I'm replacing my ADP coil after two years of operation. I have a small leak in one of the capillary tubes. When I spoke with a Trane authorized dealer I was informed of two things. First the ADP coil does not carry the same warranty as Trane 1-5yrs in my case vs. 5-10 for trane. Second, even though ADP is going to replace the coil they will not warranty it beyond the date of the original start-up. ADP's clock starts running 1yr after manufacturing. They don't keep records of when they were sold or who they sold them to. This is probably not the case it's their customer service center passing this along. So as I would see it if your Heat and AC guy is pairing an ADP coil with your AC it's about cost. Here in Ga many companies working for builders rig these combos to save the builder money and to keep a job with them. Save yourself the headache and go with all trane parts because you aren't going to get the warranty with ADP. Most importantly our service men are receiving calls on these all the time. ADP builds them to order now so they don't have as much standing inventory as they once did, but consider this. They build a coil in the hay-day of building and it sits on a shelf for 6 mos. The builder has a system installed around that same time but doesn't sell the house and 18 mos later the bank owns it. Someone comes along buys the house from the bank and has the system turned on and the coil is already out its 1yr warranty. The Trane furnace is still in warranty but the coil is not. Just a thought.

Everything needs to be new & the ductwork new & done right. There is NO advantage buying high SEER if everything is not done correctly & matched. A quality installation & setup of the equipment is the most important factor in achieving a rated SEER. Florida varies from 2000 to 2800 hours of run time per year, therefore get everything done right. First, do all you can to reduce the heat-gain & then have a manual J heat-gain calc done. Then, a manual S for sizing equipment, then a manual D for doing the Duct System. DISCLAIMER: I assume NO responsibility for how anyone uses the information I provide in posts or on my websites. I provide information for better understanding, edification & communication between contractors, techs & customers'. A licensed Contractor & licensed Techs should always do all HVAC/R work! - udarrell Here is a link that might be useful: udarrell.com

Thanks very much for your reply. The upstairs is 1100 sq ft. The main level is the same, as is the basement. The upstairs furnace is 50 BTU. The heating is natural gas. There is ductwork in the basement that supplies the main floor. The basement is unfinished currently. That may change. There are six vents upstairs with one return in the hall area. The return is 12x24. There are eight vents downstairs with one return in the hall area. The return is 12x24. I was told that the unit upstairs had a leak/crack in the compressor that could possibly leak carbon monoxide. There are marks on the outside of the unit that looks like burn marks. The heating unit performed fine the last time we used it before we found out about the burn marks. It is about 25 years old and about 8 SEER. The cooling unit seems to run almost all of the time in the summer. The downstairs unit also performs ok but needs a serious duct cleaning due to water from a pipe bursting in the kitchen getting into some of the ducts. We haven't used it in quite a while. The house has humidity problems sometimes (window condensation and my indoor hygrometer can get near 80% in the summer but is around 50% in the winter) and we would like a system that can take care of that and be more efficient. The upstairs unit seems to run all of the time in the summer. The stat is usually set around 75. I was told that 16 SEER two-stage would fit the bill. Other ac companies told me I needed nothing more than the typical 13 SEER. Some family members have asthma and I also want something that will help with that. How can I tell if my ductwork really needs to be enlarged? Thanks much for your input

Tigerdunes brought up demand defrost versus timed defrost. For the past 18 years, I have dealt with my Lennox defrost scheme. The only times I heard it go into defrost mode were when the unit was first running in heat mode. The unit would switch over from heat to defrost, the defrost cycle would complete and everything would turn off. I never heard it run a defrost cycle when it was not first heating. I rarely heard it go into defrost. I never heard it defrost on a fixed cycle such as every 90 minutes. Am I to understand that a Carrier will just go into defrost mode every X minutes whether it needs it or not and is not in a heating cycle; just turn on and defrost itself? I found this information in the Carrier 25HNB6 heat pump installation instructions: AUTO defrost adjusts the defrost interval time based on the last defrost time as follows: When defrost time When defrost time 3-5 minutes, the next defrost interval=90 minutes. When defrost time 5-7 minutes, the next defrost interval=60 minutes. When defrost time >7 minutes, the next defrost interval=30 minutes. The control board accumulates compressor run time. As the accumulated run time approaches the selected defrost interval time, the control board monitors the coil temperature sensor for a defrost demand. If a defrost demand exists, a defrost cycle will be initiated at the end of the selected time interval. A defrost demand exists when the coil temperature is at or below 32_F (0_C) for 4 minutes during the interval. From that description, if the time interval elapses and the coil is not at 32 degress, then no defrost will take place. That, to me, sounds like a form of demand defrost. Is Baldloonie saying that the coil could be at 32 degrees or less without frost and, therefore, a defrost cycle would be unnecessary? What kind of ambient sensor detects presence or absence of frost? Neohioheatpump asked, "When your old A/C would run, was it producing water?" It was producing water and I saw it dripping from the condensate drain. One weekend I went out of town and came back to find water on the floor around the return box that the fan coil sits on. I opened up the access and found the interior insulation of that box soaked. Turns out the condensate line was plugged. Took awhile for that to dry out. On the other hand, this past summer I did not see water dripping from the condensate drain. The drain line was not plugged and the drip pan seemed dry. I thought it was because I had dried out the air so much with the two dehumidifiers that there wasn't enough remaining for the A/C to remove. Cooling was normal. Running the fan on manual started with the installation of the Lennox and an associated Honeywell Electronic Air Cleaner. The house suddenly became dusty and I blamed the EAC for not doing its job. The Honeywell zone representative came to my house, sized up the situation, and told me to run the fan on manual so that the dust would remain suspended in the air and available to be captured by the EAC. I did that and it was of no help for the dust situation but it did help reduce the temperature differential between the first and second floors during cooling so I kept doing it as a matter of routine. Thus, I cannot say that not running the fan reduced the humidity. Though I complained about humidity, the heat pump contractor never told me that I was humidifying the house by running the fan (on orders from the Honeywell rep). I will continue to run at least one dehumidifier in the completely below grade basement during the summer because I want that area to be warm and dry to avoid mold and mildew. I've been in the basements of other houses in the area that don't use dehumidifiers and they stink. Mike Home said, "You stated in an earlier post that you run the fan in the summer because the upper floor is 2-3 degrees hotter than the lower floor. I think adding the attic insulation will help this." I agree that adding attic insulation could help. But, having a Dutch Colonial house with a barn-like roof that is covered in dark shingles on the east and west sides causes a lot of heat gain through the second floor walls. I'm not keen on opening the walls to determine the amount of insulation or add to it. Changing to a light-colored roof would make the house look out of character with the neighborhood. There are newer shingles that reject heat gain that I will investigate. Mike Home also said, "You could also zone the first and second floors, but this is expensive and probably not feasible with your current duct work." There is but one main feed duct and it runs through the basement. There is no way to segregate the room feeds in this scheme without doing each one individually. I'll leave that expense to the next owner.