The ZV9S zone board from TTS Thermaltech Systems simplifies valve wiring, diagnostics and testing when used in 24VAC hydronic systems where four-wire zone valves are used. Three-wire zone valves are also supported. Visual indication using LED indicator lamps is provided for both supply power as well as individual zone operation. An easy to use Off/On /Thermostat switch makes testing, maintenance and diagnostics easy. www.thermaltechsystems.com/zv9s