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Thread: A/C coil size

  1. #1
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    A/C coil size

    My son has a furnace rated to have a minimum 2 1/2 ton A/C coil. The contractor who installed his A/C a few years back put in a 2 ton condenser but used a 2 1/2 ton evaporator coil to satisfy the furnace specs.

    This doesn't sound right to me as I suspect he still has 2 tons of cooling and, therefore, the furnace air flow to to high for proper de-humidification.

    Although it seems to work okay, I'm interested in what the experts here think.

  2. #2
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    Usually can make this work by doing some airflow measurements and adjust speed lower if necessary.

  3. #3
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    Quote Originally Posted by SBKold View Post
    Usually can make this work by doing some airflow measurements and adjust speed lower if necessary.
    It is working okay, but did it make any sense to use a 2 1/2 ton evaporator coil with a two ton compressor?

    Especially since this was not an "A" coil, it was a flat car radiator shape. In fact, lying directly on top it overlapped the furnace supply by maybe 3/4" on each side and maybe 2" in the front and back. So to my mind, it was less efficient than a 2 ton coil that might have fit the furnace supply better.

    But even without the overlap issue was anything gained using a 2 1/2 ton coil?

  4. #4
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    Not a probelm at all. Just as long as the coil was rated with the a/c condenser.

    That sometimes happens when retrofitting. It also might have made it a little more efficent?

  5. #5
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    Quote Originally Posted by don87109 View Post
    It is working okay, but did it make any sense to use a 2 1/2 ton evaporator coil with a two ton compressor?

    Especially since this was not an "A" coil, it was a flat car radiator shape. In fact, lying directly on top it overlapped the furnace supply by maybe 3/4" on each side and maybe 2" in the front and back. So to my mind, it was less efficient than a 2 ton coil that might have fit the furnace supply better.

    But even without the overlap issue was anything gained using a 2 1/2 ton coil?

    Sounds like you are talking about a slab coil. No real reason to do that other then maybe trying to get a little more efficent?

    The only really way to know would be to ask the installer!

  6. #6
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    Quote Originally Posted by duckman06 View Post
    Sounds like you are talking about a slab coil. No real reason to do that other then maybe trying to get a little more efficent?

    The only really way to know would be to ask the installer!
    The install was done maybe 12 years ago. I'm trying to decide if I should use that company for another job.

  7. #7
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    Quote Originally Posted by don87109 View Post
    The install was done maybe 12 years ago. I'm trying to decide if I should use that company for another job.
    12 years ago is more than a few years back.

    It's not abnormal.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  8. #8
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    Quote Originally Posted by hvacvegas View Post
    12 years ago is more than a few years back.

    It's not abnormal.
    I agree. Since the system has worked find and their might have been a good reason why he installed that coil, I would let him do other work for you!

  9. #9
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    Despite manufacturer's insisting on putting capacity designations on indoor coils, there is no such thing as a 2-1/2 ton or any other capacity coil. The indoor coil is nothing more than tubing and fins with a metering device. What is considered a "nominal" (b: of, being, or relating to a designated or theoretical size that may vary from the actual : approximate <the pipe's nominal size>) 2-1/2 ton coil may be a rated match for systems using 1.5 to 3 ton systems.,
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  10. #10
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    The reason the installer used a 2 1/2 ton coil was that was the furnace minimum A/C rating.

    My guess is that did nothing since he still only had two tons of cooling dictated by the size of the compressor. Actually, it may have done some harm since the coil was probably bigger and overlapped the furnace supply duct more than a two ton coil. Meaning that some admittedly small parts of the coil were not in the flow of air.

    So although it seems to work okay, it doesn't sound like the guy really knows what he is doing.

  11. #11
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    Quote Originally Posted by don87109 View Post
    The reason the installer used a 2 1/2 ton coil was that was the furnace minimum A/C rating.

    My guess is that did nothing since he still only had two tons of cooling dictated by the size of the compressor. Actually, it may have done some harm since the coil was probably bigger and overlapped the furnace supply duct more than a two ton coil. Meaning that some admittedly small parts of the coil were not in the flow of air.

    So although it seems to work okay, it doesn't sound like the guy really knows what he is doing.
    What robotek was trying to say is that the metering device is what determines the tonnage between 1.5 to 3 tons. You have no idea why the installer choose to use that coil, it might have been do to install difficulties on the original changeout. If the company has been around for 12 yrs I would imagine he knows what he is doing, furthermore, twelve more yrs of experience can't be a bad thing.
    My name is TooCoolforschool and I am a chronic over charger.

  12. #12
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    Quote Originally Posted by don87109 View Post
    The reason the installer used a 2 1/2 ton coil was that was the furnace minimum A/C rating.

    My guess is that did nothing since he still only had two tons of cooling dictated by the size of the compressor. Actually, it may have done some harm since the coil was probably bigger and overlapped the furnace supply duct more than a two ton coil. Meaning that some admittedly small parts of the coil were not in the flow of air.

    So although it seems to work okay, it doesn't sound like the guy really knows what he is doing.
    Robo is right they do not make 2 1/2 ton coils. What have is either a 2 ton or 3 ton coil rated for 2 tons of cooling. What they do is have a 3 ton coils rated for 2 1/2 tons or even 2 tons frigerant flow with the proper sized metering devices. Actually if it is a 3 ton coil you have a higher efficienty rating overall because of the increased coil surface. Bottom line is you have noting to worry about there especially if it is cooling and heating fine.

    The furnace mfg. probally wanted a least a 3 ton coil for the required air flow across the coil when heating to make sure the air flow wasn't restricted to much. So if you put a "2 1/2 ton" coil on there you really have a 3 ton coil with a 2 1/2 ton condenser or in your case a 2 ton condenser. Lighten up there and relax. Thank you very much
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  13. #13
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    Quote Originally Posted by toocoolforschool View Post
    What robotek was trying to say is that the metering device is what determines the tonnage between 1.5 to 3 tons. You have no idea why the installer choose to use that coil, it might have been do to install difficulties on the original changeout. If the company has been around for 12 yrs I would imagine he knows what he is doing, furthermore, twelve more yrs of experience can't be a bad thing.
    At the time the installer said why he did it.....to accommodate the furnace specs.

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