My Pressure Valve for My Sprinkler Is Frozen

About Pressure Vacuum Breaker Valves

• The pressure vacuum breaker valve sits at least 18 inches above the highest sprinkler on the system. It must be installed above the sprinkler lines because it uses air pressure differentials to prevent water from flowing backward into your main line. This is a critical function as water that enters a sprinkler system is no longer potable and must be prevented from flowing back into a main line. In most municipalities, vacuum breakers are required by code.

Effects of Frozen Water

• Water expands as it freezes. This expansion can cause severe damage to sprinkler systems, including pipes, valves and the pressure vacuum breaker. When water is allowed to freeze inside the breaker, it expands through the top of the valve. This action will crush the internal parts, known as a poppet and bonnet. These pieces are designed to break in the event of freezing to prevent more widespread damage. However, large amounts of water that are allowed to freeze inside a vacuum breaker can create so much pressure that the body of the breaker will crack. A cracked breaker is a costly repair, as the entire unit must be replaced.

Replacing Internal Parts

• The poppet and bonnet are the two main components inside a pressure vacuum breaker. These pieces sit on top of each other in the middle of the breaker. When water freezes around these pieces, they will crack and must be replaced. Most poppets and bonnets can be replaced with a repair kit by the manufacturer or an aftermarket kit. Unscrew the top of the breaker and remove the cap to expose the internal parts. Pull out the damaged unit and place the new poppet and bonnet inside the breaker before replacing the cap.

Replacing the Entire Unit

• When the body of a vacuum breaker is cracked by frozen water, chances are the entire unit must be replaced. However, if the cracks are located on either of the ball valves, those pieces can be replaced independent of the main body. To check the location of the crack, turn on the water to the sprinklers at the main ball valve and watch for where water sprays out of the breaker's body. If the water is coming from the two horizontal pieces with ball valves, the valves should be removed and replaced with comparable units.