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  1. #1

    Replace Furnace or just AC

    Hello, my 14 year old construction grade AC units are starting to get tired and have been diagnosed with a few leaks. I would also like to get them proactively replaced before they give out in the middle of the summer. I have received 3 different quotes so far, 2 of which proposed full system replacements and moving to a minimum 16 seer and thus include furnace replacement. There will be no improvement in furnace efficiency as I already have 95% down and 80% up.

    The third quote recommended AC replacement only, and just installing a 13 seer unit. He also recommended the installation of heat pumps. His rationale was that a furnace can easily be fixed if it breaks in the future, and likely we will get 5-10 more years (if not longer) from the existing units. He also indicated that the installation of new furnace units later on will not be more than a few hundred dollars more than doing it with the AC now. The heat pumps he recommended for all the standard reasons.

    Before speaking with the third quote, I was on board with full system replacement and moving to 16 seer, but now am questioning this as I respect the third company well.

    We are located in the North Carolina piedmont and see regular summer highs of 85+ and winter lows of 20-40. Budget is not a concern given the quotes we have gotten to date.

    Thank you in advance for your opinions on what makes the most sense.

  2. #2
    Join Date
    Dec 2010
    The Quad-Cities area (midwest).
    I need some more information. Are you planning to replace both A/C (or H/P) units? I would assume that both furnaces are 14 years old as well? I like the heat pump idea but need a little more info. Thanks.

  3. #3
    Sure, and thanks. I will be replacing both A/C units (no heat pump yet). Both furnaces are 14 years old also, but have not had any issues as of yet. Replacement of the furnaces would be proactive rather than reactive. I had originally expected to do that, but then this third quote really got me wondering if I needed to do so.

    One question I am really curious about is if it truly won't cost much more to replace the furnace later on over doing it now. Budget isn't an issue today, but I don't want to spend the money now if I don't have to.

  4. #4
    Join Date
    Jan 2009
    Keokuk, IA
    Are you propane or natural gas? What are your fuel costs? Heat pump is ideal, especailyl with a 80% furnace for upstairs units since the heat loss is usually fairly small. Downstairs heat pumps add a nice extra stage of heating on mild days.

    In your climate, you might want a VS blower with the ability to dehumidify on demand, at least for the upstairs unit. A single stage 14 SEER would be fine. Downstairs usually had greater load diversity due to occupancy and solar heat gain, so that's where you might want a 2 stage 16 SEER unit. It also does most of the heating, so a 2 stage furnace is nice there too.

    Be sure load calculations are done and it's sized right. In humid climates in the SE you don't want it oversized or it won't dehumidify well and will use more energy due ot short cycling. Don't assume they were sized correctly originally. The comfort difference of a properly sized unit compared to a oversized unit is night and day.

  5. #5
    Natural gas, but it is pretty inexpensive. Rates are below

    Electric Rates (excluding any adjustments):
    Basic Facilities Charge $22.50
    Energy Charges*:
    Summer (June - October)
    All kWh $0.09970
    Winter (November - May)
    First 1,000 kWh $0.09970
    All other kWh $0.09476

    NatGas Rates:
    Monthly Charge 10.00

    Per Therm
    November-March 0.94019
    April-October 0.84591

    My gas bill rarely exceeds $100 (only 2 months this past winter) while my electric bill often exceeds $100 and usually $200 for at least a couple months of the year. So I'm not sure the heat pump will have any immediate or long term impact on costs.

    All 3 quotes have done a detailed calculation and come back with the same number, so we are square on that aspect and it matches what we currently have installed.

  6. #6
    Join Date
    Dec 2010
    The Quad-Cities area (midwest).
    Heat pumps are ideal for your climate. I would at least consider one for the 1st floor. As mentioned, a variable-speed blower is terrific. I swear by them, but, would I recommend replacing (both) 14 year old furnaces, probably not.

    There is no significant cost difference in the furnace installation now verse later. However, that said, if you want a variable-speed blower and you don't have a hi-efficiency air cleaner, you may want to replace at least the "workhorse" furnace to get those items.

    There are so many ways to go. I don't mean to confuse you. But, the third guy made a good point (one of many to consider).

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