“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.” , explains Li. She says the typical three-month replacement recommendation is based on the assumption of 20 percent battery life for your HVAC system (about five hours per day). It largely depends on your climate, but Li says a recent study found that the median HVAC run time of 20 homes over a year in Toronto was 10 percent, meaning these people would be able to replace their filters less often.
As for the verdict on MERV 13, Li says a higher flow resistance will make the HVAC fan work harder. Depending on your system, the fan may stop working as hard, decreasing airflow and potentially damaging the cooling coils. However, a higher MERV rating does not equate to 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 it’s a relatively new system and in good condition and you’re using the MERV 8 filters with no issues, then I don’t think there will be any issues using the MERV 11, MERV 13 or even MERV 14 simply because even though there is a difference in the resistance to flow, it is relatively small,” she says. “I think most systems will be able to 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 at all. She suggests listening to the sound and feeling the flow coming from your home’s cooling and heating vents.
The good news is that Woosh’s smart filter can detect problems in your HVAC system. The company claims to be able to identify early signs of coil freezing, which, if left untreated, can cause irreparable damage. It manages this by checking pressure drop and flow as well as temperature and humidity levels.
Fortunately, using a MERV 13 filter does not appear to have any adverse effects on my system and I have not received any notifications of any issues with my HVAC. My only concern is that according to the app I always 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.
