How to Drain Your Water Heater and Replace The Expansion Tank - YouTube
Amazon.com: Camco 10423 1/2" Temperature and Pressure Relief Valve with 4" Epoxy-Coated Probe : Automotive
Davidson Water, Inc.
This device takes does the same job, but takes up 90% less space. Why you should opt for a thermal expansion valve over a traditional expansion tank - Mifab