What do AC Filters do?

Ac FiltersThe air filter keeps pollution and debris out of your HVAC system, ensuring proper and efficient operation. A dirty filter will slow down the air flow, making both the furnace work harder to heat your home and your AC work harder to cool it. This wastes energy and can result in higher energy bills.

To change the temperature in your home, your heating and air-conditioning system sucks in air from a room, pulls it over coils to heat or chill it, then blows the tempered air through ducts to the other rooms in your home. The air filter is stationed at the point where air is pulled into the system. It traps air-born particles that get sucked in with the air and keeps them from blocking the blower and clogging up the coils. Clogged coils can not heat or cool the air passing over them, and they may damage the system. So, the air filter helps your heating and cooling system do its job, keeps it running efficiently and protects it so it will last longer.

As the filter does it’s job, it gets loaded with more and more particles. This actually has the effect of making it more efficient, but it also increases resistance and reducing airflow. When this happens, it is time to change the filter. How long it will take to happen depends on the MERV rating (MERV stands for Minimum Efficiency Reporting Value) of the filter; the amount of dirt particles in the air and the size of the filter.

The MERV ratings indicates the percentage of particles the filter will remove from the air passing through it. In general, a MERV rating of 6 indicates that the filter will capture up to half of the particles in the air; a filter with a rating of 8 will trap 70 to 85 percent of air-born particles it encounters; and a rating of 11 or higher means that the air passing through the filter is up to 95 percent cleaner when it comes out of the filter than it was when it went into it [source: Lowe’s].

If you do not change the filter, the air flow will decrease, and the system will not perform well. In Addition, if the filter is too dirty, it starts to become a source or air pollution itself.

Dirty AC Filter

Dirty AC Filter

If you take the filter out completely, you would solve the low air flow problem, but this victory would be short lived. The particles that the filter would have taken out will now build up on your evaporator coil and eventually cause it to fail.