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What Kind of Furnace Filter Should I Buy?

Just what kind of furnace filter should you get for maximum efficiency? Low efficiency filters, as their name might suggest, just aren’t all that when it comes to dusting properly.

However on the other hand, high efficiency furnace filters can actually slow down air flow a bit too much, which isn’t exactly what you need.

The question remains: what are you supposed to buy?

Well, your decision will depend on a number of factors. When buying furnace air filters for your furnace, you’ll need to consider what exactly you’re trying to filter, your own diligence when it comes to changing the filter, and your budget.

The MERV scale

The MERV scale refers to the minimum efficiency reporting value (MERV). This range goes from 1 to 16. Residential filters will tend to fall anywhere in between 4 to 12. The MERV 4 filter is an inexpensive one, and will be able to capture roughly around eighty percent of all particles larger than 50 microns. However, it will only be able to capture around twenty five percent of the particles falling between the 3 to 10 micron range.

Furnace manufacturers tend to have a preference for the traditional spun fiberglass ac filters. These MERV 2 filters will provide maximum air flow, even as they filter out a sufficient amount of large particles to protect the furnace. This maintenance of the air flow as specified by the furnace manufacturer is a critical aspect of achieving maximum life and energy efficiency from the heat exchanger and blower motor.

Generally speaking, most homeowners will find the MERV 7 or 8 pleated filter to be a sufficient balance between filtration efficiency and cost. These filters are relatively more expensive, but manage to capture around eighty to ninety five percent of the particles 5 microns or larger. This is sufficient filtration for the vast majority of households.

Unfortunately, this may not be enough for households with family members who have low immunity issues or allergies. For these households, you will likely have to spend more on a high efficiency filter – MERV 11 or even higher. In such cases, you’ll need to carry out more frequent filter changes in order to maintain your furnace.

These high efficiency filters have the ability to trap around ninety nine percent of particles as small as 0.3 microns, enough to capture pollen, fumes, bacteria and viruses. However, you will need to run your furnace fan all the time in order to obtain the maximum benefit of the filter. This will cost you more.

Whatever you decide is best for your home, make sure you never ever switch to a high efficiency filter from a fiberglass filter without first consulting with your HVAC technician. Your technician will be able to boost the fan speed in order to make up for the decreased air flow. You will also need to keep replacing the filter on a regular basis so the filter doesn’t get clogged. Clogged filters can end up costing you by damaging the heat exchanger or burning out the blower motor, so remain diligent.