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This article describes How to Find & Maintain the Water Tank Air Volume Control. Readers of this document should also see Water pump and pressure tank repair diagnosis & cost an specific case which offers an example of diagnosis of loss of water pressure, loss of water, and analyzes the actual repair cost.

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WATER TANK AIR VOLUME CONTROLS

The air volume control or "AVC" device mounted (usually) on older steel water tanks (ones that do not use an internal bladder to keep water and air separate) is designed to automatically add air to the water pressure tank when it's needed. If a water tank loses its air charge it stops working properly and usually results in the water pump turning on and off rapidly - "short cycling" of the water pump. This condition, in turn, can damage or even burn up the water pump. The air volume control might also be located right on top of a one line or two line jet pump such as is visible at the top center in this photo.

This alternative air volume control does not include a disc-shaped device and has no connection to the water system's pump or other piping. The hole seen in the end of the brass screw is the air inlet for this ari volume control. But you may hear air hissing in at this fixture (it's working), or you may see water leaking out of it (meaning it needs repair). Here is a perspective view of where air volume controls are typically installed on a steel water tank. You won't see a control like this installed on a bladder-type captive air water tank. See AIR VOLUME CONTROLS for a detailed discussion of the repair and replacement of air volume controls on water tanks.

> 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. Remember if you see this device on your water tank, the tank is not a bladder-type or "captive air" or "Well-X-Trol" (TM) 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. See AIR VOLUME CONTROLS for a detailed discussion of air volume controls and their repair or replacement.

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PLUMBING TOPICS
OIL TANKS
SEPTIC SYSTEMS
WATER PRESSURE & FLOW MEASUREMENT
WATER PRESSURE LOSS DIAGNOSIS GUIDE
  WATER PUMP PRESSURE CONTROL ADJUSTMENT
  WATER PUMP PRESSURE CONTROL REPAIR
  WATER PRESSURE REGULATOR ADJUST
WATER PRESSURE REGULATOR ADJUST
WATER PRESSURE REPAIR GUIDE & COSTS
WATER PUMPS & WELL TANKS
WATER PUMP CONTROLS & SWITCHES
  IDENTIFY WELL PUMP TANK COMPONENTS
  MAIN WATER SHUTOFF VALVE
  WATER PUMP ELECTRICAL SWITCHES
  WATER PUMP PRESSURE CONTROL
    WATER PUMP PRESSURE CONTROL ADJUSTMENT
    WATER PUMP PRESSURE CONTROL REPAIR
    WATER PUMP PRESSURE CONTROL REPLACE
  WATER PRESSURE REGULATOR ADJUST
  WATER PUMP RELAY SWITCH
  TANK AIR VOLUME CONTROLS
  TANK AIR INLET VALVE
  WATER TANK PRESSURE GAUGE
  WATER TANK DRAIN VALVE
  WATER TANK RELIEF VALVE
  CHECK VALVES
  WATER FILTERS
  WATER FILTERS
WATER PUMP TYPES & LIFE EXPECTANCY
WATER PUMP & TANK SAFETY
WATER SUPPLY & DRAIN PIPING
WATER TANK TYPES: WATER, OIL, EXPANSION, ALL
WATER TANK LIFE EXPECTANCY
WATER TANK REPAIRS
WATER TANK AIR, HOW TO ADD
WATER TANK BLADDERS & CAPTIVE AIR
WATER TANK BLADDER PRESSURE ADJUSTMENT
WATER TANK PRESSURE CALCULATIONS
WATER TANK SIZE & VOLUME
WATER TANKS HOW THEY WORK
WATER TESTING
WATER TREATMENT EQUIPMENT CHOICES
WELLS CISTERNS & SPRINGS
WELL, PUMP, TANK LIFE EXPECTANCY

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