“This is a useful way to monitor the pressure drop across the filter – a good way to know when it's time to replace the filter because otherwise, there's a lot of guess work,” says Lee. She says the typical three-month replacement recommendation is based on the assumption of 20 percent runtime of your HVAC system (about five hours per day). Much of this depends on your climate, but Lee says a recent study found that the average HVAC runtime of 20 homes in Toronto over a year was down 10 percent, meaning those people would be able to change their filters less frequently.
As far as the verdict on MERV 13 is concerned, Lee says the higher flow resistance will force the HVAC fan to work harder. Depending on your system, the fan may be to stop Working hard, reducing air flow 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 Lee says he has seen MERV 13 filters with lower flow resistance than MERV 8. Ultimately, Lee 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 a MERV 8 filter without any problems, I don't see much point in using a MERV 11, MERV 13, or even MERV 14 filter.” There will be no trouble 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 keep your filter for the whole year. Don't change.”
Those 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 coming from the cooling and heating vents in your home and feeling the flow.
The good news is that Voosh's Smart Filter can detect problems with your HVAC system. The company says it can identify early signs of coil freezing, which if ignored can cause irreparable damage. It manages this by checking temperature and humidity levels as well as pressure drop and flow rate.
Thankfully, using a MERV 13 filter has no adverse effects on my system and I have not noticed any issues with my HVAC. My only concern is that, according to the app, I still I have never had to change my filter, even though it's been nine months since it was installed. My wallet is happy, but everything I've heard and read about the filter suggests I should have replaced it by now.