I understand that a expansion tank is required on a water heater only if it is a closed system. Aren’t most systems closed if there is a check valve or backflow preventer on the main water service?
a check valve or backflow preventer on the main definitively makes it a closed system, that is correct.
Thanks! So technically every residential water heater should have an expansion tank because every water supply line is required to have a check valve or backflow unless it is a well that doesn’t have these?
No I commonly see older homes in my area that don’t have a backflow/PRV/check valve that aren’t required to have an expansion tank.
I disagree. I generally only see these devices on homes built in the last 20 years or so.
Are they a good idea? Absolutely, just not required across the board!
Note: Take into consideration that you are in the suburbs of Chicago. There is a huge demand for potable water, and the risk for cross-contamination is high. I am in a small Minnesota town of 26,000 on municipal well water. Our concerns are not so high… yet.
I am in agreement. Some very large counties in my area only require these devices on irrigation systems, which are often on a second meter. Conversely, nearly all municipalities I encounter require them on commercial properties. So in the end, it definitely varies from one municipality to another in my experience.
Just wanted to share.
IMO… Expansion Tanks resting atop a WH on CPVC/Plastic piping without metal strapping or support is NEVER a good idea!!