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  1. #1

    Advice needed!! Replace AC only or change to heat pump and new furnace

    We live in Connecticut. Our home is just about 10 years old and the AC compressor is dead. We interviewed a few contractors. One of them said that with the current oil furnace (81 AFUE, barely 10 years old, Lennox), we should not install AC that is above 14 SEER. Is this true?

    We were then told the best thing is to replace the oil furnace at the same time to a Trane XV80 variable speed furnace, which is 82 AFUE, at the same time. In addition, in stead of AC, get a heat pump (15 SEER) with the new furnace to use the oil heating as a backup when it gets really cold (below 35).

    We moved from Maryland to Connecticut last year. It seems to us that the weather is not really hot here. So, it may not really worth it to have a AC/heat pump of higher efficiency.

    Please help us. None of us have engineer background.

  2. #2
    Join Date
    May 2007
    Location
    DC Metro Area (MD)
    Posts
    3,371
    "We live in Connecticut. Our home is just about 10 years old and the AC compressor is dead. We interviewed a few contractors. One of them said that with the current oil furnace (81 AFUE, barely 10 years old, Lennox), we should not install AC that is above 14 SEER. Is this true?" Yes, without a variable-speed blower, it's difficult to get more than 14 SEER for many system matchups. However, if you plan on replacing the oil furnace in a few years, then you could "future proof."

    "We were then told the best thing is to replace the oil furnace at the same time to a Trane XV80 variable speed furnace, which is 82 AFUE, at the same time. In addition, in stead of AC, get a heat pump (15 SEER) with the new furnace to use the oil heating as a backup when it gets really cold (below 35)." A good dual fuel idea, but you'd have to weigh the costs of each option. The oil furnace isn't that old relative to numerous others out there, but it is getting up there... Might be worth it just for the warranty and comfort that a new furnace would provide. You could also add a 13/14 SEER heat pump to the old oil furnace.

  3. #3
    Join Date
    Mar 2008
    Location
    Houston, Texas
    Posts
    352
    At 10 years with your compressor dead, I would suggest replacing the condenser and evap with a heat pump (for your area). Change over to 410a. The higher seer the better. I would have a adjustable temp setting on the heat side of it. This would allow you to adjust as need depending on outside temp and fuel cost. use your existing furnace mainly for air movement (assuming it can deliver) and backup heat.

  4. #4
    Join Date
    Jun 2008
    Posts
    35
    question for the old heads, Connecticut gets pretty cold. I thought Heat Pumps were mainly for southern regions of country. He will need furnace for when the temp drops. Why install two systems. Is the dual worth it?

  5. #5
    Join Date
    Jun 2008
    Posts
    13
    I am facing the same problem here in Northern Virginia. I just found this neat online calculator:
    http://www.hvacopcost.com/

    However, I don't know how it does the calculations. And I don't know who is behind the site - maybe the heat pump manufacturers?

    Please let me know if you find out how to do the calculations.

  6. #6
    Join Date
    Jun 2007
    Location
    The Twilight Zone
    Posts
    2,964
    Quote Originally Posted by hopeqing View Post
    We live in Connecticut. Our home is just about 10 years old and the AC compressor is dead. We interviewed a few contractors. One of them said that with the current oil furnace (81 AFUE, barely 10 years old, Lennox), we should not install AC that is above 14 SEER. Is this true?

    We were then told the best thing is to replace the oil furnace at the same time to a Trane XV80 variable speed furnace, which is 82 AFUE, at the same time. In addition, in stead of AC, get a heat pump (15 SEER) with the new furnace to use the oil heating as a backup when it gets really cold (below 35).

    We moved from Maryland to Connecticut last year. It seems to us that the weather is not really hot here. So, it may not really worth it to have a AC/heat pump of higher efficiency.

    Please help us. None of us have engineer background.
    What is your delivered cost of electricity? Delivered cost = generating + transmission + distribution costs.

    Fuel oil may be $4.50 per gallon this winter. What are your costs for fuel oil?

    If you decide to go heat pump, I would get an HSPF (Heating Seasonal Performance Factor) of at least 9. HSPF is similar to SEER except for heating. I would also get as many heating btu's as the system is rated for (anotherwords, a 3-ton heat pump should put out 36,000 btu's of heat, not 32,000 as some systems do). 14 SEER offers the best combination of purchase price and true operating costs, in my opinion.

    Good luck.

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