Air volume control adjustment procedure: this article explains how set or adjust those AVCs that can be adjusted, so that it keeps the proper air charge in a bladderless water pressure tank.

How do I adjust the air volume control to keep the proper amount of air in a bladderless water tank?

Too much air leads to air discharge at the faucets. Too little air leads to well pump short-cycling and damage. Some AVCs are adjustable and can be re-set if needed, as we explain here.

How is the US Gauge Type WJ Air Volume Control Adjusted?

The simple disc-type AVC shown at the top of this page is not adjustable. But some models can be adjusted, as we describe here.

Turning the US Gauge WJ AVC screw counter-clockwise:

Loosening the lock nut and turning the center adjusting screw counter-clockwise (backing the screw out, or to the left) will increase the amount of air vented from the tank or the rate at which it is vented until rising water level in the tank closes the valve.

The result will be less air in the water pressure tank - which you want basically and only if excess air is blowing out of the home faucets.

Turning the US Gauge WJ AVC screw clockwise:

If your well pump is short cycling (meaning

you want more air in the pressure tank) you want to turn the screw clockwise (to the right, or "in")

This will decrease the amount of air vented from the tank at each pump cycle, increasing the air volume in the pressure tank.

Above is one more photo of a (probably not working) air volume control attachment on a water tank, to help you recognize just what these devices may look like.

 

Does My Water Tank Use an Internal Bladder? Not if It's Using an AVC.

Remember if you see this device on your water tank, the tank is not a bladder-type or "captive air" or "Well-X-Trol" ™ type water tank.

It's an older steel water tank wherein the air charge is ultimately lost either by absorption into the water passing through the tank or by leaks.

Watch out: On a water tank that uses an internal bladder (keeping water and air separated), the air charge is not normally lost and the air volume does not normally need adjustment.

And you couldn't retrofit one of these devices anyway - no place to mount it, and no room for the float to move - just no way.

If an auto-venting AVC is working you will occasionally hear air hissing out of the fitting, as we discuss

at AIR VOLUME CONTROLS, HISSING.

 

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2020-11-24 by (mod) - do all systems have drain back inside well?

Paul

No not all well systems use a drain-back valve; we find that on deep wells that use a submersible pump (pump is in the well) and where the water pressure tank was one that did NOT include an internal bladder.

For example when we replaced a bladderless water pressure tank at a private tank and well system recently the plumber/well service company had to

- replace the old steel bladderless tank with a new tank that used an internal bladder

- pull the well piping at the well and on that piping, remove the drain back valve

Otherwise we'd have had excess air constantly being put into the piping and tank system.

At buildings where we must preserve a drain-back system, such as where the well piping can't be buried deep enough to avoid freezing, the installer will often use this older and well-established system that combines a drain-back valve, snifter valve, and a pressure tank that does NOT use an internal bladder, and an AVC on or at the tank.

In addition to the link I gave before you might also want to see

DRAIN BACK & SNIFTER VALVE SYSTEM COMPONENTS

On 2020-11-24 by Paul

So do all systems have drain back inside well, no matter what’s inside house??

On 2020-11-24 by Paul

Hi
The AVC is inside the house on the tank, the schrader valve is ahead of the checkvalve just before the tank. I noticed there was no lag when the pump turns on @40 psi, instantaneous water, but before there was a lag as it pushed air out first. Is it possible pump picked up debris, letting water in but not out?

On 2020-11-23 by (mod) - After changing air control valve and schrader, the water still doesn’t drain back

Paul:

you may know this but there are 2 parts to the drainback system:

a drainback valve that is in the well, on the piping, above the high water level in the well lets water out and air in to the well pipe

a snifter valve or Schrader valve near the pressure tank opens to let air into the piping when water is draining back out.

And some systems use an air volume control right on the pressure tank.

So if when the Schrader valve stem is fully removed and no air goes into that valve at the end of a pump-on cycle (when the pump has just shut off) then I suspect the drain-back valve in the well is stuck or debris clogged.

See details at SNIFTER & DRAIN BACK VALVES and let me know what you find or think or ask.

On 2020-11-23 by Paul

Hi
I have a deep well with the drain back system for cold weather. After changing air control valve and schrader, the water still doesn’t drain back. Taking valve out of schrader didn’t work, to drain it! If I lift pipe in well off of the blind fitting, the water rushes out of pipe from house.
Is there something in pump stopping the drain back?

