AC requirements for Energy Star home

Discussion in 'Off Topic' started by mauricio789, May 22, 2014.

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  1. May 22, 2014 #1

    mauricio789

    mauricio789

    mauricio789

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    I'm appealing to the vast ExpessJet family, specially to the engineers or home builder savvy in order to try to find out the correct size for an AC unit for a 2098 Sq ft new Energy Star home.
    I have tried google it but haven't found anything official or concrete on the matter.
    Any help is appreciated.
    Thanks.
     
  2. May 22, 2014 #2

    Mitch

    Mitch

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    Depends on a lot of things very specific to the house. Only a schedule J done by a professional will tell you the true size required. Ballpark says a 4 ton unit, but if the insulation and windows and eveything else are super efficient, it may actually be 3.5 or even less.

    Most AC places won't want to do the full test, but if you want to know for sure, it has to be done.

    Variable speed compressor, 4 tons, at least 16 seer...be interesting to know if that is what they're trying to sell you...


    Edit...I'm just a home owner that did waaaaay too much research before buying my new AC in FL
     
    Last edited: May 22, 2014
  3. May 22, 2014 #3

    ca777

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    I worked in the HVAC industry for 3yrs and my experience is to go for the best 2 stage compressor with highest Seer ratings and check the energy usage per the energy sheet, you can afford. don't forget to get the warrantee. Usually the same size ton you have on the house now will work for future, unless It never kept up with the demand of the house, then up size. Even if you added alot of insulation and windows, down sizing will not help save energy, it will run longer and kill the compressor fastor. Stay away from goodman, janitrol, trane are ok but the parts on them are junk, get a Rheem. Best ones out there are the Rheem/Rudd. Last forever and still made in NJ.
     
  4. May 22, 2014 #4

    Mitch

    Mitch

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    Too big of a new AC and it won't run long enough to pull the humidity out of the air, which would SUCK in Houston. Most better units will have a humidity setting on the thermostat too, but then it will run and not keep the temp you want in order to get to the humidity level. The one I went with will lower the temp by up to three degrees when running to dehumidify before giving up on the % humidity.

    Slightly smaller is better than too big. As the previous poster said...if its too small, it will run more, but if the compressor is warranteed, who cares. Best to just get the right size and not worry about it. I will say though, if the old unit couldn't keep up, it probably wasn't because it was too small, it was probably just inefficient. The contractor grade unit I replaced ran CONSTANTLY to keep my house at 78 in the summer. I replaced it with the same size unit, and it rarely ever even has to kick up to the second stage to do it now. Only time it will is when I get home from a trip and I go from the "away" setting to the "home" setting. Cools and dehumidifies in no time. I went from $300/mo summer electric bills in FL, to $130 and the house is 1000x more comfortable. (new AC, attic insulation, and windows.)
     
  5. May 22, 2014 #5

    mauricio789

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    Thank you guys so much for the info.
    Here's a little more details.

    I'm buying a new house (new construction) and after the Inspection they questioned the size of the ac unit vs the size of the house.
    It's a 2098 sq ft house and they have a 3 ton unit on it to what the inspector thought was too small.
    He mentioned that maybe because of the extra insulation, double panel windows and other features, the builder could get the ac reduced to a 3 ton but he wasn't sure.
    I just want to find some official manual o regulation that I can take to the builder in case they refuse to change it or provide proof that that unit in fact will keep up with the Houston summer months.
    They offer a 2 year warranty on the unit so, shouldn't I be worried or how does the size of the ac affects its performance and also will this mean that the electric bill will be Lower with a smaller unit or higher because it will be running all the time.
    Thanks again for all the input.
     
  6. May 22, 2014 #6

    Mitch

    Mitch

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    Look for a company to do that Manual J analysis. You might even be able to insist the builder have it done. That is the most common official scale to determine your specific needs.

    The OLD rule of thumb was 1 ton per 500 sq ft. But with so many advancements in the efficiency of homes, it is probably higher than necessary now. 3 ton could very well be enough and of course the builder isn't gonna buy bigger than absolutely necessary since it would cost them money. Knowing nothing about your new home other than what you posted, 3 ton does seem possible, but small. If you're insulated to the hilt and have low E, argon filled windows, I would think a 2 speed 3.5 ton would be what I was expecting. Again...that is simply as a home owner that had to replace an AC recently.
     
  7. May 23, 2014 #7

    scotts

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    2 year warranty seems short. Is it a 2 story? Do you have large windows facing West (afternoon sun)? Tree's (shade helps)? My house in Magnolia is 2142 sq. ft. and we have a 4 ton. The builder special unit (12 seer) lasted 6 years (leaking coil replaced under warranty after 3 months, second coil is what did it in later), and it had a 5 year warranty. I replaced it with a Trane 16 seer single stage unit and it works well with our house. One story all brick with high roof, good windows, and lots of attic blown in insulation. Summer electric bill runs around $300 a month.

    Anyway, I would look into this carefully to avoid a large expense in the next few years. Our Trane replacement unit (everything but the ductwork) cost us around $7500 installed, so having to replace your system soon after moving in because it's inadequate would be a very unwelcome expense.

    If the property is too good to resist, look into a 3rd party home insurance policy that will replace your a/c if it goes bad after two years. However if it is merely inadequate an insurance policy might not help you.

    Good luck.
     
  8. Sep 20, 2016 #8

    afifaadam

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    it totally depends on a lot of things.and specilay depend on the house that which type of house is??.i think small is better than big.Cools and dehumidifies is required.just good quality compresser is needed.
     

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