Macurco (GBC-24-2) Gas boiler controller – 2 relays

The Macurco GBC-24-2 is a gas boiler shutdown controller with two relays. Specifically, it pairs with Macurco gas detectors to interrupt boiler operation on a gas alarm. Therefore, it provides automatic mechanical-room safety response.

First, the controller accepts inputs from up to four Macurco gas detection heads. Then, it drives two of its built-in 10A SPDT relays for boiler shutdown and equipment interlock. As a result, a single GBC enclosure handles small to mid-size boiler rooms.

Macurco GBC-24-2 application

The GBC family addresses NFPA 54 / IFC mechanical-room shutdown intent on CO or combustible-gas detection. However, the GBC itself is not a fire alarm panel. Instead, it is a dedicated shutdown controller for gas-fired equipment.

Verified specifications

• Power input: 24 VAC or 24 VDC
• Relays: 2 of up to 8 SPDT outputs, 10 A contact rating
• Detector inputs: up to 4 Macurco gas detector heads
• Horn / strobe output: 24 VDC, 250 mA max for one remote notification appliance
• Indicators: green power LED, red alarm LED, audible buzzer
• Reset: front-panel boiler reset button
• Expansion: supports up to 4 expansion relay boards (8 total outputs)

Installation guidance

First, wire the 24V supply and Macurco detector heads to the GBC. Then, land the relay outputs at the gas valve, blower, or boiler control circuit. Finally, follow the Macurco GBC manual (Rev 1.4) for jumper, address, and supervision settings.

Furthermore, for installations needing four shutdown circuits or four detector zones, choose the GBC-24-4 instead.

For more information, contact the Life Safety Consultants team at (888) 557-0558, or email us at: sales@lifesafetycom.com