Time to change the furnace filter

Dec 31, 2017
SE British Columbia, Canada
That time of year. I change it once a year.

I change every 90 days with a MERV 4 or less....much easier on the motor and the airflow...
My furnace tells me when, it has an algorithm that calculates the hours of service and then sends a reminder on my thermostat.
I then check it and if I find that it's not dirty I don't change it.
I use one just like yours...I get them at Lowes.. They are a low MERV rating around a 5... Good air flow and still filter good too....
I change 2x a year, when I change from heat to cooling and then when I go back to heat. I would love to change more often but my air handler is in the crawl space and I have to crawl 20 ft to get to it. My knees dont like that and I dont like the spiders.
I'm a big fan of Nordic Pure for odd wide filters like our new house has. 4 inch filters in a variety of MERV's for 20 bucks or so. $50+ anywhere else.

I change mine every 90 days but they are never very dirty. Probably doing it too often..