Woosh Smart Air Filter Review: No more guessing

“It’s a useful approach to monitor the pressure drop across the filter – this is a good way to know when it’s the right time to change the filter because otherwise, there’s a lot of guess work,” says Li. She says the typical three-month replacement recommendation is based on assuming 20 percent runtime of your HVAC system (about five hours a day). Much of this depends on your climate, but Li says a recent study found that the average lifespan of the HVAC of 20 homes in one year in Toronto was 10 percent, meaning that those people could replace their filters less often.

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

“If this is a relatively new system in good condition, and you’ve used MERV 8 filters without a problem, then I don’t think there will be any problems with MERV 11, MERV 13, or even MERV 14 filters just because even if there is a difference in flow resistance, is relatively small,” he says. “I think most systems can handle this, 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. She suggests listening to the sound and feel of the flow coming from the cooling and heating vents in your home.

The good news is that Woosh’s smart filter can detect problems with your HVAC system. The company says it can identify the first signs of coil freezing, which if not addressed can cause irreparable damage. Manage this by controlling pressure drop and flow with temperature and humidity levels.

Fortunately, using a MERV 13 filter does not seem to cause any adverse effects on my system and I have not received any notifications 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 filters suggests I should have changed it now.