Photograph of a water pressure tank air volume controlAir Volume Control (AVC) Repair Procedures
How to repair the water tank air volume control

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How to fix the water tank air volume control device: this article describes the repair of several problems at air volume controls including water leaks at the AVC, too much air in the water tank, not enough air in the water tank, or an air volume control that is simply not working as it should.

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How to Repair a Leaky US Gauge Type WJ or Type 300L Drainback System or Snifter Valve System Pressure Tank Air Volume Control

Photograph of a water pressure tank air volume control
  • Leaks at the valve mount: this is a standard plumbing problem. If your pressure tank or the valve mount tapping threads are not badly corroded, remove the valve, clean all threads, reassemble using pipe sealant or teflon tape.
  • Leaks at the Type WJ adjustment screw: you may be able to disassemble, clean the tapping, and replace the existing parts. Replacement parts are available from US Gauge at AMTEK [2] The company sells a Type 310 valve assembly, Spec No. 085043A
  • US Gauge Type 310 WJ not working: AMTEK sells Type 310 valve seat replacements, Spec No. 085392A.
  • US Gauge Type 6 or Type 300L Shallow Well AVC not working: contact the company's customer service line 727-536-7831 to ask about spare parts.
  • Air leaks or hissing at the AVC are discussed separately at AIR VOLUME CONTROLS, HISSING

[Click to enlarge any image]

Recapping, both types of these air volume controls are used only on bladderless water pressure tanks - tanks that do not use an internal bladder. At above left a photo of a US Gauge a Type 6 Air Volume Control showing its operating float (that you cannot normally see as it is inside the water tank). This control is used on shallow wells and jet pumps.

Available at plumbing supplies and via Grainger online who describe the product as "Maintains Balanced Air Volume in Standard Air Over Water Storage Tanks when Using Shallow Well Pump." The installation kit includes 2" Diameter 0-100 Pounds Gauge, 48" Polyethylene, 1/4" Tubing and 1/4" Connectors

On the deep well model WJ 300 or WJ310 AVC from U.S. Gauge, the device excludes the tube connecting from the AVC to the well pump and you won't see the brass fitting on the bottom of the shallow-well AVC model illustrated at Can I Replace a Round Diaphragm AVC .

Reader Question: how to fix water leaks at a round Brady AV-series air volume control

Brady AV30 air volume control - repairable - & 7/16/14 anonymous said:

I had a Brady AV-30 air volume control installed when a new water pump was installed 19 months ago. What could be causing the air volume control to leak water from the middle of the thumbnut at the bottom of the control?

The thumb-nut is not loose and is apparently not to be turned with a pliers or wrench. It is leaking enough to nearly fill a bucket in 12 hours.

What is the purpose of the thumb nut? Can this leak be repaired? I have called the pump repairman, but he has not yet called back.

The pump is operating normally and is not short cycling, although it may run once every few hours due to this leak even though no other water is being used..



Brady air volume controls, repairable and non-repairable (C) InspectAPediaThe Wayne - Brady AV-series air volume controls use an internal diaphragm to operate the device. If the diaphragm has ruptured the air volume control may leak and needs repair or replacement.

If your AV unit is assembled with screws around its round outer perimeter the device is repairable - a new internal diaphragm and spring can be installed. If the round exterior perimeter is simply crimped together, the unit is not repairable and simply is replaced.

Your model, the Wayne Brady AV30 is intended for a 42-gallon water pressure tank and is a repairable model. There are two ports on these AVCs, a 1/4" threaded tank port and a 7/16"x24 suction port. The thumbscrew which contains a warning "do not use wrench" is an air inlet.

In addition to the air port some Brady air volume controls include a tapped gauge port. Below we give sources for purchasing this air volume control device and repair parts for it.

Where to buy Round Wayne Brady Air Volume Controls & Parts

The Brady AVC is manufactured by Simmons Manufacturing Company, 1608 Highway 20 East McDonough, GA, 30252 USA, Sales Order Desk: 800-241-1935, Website: These air volume controls are sold at the following outlets:

  • Wayne - Brady AV-series air volume controls are distributed by local plumbing suppliers in the United States & Canada and are
  • Wayne - Brady AV-series air volume controls are also sold online at
    • Amazon,
    • EBay, and various online plumbing suppliers such as
  • Repair Kits for the repairable Brady Air Volume Control are available from the manufacturer and from various suppliers.

Brady Air Volume Control Repair Kits

AVC Model Repair Kit Part No
AV30 1190
AV42 1191
AV80 1192
AV120 1193

Source: - retrieved 7/16/14



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