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  1. #1
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    Apr 2018
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    Need help to determine tonnage of a/c

    Guys im trying to figure out whats tonnage on my ancient lennox heat pump. I know its in 80s. All labels have disappeared but i was told i could look on compressor. The number on copeland compressor is cr37k0pfv980wb. I went to copelands website and it said 3 ton..Is this correct? I thought it was bigger due to sq. foot of house.. Upstairs has 2 ton and 800 square foot and lower level has 2200 square. Is the 3 ton enough for that..thanks for help

  2. #2
    Join Date
    Aug 2002
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    Southold, NY
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    Whats there doesn’t matter.
    Manual “J” calculation will say what size you need.
    2-Tons for 800 sq ft is rediculas unless there’s no insulation.

  3. Likes kdean1 liked this post
  4. #3
    Join Date
    Jun 2014
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    Dover, DE
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    Sizing shouldn’t be done via square footage.
    Manual J and S for determining required equipment size.
    You can do a free manual J here-

    www.loadcalc.net
    “I haven’t failed. I’ve just found 10,000 ways that won’t work.” - Thomas Edison

    “It’s not whether you get knocked down, it’s whether you get up.” - Vince Lombardi

    "In this house we obey the laws of thermodynamics" - Homer Simpson

  5. #4
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    Apr 2018
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    Thread Starter
    no its got r15 in walls and r30 in attic ..double pane windows that are new..well insulated.. I was just trying to figure out if that compressor means its 3 ton.

  6. #5
    Join Date
    Aug 2002
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    Quote Originally Posted by pigwilly View Post
    no its got r15 in walls and r30 in attic ..double pane windows that are new..well insulated..
    Could get away with 1-Ton upstairs.
    Need to measure the walls, doors, windows.

  7. #6
    Join Date
    Nov 2004
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    SW FL
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    Manual J needed

    Quote Originally Posted by pigwilly View Post
    Guys im trying to figure out whats tonnage on my ancient lennox heat pump.
    I know its in 80s.
    All labels have disappeared but i was told i could look on compressor.

    The number on copeland compressor is cr37k0pfv980wb.
    I went to copelands website and it said 3 ton.
    Is this correct? YES

    I thought it was bigger due to sq. foot of house..

    Upstairs has 2 ton and 800 square foot and lower level has 2200 square.
    Is the 3 ton enough for that?
    3-ton might be sufficient for an " Effectively New " 3,000 Sq Foot residence
    _ NORTH of ~ 41'N latitude.

    " Effectively NEW ":
    1. Double pane, Insulated windows: U-Factor < 0.3
    2. R-15 Walls, R-30 Ceiling
    3. Low/Medium Infiltration: A.C.H. < 0.33 ___ Air Changes per Hour
    4. Duct work within Building Thermal Envelope
    5. 41'N
    ___ i.e. Fort Wayne IN; 88.3'F DB / 73.1'F WB
    ________________ Dry Bulb / Wet Bulb - ASHRAE FUNDAMENTALS, CHAPTER 14, 2013 Edition, 1%
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  8. #7
    Join Date
    Nov 2004
    Location
    SW FL
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    MANUAL J

    GENERIC - 1980.s Enhanced
    BUILDING THERMAL ENVELOPE

    3,000 Square Feet

    89'F & 5'F

    47,900 BTU/HR HEAT LOSS at 5'F
    28,000 ________________ at 32'F

    29,120 BTU/HR Q. Sensible HEAT GAIN

    ATTACHMENT

    ________ ___ ___ ___ ___ __________
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  9. #8
    Join Date
    Mar 2009
    Location
    Mount Holly, NC
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    Quote Originally Posted by pigwilly View Post
    Guys im trying to figure out whats tonnage on my ancient lennox heat pump. I know its in 80s. All labels have disappeared but i was told i could look on compressor. The number on copeland compressor is cr37k0pfv980wb. I went to copelands website and it said 3 ton..Is this correct? I thought it was bigger due to sq. foot of house.. Upstairs has 2 ton and 800 square foot and lower level has 2200 square. Is the 3 ton enough for that..thanks for help
    I'll try to answer this the best way for you.

    what is there is of no importance unless you are trying to repair the unit. if so, then the tech should just match the compressor in place.

    if you are planning to replace the unit, you need to discover waht airflow and cooling load your house currently has, and get the equipment sized to support that.

    most old equipment has poor airflow, leaking into crawlspace, or attic, and poor sizing that relies on massive dehumidification of the old 5SEER units to handle comfort.

    new equipment does NOT work this way. the ductwork needs to be sealed and sized for total air distribution. the home likely needs dedicated dehumidification, and improvements in the insulation and the attic design.

    now...

    let me ask you something.


    why are you trying to find out the old unit tonnage?
    The TRUE highest cost system is the system not installed properly...

    Find a HVAC-Talk Contractor by clicking here

    Do you go to a boat repairman with a sinking boat, and tell him to put in a bigger motor when he tells you to fix the holes?

    I am yourmrfixit

  10. #9
    Join Date
    Oct 2002
    Location
    Plano, TX
    Posts
    2,177
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    Quote Originally Posted by pigwilly View Post
    Guys im trying to figure out whats tonnage on my ancient lennox heat pump. I know its in 80s. All labels have disappeared but i was told i could look on compressor. The number on copeland compressor is cr37k0pfv980wb. I went to copelands website and it said 3 ton..Is this correct? I thought it was bigger due to sq. foot of house.. Upstairs has 2 ton and 800 square foot and lower level has 2200 square. Is the 3 ton enough for that..thanks for help
    I am thinking compressor is fitted to a 3.5 ton condenser capacity.

  11. #10
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
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    Somewhere in there. I looked a bit at Lennox Pros and found the HP16 3 ton uses a CR34 compressor. Looked at HS18 3.5 ton and it uses a 42 compressor.

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