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Thread: 3 ton problems

  1. #1
    Join Date
    Jul 2005
    Posts
    11

    Frown

    Hello everyone, new to site. I have a problem with a 3 ton unit. This unit is a Trane air handler with Trane coil and it replaced the Carrier 2.5 ton that was installed when my house was built in 88. Prior to the replacement there was no problem cooling down the area (65 deg.) and the unit cycled regularly. Now the Trane unit runs all night before it ever gets to this cooling range. It is cooling approx. 800 sf, its located in the attic, and the area to be cooled is two BR and a bath on the north side and 1 BR and bath on the south side of the house. Also, the grille in the bath on the north side sweats. I have had it checked numerous times and just recently I had the plenum changed and an area of ductwork placed between the air handler and the coil to provide access for cleaning. The fan speed was changed at this time to HI from MED. Comparing the two units it seems to me that the Trane is not moving the same amount of air as the Carrier. The area at the return seems to be the warmest part of the area being cooled and you really can't tell that there is any air moving. I have checked for restrictions in the RA and all seems clear. I called the guy back that did the work recently about the sweating grille and he decided that there wasn't enough air moving through the unit. Every time that I try a different AC company there is a new story. I'm really frustrated with this situation. Any help will be GREATLY appreciated.



  2. #2
    Join Date
    Jul 2005
    Posts
    11
    I'm in central La.

  3. #3
    Join Date
    Jan 2002
    Location
    Ft.Worth,Tx
    Posts
    4,581
    Originally posted by jeffdavis
    Hello everyone, new to site. I have a problem with a 3 ton unit. This unit is a Trane air handler with Trane coil and it replaced the Carrier 2.5 ton that was installed when my house was built in 88. Prior to the replacement there was no problem cooling down the area (65 deg.) and the unit cycled regularly. Now the Trane unit runs all night before it ever gets to this cooling range. It is cooling approx. 800 sf, its located in the attic, and the area to be cooled is two BR and a bath on the north side and 1 BR and bath on the south side of the house. Also, the grille in the bath on the north side sweats. I have had it checked numerous times and just recently I had the plenum changed and an area of ductwork placed between the air handler and the coil to provide access for cleaning. The fan speed was changed at this time to HI from MED. Comparing the two units it seems to me that the Trane is not moving the same amount of air as the Carrier. The area at the return seems to be the warmest part of the area being cooled and you really can't tell that there is any air moving. I have checked for restrictions in the RA and all seems clear. I called the guy back that did the work recently about the sweating grille and he decided that there wasn't enough air moving through the unit. Every time that I try a different AC company there is a new story. I'm really frustrated with this situation. Any help will be GREATLY appreciated.


    Might be that when the air handler is running it is sucking the insulation inside the blower compartment against the blower thus cutting off airflow, sometimes not noticed by serviceman if not looking for that problem.

    Also did you add any supply registers or returns after you up-graded to (36,000 btu) system? Ductwork was designed for 2.5 ton system not 3.0 ton system.Return's also designed for 2.5 ton, was it en-larged? Better to get professional help to retro-fit and not change-out hacker's.
    "Everyday above ground, is a good day".
    "But everyday that you have made a difference in someones life, may insure you stay above ground a little longer".<aircooled>

  4. #4
    Join Date
    Jan 2002
    Location
    Ft.Worth,Tx
    Posts
    4,581
    Originally posted by aircooled53
    Originally posted by jeffdavis
    Hello everyone, new to site. I have a problem with a 3 ton unit. This unit is a Trane air handler with Trane coil and it replaced the Carrier 2.5 ton that was installed when my house was built in 88. Prior to the replacement there was no problem cooling down the area (65 deg.) and the unit cycled regularly. Now the Trane unit runs all night before it ever gets to this cooling range. It is cooling approx. 800 sf, its located in the attic, and the area to be cooled is two BR and a bath on the north side and 1 BR and bath on the south side of the house. Also, the grille in the bath on the north side sweats. I have had it checked numerous times and just recently I had the plenum changed and an area of ductwork placed between the air handler and the coil to provide access for cleaning. The fan speed was changed at this time to HI from MED. Comparing the two units it seems to me that the Trane is not moving the same amount of air as the Carrier. The area at the return seems to be the warmest part of the area being cooled and you really can't tell that there is any air moving. I have checked for restrictions in the RA and all seems clear. I called the guy back that did the work recently about the sweating grille and he decided that there wasn't enough air moving through the unit. Every time that I try a different AC company there is a new story. I'm really frustrated with this situation. Any help will be GREATLY appreciated.


    Might be that when the air handler is running it is sucking the insulation inside the blower compartment against the blower thus cutting off airflow, sometimes not noticed by serviceman if not looking for that problem.

    Also did you add any supply registers or returns after you up-graded to (36,000 btu) system? Ductwork was designed for 2.5 ton system not 3.0 ton system.Return's also designed for 2.5 ton, was it en-larged? Better to get a professional help to retro-fit system and not change-out hacker's.
    "Everyday above ground, is a good day".
    "But everyday that you have made a difference in someones life, may insure you stay above ground a little longer".<aircooled>

  5. #5
    Join Date
    Jul 2005
    Posts
    11
    aircooled53,

    The replacement was done by the same contractor that installed the original unit. I have had them back as well as the Lennox and Frigid-aire dealers. The last dealer has helped the most but problem still exists.

    As far as I know the ducts are the same size as the original with none added. The duct going to the registers in the rooms is flex. The RA is original as well. The Trane unit is smaller dimensionally than the Carrier it replaced and I think that the coil is smaller as well. Would this cause the problem I am experiencing?

  6. #6
    Join Date
    Jun 2003
    Location
    Jacksonville, FL.
    Posts
    4,313
    Maybe I did read it right, but....

    Did you say you have a 3ton system cooling 800sq.ft.? Seems a little oversized to me.

    And ditto what Aircooled said.

  7. #7
    Join Date
    Jul 2005
    Posts
    11
    Let me get my Model Nos. so that I'm sure what I am talking about.

  8. #8
    Join Date
    Jul 2005
    Posts
    435
    Jeff need to know what Trane system was installed. If it is the two stage system, it is not uncommon for the low stage to keep running on the smaller compressor as compared to a 1 stage system. The Trane 2 stage systems have two compressors in the outside unit. If it is a 3 ton unit as you say, and it is a 2 stage system the first stage is around 1.5 tons, the second is 3 tons. By continually running on the first stage, it provides even cooling and dehumidification at very effecient use. Single stage units have the large compressor that runs at full with the large compressor, blows at max cfm until the temp is reached and shuts down. Not only does this not dehumidfy as well as the 2 stage system, it also gives you a blast of cold air, then it shuts off and you feel inconsistancies in the room temp.

  9. #9
    Join Date
    Jan 2005
    Posts
    340
    Originally posted by jeffdavis
    I have a problem with a 3 ton unit. This unit is a Trane air handler with Trane coil and it replaced the Carrier 2.5 ton that was installed when my house was built in 88.
    If the old system worked so well, why did your contractor upsize it? Did anyone do a heat gain calculation before selecting and installing the new system? Were the ducts enlarged to handle the additional airflow?

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