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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.

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. See SHORT CYCLING CAUSES for details. 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 lost any connection to the water system's pump or other piping. We wouldn't assume it's working. 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). For a perspective view of where this device was installed on this galvanized steel water tank click the photo. 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 air volume controls and their repair or replacement.

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PLUMBING TOPICS
OIL TANKS
SEPTIC SYSTEMS
WATER PRESSURE DIAGNOSIS, REPAIR & COSTS
WATER PRESSURE LOSS DIAGNOSIS
WATER PRESSURE REGULATOR ADJUST
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
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 BLADDER PRESSURE ADJUSTMENT
WATER TANK PRESSURE CALCULATIONS
WATER TANK SIZE & VOLUME
WATER TANKS HOW THEY WORK
WATER TESTING
WELLS CISTERNS & SPRINGS

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