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  1. #27
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,444
    Quote Originally Posted by fitterchick View Post
    Word has it in my shop that upsizing the evap coil will give you maximum dehumidification.
    Question for you is: a 3 ton evap coil with txv going to work with a 2.5 ton 13 seer condenser?
    I spoke to the mfg. and they said you dont need a txv with a 13 seer only the 14 seer. I thought all 13 seers required txv for maximum eff. ???

    Now I am asking this question looking for real answers so for those of you who enjoy bashing people (you know who you are) please keep your comments to yourself.

    Thanks..........
    If you are unable to fine tune the air flow over the coil, smaller coils remove a higher latent ratio because they are colder-less eff.-slower cooling. If you can fine tune air flow and can handle very cold air without getting condensation on the ducts, larger coils remove more moisture. Mainly because you can get the air colder without freezing. The negative of large coils is much more moisture retention to evaporate back to the structure during the off cycle. Most are better off not messing with this. The modern a/c has a larger coil with a smaller compressor. The current two speed a/cs use low speed on the entire coil. How good does that work? OK
    Real humidity control is supplemental dehumidification for low/no cooling load conditions. 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"

  2. #28
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,104
    A former member of this board used much smaller rated coils with condensers to remove more humidity.
    The larger coils couldn't have the air slowed enough to to remove as much moisture.
    Even though the sensible drops with lower air flow, it doesn't drop enough, and the stat is satisfied too soon.
    The smaller coil with lower air flow already having a lower sensible heat capacity will still remove more moisture because of the lower run time required to drop teh temp to stat set point.

    You can't apply the same pricipals of a decicated dehumidifier (where a larger coil may be better)to an A/C that also has to remove sensible heat.
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  3. #29
    Quote Originally Posted by teddy bear View Post
    The negative of large coils is much more moisture retention to evaporate back to the structure during the off cycle. TB
    can you explain that.......structure meaning plenum or evap coil?

    Sorry

    I would like to thank everyone with their replys, my service manager has been upsizing the evaps for a while and everytime I have asked why he tells be its for better eff. and dehumidification, I am glad to here other peoples point of views.

  4. #30
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,104
    What ever brand your company installs.

    Gather up some of the model numbers of the condensers and coils you have been putting in.
    Go to the ARI website, enter those numbers and pull up the efficiency rating for those matches. And then look what the rating is for a smaller coil.

    If you can get the spec/technical guide for your brand, look at the ratings of the various matches. It should have efficiency ratings, and give you the TC, and SC of the match.

    You'll find that some 1/2 ton bigger match ups don't get more then a .5 SEER increase if that, and will have a lower latent capacity. With that lower latent capacity, some people turn their stats lower, so they use more electric then if a smaller coil was used.

    Structure, in Teddy's reference, would be the house, or building that the system is installed in.
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  5. #31
    Hi, new guy here looking to install a new system in my home. I've been looking at Trane equipment, and am wondering why ARI would list virtually all 5-ton evap coils with a 4-ton condenser.

    eg, doing a search with:
    outdoor unit: 4TTX5048
    indoor unit: 4TXC

    yields 111 results, 3 of which are 4-ton coils.

    Is this a mismatch of equipment, am I looking it up wrong, or ... ?

  6. #32
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,104
    Thats how they get the higher SEER rating.

    Your contractor can explain it in detail if you ask him about it.
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  7. #33
    I see that the higher SEER ratings are found with that type of setup, but I guess I had thought that the ARI rated matchings were independent of trying to get high SEER ratings, but indicative of a 'sanctioned' matching of equipment. So I suppose I was looking for the matching of the 4-ton equipment, even if the SEER rating were slightly lower.

  8. #34
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,104
    ARI is an independant rating organization.

    As long as the performance matches what the manufacturer says, they don't care if its a 10 ton coil.
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