Review on Taco SR503 4 Zone Relay for Enhanced Switching and Control by Justin Santiago

Upgrading my oven this fall was easy - thanks to this. Replacing a number of old separate components, this box simplified wiring and made future troubleshooting much easier. I removed one zone and currently only use two but am planning to expand to add a zone for a garage heater and a pool heater so it was easy as it cost a little more than the two zone version. It was nice to ditch those old, bulky controllers and an external transformer. What wasn't entirely obvious was how to get this to interact with the zone valves, but I removed them and now rely solely on the circulation pumps. The switched output for the pumps is 110v but wiring my zone valves in line with the t-stat like my original Honeywell system did did not work with this unit.