I have two fairly new AC (one is Trane 13 sheer replaced in 2008 and another is Trane 15 sheer (new type of coolant) replaced in 2010). Home Depot sells FPR rating 5, 6 and 7. There are huge differences in pricing. For example FPR 5 costs 2.50 a piece but FPR 6 or 7 costs 9.0 a piece. If I use the most expensive, I need to buy 8 of them a year (every 3 months for two AC). that's $72.00. But least expensive ones will cost 1/3 of that. I have been using FPR 7 which says if you are allergic to small particles, use it. Since we are not allergic to anything, I'v purchased FPR 5 and wanted to start using these for cutting cost. I went through my AC documents, they don't say which rating to use. Rather they say use the same filter which was provided by the installation dealer. For me, they didn't even provider filters. So I wonder if FPR 5 is sufficient for my AC (TRANE) I appreciate any comments.

I'll try to keep this brief, as it's been a saga! A couple of months ago, saw water dripping out of my AC drain holes on the side of the house. Went into the attic and the drain pan was full, rusted out, etc. I called the AC guys and they replaced the drain pan and rerouted the servicing line to the front of the unit instead of at the back of the unit in a very hard to reach crawl space. Things seemed fine. Couple of days ago, I noticed water leaking again. Went upstairs and the pan was filling up again. I poured bleach down the T connector but that didn't help. I called the AC guys out again, they said the primary drain line is clogged. They blew it out, but said if problems persist, I would need a plumber. Well two days after they left, problem still happening. I went to the sink where the AC drains to, and took the P trap off the bottom of the sink. When I did, immediately some water started to gush (main water was off already) and I saw a huge clump of hair descending down. I fished it out and fished out some crud from the AC drain line itself. I could feel air blow out the end of the line and the water running steady. However, I noticed that for like 30 seconds when the AC unit comes on, it will still leak water out the primary drain line into the pan, then stops, which is better than before when it did it all the time when on and never stopped. I have blown out the line both ways myself with a compressor, and I have poured hot boiling water down the servicing T connector on the main drain line. However, I still want to know why water is still leaking into the pan for those 30 seconds at a time when it initially fires on. Also, a new problem I have now is that the sink has a gurgling noise on it, whereas before all this crap started it did not. What is causing it and how to prevent it. do I still have a problem with a clogged line? thanks for any help guys!