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There is not a replacement for this product as it has been discontiuned. Documents and resources are accessible below.

Switching Relay with Outdoor Reset

This product is no longer available. Documents and resources are still accessible.

The FuelMizer ® (SR501-OR) is a microprocessor-based control designed to regulate the supply water temperature of a single boiler, based on the outdoor temperature. The FuelMizer ® is a boiler reset control and switching relay in one unit; it is ideal for retrofit application, but may also be used in new installations. Its quality features include full outdoor boiler reset control: it can control the system or zone valve circulator, or it can override outdoor reset when DHW tank is calling. It’s easy to install and set and will not affect the boiler’s warranty. Front mounted LED lights offer full diagnostic information. The FuelMizer’s typical energy savings is about 14%, with some customers experiencing 30%.

Instruction Sheet
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Performance Data

Control:  Microprocessor control. This is not a safety (limit)control.
Enclosure: TYPE 1
Dimensions: 4-1⁄4″ W x 5-1⁄4″ H x 2-3⁄4″ D
Approvals: UL listed for US and Canada, Temperature Indicating and Regulating Equipment.
Power Supply: 120/60/1 VAC, 12 amps maximum
Relays: Boiler Relay 1 amp @ 24 VAC Circulator Relay 1⁄3 HP (6 FLA, 36 LRA)
Thermostat: 24 VAC Class 2 Output
Sensors: NTC thermistor, 10 kΩ @ 77°F (25°C ±0.2°C) ß=3892
Outdoor Design Temp.: .-30°F to 40°F (-35°C to 5°C)
Boiler Minimum: 70°F or 140°F .(21°C or 60°C)
Differential: 10°F or 20°F (6°C or 12°C)
WWSD: 70°F (21°C)

  • Full outdoor boiler reset control
  • Control system or zone valve circulator
  • Over-ride of outdoor reset when DHW tank is calling
  • Easy to install and set; will not affect boiler’s warranty
  • Front mounted LED lights for full diagnostic information
  • Ideal for retrofit applications of just about any hot water boiler
  • Typical energy savings is about 14% with some customers experiencing up to 30%
  • Boiler Reset Control
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