New Trane Unit not reaching set point - Page 2
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  1. #14
    Join Date
    Jun 2005
    Posts
    13
    Yes, this is an R22 version. I will check with the installer when they return this week regarding installing a new coil to handle the 12 SEER compressor. I had another installer for an estimate, and he, too, said that the inside unit should be fine for a 10-12 SEER unit. Anything over 12 would need a new coil. This was based on both of these contractors' previous experience in our condo complex units (all had same Lennox products when built in 1986).

  2. #15
    Join Date
    Jan 2005
    Posts
    340
    First, they need to do a "Manual J" heat gain / loss calculation to make sure that 2.0 ton is sized right for your condo. Assuming that it is, then have them install a matched coil with a TXV (thermal expansion valve), making sure that there isn't any room around the sides of the new coil for air to bypass it.

    [Edited by travisfl on 06-27-2005 at 06:19 PM]

  3. #16
    Join Date
    Jun 2005
    Posts
    13
    What is the significance/source of the water I'm finding seeping out (slowly) from under the outside compressor?


  4. #17
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    You say you live in a condo.
    Is the indoor unit an air handler in the cieling, like over a bathtub, or in a hall?

    If so, there is no way that air handler is the least bit compatable with a 12 SEER outdoor unit. Most of the time 10 SEER outdoor units barely work something like acceptably with them.

    You need to replace your indoor unit for the system to work correctly. With the age of the system, it is about time for it anyway.
    If more government is the answer, then it's a really stupid question.

  5. #18
    Join Date
    Jun 2005
    Posts
    13
    The air handler is in the lower level, with one intake vent on each floor (one is in one of the walls in our front foyer(upstairs/ground-level) ; the other is in one of the walls to the small room where the air handler/furnace is located in the lower level). The filter is new.

  6. #19
    Join Date
    Sep 2004
    Posts
    172
    I think the key here is that water is seeping out of the new condensing coil unit the poster has mentioned that at least twice and he is correct that it is unusual and indicates a problem. This would indicate that saturated liquid is being returned to the condensing unit and suction line and compressor are sweating profusely. Severe Overcharge most likely. The condensor can be made to work but a proper superheat and subcooling has to be done to adjust the charge level to work with the system as it is set up, do not run the unit untill the charge level has been set correctly. If you want 12 SEER performance change out the evaporator for a matched coil, this setup that you have will be very inefficient. It can be made to cool though with a bit of tweaking. You may have to call the owner of the company you are dealing with and explain the mismatched coil situation, and that you want someone to check the charge level and set it up using the superheat/subcooling method, hopefuly he has at least one guy that can do that.

  7. #20
    Join Date
    Jun 2005
    Posts
    13
    Interesting point, DNT. Let me elaborate. When they installed the condensor on Thursday, the technician said that he was surprised to find that the "precharged" amount of freon in the new unit was not enough to "fill" the system and that he had to add more to get the proper gauge readings. He used a tank (which was apparantly almost empty as he had to shake/turn upside down/etc. the tank to get a proper reading from the system). When the technician and one of the service managers came back the next morning after my phone call to them regarding the cooling problem, they checked the readings and although they appeared fine, they used a second tank to put more freon in. The manager said that "he knows how much can go in" without causing problems... I guess the point is that the problem with the water was occurring even after the first day when the technician installed the unit, so perhaps it was even overcharged at that point?


  8. #21
    Join Date
    Nov 2001
    Location
    Port Saint Lucie, FL
    Posts
    1,594
    Not to be presumptious, but did the installing contractor offer to replace the system as a whole rather than just the condenser? If so...did you deny? If not, then he should have. That being said... sounds to me like a severly overcharged system OR an unknown condition cap tube evap coil...OR take your pick seeing as how we don't know all the variables...plugged filter,low airflow, dirty evap coil,refrigerant restriction,condensibles in the system,duct problem(airflow again). Tell us the superheat and/or subcool readings and pressures this tech recorded on his last visit. If this company can't provide these....call someone who can.


  9. #22
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    When it is humid out, there can be enough condensation on the suction line in the outdoor unit to cause some water to trickle out of the unit. Even with a correct charge.

    Putting a 12 SEER outdoor unit in with an 18+ year old cap tube evaperator coil intended for an 8 SEER system is just stupid.
    It can never be made to work correctly. It can be made to blow cool air, but thats about it.

    Unless the refrigerant lines are short, refrigerant generally does have to be added to the system when a new condensor is installed. Most manufacturers ship them with enough refrigerant for the outdoor unit, matched indoor coil and 15' of lines.

    Likely when they started the system up, it was doing what a grossly mismatched equipment like this usually does.
    Low suction pressure, high super heat, normal seeming head pressure, high sub cooling.
    Since many people mistakingly never even look at the subcooling on fixed metering systems, they start adding refrigerant to bring the suction pressure up and the superheat down. Meanwhile the subcooling keeps going up, and the head pressure raises a little, sometimes a lot.
    The end result is a system that is grossly overcharged, just go get a "normal" suction pressure and superheat.

    Nothing they do, short of changing out the evaperator coil, can make the mismatched system you have now work as well as the old matched system did.
    Untill a matching indoor coil is installed, the system is not working at anything close to full capacity. It may even be using more energy than your old 8 SEER unit. It isn't keeping you comforterable, and the life of the new compressor is being shortened.

    2 weeks ago I got a no cooling call on a similar situation. 2 year old 12 SEER outdoor unit, 25 year old cap tube evaperator. The Climatuff compressor in the new American Standard outdoor unit was killed because of the mismatch and the gross overcharge of refrigerant someone did to try and compensate.
    If more government is the answer, then it's a really stupid question.

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