Taco ESP Zone Valves (or Energy Storage Principal Zone Valves) are just an older model of current EBV Zone Valves (Electronic Ball Valve). The EBV's are a direct replacement of the ESP, only the name has changed, so if you're looking to replace your ESP Zone Valve, just make sure that the sizing matches up for your new EBV Zone Valve.
Zone valves and Taco EBV Zone Valves can be found at www.supplyhouse.com
