Components

• Shut-off valves: Allows isolation of the water heater from boiler system during service.
• Dielectric Unions: Field supplied dielectric unions are required and designed to be installed between pipe made
from dissimilar metals to prevent accelerated corrosion and deterioration in the piping system due to stray current
discharges.
• Vacuum Breaker: Protects the water heater from collapse if a hot tank is shut off to service other components in
the system. Required for Commonwealth of Massachusetts.
• Thermal Expansion Tank: If the water heater is installed in a closed water supply system, such as a system
having a back flow preventer in the cold water supply line, installation of a thermal expansion tank is
required.
• Water Hammer Arrester: Dishwashers, clothes washers, and fast-closing positive shutoff valves incorporated in
the system all contribute to creating water hammer. Install a water hammer arrester to prevent damage to pipes
and appliances. See water hammer arrester manufacturer’s instructions for application and installation.
• Backflow Preventer: Protects potable water supplies from contamination due to backflow. Requirements for
Commonwealth of Massachusetts. Boiler installation shall conform to the Commonwealth of Massachusetts code
248 CMR which includes but is not limited to: Installation by licensed plumber or gas fitter.