The system is probably not undersized. More likely, you have an inefficient system and leaking ductwork. Do you have a lot of dust? Do you have mold growing around refrigerator door and in the bathroom? If so, ductwork needs to be replaced. New ductwork needs to be sealed properly! Also, location of air handler is a problem. When the ac runs, does the AH sweat? If so, this indicates a further (large) loss of efficiency. Moving AH to basement and installing properly sealed ductwork will easily save you 15% or more of your energy dollar. Best and cheapest (by far) way to save money is to re-insulate your house. Brand? Get the right contractor. Then, look for Trane (American Standard) and Ruud (Rheem). Other brands are not far behind. No matter what brand, get the right contractor. You can investigate brands until you are blue in the face and still end up with a terrible system.

Hi TD and thanks. We do have other gas appliances, and still are considering the gas generator backup so I feel that the dual fuel system is still of most interest. At present, one major dilemma is replacement of all of the ductwork, which was suggested by the Carrier dealer with the high prices, and the Trane dealer who miscalculated, waited weeks to give an estimate and did so only after I called them numerous times. They also have not yet gotten back to me with the corrected estimate. Also the latter really did not want to give me the equipment specs. The Lennox dealer has been very responsive. He initially recommended replacing only some of the ductwork, but thought we could leave the trunk lines alone for the most part. So one of the elements, which adds quite alot of expense, is whether or not to replace all of the ductwork. The Lennox dealer would be willing to do that, but it would add over 4k to the cost. Any thoughts on that? All the dealers commented on the adequacy of the duct system after a rather cursory inspection. When I questioned the Carrier rep. further he indicated that he could tell just by looking at a few spots that the ductwork was "too big in some lines and too small in others), and the branching from the main duct was not done properly. Also any thoughts on a good Lennox package? Is the package suggested by their bid adequate? It has I think a single speed (coil? compressor?) paired with a 15 SEER unit. He calculated that would give a 14 SEER used together. I have tried to find another Carrier dealer who services my area with no luck. The only other Carrier dealer is a national chain store. I had scheduled a visit for them to give me an estimate at the very beginning of this process; however, the appointment was cancelled with no follow-up. I called them back to reschedule and the earliest appointment that they have would be mid-June--I hoped to have installation complete by then! THe Lennox dealer said that had previously offered Carrier, but that the distribution center for our area was so unresponsive that they had many concerns about dealing with them because they had problems obtaining parts in a timely manner. The Carrier dealer also said that the distribution center did not carry some equipment such as the Carrier 14 SEER heat pump. Unfortunately, we live in a small town, and even the dealers from whom I am receiving estimates are in other surrounding towns--no one competent in our community! Thanks again for all of your help. Regards, Beth

1 and 3 would need externally mounted hot water coils and the pump as you say. Be nice to have the all in one unit from First Co. The Bryant quoted can do 16 SEER but not on a mismatched air handler, probably more like 14 SEER. The variable speed blowers on 1 and 3 are nice as well. The Carrier is a 2 stage outdoor unit that rates up to 17 SEER and would qualify for the $1500 tax credit and maybe other utility or state incentives. The A-S proposal is the builder model, not the Allegiance. Not quite as nice of a unit. The system quoted is 14.75 SEER, if a different air handler is used, you'd get over 16 and a tax credit. Pretty dumb of him to quote you the 4TEE3F31.

Thanks, I found the plenum/evap manuafcturer (AllStyle ASLBX84422T ) and they sell the units with duct board so probably best to stay with it. I have actually worked with duct board a litle but on this unit it looks like you have to disconnect the the coolant line to get the top off - the manufacturers manual does't really say anything about this but it seems obvious from this pic - I stopped an AC guy visiting my neighbor and he seemed to say that he would put the sheet metal over the ductboard - I suppose this would work but probably just as much work as replacing ductboard and recharging AC.