Understanding Dry Contacts in an AprilAire Steam Humidifier (Model 800)

In this video, I explain the concept of a dry contact and its application in the AprilAire Steam Humidifier (Model 800). Using the terminals labeled 1 & 2 on the control board, identified as “Humidistat,” I demonstrate how to perform a simple continuity test to confirm the dry contact mechanism. This mechanism determines when the steam humidifier is energized, setting it apart from the typical 24-volt signal sent by the R terminal found on standard control boards, like those in gas furnaces or crossover air handlers.

Additionally, I highlight how this dry contact functionality provides a unique control method for the humidifier, enabling more precise and efficient operation.

Stay tuned for the follow-up video, where I’ll illustrate how to bypass additional devices, such as the included humidistat, by integrating an ecobee smart thermostat. This approach simplifies the setup, allowing full control of your humidification system through your thermostat—as long as it supports a dry contact signal for humidification.

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Видео Understanding Dry Contacts in an AprilAire Steam Humidifier (Model 800) канала Nelson's HVAC, LLC