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  1. #1
    Join Date
    Aug 2006
    Posts
    20
    Hi,
    I'm creating an enclosed porch from a screen porch
    and am trying to determine if my existing a/c unit will handle the extra sq feet.
    My A/C says Trane XE1200 on it. My house is 2350 sq feet and about 300 sq feet additional will be added.
    Also, how do I determine how many tons my unit is?

    Help !
    thx.

  2. #2
    Join Date
    Feb 2005
    Location
    Central Alabama
    Posts
    466
    We need the model number off of the silver tag.



    xe 1200 is a 12 seer unit that is all i can tell you

  3. #3
    Join Date
    Dec 2005
    Location
    Cleveland, OH
    Posts
    2,771
    You'll need the model number off of it. XL1200 means it's a 12 SEER unit, but it doesn't tell you the size. Somewhere on the unit (usually by where the electric is connected) will be a name plate. Your unit will have a model # of TTX0------ Fill in the blanks and we'll know what size it is.

    Good? Bad? I'm the guy with the gun.

  4. #4
    Join Date
    Aug 2006
    Posts
    20
    Thanks guys.
    I'll try to find the specific model #, but in the meantime my manual shows two models: TTP018-42C and TTP048-60D.
    Does that help ?

  5. #5
    Join Date
    Feb 2005
    Location
    Central Alabama
    Posts
    466
    no that don't help but compare mod. to these below.

    TTP018---1-1/2ton

    TTP024---2 ton

    TTP030---2 1/2 yon

    TTP036---3 ton

    TTP042---3 1/2 ton

    TTP048---4 ton

  6. #6
    Join Date
    Aug 2006
    Posts
    20
    So, it looks like it's either a 3.5 or 4 ton unit.
    I'll step out now and see if I can find the tag.

  7. #7
    Join Date
    Aug 2006
    Posts
    20

    Found it.

    OK, it is a TTP048D100A0
    The manufacturer's Date is 5/99.
    4 Ton ?
    I realize from reading some thread that just stating the square footage of the house and proposed new room is not necessarily very accurate to determine whether my unit will handle the extra volume.
    But, I also read up that a unit that is small might be ok if it takes awhile to cool down since a smaller unit might remove more humidity. A unit that is too large might cool quickly but not efficiently remove humidity. I think my unit is more towards the too big size for the following reason: I can put the thermostat to 65 and from 75 it will probably get down there in close to an hour or less.
    In fact, I think I'll try that right now because it's really hot and humid outside right now. I did this once or twice before just to see what would happen.
    But, doesn't that sound like adding another 300 sq feet should not be a problem ?

  8. #8
    Join Date
    Aug 2006
    Posts
    20
    I guess last night was a good night to test this.
    The temperature did not go down in the house nearly as fast as I've seen it in the past since it was so hot and humid yesterday. It went down about 1 degree per hour. After about 5 hours it was down to 68 degrees when I put it back to normal.
    So, the question is still; does anyone think my existing a/c unit will handle the new 300 sq feet? That would be a 4 ton unit (guessing from info above) servicing about 2750 sq feet.

  9. #9
    We really can not answer that question any further than we already have....you need to have a load calculation done that takes everything into consideration. Anything else would be guessing. In most cases, the original unit takes care of what you have...but if you add more space then it needs more unit. Generally speaking.

  10. #10
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,429
    Originally posted by jhh
    I guess last night was a good night to test this.

    The temperature did not go down in the house nearly as fast as I've seen it in the past since it was so hot and humid yesterday. It went down about 1 degree per hour.

    After about 5 hours it was down to 68 degrees when I put it back to normal.

    So, the question is still; does anyone think my existing a/c unit will handle the new 300 sq feet? That would be a 4 ton unit (guessing from info above) servicing about 2750 sq feet.
    Location ?
    House Orientation ?
    Age of house?

    .. so hot and humid ...
    needs to be described in detail
    .. i.e. 90'F and 60% relative humidity
    or ___ 'F and ___

    Cooling rate of 1'F / Hr is normal at < Peak load.

    Testing at night will not be meaningful in estimating whether the propsoed addition has an impact
    on afternoon performance.

    Set thermostat to 76'F in the morning and
    turn it down to 70'F at 3 PM on a design temperature day
    ( > 90'F ) to get a clue on whether there may be additional capacity that may serve the 300 sq. foot addition.

    I suspect that the actual "Reserve Cooling"
    may be something like
    1'F in 2 hours
    for late afternoon.

    Will the 300 Sq. Feet addition add
    or reduce the overall glass area?

    Number of current windows on each side of the house
    would assist in evaluating overall cooling needs.
    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

  11. #11
    Join Date
    Aug 2006
    Posts
    20

    understood

    Thanks for your replies.
    I had a feeling it would come down to much more technical info. One thing that might be skewing the test yesterday was the fact that I'm installing a new bathroom in the laundry area of the house. There are open walls to the hot air in the attic and holes to the crawl space under the house during this construction. I kept the door closed to that room last night, but it still may have had a bad effect on the cooling ability.
    The new room will be adding lots of window space. It is a screen porch currently, so I'm replacing the screens with large windows. They are the low-E argon filled, but there are six of them.

