beth answers going down your list.... 1.length of life can vary depending on use, environment, yearly PMs, and quality of original install I personally believe 15 yrs min is a good target for good equipment and believe me there are some real junk HVAC on the market 2.you can not compare today's HPs against those 10 yrs and older. as different as night and day especially in the area of supply temp. Supply temp on a properly charged HP should easily be in low 90s depending on outside temperature. one reason I put in a dual fuel system was because while I liked the idea of operating savings of electric vs nat gas, I was somewhat skeptical of the acceptibility by myself and family as far as comfort. No problem. it is fine. In fact, I wish I had gone with an air handler rather than backup var speed furnace. This past season I used about 60 therms of nat gas for heating as the heat pump did the primary heating. 3.I really think you are confused on question 3. Temperature is temperature regardless of the speed it is delivered. On today's high eff furnaces that are two stg (newest mdls can have three stgs) models with var speed blowers, the heat that is delivered is what I call soft, quiet, gentile heat as opposed to the conventional furnaces that deliver very hot noisy heat. The temperature from the high eff var speed condensing furnaces while higher than today's high eff heat pumps is lower than the hot blast of non condensing furnaces. You may get some debate on this subject but based on my measurements that statement is correct. 4.There is no such thing as a dual fuel heat pump. A heat pump with backup furnace(as opposed to an air handler with heat strip backup) is called a dual fuel or hybrid application. The operating savings depends on the price of electricity and price of nat gas as well as the efficiency of equipment for a high eff heat pump and nat gas furnace. A heat pump provides AC just the same as an AC condenser. I believe I have given you the fuel comparison calculator in your previous thread which offers an accurate indication of possible savings. I really believe you are overthinking your situation. These are the minimum specs I would use for HP selection. 15 SEER, 12 EER, 9 HSPF full BTUs in both heating and cooling mode matching var speed air handler or var speed furnace scroll compressor preferred electronic demand defrost thermostat that controls blower speed like the HW VisionPro IAQ IMO

I agree, With a 2 stage system, there won't be much difference between the 2. I would suggest the NATE dealer if for no other reason than they take the time to be educated and really, the installing dealer makes a big difference in the satisfactory outcome. They will have more resources to fall back on if they run into a question on your job, and they will also generally have a more thorough understanding of the little things about unit start up and such that can make a big difference in the long term performance of the system. This is not to say that the other sources you have mentioned may not be fine. It is just my opinion that dealers who care enough to take continuing classes and training will probably care enough to satisfy you better. As to heatpump vs AC. The advantage of a good heatpump with a low ambient control is that you can run it for heat when the outdoor temperature is around 30 or higher. A good Thermostat will automatically switch your system to furnace from heatpump based on the outdoor temperature. You are insightful enough to realize that is it usually either cool and mild, or really cold where you are. That is why the heatpump is such a good fit.

where does one find "degree days Centigrade scale" for their climate? I am in Sarnia, Ontario and this is an area where a heat pump supposedly feasible. (i would mate it with a high efficiency furnace), but all the techs i speak to have advised against it saying i am wasting my money, it won't work...etc. I have gotten a couple of quotes for 16 seer 2 stage heat pumps with HE furnace and they have been 11-12K. i can get the same setup with 16 seer ac for about 8K... doesn't that seem like a huge jump for a heat pump over an a/c condensor? i'm about to give in and just go with an a/c unit, but the math says it is about 30% cheaper to heat my house with at heat pump over a 95% efficency furnace...and that is using a COP of 2.5 at 30 deg f. i am thinking about importing my own equipment from the states where prices seem much more reasonable (96% amana furnace 16 seer 2 stage heatpump, coil, txv for $3800) and just having a local guy who is willing to install it. that blows some of the rebates that are available, but it still might be worth it. all i know is it would take more than a decade (and likely much more...) to recoup an extra $4k.

A heat pump is best used in mild climates in which average winter temps are above freezing most of the time. While you can use them in more harsh climates, there are times in which out door ambient challenges must be over come. (They operate by removing heat from outside and placing it inside the structure.) The best bang for the buck comes from when your only other options are propane, or electric resistance heating. A heat pump (depending on climate) is more efficient (typically) than propane or electric resistance heating methods. If your furnace is natural gas a heat pump isn't probably your best bet. Even though Seattle climate is probably a good fit for a heat pump.