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  1. #1
    Join Date
    Jun 2005
    Posts
    5

    Question

    I live in plano and have a 1475 sq.ft. home which originally came with a 2.5 ton heat pump system. I upgraded 3 years ago to a 3 ton condenser outside and kept the original ceiling mount indoor coil 2.5 ton. Now the inside drain pan is totally
    rusted and leaking. Would I be better off trying to make a 3 ton indoor coil fit with modification or just get a new 2.5 ton for an exact fit? Will I have better humidity removal with the smaller(2.5) indoor coil with reduced effiency? Any ideas thanks alot.



    [Edited by Plano AK on 06-13-2005 at 10:47 PM]

  2. #2
    Join Date
    Jun 2003
    Location
    Hell Hole Swamp
    Posts
    4,180
    You should have installed a matching air handler when the condenser was replaced, its not just coil capacity, the 2.5 ton blower is 200 cfm short also, you new compresor will die an early death if left this way, have a matching air handler installed.

  3. #3
    Join Date
    Jun 2005
    Posts
    5
    The compressor was installed about 3 years ago and the air handler is above the master tub in a very tight area and also I don't have traditional ducting there is nothing in my attic its kinda like a false ceiling square kinda ducts made of thick fiber board. I called Tom Tinan's radio show here in Dallas a year ago and he told me that the pratice is kind of common installing a half ton less air handler helps remove more humidity here in Texas. As far as 200 cfm wouldn't that make all those variable speed blowers aslo fail too since they run lower cfm's initially to help remove more humidity then speed up? Seems to me I can just make my thermostst have a slightly longer run time after the compressor stops to make up for the less cfm's..

    [Edited by Plano AK on 06-13-2005 at 10:43 PM]

  4. #4
    install a 3 ton air handler with a txv. thats what us nieghbors next door in fort worth would do. email me at airworxhvac@aol.com for a price.

  5. #5
    Join Date
    Oct 2004
    Posts
    1,722
    I never heard of going up a half ton on the compressor. Now on the A/H, I've been told and have installed half ton bigger than the compressor.
    Get back to work.

  6. #6
    Join Date
    Mar 2005
    Location
    Phoenix Arizona
    Posts
    697
    Compressor will fail , always good rule of thumb, inside <air handler> is to be same size or up to one half ton larger.

    If you had a 2.5 ton condensor and a 3 ton air handler, typically if its a matched system you could make a 12 seer, 13 seer. If installed properly!

  7. #7

    Arrow

    Check out http://www.ariprimenet.org.
    You can upsize condensers in some cases.

  8. #8
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,347
    Originally posted by plano ak
    I live in plano and have a 1475 sq.ft. home which originally came with a 2.5 ton heat pump system. I upgraded 3 years ago to a 3 ton condenser outside and kept the original ceiling mount indoor coil 2.5 ton. Now the inside drain pan is totally
    rusted and leaking. Would I be better off trying to make a 3 ton indoor coil fit with modification or just get a new 2.5 ton for an exact fit? Will I have better humidity removal with the smaller(2.5) indoor coil with reduced effiency? Any ideas thanks alot.



    [Edited by Plano AK on 06-13-2005 at 10:47 PM]
    If you go with the 2.5 ton indoor coil, I would specify a thermostatic expansion valve (TXV) to get the best performance and dehumidification out of that coil.

    I'm thinking your house might be a Fox & Jacobs? I'm also in the Plano area and my house has the dropped ductwork in a furdown. Doesn't have the air handler over the bathtub, though. Standard upflow furnace. Other newer F & J's have the First Co. indoor fan coils in a furdown over the baths, just like apartment construction.

    My advice as a F & J owner is do NOT oversize a/c on these houses! (as you would not on most any house). With the ductwork below the attic there is little heat gain other than what makes it through the insulation and enters the chase and ductwork. The previous owners of our house oversized the a/c in anticipation of taking in the garage, which we eventually did. Even with the additional space the unit is too big, but I've tweaked it so we do all right. Could be much better, efficiency wise, if it was sized correctly for the heat load.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  9. #9
    Join Date
    Jun 2005
    Posts
    5
    Quote Originally Posted by Swampfox View Post
    You should have installed a matching air handler when the condenser was replaced, its not just coil capacity, the 2.5 ton blower is 200 cfm short also, you new compresor will die an early death if left this way, have a matching air handler installed.
    Bringing back from the dead... Update I still have the same system and it has been running fine for 12 years! I even was using those filtrete ultra allergen filters too! I did allow more time for my air handler to run after the compressor stopped. Just recently though on the advice of a good friend started using the cheap fiberglass filters to get more air flow out of the registers. So much for the air compressor will die an early death theory

  10. #10
    Join Date
    Mar 2009
    Location
    Mount Holly, NC
    Posts
    3,205
    well, you've successfully gotten the system to operate for the 12 years, odds are good that the system has been operating very inefficiently. the 1/2 ton short of coil surface area, is the biggest problem. add in that it's likely a fixed orifice, and you have wasted 12 years of energy... the correct size coil, with a TXV for refrigerant control would get the condenser MUCH happier. then your lower cfm could indeed be usefull for additional humidity removal... oh well.
    but congrats of keeping it running! that 1K savings has likely been eaten up in wasted power, but to each his own!
    The TRUE highest cost system is the system not installed properly...
    The three big summer hearththrobs...
    Mel Gibson
    Dwane Johnson
    The A/C repairman

  11. #11
    Join Date
    Aug 2010
    Location
    West Monroe, LA
    Posts
    1,535
    Quote Originally Posted by plano ak View Post
    I live in plano and have a 1475 sq.ft. home which originally came with a 2.5 ton heat pump system. I upgraded 3 years ago to a 3 ton condenser outside and kept the original ceiling mount indoor coil 2.5 ton. Now the inside drain pan is totally
    rusted and leaking. Would I be better off trying to make a 3 ton indoor coil fit with modification or just get a new 2.5 ton for an exact fit? Will I have better humidity removal with the smaller(2.5) indoor coil with reduced effiency? Any ideas thanks alot.



    [Edited by Plano AK on 06-13-2005 at 10:47 PM]
    What equipment to you have name brand? It's possiable to have air handler that is 1/2 Ton smaller as long as it can move the rated cfm for the outdoor unit it can work.

    I have installed a Trane heat pumps (3) ton with (2.5) Ton Hyperion air handler for better humidity removel, increased capacity for seniable and total capacity, size if the closet etc...

    The Common matchup I do is say a Trane (3) ton heat pump with variable speed Hyperion air hander that the cfm can be increased to meet the cooling and heating rated cfm.

    Ahri rated equipment is the key. Need to speck with your installer on options for a new system.

  12. #12
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,665
    There is way more to it that just the number on the air handler .
    We really need change now

  13. #13
    Join Date
    Aug 2010
    Location
    West Monroe, LA
    Posts
    1,535
    Quote Originally Posted by catmanacman View Post
    There is way more to it that just the number on the air handler .

    Yes sir you are correct but most only use one size heat pump or condenser and match it with the same size air handler or coil and never review Ahri to see what could work better.

    There are hundreds of matched systems from any manfactor that shows a smaller indoor coil or air handler that will work. In many cases I find them to either yield better total capacity or seniable which are the true #'s we should all be looking at.

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