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  1. #14
    Join Date
    Sep 2012
    Posts
    71
    Quote Originally Posted by jtrammel View Post
    Have a blower door test performed just so you know how much and where you could improve and if the 2 ton won't get it done, which I feel it would, then you can go about improving the home until it will get the job done whether its 80F or 100F. Even if it won't keep it 74 when it's 95F outside the humidity will be so low from continuously running it won't feel uncomfortable at 78F inside
    I didn't have a blower door test.

    Quote Originally Posted by leaker2 View Post
    Whats the warrenty on the units? I know certified trane contractors have 10 year. If bumped up to 3 ton just based on what you said about a 2 stage, it might be just a sales man. How close were the calculation to the thresholds of being a 2 vs 3 ton? And of course they can just fudge em too. what was previously installed? Did it hold up on peak temp days?

    Sent from my SPH-D710 using Tapatalk 2
    I really am not sure how close the calculations were, I guess I should have asked for them. The old unit that is currently working, on the hottest days seemed to run pretty much all day during the height of the heat, say from 10AM to 8PM. The old unit may not have been producing 3 tons anyway for all I know. The last 4 years it has sounded like a jet engine.

    I am not sure how to convey this, but we had to keep the temp close to 70 degrees or it didn't feel cold enough. But in the evening/overnight it felt too cold at the same temps. I am guessing that is a humidity issue right?

    I am just afraid to go from 3 ton to 2 ton even knowing the new technology is far superior to what I have.

    Like I mentioned, my house is only 1500 s/f on one level. It is well insulated in my opinion and I think it is pretty much "draft-free".

    Maybe a 2 ton, 2 stage is the way to go as a 3 ton 2 stage may be overkill. ???

  2. #15
    Join Date
    May 2007
    Location
    DC Metro Area (MD)
    Posts
    3,371
    Quote Originally Posted by Zomby View Post

    XR15 2-ton single stage condenser - 16 SEER
    XV95 2-stage, variable speed gas furnace
    "matching coil"
    TCONT thermostat
    Best to get the model number of the coil to be installed. May or may not be a Trane coil. There are third-party coils that are approved "matches" in the AHRI directory.

    I would look at the XR16 or XL16i as comparable units to the Bryant 127A. Proper sizing is very important, 2-stage or not. I'd be curious why the Trane contractor arrived at 2 tons and the others 2.5-3 tons if they all supposedly did Manual J's. There must be some differences in their input values or design temperatures, or some didn't do a load calculation and sized off of square footage/existing equipment. Something to look into. As BL mentioned, if a 2 ton unit will do the job at design conditions, then that's what I would get -- nothing more. Longer runtimes achieved with properly sized systems are better for the equipment itself, energy efficiency, and your comfort. An XL16i with an XV95 and matching Trane coil would be a very nice system.

  3. #16
    Join Date
    Sep 2012
    Posts
    71
    Quote Originally Posted by RyanHughes View Post
    Best to get the model number of the coil to be installed. May or may not be a Trane coil. There are third-party coils that are approved "matches" in the AHRI directory.

    I would look at the XR16 or XL16i as comparable units to the Bryant 127A. Proper sizing is very important, 2-stage or not. I'd be curious why the Trane contractor arrived at 2 tons and the others 2.5-3 tons if they all supposedly did Manual J's. There must be some differences in their input values or design temperatures, or some didn't do a load calculation and sized off of square footage/existing equipment. Something to look into. As BL mentioned, if a 2 ton unit will do the job at design conditions, then that's what I would get -- nothing more. Longer runtimes achieved with properly sized systems are better for the equipment itself, energy efficiency, and your comfort. An XL16i with an XV95 and matching Trane coil would be a very nice system.
    On the AHRI sheet the coil model number is listed, I just can't find the sheet now. Thanks for your advice!

  4. #17
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,429
    Quote Originally Posted by Zomby View Post
    I guess we need to throw away this years heat wave huh?
    This area gets hot and humid, but we probably average 15 days over 95 degrees during a "normal" summer.

    So considering the fact that the Trane rep (Who I had a lot of respect for as he was extremely knowledgeable) was adamant about 2 tons, maybe I should listen to what he was preaching and go with the 2 ton.
    What would someone from Dallas say about " throw away this years heat wave"?

    I truly wonder if one or two years becomes one or two DECADES of HIGHER THAN EXPECTED summer temperatures?

    I.E. ... the area of 20+ days > 96F' could be enlarged
    I guess I should review the latest temperature trend in Chicago ?!!

