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  1. #14
    You can do your own load calculation by clicking on the red tab above.

    The program is by the developer of this great site.

  2. #15
    Join Date
    Oct 2005
    Location
    N Metro Atlanta GA
    Posts
    70
    I am working on my calculation. I entered something wrong somewhere and am looking for the bad entries now. I'll post what I get after the results look like they may make sense.

    But after I get the numbers, I don't know how to mix and match the parts of the system.

  3. #16
    Originally posted by i g norant
    But after I get the numbers, I don't know how to mix and match the parts of the system.
    That's the simple part, you find a competent HVAC Company that will size your unit properly.

    You'll know if he is close by your calculations.

  4. #17
    Join Date
    Oct 2005
    Location
    N Metro Atlanta GA
    Posts
    70

    My Numbers UP

    Design conditions: Average infiltration (ACH 0.41 summer 0.83 winter)
    and Default values
    ......Indoor:...................... Outdoor:
    Summer temperature: 75.....Summer temperature: 92
    Winter temperature: 72.....Winter temperature: 22
    Relative humidity: 50......Summer grains of moisture: 99
    ...........................Daily temperature range: Medium

    4 people on first floor, 1 person on second floor

    Sensible..Latent...Total...... Total
    Gain.......Gain..Heat Gain...Heat Loss
    24,362....3,403...27,765......47,889
    .......................(2.5 tons)

    Change only these design conditions:
    Indoor Summer Temperature 70....Outdoor summer Temperature 95

    29,310....3,983...33,293......47,889
    ........................(3 tons)

    I sent the guy an e-mail and asked for a copy of his load calc results.

  5. #18
    Join Date
    Apr 2004
    Location
    Bartlett, IL
    Posts
    6,619
    Well, go ahead and put the equipment size you came up with in...this way you have no one else to blame but yourself...sounds to me like you're good to go.

  6. #19
    Join Date
    Oct 2005
    Location
    N Metro Atlanta GA
    Posts
    70
    2hot - 2 weeks ago I couldn't spell refreejurant. Would you trust my calculations??

    Steve - he quoted 2 filters. A 5 inch and Trane's Clean Effects. I thought I would start another thread about filters tomorrow ;-)

  7. #20
    Originally posted by i g norant
    2hot - 2 weeks ago I couldn't spell refreejurant. Would you trust my calculations??
    No, but you are closer than the guys you have been talking too!

  8. #21
    Join Date
    Aug 2004
    Location
    Tyler TX
    Posts
    676
    Looking at your first numbers a 3 ton looks ideal. Unless you had problems with the old unit from the start I would suggest going back with a 3 ton. If you go with your second set of numbers you may have to keep the house at 70 deg to be comfortable.

    You may want to have the contractors you deal with look at what you have input to verify that you did not miss anything

    [Edited by dpatty on 10-22-2005 at 01:03 AM]
    HVAC Contractor, Tyler Texas.

  9. #22
    Join Date
    Sep 2001
    Location
    Vancouver Canada
    Posts
    996
    Ditch the furnace, variable speed airhandler with back up electric strip. In your climate I don't see you using the back up heat very often. 90% variable speed Trane is going to cost bongo bucks. Same unit in a Heil 2 stage 90 variable would be considerably cheaper if you are still convinced that you need to go the furnace route. 100k furnace is way oversized for your conditions. Trane does make a 4 ton in 80,000 btu. You will definetly pay a premium for trane or American Standard. It is good equipment but I often wonder if the cost is justified especially in a climate like yours where the furnace will be mainly used as an air handler.
    "Go big or Go Home"

  10. #23
    Join Date
    Oct 2005
    Location
    N Metro Atlanta GA
    Posts
    70
    Originally posted by dpatty
    If you go with your second set of numbers you may have to keep the house at 70 deg to be comfortable.

    You may want to have the contractors you deal with look at what you have input to verify that you did not miss anything
    I don't really want it at 70 deg. The contractor said he had set up his computer for Atlanta too long ago & did not remember the design temps. I was just trying to get a higher load after I saw his. ;-) Are the first numbers (closer to what I will actually do) OK for Atlanta?

    I will talk over my calc with the others that did not do calcs after their bids are in next week.

    Thanks for your help.

  11. #24
    Join Date
    Oct 2005
    Location
    N Metro Atlanta GA
    Posts
    70
    Originally posted by Black Adder
    Same unit in a Heil 2 stage 90 variable would be considerably cheaper if you are still convinced that you need to go the furnace route.
    We have several nights in the 20's, some in the teens and some days when it is never above freezing. Sorry, but I don't have the number of days. That is why I am thinking furnace. My original idea was to keep the 23 year old dinosaur (100K BTU 60%) as backup. Wouldn't I save money on the labor by replacing everything now and increase both heating & cooling efficiency? (Bold item added in edit)
    Originally posted by Black Adder
    You will definetly pay a premium for trane or American Standard. It is good equipment but I often wonder if the cost is justified especially in a climate like yours where the furnace will be mainly used as an air handler.
    I agree. But I can't sem to find any contractors except the "big advertiser" brand names. If anyone can recommend a contractor, I will absolutely contact them.

    [Edited by i g norant on 10-22-2005 at 11:54 AM]

  12. #25
    Join Date
    Oct 2005
    Location
    N Metro Atlanta GA
    Posts
    70

    Uh Oh! Look Out Now!

    I found a publication that has data for each Trane model 4TWX4 018-060, ratings with auxiliary devices, etc.
    Now I am really dangerous
    but not stupid enough to specify models myself.

  13. #26
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,628
    I would go back with what you had is size. I would also install a heat pump with gas backup for the coldest nights.

    If you said your a/c ran for 10 hours and never reached setpoint i would say go larger, but the longer it runs the more effecient it is. Ideally a cooling unit should never shut off at design temp,same with heating, but you should never reach the design in atlanta since you have to size the blower for cooling.
    Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced

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