1. Product Overview
The Taco SR501 Single Zone Hot Water Circulator Switching Relay is designed to manage a single zone hot water circulator pump in heating systems. This device simplifies wiring and offers reliable control for your heating system. Its design allows for easy replacement of existing single zone switching relays without needing to replace the entire enclosure.
Key features include:
- External Indicator Lights for instant diagnostic feedback.
- Universal replaceability with a snap-in PC board.
- Simplified wiring for straightforward installation.
- Fully enclosed snap-out relays.
- 100% factory tested for reliability.
- Contractor-friendly PC board layout.
- Universal thermostat compatibility.
- UL and CSA approved for safety standards.
Figure 1: The Taco SR501 Single Zone Hot Water Circulator Switching Relay. This image shows the compact green enclosure of the relay unit with its product label visible.
2. Important Safety Information
WARNING: Risk of Electric Shock. Disconnect power before installation or servicing.
- All wiring must conform to local electrical codes and ordinances.
- Installation and servicing should only be performed by qualified personnel.
- Ensure the power supply to the heating system is completely disconnected before beginning any work on the relay.
- Do not operate the device with damaged wiring or if the enclosure is open.
- This device is designed for indoor use only.
3. Installation Instructions
The Taco SR501 is designed for straightforward installation and can often replace older single zone relays without extensive modifications.
3.1 Pre-Installation Steps
- Disconnect Power: Turn off the main power supply to the boiler or heating system at the circuit breaker. Verify power is off using a voltage tester.
- Identify Wiring: Carefully label all existing wires connected to the old relay (if replacing one) to ensure correct re-connection.
- Mounting Location: Choose a suitable mounting location near the boiler or circulator pump, ensuring it is dry and easily accessible for future servicing.
3.2 Wiring the SR501
The SR501 features a contractor-friendly PC board layout and simplified wiring terminals.
- Power Connection: Connect the incoming 120V AC power supply to the designated terminals on the relay.
- Thermostat Connection: Connect the thermostat wires to the low voltage thermostat terminals. The SR501 is compatible with conventional and programmable thermostats.
- Circulator Pump Connection: Connect the circulator pump wiring to the appropriate pump terminals.
- Grounding: Ensure the unit is properly grounded according to local electrical codes.
Note: The snap-in PC board design facilitates easy replacement. If replacing an older unit, the new SR501's PC board can often be swapped into the existing enclosure, provided the knockout configuration is suitable. Consult the wiring diagram provided with the product for specific terminal assignments.
4. Operating Instructions
The Taco SR501 operates automatically in response to thermostat calls for heat.
4.1 Initial Power-Up
- After completing all wiring and securing the cover, restore power to the heating system at the circuit breaker.
- Observe the external indicator lights. A power indicator light should illuminate, confirming the unit is receiving power.
4.2 Normal Operation
- When the connected thermostat calls for heat, the SR501 will energize the circulator pump.
- An indicator light for the zone (or pump) will illuminate, indicating that the pump is active.
- When the thermostat is satisfied, the SR501 will de-energize the circulator pump, and the zone/pump indicator light will turn off.
The SR501 uses a standard ice cube replaceable relay, which can be easily swapped if needed.
5. Maintenance
The Taco SR501 is designed for reliable, maintenance-free operation. However, periodic checks can help ensure its longevity and proper function.
- Visual Inspection: Annually, inspect the unit for any signs of physical damage, loose connections, or corrosion.
- Indicator Lights: Periodically check the external indicator lights during operation to confirm proper power and zone activation.
- Cleaning: Keep the area around the relay clean and free from dust and debris to ensure adequate ventilation.
- Relay Replacement: If the circulator pump fails to operate despite a call for heat and the thermostat is functioning, the internal ice cube relay may need replacement. Ensure power is disconnected before attempting to replace the relay.
Always disconnect power before performing any maintenance or inspection.
6. Troubleshooting Guide
Use the external indicator lights for quick diagnostics.
| Problem | Possible Cause | Solution |
|---|---|---|
| No power indicator light | No power to the unit; faulty wiring; tripped circuit breaker. | Check circuit breaker. Verify power supply connections. Ensure main power is on. |
| Circulator pump does not run when thermostat calls for heat, but power light is on. | Faulty thermostat; loose thermostat wiring; faulty internal relay. | Check thermostat operation. Verify thermostat wiring connections. Replace the internal ice cube relay. |
| Circulator pump runs continuously. | Thermostat stuck in "call for heat" position; shorted thermostat wiring; faulty internal relay. | Check thermostat. Inspect thermostat wiring for shorts. Replace the internal ice cube relay. |
If troubleshooting steps do not resolve the issue, contact a qualified HVAC technician or Taco customer support.
7. Product Specifications
| Feature | Detail |
|---|---|
| Model Number | SR501 |
| Brand | Taco |
| Contact Type | Normally Open |
| Operation Mode | Automatic |
| Number of Terminals | 2 |
| Specification Met | UL, CSA Approved |
| Item Weight | 2.05 pounds |
| Product Dimensions | 1 x 1 x 1 inches (Approximate, refer to actual product for precise measurements) |
| UPC | 687752390384 |
8. Warranty and Support
8.1 Warranty Information
The Taco SR501 Single Zone Hot Water Circulator Switching Relay comes with an Extended 3 Year Warranty from the date of purchase. This warranty covers defects in materials and workmanship under normal use and service. For full warranty terms and conditions, please refer to the official documentation provided with your product or visit the manufacturer's website.
8.2 Customer Support
For technical assistance, warranty claims, or further information regarding your Taco SR501, please contact Taco customer support:
- Website: www.tacocomfort.com
- Phone: Refer to the official Taco website for regional contact numbers.
- Email: Refer to the official Taco website for support email addresses.
When contacting support, please have your product model number (SR501) and date of purchase available.
