There are 3 different sizes in Duval. The ez way to find a good place to find them is type your number (FILXXFNC0021) into Google. This will give you the OEM filters. There are also non OEM filters available for less with the same MERV rating. You may also want to search MERV to see what that means. MERV 8 is what I use. Some may want to go to the Merv 11. I got mine from Shortys. http://www.shortyspumps.com/index.ph...d=FILXXFNC0021

It's NOT the filters. I was standing near one of the vents the other day, and it was blowing hot air. All the ventilation is in the ceiling, and the air in the "tubes" gets hot, and must clear before the cooling starts thru them. Then it cooled just fine.

At least that is what is happening in this home.

GeorgeT- Installation of 5" high efficiency filters usually requires modification of the return air ductwork.

Could someone more knowledgable than I please explain why larger is better? In filters that is:)

I was once told by an AC guy that my HVAC system would be better served by the cheap (i mean cheapest) Home Depot air filter. And just change them monthly. No real cost since they were <$1 each. Is it for the system or the person (allergy?)? Those better filters really need a large force of air to pull it through the dense filter? No?

It would depend on your system. My system has a cavity that receives a 4" thick filter. High efficiency filter which requires yearly changing.

ductwork
 

I am willing to wager up to $63.87 (which is my entire cash on hand) that you are involved in the HVAC industry. I agree 1000% with your statement.:highfive:

Mrfixit- Your intuition is correct- 37 years as an HVAC man and counting down to retirement in TV! (next year?) What were you doing prior to retirement? I can't imagine parting with all my tools but I can't take them all with me- that's going to be tough. We'll have to meet!

The 4 & 5 inch filters are often the equivalent of a HEPA filter and protect the AC coil, heat exchanger, and blower motor & wheel from dust along with helping people with allergies and keeping the dust down in the house. Yes they are very dense, however their depth and accordian style makes for a lot more filter area to overcome this density. I would rather see someone use the cheapo filters then see them use the 1" "high efficiency" filters because these filters are very dense but without the extra area necessary to overcome the static pressure.

Never could keep a job..so I went in business for myself...... I mostly cleaned the floors and:D swept the toilets. (got so good at it that my wife still lets me do all the:( cleaning at home).......BUT.... did have the good fortune to be surronded by people a heck of a lot smarter than me. SPECIALITIES involve losing Golf Balls ..AND...:beer3:...AND...feeding bait to the fish. My "PASSION" involves utilizing "my:1rotfl: skills" to help those less fortunate in our surronding communities. I brought along just enough tools to be considered dangerous......................................... .................................................. ....................... Thank you ducati1974 for your insight on HVAC. I appreciate people like you who are willing to share their knowledge. I would like to meet you,also.