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  1. #1
    Join Date
    Aug 2011
    Location
    Boston, MA
    Posts
    13

    Confidence in AHRI Certificates

    An installer of Americand Standard came in and did a room-by-room load analysis that indicated I needed a 2 ton condensor and 60K BTU furance. I have a small 1,300 square foot two story house in Massachusetts and I have been told these sizes appear reasonable.

    I have two different AHRI certificates (see below) and am trying to figure out which one will be the best combination for overall heat / cooling comfort while being reliable. I have a concern because one of the options has a 3-ton coil paired with a two two condensor and 3 ton furnace. I was under the impression the coil should not be bigger than the condensor or it can cause problems. Is one ton difference a problem? Can AHRI certificates still be generated if there are configuration issues with the system?

    The first proposal AHRI certificate No. 3850818 has the following equipment and ratings:

    Split system: Air cooled condensing unit, coil with blower

    Outdoor unit model: 4A7A6024E1
    Indoor unit model: 4TXCB004CC3
    Furnance Model No: UH2B060A9V3

    Cooling capacity 24,000
    EER rating 13.00
    SEER rating 17.75

    Allegience 16 2-ton two stage 16 SEER compressor; Platnimum High Efficiency 3-ton cased coil; Freedom 95 variable speed two stage 60K 3 ton 96.7% AFUE furnace

    The second proposal AHRI certificate No. 3459156 has the following equipment and ratings:

    Split system: Air cooled condensing unit, coil with blower

    Outdoor unit model: 4A7A5030A1
    Indoor unit model: 4CXCB036CC3
    Furnance Model No: UH2B060A9V3

    Allegience 15 2.5 ton single stage 15 SEER compressor; High Efficiency 3-ton cased coil; Freedom 95 variable speed two stage 60K 3 ton 96.7% AFUE furnace

    Cooling capacity 30,600
    EER rating 12.40
    SEER rating 15.00

    The difference in installed price for the system is small ($300) with the 16 SEER condensor option costing more even though it is 0.5 tons smaller than the 15 SEER.

  2. #2
    Join Date
    Apr 2011
    Location
    SE Washington
    Posts
    499

    AHRI

    Manufacturers Rate their equipment with a broad range of coils/ combinations to acheive diffrent ratings, Rest assured if they are in fact ARI rated combinations, then you are basically guaranteed those efficiences. If the manual J says a 2 ton, then stick with that as anything bigger will cost more over time as you are paying for the extra.

  3. #3
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,046
    Quote Originally Posted by isuredo View Post
    Manufacturers Rate their equipment with a broad range of coils/ combinations to acheive diffrent ratings, Rest assured if they are in fact ARI rated combinations, then you are basically guaranteed those efficiences. If the manual J says a 2 ton, then stick with that as anything bigger will cost more over time as you are paying for the extra.
    You will not be guaranteed that efficiency unless your design condition is 95 degree outdoor 80 degree indoor dry bulb and 67 degree wet bulb.

  4. #4
    Join Date
    Aug 2011
    Location
    Boston, MA
    Posts
    13
    Thanks for the advice. I do not understand what dry bulb and wet bulb mean but I can ask my contractor.

    As far as having a 2 ton condensor attached to a 3 ton coil though I should not be concerned if it is AHRI certified?

  5. #5
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,046
    Quote Originally Posted by kyler View Post
    An installer of Americand Standard came in and did a room-by-room load analysis that indicated I needed a 2 ton condensor and 60K BTU furance. I have a small 1,300 square foot two story house in Massachusetts and I have been told these sizes appear reasonable.

    I have two different AHRI certificates (see below) and am trying to figure out which one will be the best combination for overall heat / cooling comfort while being reliable. I have a concern because one of the options has a 3-ton coil paired with a two two condensor and 3 ton furnace. I was under the impression the coil should not be bigger than the condensor or it can cause problems. Is one ton difference a problem? Can AHRI certificates still be generated if there are configuration issues with the system?

    The first proposal AHRI certificate No. 3850818 has the following equipment and ratings:

    Split system: Air cooled condensing unit, coil with blower

    Outdoor unit model: 4A7A6024E1
    Indoor unit model: 4TXCB004CC3
    Furnance Model No: UH2B060A9V3

    Cooling capacity 24,000
    EER rating 13.00
    SEER rating 17.75

    Allegience 16 2-ton two stage 16 SEER compressor; Platnimum High Efficiency 3-ton cased coil; Freedom 95 variable speed two stage 60K 3 ton 96.7% AFUE furnace

    The second proposal AHRI certificate No. 3459156 has the following equipment and ratings:

    Split system: Air cooled condensing unit, coil with blower

    Outdoor unit model: 4A7A5030A1
    Indoor unit model: 4CXCB036CC3
    Furnance Model No: UH2B060A9V3

    Allegience 15 2.5 ton single stage 15 SEER compressor; High Efficiency 3-ton cased coil; Freedom 95 variable speed two stage 60K 3 ton 96.7% AFUE furnace

    Cooling capacity 30,600
    EER rating 12.40
    SEER rating 15.00

    The difference in installed price for the system is small ($300) with the 16 SEER condensor option costing more even though it is 0.5 tons smaller than the 15 SEER.
    If your dealer did a load calculation they would be able to show you your latent and sensible on your house and be able to pick the combination of indoor and outdoor equipment to match your load.

