If a mod thinks it's beneficial, he/she can feel free to pin this thread to the top of the Residential HVAC forum.
There have been many recent threads with people seeking advice on newly proposed systems. In almost every thread, the AHRI matching data comes into discussion, and at times it can be confusing to the original poster. Per Jerry D's suggestion, I'll give a few pointers for anyone to read through, hopefully making it easier to search through AHRI. This isn't the answer to all your problems AHRI may give you--especially the annoying, newly required security code--but hopefully it makes things easier and more comprehensible. I am not a professional and don't plan to make my advice seem as though I am one, but it is valid and has helped me look up hundreds of systems to date out of boredom (or to help somebody).
1. What is the directory? The AHRI (Air Conditioning, Heating, and Refrigeration Institute) directory contains listing of all performance data--that is, capacities (btu's) and SEER, EER, and HSPF efficiency ratings--of rated heating and cooling equipment. See below for what is rated and what the status of matchups means.
2. How do I get to the directory? The AHRI directory is located at http://www.ahridirectory.org/ahridir...ages/home.aspx. Select the system type you are researching. The most common are "Air Conditioners and Air Conditioner Coils" and "Heat Pumps and Heat Pump Coils." Step one is to know what you're looking up.
3. What equipment is rated? There are different types of ratings in the directory. For conventional systems involving an air conditioner, coil, and furnace, combination ratings are very common for newly installed equipment which involves the use of a variable speed furnace. It is a combination rating because the variable speed furnace, or a furnace with an ECM motor, increases the efficiency ratings of the entire system, so it is included in the rating. There are also ratings of standard coil and air conditioner matchups where the furnace does not change the ratings (of course, airflow from furnace over coil has to be proper to get any of these published ratings, and ductwork, and refrigerant charge, and so on, which is why these ratings can be deceptive at times--see below...). These ratings may involve the use of a 3rd-party manufactured coil or a coil from the original equipment manufacturer (OEM) such as Carrier. Heat pumps can also have combination ratings or stand-alone ratings with a coil since they can be used in dual-fuel applications. In this case, you'd search the heat pump directory as pointed out above. Knowing the tricks to searching some of these model numbers should be a thread in and of itself, and I'll post some tips on that below.
4. What do these ratings mean? Nothing really, except that the system produced those particular performance figures at ideal operating conditions determined by AHRI, which exist in nearly no home. However, they are a good indicator of how efficient the system you are purchasing is, and whether it qualifies for the new tax credit (30% of qualifying component(s) up to $1500). The ratings are good for comparative purposes, but as other members here point out, many, many aspects determine actual operating performance of and system--that is, airflow, refrigerant charge, ductwork design/size, proper configuration, etc. An "active" listing denotes equipment that is currently in production, and a "discontinued" rating denotes equipment that is currently out of production but still available, in decreasing quantities.
5. How do I search for a particular model, such as Carrier's Comfort 13 heat pump with variable speed fan coil? That's the trick--knowing the model nomenclature for each manufacturer. The hope is that your contractor has provided you with all the model numbers of the equipment to be installed. If that is the case, you would see model numbers (in this case) 25HCB336A003 and FV4BNF003T00. AHRI keeps the model numbers simple, most of the time, and unless you have been here before, you would not be aware that you would only enter 25HCB336 and FV4 to avoid errors. In general, limit your outdoor unit model numbers to all characters up to the size and coils, furnaces, and air handlers just to the first few characters of the model number. Doing this allows you to see what slightly different matchups produce. Also, many times there are subtle variations in model numbers, indicating in the directory with parenthesis (for example the FV4BNF003T00 above is entered as FV4BN(B,F)003 because it comes in both single-piece and modular configurations) or asterisks (which for some reason York/UPG loves). I'm using Carrier as an example here, but feel free to post if you need help with the model format of any other equipment. With Trane, for example, your 4TWR3036A1000AA (are there that many people on earth?) only needs to be entered as 4TWR3036.
This may or may not have helped much, mostly because of the confusion when it comes to entering the model numbers. However, I'll still do my best to look up ratings when I can--provided AHRI gets rid of the security code we have to key in each time. It's like searching CIA data now, all so AHRI can control their traffic.
I will probably be adding to this thread, but that's it for now.