Photograph of a water pressure tank air volume controlAir Volume Control (AVC) Adjustment Procedures
How to adjust the air volume control keep the proper air charge in the water pressure tank

  • AIR VOLUME CONTROL ADJUSTMENT - CONTENTS: 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.
  • POST a QUESTION or READ FAQs about how to adjust the air volume control (AVC)
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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.

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

Photograph of a water pressure tank air volume controlThe 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.

Here's 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.

Photograph of a water pressure tank air volume controlRemember 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.


Continue reading at AIR VOLUME CONTROL REPAIR or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


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AIR VOLUME CONTROL ADJUSTMENT at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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