Taco SR503 Switching Relay

The Taco SR503 Switching Relay is a compact, three-zone switching relay designed for boiler, circulator, and hydronic systems. With electronic actuation and a DPDT switch, it delivers reliable control across three zones while fitting in tight mechanical spaces. This fully enclosed snap-out relay features a NEMA 1 enclosure for safe installation and is UL and CSA listed. It operates from 120V AC, 60 Hz, 1-phase, with a 1/3 HP input and supports up to 15 A combined load (6 A full load, 36 A locked rotor).

Designed for contractor-friendly wiring, it includes a 24V AC isolated end switch (1 A), a switchable priority feature, and an external indicator light. The 24V Class 2 thermostat compatibility, compact PC board layout, and fuse-protected design simplify installation and service in busy boiler rooms.

• Three-zone DPDT switching with electronic actuation
• External indicator light and switchable priority
• Fully enclosed snap-out relay in a compact NEMA 1 enclosure
• Fuse-protected design; 120V AC, 60 Hz, 1-phase input (1/3 HP)
• 24V AC isolated end switch (1 A) and 24V Class 2 thermostat compatibility
• Contractor-friendly PC board layout with simplified wiring
• 24V power input/output terminals; UL/CSA listed