Dirty Air Filter Sensor

Looking at building a sensor for my 3 HVAC systems to tell me when it’s time to change the air filter. My plan is to use MPX5700DP 10 kpa differential pressure sensor. My question is, does anyone know a good kpa value to use to trigger a dirty air filter alarm?

I would LOVE to know what you learn here, this would be a fun project I’d like to do as well.

Actually, it looks like it is working very well, I started with MPX5700DP a 101.5 PSI max that I ordered by mistake and switched to MPX5010DP a 1.45 PSI max. I still need to gather data to set the pressure drop for a dirty filter, but the sensor is working well. I also added a K30 CO2 sensor, PSM5003 dust sensor, and Si7021 humidity sensory. They all are connected to a ESP8266 D1 Mini running ESP Easy sending MQTT data to openHAB.


Fantastic, very cool. I will probably take this project on. If you get time, you should consider writing up a how-to on this!

Just thought I would follow up - did you find the pressure drop calculations work properly?

They do for my water filters, I have not had time to finish my HVAC sensors.