Water heater component

Can someone help me as Im unsure what this item is on top of the hot water tank
I tried my best to find a label or model number


Looks like an atmospheric vacuum breaker. This is used on a water heater if the water heaters location is above point if use. Was this located in an attic?

Michael, it’s a vacuum breaker required by some jurisdictions. It’s there to prevent the WH tank from collapsing in case a fire engine is pumping water nearby.

Are you from Massachusetts?


Google plumber.

I’ve installed a number of these when water heaters were located in a finished attic. Never heard about that fire pumping thing there must be water heaters imploding all over the country.

Thanks for the replies. The tank was in a utility room connected to the garage. 2007 tank. Still operational.
The furnace on the other hand…:unamused: