How to Automate a Motorised Damper for Laundry Ventilation Using Shelly

A customer recently reached out asking how to control this motorised damper from The HVAC Shop NZ to isolate their laundry room ventilation. Their goal: automatically open or close the damper based on humidity levels.

If you’re planning something similar, here’s a step-by-step guide on how to make it work using Shelly smart devices and a humidity sensor.

✅ Goal:

Automate the opening/closing of a 24V AC motorised damper using a humidity sensor to improve laundry ventilation efficiency.

🧰 Recommended Components:

1. Shelly Plus 1 or Shelly 1 Gen 3
   These smart relays can control the damper motor by switching power based on humidity levels.

   • Dry contact outputs (potential-free)

   • Rated for up to 16A

   • Supports both 12V/24V DC or 110–240V AC control

   • Wi-Fi enabled and works with the Shelly Cloud app

2. Shelly H&T (Gen 3) or Shelly BLU H&T
   This is a smart temperature & humidity sensor that pairs seamlessly with your Shelly relay.

   • Battery-operated

   • Bluetooth (BLU version) or Wi-Fi (Gen 3 version)

   • Triggers automations in the Shelly app when humidity exceeds a set level

3. SPDT Switch (Single Pole Double Throw)
   The damper requires an SPDT switching method to toggle between open and closed. While the Shelly Plus 1 offers potential-free relay output, it functions as Normally Open (NO) or Normally Closed (NC)—not full SPDT.

   ⚠️ Some SPDT dampers may not function correctly with Shelly alone. You may need to add a latching relay module or alternative hardware if precise SPDT functionality is essential.

   
   

⚙️ How to Wire It:

1. Connect the Shelly relay to control the damper’s open/close wiring using the NC or NO terminals, depending on the default position.

2. Install the humidity sensor (H&T) in your laundry space.

3. Use the Shelly Cloud app to set automation rules:

   • Example: "If humidity > 70%, turn on Shelly relay (open damper)"

   • "If humidity < 60%, turn off Shelly relay (close damper)"

This way, your damper responds to real-time humidity changes without any manual input.

🏁 Conclusion:

Using a Shelly Plus 1 or Shelly 1 Gen 3 combined with a Shelly H&T humidity sensor, you can effectively control a motorised damper for laundry ventilation. While SPDT compatibility may need additional hardware, this setup gives you a powerful and automated way to improve air quality and energy efficiency in your home.