On 2020-08-17 by Shaun

Just noticed water dripping out of hole in center of adjustment screw on valve. What causes that?

On 2020-05-28 - by (mod) -

Rapid clicking at the pressure controller often means a waterlogged pressure tank or some equivalent problem like inability to sense the water pressure correctly.

A pump that won't start may indeed need replacement or perhaps it's possible to repair.

Before going further an expert would check for shorted wiring and for a seized pump motor by noting current draw.

You know you can be shocked or killed, right?

On 2020-05-28 by Anonymous

Thank you so much for replying to my question. At this point I may have other problems. After the pump kept tripping the breaker I thought that maybe there something wrong with the control box or pressure switch. So I went to the store and bought new ones, which I reinstalled. When I fired up the pump the relay in the control box just rapidly clicks and the pump does not activate. It's a 1 hp Everbilt from Home Depot.

I bought it because it was relatively inexpensive, and most of the reviews were good. It also came with a 3 year warranty. I'm sure everything up top is wired correctly. But it seems as though the pump itself is no longer starting. Before I pull the pump (huge pain) is there anything I can do at this point. It's a three wire pump (3 wires and ground) sitting right at 100'.

Last question and then I'll wait for an answer: The only reason I went with 1 hp was because the old pump was a 1 hp. At 100' couldn't I go instead with 3/4 hp or even 1/2 hp? The only reason I ask is because Everbilt will have to ship me 1 hp pump. None of the Home Depots in my state carry a three wire 1 hp pump in stock. But they do carry a 3/4 hp pump. The 3/4 hp has the same GPM at my well's depth.

Sorry for all the questions, my wife and family are losing their mind at this point. I feel like I did everything right. The well ran perfectly for last few weeks. I basically replaced all the same components with like components and was careful in my installation.

On 2020-05-27 - by (mod) -

Ed if your pump CUT-IN pressure is 40 psi you set the air pre-charge to 2 psi below that, or 38 psi.

On 2020-05-27 by Ed

I have the following set-up:

1 hp 3 wire 1hp Everbilt submersible well pump (new)

42 Gallon Flotec Air over Water pressure tank (new)

American Granby Harvard Deep Well Air Release / Air Volume Control 1 1/4" MPT (new)

D square 40-60 pressure control switch new

New control box

I had a 20 year old pump go a few weeks ago. So I pulled the pump replaced it along with new 1-1/4" poly pipe. The pump has a built in check valve but I added 1 check valve above it at the water table line. There is also one check valve above ground. The pump is sitting right at around 100", the water table is 20-25" down. and the well shaft is at least 120' deep.

The system operated perfectly for the last two weeks. But today it tripped the breaker switch.

The ACV is factory set at 25lbs, Should this be adjusted up or down, I think my pressure tank is getting waterlogged. It's warm and humid right now, and judging from the condensation line on the tank (which is outside at the well inside a well cover) it looks to me like the water level is very high. Like at least 3/4ths of the tank.

I'm reaching here. Because everything was working perfectly, and now it's not. I drained the tank completely and restarted it. And the pump worked fine. It built pressure up to 60lbs fast and no problem. Then on the next few cycles it tripped the breaker again.

Bad switch control? Bad pressure control? Bad control valve? I do not think it's the pump, that seems to working like a champ. Any and all trouble shooting advice is welcome.

On 2017-03-21 - by (mod) -

Denice

You could set the air injector pressure up a bit, though the system will probably work fine as it is from the factory.

But do not put the air precharge pressure higher than 2 psi below the pressure switch cut-in. That'd be 28 psi in your case. So you can see that 25 psi is pretty close and should be ok. This stuff is not lab-grade precise equipment anyway.

On 2016-05-03 by DENICE

we just installed a new air injector and a 30/50 pressure switch. the instructions state that the air injector is factory set at 25 psi with a cut out of 40 psi. if we have a 30/50 and 50 psi is the cut out do we then need to increase the air injector setting from 25 psi to 35 psi. it is a bladderless steel tank

...

Continue reading at AIR VOLUME CONTROL REPAIR or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

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• AIR VOLUME CONTROL ADJUSTMENT
• AIR VOLUME CONTROLS, GET RID OF
• AIR VOLUME CONTROLS, HISSING
• AIR VOLUME CONTROL REPAIR repair procedures for Brady and other air volume control devices
• AIR VOLUME CONTROL TEST
• WATER TANK AIR VOLUME CONTROLS - home
• WATER TANK BLADDERS

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