Thanks for the quick responses! The existing furnace is an oil-fired York, 125 KBTU, which is at least 30 years old. I have been told it's horribly inefficient, but I don't know the number. The AC condenser is 3 tons and 25 years old (also not efficient). The house should probably have 2 zones (especially to deal with better cooling the second floor in the heat of summer), but I have been told that's not possible (at least not for a reasonable price). Otherwise, there are no noticeable issues with the current system, other than those endemic to scorched air heat. Each room has at least one supply vent and one return. The basement is below grade and is used as living area. There are two supply vents and one return in the basement area. There is no insulation between floors, but the basement walls are insulated (R-7.5). Beefing up the attic insulation is on the near-term to do list. The house currently does not have a humidifier, and while no one is suffering nose bleeds, the air is dry. So, I thought a humidifier would be helpful. I would definitely like to tighten the house (and new windows may be on the radar in the near future), but given that it is an older home, I think there is only so much that can be done. The Carrier dealer said the furnace would be no more than 100 KBTU, with the final determination after the house is measured and a load calculation performed. Both companies will also do a whole house energy audit prior to commencing work. So I would assume (and hope) the Lennox dealer will modify his numbers accordingly after the load calculation and energy audit. Our natural gas marginal price/therm is $0.83 Our electricity marginal price/kWh is $0.22 for on peak, and $0.07 for off peak. With regard to the Carrier condenser, what makes the 24ANB6 superior to the 24ACC6? I know a lot of people on this forum prefer Carrier over Lennox. All else equal, I have no problem going with Carrier (I know the Infinity controls are fantastic), but there is a $1,500 price difference... Thanks again for your help.

NC, 50 year old two story house with unfinished basement. Insulation is spotty. New windows all around, added air vents on the roof peaks. Exterior has wood siding with brick facing added 30 years ago. Basically a square house, the upstairs rooms are in a T formation with the roof double peaked. Oil furnace for first floor, 1300sqft, ductwork in basement which is unfinished clay floor, Window AC. Very little insulation except for partial ceilings(blown) and bathrooms which are well insulated during remodels. Second floor 800+Sqft - no ductwork, unheated. Insulation on side walls but nothing on ceiling. I also have a wood stove w/blower and run it normally during cold parts of winter. Keeps the oil bill down and is very warm except for far side of house. Want to ditch oil furnace, go with heat pumps. Thinking of maybe adding gas for backup heat, not sure yet. Looking at 2.5 ton HP for first floor and 1.5-2 for second floor. Guy is trying to sell me ductless for upstairs with two units, are these as good as running ducts and a standard heat pump? A friend recommended getting a "gas pack." for the down stairs. Not sure what he means unless it is a "dual system" I have been reading about. I guess I want the heat pump for heating and cooling but, I think I may need something else for when it gets cold. Wood stove would keep the downstairs pretty warm with the HP blower fan recirculating but, the upstairs will be a little cooler, especially farthest from the wood stove which has been closed off until now. Cooling is the biggest problem upstairs. I would like to use the wood stove sparingly and not have to run it at night. I will be insulating this fall as much as I can. I plan on pumping low expansion foam for the 1st floor walls and pink batting on the second floor ceiling. Any input would be great, I have been reading about options for several weeks online, but I need some real world experience and the forums here seem to be good. 3 kids upstairs now with a new one on the way in two months. Sorry for length but wanted to give a good picture of my predicament.

kaib don't put the cart before the horse. with all the updating you are performing including tightening up your home's envelope, I would start with a professional load calculation both heating and cooling. Get load calc in writing and on the software letterhead. Review carefully. Make certain both heating and cooling design temps used both inside and outside are correct for you and your area's climate. No fudging here. then I would do same for your ductwork system-supply,return, leaks,insulation qualities,size,etc. any issues with hot/cold spots in home should be addressed. you have central return in existing structure? how many? if just one, I would add another return to improve airflow in original structure. One return in new addition should be sufficient. your home is all electric? I do not like the idea of the mini splits. that would be starting point. equipment selection later. IMO

I'm disappointed that what had at first seemed a very balanced comment was followed by what seems to be misinformation and misdirection. People buy ground source heat pump equipment because they want to and can afford it. Or decide they need to in their locations. They're hugely more expensive than alternatives, which is why they're still not very common. "When’s the payback on a Tesla? People still choose to buy them for reasons other than the ‘bottom line’." Not a comparable. A false analogy. "I would not choose natural gas or propane for reasons relating to the environment, safety, IAQ & paying for yet another utility hookup for an energy source that might not even be used for months on end during the year." What effect having a gas furnace has on indoor air quality. Another hookup? Most people prefer gas cooking appliances and besides, the OP is talking about an existing home, he either has gas service or he doesn't. "Rather than spending perhaps tens of thousands of dollars on a Solar Array, I would sooner invest that same money, hopefully less, in a ground loop for a Geothermal system." Sure you would, that's the business you're in. The ground source heat pump market is not growing as expected by those in the industry, which suggests that your opinion isn't widely held or easily sellable. In many parts of the country, solar panels can have a quick payback. Not so ground source heat pumps. "I often hear about Solar Panels when geothermal is mentioned, as an alternative way to save money by creating energy." In a place like Texas, where electricity is cheap (other than during cold weather crises as they just experienced) there's likely no payback from a solar panel installation. People do it as a personal statement, call it for environmental or other personal reasons. Like buying the Tesla, not a financial decision. An HVAC system blows warm air when it's cold, cool air when it's hot. It's one of those things people don't care about - either it works or it doesn't work. Spending extra money for an exotic system doesn't equate to extra payback when the home is sold. Neither owners, nor visitors, nor people passing by, nor anyone else, concern themselves with what's doing the work. It's equipment that doesn't produce an experience for someone in the house if it's working. In the US, there are vast areas where electricity is cheap. It will remain so for some time. People don't spend money today to potentially save money 10 years out when market conditions may or may be different. I suspect you could build a house with mahogany or teak framing. Or you could paint the framing bright colors. Why bother, you can spend less money and effort and get something else that will do the same job. "We almost never use setbacks at our home - even when going on vacation for weeks on end with no one home, our geothermal just runs." You're combining two different things to produce confusion. Thermostats that have a setback feature ALL are set up to provide lower overnight temperatures to have more comfortable sleeping conditions and then a recovery in the morning before wakeup time. As sleep specialists recommend. That in demand comfort features isn't possible with ground source heat pumps because the warm up period from a setback is too slow to be convenient to use, absent triggering a secondary heating source (like a furnace) to help. THAT'S why you don't "believe" in setbacks with a heat pump - they don't work. Turning down a thermostat during heating season when the home will be unoccupied is not a "setback" as that word is most commonly used. It's done to save money, why heat a vacant house? No setback thermostat is needed, even a dumb 50 year old analog thermostat can be turned down.