since nearly every web search and every webpage only talk about bladder or diaphragm tanks and being able to add air or that the rubber is torn. As far as I can tell, this style of tank doesn't have that.

Is there a proper method for diagnosing if I need a new tank? I don't seem to have any water leaks and I am not able to detect air leaks. Is it reasonable to shut the pump down, drain the tank, and let it refill with ambient air, then power the pump back on, or should I just call the company that did the install (local plumbing outfit).

i also understand it is easy to say 'just get a diaphragm tank and be done with it' , but I'm looking for a way to fix this or confirm that replacement is the right path.

Just for context, here's the tank. For reference, there is no schrader valve on the tank. you can also see the manual above it.
Image
 
#2 ·
True newer bladder type tanks can produce more volume at pressure than the older can type, but you may have some life left in it. Definitely drain it completely with the power off, of course. Once it has started draining and the pressure drops, loosen the plug on top to let air into the tank and complete the drain. Replace the plug with good thread sealant and turn the pump back on. It should hold steady pressure once everything has equalized and should not rapid cycle.

If that condition does not remain, then it may be time for a new bladder tank after all. Yours seems to be in pretty good shape, however.
 
#3 · (Edited)
I have a non-bladder well pressure tank that's been in service for 50 years . It needs draining for air re-newel or add compressed air in the top about once / month to 6 weeks . I wouldn't trade it for a box car load of bladder tanks .
I don't have permission to add pics .

The plug in the top of yours looks as if some idiot buried ( plumbing term ) the plug so for time being draining to admit air is correct . That plug may be a beetch to remove . If the condensation won't form because of temperature / dew point conditions our hand is sensatuve enough to determine where water level is .
 
#5 ·
lenaitch said:
I'm not familiar with non-bladder tanks. Does it not have Schrader valve to add compressed air?
Click to expand...
No schrader valve, just pure air on top of water. Since water is partially air, it absorbs it and creeps up. Once it gets to a certain height the pump will rapid cycle until the air is replenished on top of the water. Bladders eliminate this by separating air from water.
 
#6 ·
The Schrader is the bike tire style valve on the top of your tank, used to add pressure. True, in a perfect world, the bladder will last forever and prevent the air from being absorbed into the water, but if your bladder fails then you are back to basics like an old school tank. Your tank is still perfectly good after the bladder fails, but you are banished to the netherworld of old-school tanks that were (and are) used by millions of people for decades. Pump up the air pressure in your tank to 2 or 3 pounds below your pump switch cut in setting. Wait a month of normal usage, then repeat monthly until you want to shell out for a new tank, or until you are totally muscular, whichever comes first. At my age, buying a new tank came way first. Remember you are never going to compress the water in your tank, you can only compress the air. Any tank is only as good as the air charge inside it.
 
#9 ·
Hold up just a minute here, lest you misunderstand me. I have been pumping up non-bladder tanks for literally 40 years, and every single one of them has had a Schrader valve. That's the only possible way they can function, because they have to be pumped up regularly..... by guys like me with a truck tank, a compressor, or a bike pump. Yep, I have literally pumped up hundreds of tanks over the years via a Schrader valve. I am unaware of an old school tank without one. Anywhere. Right on the top of the tank where you simply can't miss it..... You're pulling my leg, right?
 
#10 ·
No air valve on a PentAir. Sorry. Instructions say to remove water from tank, seal everything and turn the water back on. I used to do this on an old tank I had at a lake house once at the beginning of season. Again, no air valve. Not sure why you would need an air compressor since the water would be evacuated creating an air bubble when turned back on.
 
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#11 ·
wigginsr181 said:
I have a non-bladder well pressure tank that's been in service for 50 years . It needs draining for air re-newel or add compressed air in the top about once / month to 6 weeks . I wouldn't trade it for a box car load of bladder tanks .
Click to expand...
That seems like a task that I'd rather not do every 4-6 weeks. Why do you prefer the non-bladder tank?
 
#12 ·
Discussion starter · #13 ·
Thanks everyone. I'm going to try a dump and fil when I have some time. I may also replace the pressure switch, since I have no idea when it was replaced last, and certainly wasn't replaced when our well pump went out a couple years ago.
 
#14 · (Edited)
You must add air to a pressure tank when needed. You may be able to retrofit yours with a Schrader valve to make adding the air easy.

Non-bladder tanks are usually larger than bladder tanks because the dump and fill method does not create the optimum starting pressure for the air pocket or air cushion inside.

If a power failure ot other failure of the pump to start results in faucets spouting large quantities of air then a non-bladder tank will need immediate recharge to get the system working properly.

Some well systems with non bladder tanks have a mechanism to automatically add more air to the pressure tank as small bursts at frequent times. Small random bursts of air from faucets can occur, enough to startle you and knock a glass drinking cup out of your hand..

Depending on the location of the tear, a bladder tank with a torn bladder can behave unpredictably and at some times the performance can be worse than a non-bladder tank.
 
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#15 ·
I have no idea how air would be involved at a faucet from a tank that's water logged other than possibly air in the line from new installation then no more . I have 2 wells and one tank of each style . Yes , rapid cycle on both but never air from a water logged tank .
 
#17 ·
Amazed that the Pentair doesn't appear to have a valve to add pressure. Does it not then have an upstream mechanical injector to regulate pressure? Or do you just dispose of it if the bladder ruptures? How would they factory charge the tank given that people's pressure needs vary significantly. you have to order a tank with a specific pressure charge? Anyways thanks for the clarification/lesson. You guys are awesome. I have simply never seen an older pressure tank without a Schrader, but some (all?) bladder tanks like the Pentair are apparently "unserviceable" in that respect. Not sure if I like that, but it is what it is. Anyhow, I never had any real preference for older plain "wet" tanks, but for decades that is all there was, and pumping people's tanks up with a truck tank or even a bike pump was a very common occurrence. I recall people getting "sputter" on an empty tank if their well ran dry during a hot season. It was always a bad sign.
 
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