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  1. #1

    New house. No clue what to pick

    Help if you could
    My house is located in South Carolina and is roughly 2300sqft--one floor\brick. I upgraded the windows to a Low-e\argon\1" glass that according to the "specs" perform very well. The exterior walls will have regular fiberglass (R13) batt insulation. I am condsidering foam in the exterior walls with fiberglass\cellous in the rest.

    I had a Manual J study done and it only recommened a 3.5 ton unit. Does this seem correct? I realize some people do it by sqft, but shouldnt the study be somewhat helpful?

    What should I look for in a unit?
    The builder is only going to put in a seer13. Is that a waste considering the upgrade to the windows?
    Should I increase the seer rating versus "foaming" the walls?

    any ideas?

  2. #2
    Join Date
    Sep 2005
    Location
    Atlanta GA area
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    Do you live in a humid climate close to the ocean?

    The reason I ask is that humidity control is part of what A/C does.

    Over here in Atlanta, we do not have the humidity the folks on the coast have. But humidity is an issue.

    You will accomplish more in the way of humidity control with a 2 stage variable speed blower furnace than with a special A/C unit.

    Your house will be tight enough already, I doubt a 14 SEER would help that much. And 16 SEER or higher equipment requires lots of maintenance... it is really better suited for really HOT climates like Az.
    GA-HVAC-Tech

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    2 Chronicles 7:14

  3. #3
    Join Date
    Jul 2008
    Location
    Poestenkill, NY
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    769
    Way too many topics to cover in one post.

    Here is my tid-bit of info:

    Spray foam the entire house. The reduction in infitration is significant, R-value is only a part of the picture. In practice, spray foam insulation out-performs fiberglass by a large margin.

    Let your HVAC contractor know your insulation intentions. A spray foam house will have significantly smaller heating and cooling loads. And a mechanical fresh air system of some sort will be necessary. But the savings will be there year after year....

    Others will chime in all sorts of info...

    Welcome...

  4. #4
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
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    18,836
    kellarm,

    Foam the walls ,you'll nevr get another chance to do so,the A/C system will be replaced in 10 to 15 years.

    Load calc. results sound oversized have them double check,did they know about the window upgrade?Tell them about the foamed walls too.

    I'd go with a variable speed indoor unit 14SEER ,or more if you can swing it.Ask to talk directly with the HVAC sub..

  5. #5
    Join Date
    Sep 2005
    Location
    Atlanta GA area
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    21,719
    Things are different with each contractor;

    RNC residential new construction is a different market and business than replacement systems in an existing home.

    New construction is sometimes less technical and less feature rich... Be sure your HVAC contractor understands both markets. And be sure your contractor understands load calculations. The advise given to tell your HVAC contractor about the foam and the windows is good advise. The more he knows, the better he can do your load calc. Also the advise about some form of fresh air; you probably will need an ERV unit (energy recovery ventilator) is worth it.

    Also be sure you have a Manual D duct design. You can have the right sized equipment; but if the air is not moved around the house properly, there will be warm and cool spots.

    The more information the HVAC guy gets, the better he can design and install your system.
    GA-HVAC-Tech

    Quality work at a fair price with excellent customer service!

    Romans Ch's 5-6-7-8

    2 Chronicles 7:14

  6. #6
    Join Date
    Jan 2004
    Location
    PA
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    68,770
    Foam those walls, you won't regret it. It will save you money in both heating and cooling season. And pay for its self quicker then the highest efficiency furnace or A/C can.
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    How many times must one fix something before it is fixed?

  7. #7
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    6,638
    Most heat and air goes up through the ceiling. Foam roof deck is the best. Someone mentioned fresh air and humidity control. Both are important. You should have an air change every 4-5 hours when the home is occupied. This is about 75-100 cfm of fresh air which purges indoor pollutants and renew oxygen. <50% RH is ideal for comfort and indoor air quality. A good air tight home saves energy. During wet cool weather with sufficient fresh air and occupants, 40-70 lbs. per day of moisture (no cooling load) must be removed to maintain <50%RH. A whole house venitilating dehumidifier is an ideal device to add to an a/c system. I am involved with Ultra-Aire VDH for 15 years. This is highest efficiency dehu in the world. Fresh air and dry even when the a/c is not operating. Check thermastor.com Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  8. #8
    Join Date
    Jul 2008
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    Poestenkill, NY
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    Quote Originally Posted by teddy bear View Post
    Most heat and air goes up through the ceiling. Foam roof deck is the best.
    Yes - I agree. It's worth saying agin - foam the whole house. Money well spent. Rediculously fast payback.

  9. #9
    Join Date
    May 2004
    Location
    south louisiana
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    3,319
    foam the roof line. ductwork will benefit, unit's life will be longer in semiconditioned attic.
    air seal walls with conventional insulation and air tight drywall approach.
    the study you had done is helpful, but with foam insulation and the window
    upgrade the size required will be less.
    are you installing a heat pump?

    best of luck.
    The cure of the part should not be attempted without the cure of the whole. ~Plato

  10. #10
    Join Date
    Jun 2007
    Location
    south carolina
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    176
    Your house will be tight enough already, I doubt a 14 SEER would help that much. And 16 SEER or higher equipment requires lots of maintenance... it is really better suited for really HOT climates like Az.



    What more maintenance does a 16 seer require. I've never had any more maintenance to do on 16 seer's.

    I would strongly recommend a higher seer system I'm not sure where in sc you are but here in the hilton head island area it's well worth it. As far as brand if your near the water i would say stick to carrier/bryant or lennox they stand up better then others to salt air

  11. #11
    Join Date
    Sep 2005
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    Atlanta GA area
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    It has been my experience that higher SEER equipment does not work at its rated SEER unless it is cleaned every year. All equipment does better when it is maintained properly. But high SEER equipment is more sensitive than basic 13 SEER.

    One might remember that with many brands, IF the installation is done properly, and a VS furnace or AH is installed, one generally gets 14 SEER. Not all equipment is this good, but many are.

    We can add to this in a humid climate if one sets up a dehumidification cycle with the VS blower, the RH inside can be held down to a level where it feels comfortable with the T-stat set a few D higher. This means energy savings.

    Now tell me: What percentage of your customers do a full service including cleaning the condenser and coil EVERY year?
    GA-HVAC-Tech

    Quality work at a fair price with excellent customer service!

    Romans Ch's 5-6-7-8

    2 Chronicles 7:14

  12. #12
    Join Date
    Jan 2004
    Location
    PA
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    Quote Originally Posted by ga-hvac-tech View Post
    It has been my experience that higher SEER equipment does not work at its rated SEER unless it is cleaned every year. All equipment does better when it is maintained properly. But high SEER equipment is more sensitive than basic 13 SEER.
    Are you sure your getting 13 SEER from a 13 SEER unit?
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  13. #13
    Join Date
    Sep 2005
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    Quote Originally Posted by beenthere View Post
    Are you sure your getting 13 SEER from a 13 SEER unit?
    OK Been, tell me which hairs you want to split, and we can get out the razor knife and attempt to split them...

    If an installation done by ABC contracting of a 13 SEER system does not do 13 SEER, would an installation of a 14 or 16 SEER system by the same ABC contractor do 14 or 16 SEER?
    GA-HVAC-Tech

    Quality work at a fair price with excellent customer service!

    Romans Ch's 5-6-7-8

    2 Chronicles 7:14

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