NIOB Taco SR501 Switching Relay
- The SR501 is a single-zone switching relay designed to control the operation of a circulator pump in a hydronic heating system.
- It simplifies wiring and provides a reliable interface between a thermostat and the circulator pump.
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Features:
- External Indicator Lights: These lights help diagnose the relay’s functionality.
- Universal Replaceability: The snap-in PC board allows easy replacement without rewiring.
- Simplified Wiring: The layout streamlines installation and service work.
- Sealed Relays: Ensures durability and reliability.
- Fuse Protected Outputs: Protects against overloads.
- Contractor Friendly: Designed for ease of use.
- Universal Thermostat Compatibility: Works with various thermostat models.
- UL Approved: Meets safety standards.
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Operation:
- Connect a thermostat to the “T T” terminals on the switching relay.
- When the thermostat calls for heat, the relay is energized, and power is given to the circulator.
- Power Input: Connect 120V AC power to terminals N and H.
- Jumper Placement: The factory-installed jumper between terminals H and 3 switches power on terminals 4 (normally open) and 4 (normally closed).
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Wiring Example:
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Connect the thermostat as follows:
- T & T: Thermostat connection.
- COM: Common terminal for 4 (normally open) and 4 (normally closed).
- W: Boiler operating control.
- 24VAC: Thermostat output.
- A resistor (1KΩ, 1⁄2 W) may be needed between W and C terminals for digital thermostats to work correctly.
- Ensure proper wiring to avoid secondary power sources activating the boiler unexpectedly.
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Specifications:
- Input Voltage: 120V AC, 60Hz, 1 phase.
- Maximum Combined Load: 12 amps.
- Enclosure Dimensions: 4 7/8" (width) x 6 5/8" (height) x 2 3/8" (depth).
- Circulator Relay Connections: Rated 1/3 hp (6 FLA, 36 LRA) at 120V AC.
- Thermostat Connection: Supplies a 24VAC class 2 output.
Remember, the SR501 is a workhorse in heating systems, ensuring efficient circulation and comfort.