    If they can not show you the numbers call someone else. There are companies out there that know what they are doing.


    As far as the larger indoor coil goes it does not cause problems unless it does not match you load condition. The indoor coil can be larger than the outdoor coil just not in reverse.

  6. #6
    Join Date
    Mar 2010
    Posts
    195

    The 2 Stage unit will be much more comfortable

    Quote Originally Posted by kyler View Post
    An installer of Americand Standard came in and did a room-by-room load analysis that indicated I needed a 2 ton condensor and 60K BTU furance. I have a small 1,300 square foot two story house in Massachusetts and I have been told these sizes appear reasonable.

    I have two different AHRI certificates (see below) and am trying to figure out which one will be the best combination for overall heat / cooling comfort while being reliable. I have a concern because one of the options has a 3-ton coil paired with a two two condensor and 3 ton furnace. I was under the impression the coil should not be bigger than the condensor or it can cause problems. Is one ton difference a problem? Can AHRI certificates still be generated if there are configuration issues with the system?

    The first proposal AHRI certificate No. 3850818 has the following equipment and ratings:

    Split system: Air cooled condensing unit, coil with blower

    Outdoor unit model: 4A7A6024E1
    Indoor unit model: 4TXCB004CC3
    Furnance Model No: UH2B060A9V3

    Cooling capacity 24,000
    EER rating 13.00
    SEER rating 17.75

    Allegience 16 2-ton two stage 16 SEER compressor; Platnimum High Efficiency 3-ton cased coil; Freedom 95 variable speed two stage 60K 3 ton 96.7% AFUE furnace

    The second proposal AHRI certificate No. 3459156 has the following equipment and ratings:

    Split system: Air cooled condensing unit, coil with blower

    Outdoor unit model: 4A7A5030A1
    Indoor unit model: 4CXCB036CC3
    Furnance Model No: UH2B060A9V3

    Allegience 15 2.5 ton single stage 15 SEER compressor; High Efficiency 3-ton cased coil; Freedom 95 variable speed two stage 60K 3 ton 96.7% AFUE furnace

    Cooling capacity 30,600
    EER rating 12.40
    SEER rating 15.00

    The difference in installed price for the system is small ($300) with the 16 SEER condensor option costing more even though it is 0.5 tons smaller than the 15 SEER.
    Hey,

    With the two stage unit you will be much more comfortable.It will run on 1st stage over 80% of the time, moving air,better IAQ, dehumidifying much better, where as the single stage will always be oversized except at design temp.

    So, even if you believe your load calc, the single stage AC unit is too big and short cycling, over 97% of the time.

    ACBD

  7. #7
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,046
    Quote Originally Posted by kyler View Post
    Thanks for the advice. I do not understand what dry bulb and wet bulb mean but I can ask my contractor.

    As far as having a 2 ton condensor attached to a 3 ton coil though I should not be concerned if it is AHRI certified?
    Just because a combination has an AHRI certification only means that it has been tested at a specific standard conditions. There are multiple combinations in your tonage. Your dealer should be able to show you the performance standards that match you specifications.

    Do you keep the inside of your home at 80 degrees and 50% relative humidity? probably not. And if you dealer did not ask you these questions that is a good indication that he is picking a system without design input.

  8. #8
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,046
    Quote Originally Posted by kyler View Post
    Thanks for the advice. I do not understand what dry bulb and wet bulb mean but I can ask my contractor.

    As far as having a 2 ton condensor attached to a 3 ton coil though I should not be concerned if it is AHRI certified?
    Just because a combination has an AHRI certification only means that it has been tested at a specific standard conditions. There are multiple combinations in your tonage. Your dealer should be able to show you the performance standards that match you specifications.

    Do you keep the inside of your home at 80 degrees and 50% relative humidity? probably not. And if you dealer did not ask you these questions that is a good indication that he is picking a system without design input.

  9. #9
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    24,947
    Quote Originally Posted by second opinion View Post
    You will not be guaranteed that efficiency unless your design condition is 95 degree outdoor 80 degree indoor dry bulb and 67 degree wet bulb.
    Quote Originally Posted by AC Bad Dog View Post
    Hey,

    With the two stage unit you will be much more comfortable.It will run on 1st stage over 80% of the time, moving air,better IAQ, dehumidifying much better, where as the single stage will always be oversized except at design temp.

    So, even if you believe your load calc, the single stage AC unit is too big and short cycling, over 97% of the time.

    ACBD
    You both need to apply for AOP Professional Member * status.

    Follow the link in my signature line.

  10. #10
    Join Date
    Aug 2011
    Location
    Boston, MA
    Posts
    13
    Quote Originally Posted by second opinion View Post
    Just because a combination has an AHRI certification only means that it has been tested at a specific standard conditions. There are multiple combinations in your tonage. Your dealer should be able to show you the performance standards that match you specifications.

    Do you keep the inside of your home at 80 degrees and 50% relative humidity? probably not. And if you dealer did not ask you these questions that is a good indication that he is picking a system without design input.
    He did not ask about relatively humidity but did ask what temperature we could live with inside on a 90 degree day. I believe the load calculation says 75 degress which is fine with me if it takes most of the humidity out of the air.

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