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.
A modern sensor would be a mass airflow sensor, but a sail switch that you can adjust the amount of surface area that it hits so it alerts if the amount of air isn’t high enough it doesn’t activate when the furnace is running.