TOPIC: Expansion Tank

Does anyone know when the requirement for an expansion tank started??

This is one of those items that the local AHJ makes a determination on.  The need for the expansion tank was because municipalities were putting check valves at the meter to stop water from backing into the system.

Many water companies have not yet gone to the expense of that installation and the AHJ in those areas is more lenient on installation of the expansion tanks. 

I just had an argument with a local code inspector in a small city.  They wanted an expansion tank installed at the water heater even though the new home was on a private well and had an 80 gallon well tank about 10 feet away.  He couldn't get it through his thick head that it wasn't needed for two reasons:  the private well and the already installed large well tank.  I ended up meeting with the head inspector of the city and he agreed with me. 

You need to find out which codes are being used in the home's locale, the IRC or the UPC.

Thanks Stephen