    It's best to read and re-read the recommendations of Bald Loonie ( post #2)

    THERE will ALWAYS be a DILEMNA out there as so well expressed by TommyKnocker in post #8.

    I trust MY Calculations AFTER I review them and have assessed their inaccuracies, if any.
    ... "The Art" of equipment selection.

    Trying to maintain < 75'F inside temperature is a great benefit
    to the local utility. Equipment performance is simply not as efficient. !..!!.!!!.
    You effectively have been forced to donate an ~extra $100 / month to your favorite charity.

    I know from your post stating " running from 10 am - 8 pm" that the
    old -jet engine- unit is likely underperforming
    unless you are talking about days
    where it's still > 90'F at 7 pm.
    Last edited by dan sw fl; 10-13-2012 at 06:48 AM.
    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

  5. #18
    Join Date
    Sep 2012
    Posts
    71
    Quote Originally Posted by dan sw fl View Post
    What would someone from Dallas say about " throw away this years heat wave"?

    I truly wonder if one or two years becomes one or two DECADES of HIGHER THAN EXPECTED summer temperatures?

    I.E. ... the area of 20+ days > 96F' could be enlarged
    I guess I should review the latest temperature trend in Chicago ?!!

    It's best to read and re-read the recommendations of Bald Loonie ( post #2)

    THERE will ALWAYS be a DILEMNA out there as so well expressed by TommyKnocker in post #8.

    I trust MY Calculations AFTER I review them and have assessed their inaccuracies, if any.
    ... "The Art" of equipment selection.

    Trying to maintain < 75'F inside temperature is a great benefit
    to the local utility. Equipment performance is simply not as efficient. !..!!.!!!.
    You effectively have been forced to donate an ~extra $100 / month to your favorite charity.

    I know from your post stating " running from 10 am - 8 pm" that the
    old -jet engine- unit is likely underperforming
    unless you are talking about days
    where it's still > 90'F at 7 pm.

    So what would your suggestion be from what you have seen me post? 2 ton single stage or 3 tom two stage? I would sure appreciate your opinion!

  6. #19
    Join Date
    Sep 2012
    Posts
    71
    I mean to say 2 ton/2 stage or 3 ton/2 stage.

    All help appreciated! I have to make a decision before Monday to capitalize of our power companies financing and rebates.

  7. #20
    Join Date
    Sep 2012
    Posts
    71
    Looks like this topic died, so thanks for all the help fellas. I think I am going to go with the Bryant system but ask him to install a 2 ton/2 stage - Unless he is convincingly strong in his 3 ton recommendation.

    One question though. When in the lower stage, is it 1/2?

    Thanks,

  8. #21
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    7,775
    I think it's 70% in first stage. The only one that is half is trane's xl20i bc it has 2 seperate compressors for high and low.

  9. #22
    Join Date
    Sep 2012
    Posts
    71
    Quote Originally Posted by jtrammel View Post
    I think it's 70% in first stage. The only one that is half is trane's xl20i bc it has 2 seperate compressors for high and low.
    Thank you sir!

    I "really" think 2 ton is the way to go. I just talked to a buddy who has the same size house as me (1500 s/f) layed out very similiar and he found out he has a 3 ton and the contractor told him to go with a 2 ton.

  10. #23
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    7,775
    My house is ~1300 sq ft with a 2 1/2 ton ac and it is oversized, I have to run a dehumidifier in the summer bc the ac doesn't run long enough to keep the humidity down. I'm in upstate South Carolina with a summer design of 92F. I did a load calc and it came out to 20k btus, a little over 1 1/2 tons and I know of some problems I can fix to bring the calc down a little more.

  11. #24
    Join Date
    May 2007
    Location
    DC Metro Area (MD)
    Posts
    3,371
    Net capacity on low can be as much as 75-80% of total capacity depending on the match-up with the unloading scroll compressors used in most 2-stage units. That's why you don't want to go with a 3 ton if that's not what the space requires. On low, you'd already be at a bit over 2 tons capacity, and you wouldn't achieve the long runtimes in low as desired for comfort.

  12. #25
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,610
    Just remember that those furnaces quoted aren't meant for 2 stage A/Cs. If you go that route, you should get the variable speed models.

  13. #26
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    7,775
    Quote Originally Posted by BaldLoonie View Post
    Just remember that those furnaces quoted aren't meant for 2 stage A/Cs. If you go that route, you should get the variable speed models.
    X2

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