Types of Vacuum Breakers on Sprinkler Systems

Atmospheric Vacuum Breaker

• An atmospheric vacuum breaker is typically installed on the sprinkler supply line after the control valve. These valves must be installed on every control valve to prevent water that enters the irrigation lines from flowing back into the main line. Because atmospheric vacuum breakers use differences in air pressure to control the flow of water, they must be installed at least 6 inches higher than the elevation of the highest sprinkler on the system. Otherwise, the breaker will not function properly. Some cities and towns do not allow the use of atmospheric vacuum breakers, so it's important to check local codes before using this type of breaker.

Pressure Vacuum Breaker

• A pressure vacuum breaker also uses differences in air pressure to control the flow of water through a sprinkler system. But unlike an atmospheric vacuum breaker, a pressure vacuum breaker needs only a single unit to prevent water backflow in the entire system. That's because a pressure breaker is installed on the main water line, before the water enters the sprinkler system. These units must also be installed at least 6 inches higher than the highest sprinkler on the system to work properly.

About Breakers

• Almost all vacuum breakers are made of brass, which is highly resistant to rust and corrosion. This material creates a long-lasting unit that requires little maintenance. Inside the breaker is a series of springs and caps that work in tandem with air pressure to prevent water from flowing backward. The internal pieces can be replaced and are generally available at home improvement stores. Many vacuum breakers also act as a shut-off point for the sprinkler system through two ball valves on the side of the breaker.

Price

• Vacuum breakers are often the most expensive part on a sprinkler system. The price of a vacuum breaker depends largely on the size of the unit. The largest breakers for use on residential systems are 1-inch in diameter. Pressure breakers at this size usually range from $80 to $150 as of August 2011, depending on the brand. Smaller breakers, such as the more typical 3/4-inch units, range from $60 to $100, depending on the brand. Replacement part kits range from $15 to $30 at home improvement stores.