Just realized my furnace filter was causing uneven heating for 2 winters

I live in a 1970s bungalow in Calgary and my upstairs bedroom was always 5 degrees colder than the main floor. My neighbor who's a HVAC guy came over last month to help with something else. He took one look at my filter and said it was way too restrictive for my old ductwork. He showed me how even a MERV 11 filter can choke airflow in smaller houses like mine. Swapped to a basic MERV 4 filter and the temperature difference dropped to 1 degree. Has anyone else found that high-end filters actually make their system work worse?

3 comments

3 Comments

laurabennett24d ago

Yeah, I saw something similar on a home inspector's blog - he said most people are better off with cheap filters and changing them often.

davis.casey24d ago

I used to buy the expensive MERV 13 filters for my HVAC, thought I was being smart. Last year my furnace started cycling weird and the AC coil had this thick layer of dust on it. My HVAC guy literally laughed and said those high-end filters choke the system, makes it work way harder than it should. Switched to the cheap fiberglass ones, change them every 30 days, and my electric bill actually dropped about 15 bucks a month. The expensive ones catch more dust but they block airflow so bad it hurts the equipment. You gotta match the filter to what your system can handle.

harper_murphy2d ago

Friend got the same lecture from their HVAC guy after their system froze up. @laurabennett is right.