Why do I need an expansion tank?

As water is heated, it expands. This is called thermal expansion and it occurs every time the water heater heats water. Most building codes now require a pressure reducing valve to reduce high city water pressure and a backflow preventer to stop water from backing up into the city main and contaminating the system. These devices create a closed system with nowhere for the expanded water to go.

What happens to the water without an expansion tank?

All water heaters have a temperature and pressure relief valve which allows expanded water to escape before it damages the system. Most systems discharge this water onto the floor, creating a mess.

How does an expansion tank solve this problem?

The Water Worker Safety expansion is designed to accept the expanded water until a faucet or other hot water fixture is opened. This process prevents noisy water hammer and damage to the system.
 

Without a Water Heating Safety Tank

Heated water expands, causing pressure relief valve to open and discharge water.

With a Water Heating Safety Tank

Heated water expands into safety tank, elimination water discharge.