06/19/2026
Putting Power to Work in HVAC with Airotronics THAC Anti-Short Cycle timers
AIROTRONICS Time Delay Relays
Time delay relays (TDRs) are essential in HVAC systems for preventing compressor damage caused by short-cycling (rapid on/off switching) by enforcing a 3–5 minute delay between cycles, preventing premature failure. They protect components by reducing inrush current, enhance efficiency, manage component staging, and provide better comfort control.
Compressor Protection: TDRs prevent the compressor from turning on and off rapidly. Short-cycling can lead to excessive heat, high inrush current, and ultimate compressor failure.
Pressure Equalization: They provide a “delay on make” or off-delay, allowing system pressures (high and low sides) to equalize before restarting. This makes it easier for the motor to start, preventing damage.
Preventing Power Surges: TDRs can stagger the startup of multiple HVAC units (e.g., in a large building), preventing massive inrush currents and voltage sags.
Improved Efficiency & Comfort: They allow for fan management (e.g., blower stays on shortly after the cooling stops), which helps move remaining cold air, preventing moisture from blowing back into the room.
Protection against Short-Cycling: In the event of power fluctuations or a thermostat issue, the TDR acts as a buffer to keep the system safe.
Staging Components: TDRs ensure that different parts of the HVAC system (like multiple compressors or heating elements) start in a specific sequence rather than all at once, protecting the electrical system.
Learn more here:https://www.pelcocaz.com/pdfs/PPTW/PPTW_HVAC(Airotronics-THAC).pdf
