I have to preface by saying that this isn’t really related to Home Assistant. I can’t find a more generic home automation community on Lemmy and I figured someone here might have some experience with this so I hope is post is allowed.
I have a large masonry fireplace that I’m fixing some issues with. It has a fresh air intake that I’m venting outside the house. Code says the air intake also has to have a damper which can be closed to prevent the fire from burning out of control.
I’m planning to use a 24 volt power open/power close damper. I want to be able to modulate it with a wall control where it can be set in increments somewhere between 0% and 100% open. I’m sure I could engineer a creative solution but I wanted to see if anyone else had a simpler way of accomplishing this first.
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I know those kind of motorized vents are used in commercial HVAC. (Here’s a white paper on a stepper motor for one https://www.portescap.com/en/newsroom/whitepapers/2021/10/customized-and-reliable-stepper-motors-for-damper-applications )
A stepper would be the easiest thing because if you know it takes 10 steps to fully open from fully closed, you could keep track of how many steps you have sent each direction in Home Assistant and be able to display the current status. 
If you want a knob on the wall that controls this, I think somewhere behind it you are still going to need a control system that translates wall switch inputs into stepping logic. Home Assistant would be able to do that easily. 
Be aware that an underpowered or stuck stepper motor can “skip”, causing the position data to be incorrect.
A servo motor has active feedback, so doesn’t have this issue. Servos do have their own drawbacks too, so they are not always a suitable replacement.
You need an actuator that takes a proportional input signal. 0-10vdc is common. You’ll just need a 24vac to 10vdc power supply for the manual potentiometer.
https://cerpangha.com/products/s963b-1136-honeywell-manual-potentiometer-270a
Thank you! I think that actuator is exactly what I need.
Nice. I don’t know about the torque requirements or mounting dimensions of your existing (or new?) damper so double check those. Kinda sucks that they don’t make one that takes the pot signal directly. I know a lot of lighting dimmers are 0-10v but how they are powered and interact with that damper is uncharted territory.
I’m not familiar with that hardware, but unless there is an off the shelf option you are related to engineering it yourself. There would need to be a stepper in there you can control directly, and a way of programming the controller to know how many steps to take.
