How often do I have to replace the filters of a central A/C system?

Question

Just moved to South Carolina and it's been very hot and humid. Our house is newly built and we have 2 zone cooling/heating. The A/C units are cooling fine but I want to know how often do we change out the filters and/or clean them.

Answer 1

Replacing filters is a function of loading rather than time. If you have 9 dogs, 2 cats and 8 kids, you may be replacing your filters every two weeks. Some folks get by with every two months. Simply look at the filter and see if it is loading up with dust and debris. If so, toss it and install a new one. Some warning signs of a loaded filter are whistling, difficulty in achieving the desired temperature, and a feeling of clammy or stale air in the home.

For a 1" media, your best bet is the pleated filter right off the shelf at the building or hardware supply store. This has a zig-zag or waffle effect on the media, as opposed to the spun fiberglass which is nearly useless. I could tell you countless horror stories of "washable" filters creating big problems, but I hope you take my word that they are trouble.

Answer 2

Check them monthly. How often they need replacement (or cleaning if they're the "permanent" kind) will depend partly on what goes on in your house. For example if there are smokers the filters get dirty faster. The very cheapest filters should probably be replaced monthly regardless. The more expensive kind may last longer and filter better.

I'm not a real fan of the so-called "permanent" filters as I don't think they clean up very good.

Also - new construction can have a lot of sawdust, drywall dust, dirt, bugs, etc. in the air ducts and if this is the case, change the filter often for awhile. If the ducts are really dirty, have them cleaned.

Answer 3

In general, if you have a regular filter every 4 weeks is normal. If you have a hepa filter or something fancy refer to manufactures guidelines. I assume that thye would need to be repalvced soner since they clog up faster. Thsi also depends on amount of use. If you don't use in much them maybe go 8 weeks.

You can always check to see how dirty the filter is before replacing.

One trick we use (it only works on some units with enough space) is to put a cheep blue filter on the outside and then buy a good 3M filter in the normal spot the manufatiure slot in your AC unit. make sense? This allos you to trap some stuff in the cheep filter making the expensive filter last longer you can replace the cheep filter twice before you replace the really good filter. yoou just doubkled the life for a not a lot of green.

Answer 4

Change it once a month during hot weather when its running full time- it collects dust and pollen- and their cheap. Also check the outside Condensing Units, hose them off once in awhile- keep them clean and change those filters so the inside coil does not collect dust on it- you will get 20% more efficiency that way.

Answer 5

You should be changing your filter(s) every month. More often if you have several pets.
Also, you should have your air conditioner cleaned before the season starts, just like having your furnace cleaned before the cold season.

Answer 6

Energy-Efficient Air Conditioning
http://www.energyguide.com/library/EnergyLibraryTopic.asp?bid=austin&prd=10&TID=17224&SubjectID=8367

"In most cases, filters are easy to replace and result in more effective air conditioning. We recommend checking the air filters monthly, and replacing at least once a season as needed."

Answer 7

If you are using the the cheap blue fiberglass (?) filters, 1/month. If you are using the pleated fiber ones, they should be good for at least 3 months (?).

Answer 8

the manufacturer suggests changing the filters every month and doing a good cleaning anually

Answer 9

Monthly

Answer 10

They should be changed every six months. But I change the one I have every three months.