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  1. #1
    Join Date
    Feb 2014
    Posts
    7

    Confused New System in Houston - looking for advice

    Hello,
    I've had 3 contractors come out, one actually took the measurements to confirm that 4 ton unit was the correct size.

    House was built in 2005, 2 story. This unit services the ground floor, 2200 sq feet. Separate 3 ton 13 seer system will remain in place for 1500 sq ft 2nd story.

    I was given prices on Lenox, American Standard, and Trane. First two are pushing guys 18-20+ seer dual and VS compressors in the $-$$k range, 3rd guy says with the old ductwork (much of it between 1st and 2nd story and inaccessible) going above 16-17 is spinning your wheels. Maybe it's because he is so much cheaper, but I like what he is saying.

    Anyway - this is what I'm looking at getting and wanted an idea if this will be a good solid system for years to come:
    Trane XL15i, XV95 furnace, and XL900 t-stat.

    Anything additional that I should specifically request (coil?)

    Open to other suggestions as well.
    Last edited by beenthere; 02-19-2014 at 05:19 AM. Reason: Price range

  2. #2
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,543
    In our area the price difference between 16 and 18 SEER is such that it'll take over 15 years to save enough electricity to break even on the extra money. As for brands, there are not much difference between any brand, only the quality of the dealer. As for prices of the higher efficiency equipment....remember most sales folks are paid based on what they sell, so higher efficiency/price pays them more commission. The sales folks will quickly list all the bells and whistles, but don't expect (or ask) them to give you a ROI timetable based on a 3% increase of electricity each year. (ROI=return on investment)

  3. #3
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,999
    House was built in 2005, 2 story. This unit services the ground floor, 2200 sq feet. Separate 3 ton 13 seer system will remain in place for 1500 sq ft 2nd story.
    What climate do you live in that 4-Ton is needed to cool the ground 2200 sf below the 2nd story?
    Normally, the first floor has considerably less heat gain per sf than the 2nd floor 1500-sf 2nd floor area beneath the attic; plus heat rises, cold air seeks lower levels. Try another Free LoadCalc: http://www.loadcalc.net/

    A 3 or 3.5-Ton might work more efficiently with the existing filter area(s) & duct system & cool the ground floor better, & with better humidity control... do a manual D on that duct system it might only support 3 or 3.5-Ton of airflow!
    You'll usually gain very little, if anything, going to 18-SEER.

  4. #4
    Join Date
    Feb 2014
    Posts
    7
    I live in Houston. It is hot.

  5. #5
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,999
    Houston, 1% summer design is 94F dry bulb & 77F wet bulb or around a high 48% relative humidity.

    Humidity will be the major factor affecting your comfort level at 75 to 78F indoors, especially when temps are below 94F.
    With low humidity & some air movement you'll be comfortable at 78F.

    If the 4-Ton doesn't get humidity low enough you will have to run it lower than 75F which most codes say that should be the low-temp cut-off point.

    The duct system will be more efficient with (3.5-Ton) around 1325-CFM of airflow...
    Bigger is seldom better; down-sizing is always better when you can make it work for you; try the load-calc while selecting any cost-effective work on your home & duct system, etc., see what you get...

  6. #6
    Join Date
    Feb 2014
    Posts
    7
    Load from the contractor is 48,000. Much of the ductwork is between floors. I am stuck with the ductwork.

    We keep the house cool, 72 in the evening when we are all home until morning. Pretty much never set higher than 76.

    Is the condenser / furnace t-stat mentioned above still considered to be a solid setup? It is a few years old now, just wondering if it has held up to the newer stuff in terms of bang for the buck.

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,174
    How has your current 4 ton been doing as far as handling the humidity?

    Are you in Houston, or are you a bit further south, where its a bit more humid.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  8. #8
    Join Date
    Aug 2009
    Location
    Jurupa Valley, CA
    Posts
    1,781
    agreed, that 7 tons sounds like a LOT. Did the existing system run continuously on hot days? In that climate, I'm thinking you'd get more comfort for your dollar getting a smaller and cheaper air conditioner, and a whole home dehumidifier.

    I, personally, don't think you should be buying any equipment from a company that doesn't perform a complete ACCA Manual J load calc first.

  9. #9
    Join Date
    Feb 2014
    Posts
    7
    Yes, the system ran continuously on hot days.
    I really do not think 4 tons is overkill here, that is what we have currently.
    We also have a pool, and the kids are in and out constantly.

  10. #10
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,593
    In Houston you would benefit greatly getting a 2 stage high seer system. You really need 2 stage and an advanced control system to lower humidity.

    I would get a Lennox 80% 2 stage furnace with variable speed blower, 2 stage XC21 Condenser with I-Comfort control. You will appreciate the high seer and better humidity control found with the 2 stage systems. It more than the electric bill, high seer units run quieter, have nicer cabinetry, better components and should last longer than standard units.
    Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced

  11. #11
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,200
    15-17 SEER will get you in the range for better humidity controls
    and still a good roi. above that you'll pay a lot for not much
    better controls, just more bells & whistles.


    it is just the first floor system being replaced?

    to solve both sizing issues two stage will run in low speed
    in the months when you don't have all the in & outdoors.
    and when you actually need it the system will ramp up
    to handle the added load. you'll pay more upfront for
    the equipment, but less monthly. in the long run..
    that is your savings.

    but do...invest in load calc & have all acessable ductwork
    mastic sealed. it doesn't take long to seal each take off at
    plenum, plenums to equipment & return air.
    then seal each supply box to sheetrock. this way the
    air you pay to heat/cool actually makes it into the house.
    average duct leakage is 30%, which is a waste of money every day.
    here is a pic of how I seal supply boxes from inside
    the house with hardcast brand 1402 mastic tape. other brands
    fail, this is the one that works & lasts.
    Name:  how to seal supply box from inside with MASTIC tape only.jpg
Views: 138
Size:  91.0 KB

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

  12. #12
    Join Date
    Feb 2014
    Posts
    7
    Thanks, I'm ok with spending a little more, but an extra $ for just a small comfort increase and minimal energy savings does not make sense to me. I will make a few more calls today.

    How do maintenance costs between a tried and true single stage compressor and the newer dual stage compare. Wiping out savings with higher repair bills down the road is another concern of mine.
    Last edited by beenthere; 02-19-2014 at 01:24 PM. Reason: Price

  13. #13
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,200
    I can't answer on repair costs, but with the answer, you should factor in operating costs.
    single stage is all it has...all the time.
    two stage is what you need..when you need it.
    monthly savings adds up quickly.
    The cure of the part should not be attempted without the cure of the whole. ~Plato

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