Welcome back April. I am glad to see you have done some more homework. I own Carrier Infinity equipment, so I know it will keep you comfortable in the cold Michigan winters. I have heard mixed opinions about Lennox, but I have no direct experience. I am going assume Contractor #3 is a competent installer and he has sized your equipment properly. I am glad to see he is offering the Carrier rebates. Here are my comments for the Contractor #3 options: Furnaces: Option 1: I would not recommend an 80% AFUE furnace for your winters. Option 2: This is the two-stage Infinity furnace. It is a good furace and will work with the Infinity controller. Option 3: For $300 more you get a three-stage furnace. This would be my recommendation with the Infinity controller. Air Conditioning: Option 1: This is a single stage compressor. I think 4 tons is oversized for your climate. Option 2: This is the two-stage compressor. This is the AC to get if you have humid summers. This AC will work with the Infinity controller. I believe this AC with the 58MVC furnace will qualify for the $1000 Carrier rebate. Option 3: This AC in my opinion is over kill for your climate. It is not worth the money. Ask contractor #3 how much a 10 Carrier labor warranty would cost. You should consider getting this warranty for peace of mind for the next 10 years. I would also want to upgrade to a 4 inch media filter. This should not be a costly upgrade assuming you have to room to fit it. You should also qualify for the $500 tax credit if you haven't already used it.

Our 25HNA Carrier is on its THIRD compressor (first one failed, a second died this spring) and now we have an issue with the TXV valve. At this moment the tech is attempting to recover the valve by using some special substance that has worked "wonders" he says, to a pattern of problems with the original issue of failed compressors. He says that the refrigerant systems is meant to be sealed and that once it is cut to replace a compressor or TXV valve, it ramps up the possibility that contamination can enter the system. Between issues from faulty Bristol two-stage compressors, to those Copeland units which had a lubricant that clogged the system using the R410A refrigerant, and the openings/closings of sealed coolant lines, what does one expect? Once that happens, he says, it's IMPOSSIBLE to completely reverse that. I'm being penny wise/pound foolish as I'm paying up to $700 to attempt to cure or replace the valve (he is installing some kind of additive), but the alternative to the short term gamble, is DITCHING the unit (7 years old) and getting another $8,000 unit for a home we plan on leaving in the next two years. I'm investigating at this time whether it's possible to go for small claims ($5K cap in my state) at this stage, and perhaps the attorneys would rather settle than come to court. This kind of pattern of failure is amazing, my tech says, and I'm seeing this all over the HVAC forums here. Surprising that this hasn't yet been swept up and slathered all over the mainstream media, as it seems the big companies are trying to keep it swept under the rug.

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.

I have asked about the AC you recommended and the following comments were made by my contractor: "The Performance series a/c's do not communicate with the system. We would need to jump up to the Infinity series to communicate. There is a performance series furnace with a variable speed blower but for what the Infinity system can do I strongly feel that it is not worth it. We will need to jump to an Infinity single stage 16 seer a/c to be totally communicating" Do you agree with his comments? What 80% furnace would you recommend if I go with your recommend AC? On the Furnace, it is located in a finished basement that was completed a few years ago. In order to run new lines would require cutting several holes in our painted ceiling and that is something we would prefer to not have to do unless there is a significant difference in the higher efficiency furnaces. I still don't understand the major differences other than efficiency which will save money in the long run? Here are the revised quotes with 4-ton AC Revised Quotes 1A. CARRIER 13 SEER A/C - 80% FURNACE - $6565 58STA090---1--16 - COMFORT SERIES 88,000 BTU SINGLE STAGE FURNACE 80% 24ABB348A00 - 3COMFORT SERIES 4 TON AIR CONDITIONER CNPVP4221ALA - PERFORMANCE SERIES 3.5 TON CASED EVAPORATORCOIL TC-PAC01 - COMFORT SERIES PROGRAMMABLE THERMOSTAT FILTER CABINET & MEDIA FILTER MANUFACTURE REBATE OF $150.00 2A. CARRIER 15 SEER A/C - 80% FURNACE ARI6385839 - $7705 58CVA090---1--16 - INFINITY SERIES 88,000 BTU 2-STAGE VARIABLE SPEED FURNACE RATED 80% 24ABC648A003 - COMFORT SERIES 4 TON AIR CONDITIONER CNPVP4821ALA - PERFORMANCE SERIES 4 TON CASED EVAPORATOR COIL SYSTXCCITW01 - INFINITY TOUCH SCREEN THERMOSTAT FILTER CABINET & MEDIA FILTER MANUFACTURE REBATE OF $150.00 3A. CARRIER 15.5 SEER A/C - 80% FURNACE ARI6385574 - $7,950.00 58PHA090---1--16 - PERFORMANCE SERIES 88,000 BTU SINGLE STAGE WITH ECM FAN MOTOR RATED 80% 24ACC648A003 - PERFORMANCE SERIES 4 TON SINGLE STAGE AIR CONDITIONER CNPVP6124ALA - PERFORMANCE SERIES 5 TON CASED EVAPORATOR COIL TC-PAC01 - COMFORT SERIES PROGRAMMABLE THERMOSTAT FILTER CABINET & MEDIA FILTER 4A. CARRIER 16 SEER A/C - 80% FURNACE ARI6406556 - $9465 58CVA090---1--16 - INFINITY SERIES 88,000 BTU 2-STAGE VARIABLE SPEED FURNACE 80% 24ANB748A003 - INFINITY SERIES 4 TON 2-STAGE AIR CONDITIONER CNPVP4821ALA - PERFORMANCE SERIES 4 TON CASED EVAPORATOR COIL SYSTXCCITW01 - INFINITY TOUCH SCREEN THERMOSTAT FILTER CABINET & MEDIA FILTER MANUFACTURE REBATE OF $700.00