Forum Title: What is this object in my plumbing -- near water heater
The tan colored thing near the top of the picture. What is it and does it require any maintenance?
Category: Plumber Post By: ELSIE POWERS (Santa Clara, CA), 06/10/2017

Beat to the punch by David again..agh

- DAVID MILLER (Yuba City, CA), 09/04/2017

That is an expansion tank. discussed quit a bit here. Do a search and see what you come up with. Water does not compress when you heat it up. Pressure will increase when a closed system of water is heated. The tank has an air bladder. the air bladder will compress to prevent excessive pressure rise in system. T&P is a safety valve in case the pressure gets to high that the tank bladder can't handle

- FLORENCE AGUILAR (Fort Lee, NJ), 10/03/2017

That's a thermal expansion tank. That's there to cushion the system when water is heated. When the system is heated, there's an increase in pressure and volume as opposed to when it was cold. The bladder in the tank stores/cushions the increase until things cool down.

- SALLY NEWMAN (Asheville, NC), 10/03/2017

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