Lennox 67K66 Heat Relay

The Lennox 67K66 Heat Relay is a heavy-duty 24V 3PDT relay engineered for precise load management in Lennox residential and commercial heating equipment. Operating with a 24VAC control signal, this Triple Pole Double Throw (3PDT) component provides the necessary switching capacity to handle multiple high-voltage circuits simultaneously, common in complex air handler and furnace configurations. As a direct replacement for Lennox 67K6601 and 58C9901, it ensures seamless integration and maintains original equipment performance standards without the need for field modifications. This relay is frequently found in CB29M and HP21 series units, managing critical sequences for heating elements and auxiliary fan controls. With an 8A contact rating and 50/60 Hz compatibility, the Lennox OEM 67K66 effectively replaces worn or chattering contacts, preventing system short cycles and improving overall thermal response in the HVAC control circuit.

• Universal Application: Functions as a direct drop-in for Lennox 67K6601, 67K66, and 58C9901 part numbers.
• Multi-Circuit Control: The 3PDT configuration allows for simultaneous switching of three separate poles, ideal for staging electric heat banks.
• Precision Switching: Optimized for use with 24V HVAC control systems to ensure rapid and reliable contact closure.
• High Ampacity: Rated for up to 8 Amps, providing a robust buffer for standard domestic fan and heater loads.

How do I confirm if my relay is failing?
Technicians should check for continuity across the coil (Terminals 1 and 3) and audible "chattering" during a call for heat. If the 24V signal is present but the 3PDT contacts fail to close, a replacement is necessary.

Is this compatible with 3-pole heating stages?
Yes, this Triple Pole Double Throw design is specifically used in Lennox equipment to manage multiple legs of a heating element or to interlock fan and heat functions simultaneously.

Does the 67K66 replace 67K6601?
Correct. The 67K66 and 67K6601 are functionally and physically identical; using this OEM part ensures UL/CSA compliance for the appliance.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.