White-Rodgers 24A51 Thermal Relay

The White-Rodgers 24A51 Thermal Relay is a timed electric heat sequencer designed for commercial and industrial HVAC systems to sequence and control electric heating elements through a thermal time-delay relay. It operates on 24 V control voltage at 60 Hz and functions as a single-switch sequencer for continuous-duty heating control, featuring an approximate 35-second ON and 30-second OFF timing. The unit mounts in multiple positions to suit different installations and is commonly installed in electric furnaces, air handlers, rooftop HVAC units, and heating control assemblies. This relay supports reliable staged heating control and helps prevent electrical overload by sequencing activations over time. Maintenance teams, HVAC technicians, and system integrators rely on it for relay replacement, electric heat system repair, retrofit projects, and restoration of staged heating control performance. Common replacements include White-Rodgers 24A51-1 and Emerson 24A05Z-1 heat relays, reflecting its role in legacy electric heat control ecosystems.