    Off the subject a bit...
    If I decided to look at a ductless mini-split, I'm trying to keep the cost down and noted several relatively inexpensive models. One was Hitachi model - RAS09UH.
    It provides heating and a/c and is less than $500.
    Specs are below. Any opinions or suggestions for other units?
    Features
    Capacity Cooling [BTU/h]: 9300
    Capacity Heating @ 47F [BTU/h]: 10300
    Capacity Heating @ 17F [BTU/h]: 5600
    HSPF: 7.2
    SEER: 10.5
    EER: 9.8
    COP: 3.1
    Moisture Removal [Pts/h]: 2.3
    Air Flow [CFM] @ High|Med|Low: 450/360/282
    Sound Rating Indoor db (A): 40
    Sound Rating Outdoor db (A): 51
    Operating Range - Cooling [F]: 71.6 to 107.6
    Operating Range - Heating [F]: 30 to 70
    Power Source: 115-60-1
    Min. Ampacity [A]: 10
    Cooling Watts | Amps: 950 / 8
    Heating Watts | Amps: 950 / 8
    Max TD Fuse/Breaker [A]: 20
    Connections: Flare
    Liquid Line OD [Inch]: 1/4
    Suction Line OD [Inch]: 3/8
    Max Line Length [Ft]: 49
    Max Height Difference [Ft]: 26
    INDOOR SECTION: RAS-09UH
    Indoor WxHxD [Inch]: 32x11x7
    Indoor Shipping Weight [Lbs]: 28
    OUTDOOR SECTION: RAC-09UHV
    Outdoor WxHxD [Inch]: 32x20x8
    Outdoor Shipping Weight [Lbs]: 79


  12. #12
    Join Date
    Aug 2006
    Posts
    20

    Dan's info

    Hi Dan,
    I noted that you're from sw FL. I used to live in Cape Coral awhile back. Now that's hot !
    I'll try to answer your questions below as best I can.

    Location? - Savannah, GA
    House Orientation? - faces south
    Age of house? - 22 years

    .. so hot and humid ...
    needs to be described in detail
    .. i.e. 90'F and 60% relative humidity
    << -- or 89 'F and 94% humidity.

    Cooling rate of 1'F / Hr is normal at < Peak load.

    Testing at night will not be meaningful in estimating whether the propsoed addition has an impact
    on afternoon performance.

    Set thermostat to 76'F in the morning and
    turn it down to 70'F at 3 PM on a design temperature day
    ( > 90'F ) to get a clue on whether there may be additional capacity that may serve the 300 sq. foot addition.
    <<<----- I won't be home today at 3, so can't run this test today.

    I suspect that the actual "Reserve Cooling"
    may be something like
    1'F in 2 hours
    for late afternoon.

    What is Reserve Cooling ? <<<------------

    Will the 300 Sq. Feet addition add
    or reduce the overall glass area?
    <<<--- Will add lots of glass space (two sides of the room and a door on the third side. Low E/argon filled, sliding type. However, this screen porch is surrounded by trees and rarely gets any direct sunlight.

    Number of current windows on each side of the house
    would assist in evaluating overall cooling needs.
    <<< -- Front of the house (faces south)
    (2) double hung
    (1) 3-pane casement window in the kitchen
    (2) bay windows
    (2) thin windows next to the front door.

    << -- Rear of house (faces north)
    (2) double hung
    (4) sliding glass doors, one of which won't count as much because it's the entrance to the porch where I'm putting in the new sliding windows.
    The new sliding windows for the new sunroom will be (3) at about 42x58 and (3) at about 63 x 58.
    Hope that helps...



  13. #13
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,429

    Re: understood

    Originally posted by jhh
    I had a feeling it would come down to much more technical info.
    ...
    The new room will be adding lots of window space. It is a screen porch currently, so I'm replacing the screens with large windows. They are the low-E argon filled, but there are six of them.

    Off the subject a bit...
    If I decided to look at a ductless mini-split, I'm trying to keep the cost down and noted several relatively inexpensive models. One was Hitachi model - RAS09UH.
    It provides heating and a/c and is less than $500.
    Specs are below. Any opinions or suggestions for other units?

    Features
    Capacity Cooling [BTU/h]: 9300
    Capacity Heating @ 47F [BTU/h]: 10300
    Capacity Heating @ 17F [BTU/h]: 5600
    200 square feet of low-E, windows facing WEST
    would need close to 1.5 tons.

    TWO RAS09UH unit may work but ...

    Comprehensive LOAD evaluation is needed before one begins to think about adding equipment.
    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

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