If the old heater heated the house,then why would you suddenly need insulation is what I'd ask. You probably could use more insulation, but that's a whole other topic. (search air sealing--lots of info on here about it.) Does it blow heat and just can't keep up? Did they undersize you? Do you know how big your old system was vs the new one? Hindsight is 20/20 but Costco may not have been the route to go....I doubt the contractors who hook up with Costco are the best and the brightest. The good ones don't need Costco to get business. Sorry :( Good luck. I am curious if your house is an example of what my dealer mentioned when I thought he was oversizing me a little. He said that he didn't want me calling when the temps got unusually low (like they have been here in NJ) and saying the house is cold. BUT, most people on here say oversized is bad so I guess you have to pick your poison. My heat is great, the ac works well, but if it was smaller it would run longer and take out more humidity. At least I'm not cold. I would not contract with any of these people you've dealt with if you decide to get more insulation. Ask for referrals on here and you might be able to find a reputable installer. Or, if you only want insulation you can diy it. PS. My contractor was one of the higher priced, in demand ones, and I STILL had issues. I think I got a new guy (just one) and a Friday, beautiful fall day (like lets finish up and go home kind of day!)I Have to remember never to do important stuff on Fridays in case something goes wrong. (contractors and surgeries) I guess it's buyer beware.

That would depend on how he wired it. If he connected the single stage stat correctly, the furnace operates on 1st stage for a preset time (usually around 6-8 minutes). If the stat is not satisfied in that time period, it will go to 2nd stage and satisfy call for heat. If he jumped both stages together (w1&w2) the furnace will always go right to full fire. depending on vintage of furnace, there was some differences in jumpers/switches but this is the genearl answer. I feel you are not receiving full advantages of your furnace in both heat and AC and you should get a 2 stage heat/cool stat.

First that furnace is maybe a little big for your home and if you oversize the in your home. You will have problems with it in the future. By being over sized you will lose about a third of its life. 15 is average life of a furnace. Now take a third off that 10. The min size for your home is 73.500 btus. At 2100 sq ft. If you have a downstairs furnace you got to remember heat rises. So your downstairs furnace will help heat upstairs. What I recommend is a 90.000 btu furnace If you going with a Armstrong 95% multi-stage furnace make sure it comes with ECM blower motor. It designed to save your energy a prevent air temp swings in your home. Which makes it alot more comfortable. The price that has been given to your reasonable. UV lights are great for fighting any mold thats in your home and helps prevented you from breathing it.

I think you can. Connect the AC to the Y2 connection and change the swing setting to 0.4 degrees. The second stage AC (Y2) will activate at twice the swing setting which would be 0.8 degrees. If the set point is 75 degrees, then the AC will turn on at 75.8 degrees, and turn off at 74.2 degrees.