Woosh Smart Air Filter Review: No More Guesswork

“It’s a useful approach to monitor the pressure drop across the filter—it’s a good way to know when it’s a good time to change the filter, because otherwise it’s a lot of guesswork,” Li says. She says the typical quarterly replacement recommendation is based on an assumption of 20 percent uptime on your HVAC system (about five hours per day). Much of this depends on your climate, but Li says recent study found that the average HVAC uptime of 20 homes over a year in Toronto was 10%, meaning those people would be able to change their filters less often.

As for the MERV 13 verdict, Li says the higher flow resistance will make the HVAC fan work harder. Depending on your system, the fan may stop it runs so hard, reducing airflow and potentially damaging the cooling coils. However, a higher MERV rating does not mean higher flow resistance. It depends on the quality of the filter, as Li says she’s seen MERV 13 filters with a lower flow resistance than MERV 8. Ultimately, Li says the main factor is the age of your HVAC system.

“If it’s a relatively new system in good condition and you’ve been using MERV 8 filters without a problem, then I don’t think there will be any problems using MERV 11, MERV 13 or even MERV 14 filters just because even if there is a difference in flow resistance , it’s relatively small,” she says. “I think most systems will be able to handle it, especially if you don’t change your filter throughout the year.”

People with older systems should be careful as they may not be able to handle high efficiency filters at all. She suggests listening to the sound and feeling the flow coming from the cooling and heating vents in your home.

The good news is that the Woosh Smart Filter can detect problems with your HVAC system. The company says it can identify early signs of coil freezing which, if not addressed, can cause irreparable damage. It manages this by checking pressure drop and flow along with temperature and humidity levels.

Fortunately, using a MERV 13 filter doesn’t seem to cause any adverse effects on my system, and I haven’t received any notices of problems with my HVAC. My only concern is that according to the app I still I don’t need to change my filter even though it’s been nine months since I installed it. My wallet is happy, but everything I’ve heard and read about the filters suggests I should have changed it by now.