Need help with connecting an Aprilaire 700 humidifier to a new Google Nest 4th Generation Thermostat

[RobertRak]

I recently bought a new Google Nest 4th Generation Thermostat and want to connect it directly to my older Aprilaire model 700 Humidifier. My current setup includes a Rheem Classic 90 Plus HVAC system controlled by a White Rodgers thermostat using five wires (C, R, W1, Y1, and G).  The humidifier is managed by an older Aprilaire humidistat in the return stack.

I want to connect the humidifier to the Nest Thermostat using the AQ+ and AQ- connectors.  However, Aprilaire support informed me that this connection must be made using a "Dry Contact."  This means I need to either verify that the Nest Thermostat provides the required type of contact (if this is programmable on the Nest) or connect an AprilAire 8024 (24V Universal SPDT Isolation Relay Card) between the thermostat and the humidifier

Google Nest Thermostat support has advised me to contact a Nest Pro, which I know will not be cheap. Therefore, can I set up the AQ+ and AQ- connectors as "Dry Contacts," or will I have to install an Aprilaire 8024?

Thank you for any support!

[moralesvicente]

Hi RobertRak, 

Thanks for posting here in the community forum. I understand that you want to connect an Aprilaire 700 humidifier to the Nest Learning Thermostat (4th gen). It’s a pleasure to share more information with you. 

Regarding your concerns, I truly recommend you contact a Nest Pro to get professional assistance; an incorrect setup, either due to miswiring or wrong software settings, could cause unexpected behavior or damage to your system.

If you have more questions, please feel free to write in this post.

Best regards, 

Daniel