Check the listing for details. Taco SR501-1 Zone Switching Relay 1 Zone Circulator Pump Control Tested. Condition: Used. Listed at 80.00 USD. Meet the Taco SR501, the small-but-mighty queen that knows how to keep things simple and cozy 💅🏽🌸. Designed to control one heating zone and one circulator pump, this reliable beauty is perfect for single-zone systems that need smooth, no-stress performance 🏡🔥. This unit has been tested and ready to work, giving you peace of mind and confident comfort right out of the box 💕⚙️. With its straightforward wiring, clear indicators, and dependable Taco quality, the SR501 handles the behind-the-scenes work so your heat stays steady and drama-free. Compact, efficient, and totally trustworthy, the Taco SR501 proves that even one zone can bring all the cozy vibes 💖✨ Simple control, solid performance, and warm comfort—done the cute and confident way.