An air volume control (AVC) in a well water tank is a device that maintains the correct air-to-water ratio within the tank, ensuring efficient operation and preventing waterlogging. In a hydro-pneumatic tank system, air is essential to create pressure that pushes water out of the tank when a faucet is opened. Over time, air can be absorbed into the water, reducing the air cushion and causing the tank to become waterlogged, which can lead to frequent pump cycling and reduced efficiency.
The AVC works by automatically adding or releasing air to maintain the optimal air volume. It typically consists of a float mechanism and a vent or valve system. As water enters the tank, the float rises, and when it reaches a certain level, the AVC opens a valve to allow air to enter the tank. Conversely, if the air volume becomes too high, the AVC releases excess air through a vent.
Some AVCs use a snifter valve and a bleeder orifice system. The snifter valve, located on the pump side of the check valve, allows air to enter the system when the pump is off. The bleeder orifice, located in the drop pipe inside the well, releases water and allows air to enter the pipe when the pump stops, ensuring air is introduced into the tank.
By maintaining the correct air volume, the AVC ensures that the tank operates efficiently, reducing wear on the pump and extending its lifespan. Properly functioning AVCs help maintain consistent water pressure and prevent issues associated with waterlogged tanks, such as pump short cycling and reduced water delivery.