Space-gard And Aprilaire #4851 Aprilaire Blower Activation Relay

• 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.

This relay starts the furnace fan whenever the humidistat calls for more humification. It was reasonably priced, looks to me to be a quality device and works perfectly.