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Aprilaire 4851 Blower Activation Relay for 500, 600 & 700 Series Humidifiers (Automatic Control)

Aprilaire #4851 Blower Activation Relay.

For Aprilaire series 500, 600, and 700 humidifiers that use the Automatic Digital Humidifier Controls (# 56 and # 58).

Allows digital control (#58) to turn on system fan when there is a call for humidification (but not heat).

This device will initiate HVAC fan operation when there is a call for humidity, even when there is no heat call.