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  1. #1
    Join Date
    Aug 2010
    Location
    Toronto, Canada
    Posts
    8

    Upgrade Choice: 2-stage AC or 3-stage Furnace?

    I'm about to replace our aging furnace and air conditioner with new units from Carrier. I have had multiple quotes from qualified vendors and have settled on the Infinity 96 2-stage furnace (58MVB) and a 2-Ton single stage Performance 15 air conditioner (24APA5). I'll be installing the Infinity control with a Carrier humidifier and HRV added in as well.

    Here's my question - For slightly more $ I can either:

    1) Upgrade the choice of furnace to the 3-Stage Infinity ICS (58MVC) paired with the single stage AC
    2) Upgrade the choice of AC to a 2-Stage Performance 17 (24APA7) paired with the 2 stage furnace

    I live in a 1300 square foot backsplit home located in the Toronto, Ontario area (built in mid 1960s), and our cooling season is comparatively less than the heating season. For this reason I'm inclined to upgrade the furnace over the AC. Also, our existing single stage 2 ton AC has served us well with reasonable humidity control.

    I'm wondering what the community has to say? I'm basing my decision more on comfort than efficiency. Would a 2-stage furnace + 2 stage AC provide better comfort than a 3-stage furnace + 1 stage AC in my situation? Is the 2-stage AC overkill for my climate and size of home?

    Thanks!

  2. #2
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,837
    I'd upgrade the furnace without a doubt. In addition, you might want to investigate the costs of substituting a heat pump for the AC unit and have a dual fuel system that might also deliver greater comfort during the shoulder seasons (temps above 35F) as well as some improved economy over using the gas furnace all the time. Alternatively, if humidity is a concern in the summer, you could have a whole house dehumidifier incorporated into the duct system rather than a 2-stage AC system.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  3. #3
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,451
    Quote Originally Posted by HHM View Post
    I'm

    I'm wondering what the community has to say? I'm basing my decision more on comfort than efficiency. Would a 2-stage furnace + 2 stage AC provide better comfort than a 3-stage furnace + 1 stage AC in my situation? Is the 2-stage AC overkill for my climate and size of home?

    Thanks!
    I choose the 3 stage furnace/13 SEER single speed a/c. In your climate will need supplemental dehumidification to maintain <50%RH during the wet cool times of the warm season. On a hot day my a/c removes 6 gals of water per day, while basement dehu removes 2-3 gals/day. On wet cooler days the a/c removes 1-2 gals and the dehu removes 4-5 gals per day. I maintain <50%RH through my 2,100+1,700 sqft. structure. If I had a 2 stage a/c, I would still need the dehumidification maybe not so much? Use the money saved on the 1 verse 2 stage a/c on a good dehu like a Santa Fe Compact.

    Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  4. #4
    Join Date
    Jul 2008
    Posts
    551
    I'd choose neither of those upgrades. I don't see much improvement in comfort from either one, especially given they cost more. If you wanted to spend some money and get a better value, I think the heat pump is a great idea. You'd get a ton of use out of it in Canada, but what are your electric and gas rates? that would be the determining factor.

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