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  1. #1
    Join Date
    Jul 2005
    Posts
    31
    I will be replacing my 27 year old 200K btu Lennox G11 furnace this summer with a Trane XV90 120K btu, and it has been suggested to replace the inside A/C coil at the same time. A previous homeowner had the outside unit replaced due to hail damage, but they reused the original 27 year old inside coil.

    Currently the outside unit is a 5 ton, while the Manual J is showing 4 tons should be right for my house. Knowing that I will eventually have to replace the outside unit, is it possible to use a 4 ton inside coil with the existing 5 ton compressor? My thinking would be that when I downsize down the road I wouldn't have the added expense of another new coil. Or is this just a wasted thought on my part?

    Not being in the HVAC field, I thought you guys would be able to help me understand any problems with my train of thought.

    Thanks in advance for your ideas.

  2. #2
    Join Date
    Sep 2004
    Posts
    3,157
    Or is this just a wasted thought on my part?


    wasted thought.

    If you are going to replace the furnace , now would be the best time to replace the condenser with the proper matching coil. Something else you should consider is that the coil you install will should be rated for a puron system. If not and you chose to but the condenser at a later time you may end up having to change the coil again

    Use a 5 ton cond and a 4 ton coil---no I dont believe that will be good, they need to be matched

  3. #3
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,895
    The coil is part of the cooling system. Replace it when you replace the outdoor unit. With all the changes to efficiency & increased use of R410a, chances are a coil you put in today will not be rated with next year's units. Trane for sure has an all new coil line so if you buy a Trane coil today, it won't match anything next year.

  4. #4
    Join Date
    Jul 2005
    Posts
    31
    Thanks for the advice. I have seen posts here talking about outside units being matched to different sized inside coils, so it had just gotten me down that track. I figured it couldn't hurt to ask, and that I could probably learn something along the way.

    The more I think about it, when it does come time to replace my A/C, I will probably be going with a higher SEER unit then what I have now, anyways, so my question kind of answered itself. Live and learn.

    Since I can't afford to change out the a/c along with the new furnace (and since it is working great, and is only used 3-4 months a year in Chicago), I know I am not going to have a perfectly matched system to begin with.

    But I assume it is still a good idea to replace the original 27 year old coil with a matching one when installing the new furnace, since it was never replaced when the outside unit was changed out?


  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,721
    If the existing condenser is a 10 seer, then you should consider upgrading the indoor coil to match it.

    But, if you think you might be changing the oputdoor in the next couple of years, then wait, since the coil you put in today, may not match the 13 or higher seer you install next year or later.( Why replace it twice)
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  6. #6
    Join Date
    Jul 2005
    Posts
    31
    That was my thinking; even though the cost of a coil is nothing compared to the whole A/C system, it is enough to make me ask. When the topic was brought up, they suggested replacing the existing original coil with a matching one, which leads me to believe it is mismatched at the moment.

    I will check, just to make sure. Thanks for the help.

  7. #7
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Carrier's new outdoor unitline next year will be rated with all of this years coils/air handlers,and vice-versa.

    Trane and others may do the same thing.Not saying what the SEERs will be ,but all applicable matches will be rated.

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