Is anyone aware of a sensor (preferably Zigbee, I think), that will give me an idea of when I need to change my furnace air filter?
I am picturing something that maybe sits on the “clean” side of the filter to measure…pressure? Air quality? I don’t know.
Not automated but you can get a radon manometer to identify pressure differentials. Install on both sides of the filter. Identify where pressure is with a new filter, mark it, and see how it changes over time and determine when to replace it.