White-Rodgers 21D28-6 Evaporative Cooling Thermostat and Control Box

The 21D28-6 Time Delay Relay is for Use in Air Handlers Installed in Compressor-Run Air Conditioning and Heat Pump Systems to Delay the Blower Shut-Off After the Compressor has Shut Off. Features: Allows residual cooled air to be blown into the controlled space, increasing the efficiency of the system in cooling. Depending on electrical hookup in a heat pump system, delay of blower shut-off could also occur in heating.