I have been doing air conditioning repair in Fayetteville NC for about 5 years now and of all of the questions I am asked during service calls how to choose the right filter is high on the list as one of the the most common. When choosing a filter for their air conditioning system most people opt for the $3 wal-mart special that comes with three in a box. This is a great option for the average person. But those who suffer from allergies like myself may need something that catches a little more of those dust and pollen particles. For this I’ll start with the pleated filters.
Those pleated filters or most often reffered to as 90 day filters are definitely the best option for those that suffer with allergies. There is a concern about them though from an HVAC professionals position. Some of these filters go overboard with their ability to trap particles and actually cause the system to run a lot harder and even freeze up constantly. When a unit is starved for air major damage can occur including compressor breakdown. This is why filter selection is so important.
I personally use the filtrete brand of filters for their ease of selection. If you are an allergy sufferer I recommend that you start with these. Filtrete filters are labeled by a number value. The higher the number the more particles they trap (and the more air they starve the unit for). I wouldn’t recommend the very high valued filters they have as I have seen them do more harm than good. I personally use the filtrete 400. It keeps my allergy problems at bay and doesn’t starve the unit for air (and doesn’t cost an arm and a leg!) . If the 400 isn’t enough for you then you can try the next one up.
Can I really change them every 90 days?
Pleated filters have more surface area which allows them to last longer. If you have pets that shed a lot you may have to change them sooner. This of course would apply to any filter.
The only downside…
The only downside to A/C filters is that they do nothing against viruses and bacteria. In fact they are a cesspool for bacteria since they are collecting dirt and airborne food particles from cooking. These bacteria grow on the filters and since they are in the air stream are distributed throughout the home via the A/C system. There is a solution for this however. The Guardian air cell can be installed in the duct system and kill all bacteria on the filter and in the home in air and even on surfaces. This can be installed for less than $1000 and comes with a two year warranty.
Here is a very short ( 1 minute) video on how the guardian air works.