Woosh Smart Air Filter Review: No More Guessing

“It’s a useful approach to monitoring the pressure drop across the filter—it’s a good way to know when it’s the right time to change the filter, because otherwise there’s a lot of guesswork,” Lee says. The typical three-month replacement recommendation is based on an assumption of 20 percent uptime (about five hours per day) of your HVAC system, he says. Much of this depends on your climate, however, says Lee recent research 20 homes in Toronto had an average HVAC downtime of 10 percent over the course of a year, meaning people could change their filters less often.

As for the MERV 13 ruling, Lee says the higher flow resistance will cause the HVAC fan to run harder. Depending on your system, the fan may stop working hard, reducing airflow and potentially damaging the cooling coils. However, a higher MERV rating does not equal higher flow resistance. It depends on the quality of the filter, as Lee says he’s seen MERV 13 filters with lower flow resistance than MERV 8. Ultimately, Lee says, a key factor is the age of your HVAC system.

“If it’s a relatively new system in good condition and you’re using MERV 8 filters without any problems, then I don’t think you’ll have any problems using MERV 11, MERV 13 or even MERV 14 filters. if there is a difference in flow resistance, it is relatively small,” he says. “I think most systems should be able to handle it, especially if you don’t change your filter all year.”

People with older systems should be careful as they may not be able to handle high efficiency filters at all. He suggests listening to the sound and feeling 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 early signs of coil freeze-up, which can cause irreparable damage if left untreated. It controls this by checking pressure drop and flow rate along with temperature and humidity levels.

Fortunately, using a MERV 13 filter has not had any adverse effects on my system and I have not received any notices of HVAC issues. My only concern is that according to the program, I yet I haven’t needed 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 by now.