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  1. #1

    upflow to horizontal?

    In Fort Worth Texas, I have 2350 sq. ft. home. Four years ago, I change from two air conditioners (and furnaces) to a Trane Xl19i 5 ton two zoned system. This is a one story ranch style home, with the zones being the living room, den and kitchen on one zone, and the bedrooms (3) bathrooms (2) on the other zone. All the duct work was replaced at the time of installation.
    In the four years I have had 13 service calls for A/c failures. Four of these failures required replacing the start capacitors, and or the start relay (start kit). There have been several problems with poorly programed thermostats and "tuning" the main control board.
    Tired of worrying about the a/c running when I got home--is it, or is it not?--I have had 3 different companies out to see if they can find the real problem. (By the way, this is covered by a 10 year parts and LABOR warranty from Trane). Everyone says---ducts too small, not enough return air.
    OK. Now a Trane dealer wants to move the unit to the attic, turn it on it's side (XV80 upflow furnace) and replace the evap. coil, and redo the duct work and retrun air system.
    Question. Obviously some big money involved. Is it worth doing, or should the whole system be replaced, or should we just change the ducts to the proper size and go to plan B (don;t have that yet) for the return air.?
    Static test indicated 1.2 inches (?) of pressure. Apparantly this should be .5 or less.
    If you need more info, please let me know, I have a weeks worth of info on this system, and all it's parts.
    Thanks,

  2. #2
    Join Date
    May 2004
    Location
    Frederick, MD
    Posts
    962

    What does

    replacing capacitors and a start kit, programming a thermostat, and "tuning" the main control board have to do with the ductwork or airflow? Something not adding up here.

  3. #3
    I know. I have contacted Trane customer service twice about this unit. It's my feeling that a new high efficiency unit should last a full summer without a failure. But no. 1 failure (a/c not working resulting in a service call) in year 1. Five failures in year 2--replacing both the txv and eventually the evap coil. Three failures in year 3. and four already this year. The current dealer avoids my calls to sales or management. Trane customer service said I would be contacted in 3-5 business days 5 business days ago. Personal experience in electronic equiptment says if the same part fails over and over, you have a bad design, or SOME OTHER PROBLEM causing the systematic failure. That's why I started looking at the duct work (as well as all the posts on this board.)
    The "tuning" of the main board consisted or changing the setting of how many times the system could come on in and hour without locking out (I am told this----I have no clue.) Apparantly if the system comes of 3 times in one hour, it "thinks" there is a problem and shuts itself off. Another call was the the setting "thot" the unit was freezing up (temp at vent 54 degrees F) and turned itself off.
    Thus the control board problems. But, as I suggested, I am NOT an A/C tech. I do know the unit cools down 900 square ft. at the rate of 2 degrees an hour----at 100 outside. Then blows a starting cap.
    By the way, it's a 5 ton unit.
    Any other info I can give to assist in suggesting a solution?

  4. #4
    Join Date
    Dec 2010
    Location
    Down by the river
    Posts
    1,664
    so you have 19i right, if this unit is starting,stopping going from high compressor to low compressor excessivly yes it's wearing itself out. You could have some serious design issues for sure.

    I would start with manual J load calculation on the house, then I would have your zoned ductwork evaluated for proper size.

    there is too many contractors who think they know how to design a zoned system, now you add a 2 compressor condenser to the factor and you have problems big problems.
    It's hard to stop a Trane. but I have made one helluva living keeping them going.

  5. #5
    Join Date
    Jun 2011
    Location
    Wake Forest, NC
    Posts
    352
    Something smells fishy... Capacitors replaced for poor return air?

    Does your zoning system have a dump zone or a bypass damper of some sort? Running 2000 CFM through only one zone could cause a variety of problems.

    Improper return air can also cause issues, but not really like the ones you are talking about.... Here is my best answer on your questions:

    1. Bad TXV and a bad evaporator coil tells me one of three things (in order of most likely)

    1. Poor installation. Non-condensables are in the lineset and ruined your TXV. Possibly sludge if the new system is a R-410a system and they re-used the old lineset and did not flush it properly.
    2. Inexperienced technician who saw a problem and started throwing parts at it.
    3. You are one of the unlucky few who got a unit that was built at 4:50pm on the last day before a holiday and was thrown together by people thinking about beer and cookouts instead of making quality equipment.

    2. Adjusting CPH (how many times the system will run a cycle in an hour) doesn't have anything to do with anything best I can tell. Those settings should be made at the thermostat and the control board on installation, and the fact that they were not also points me in the direction of poor installation as the fundamental root cause of your problems.

    3. Start capacitors and start relays are purely electric and should have nothing to do with TXVs and coils. They do fail, and occasionally need to be replaced, but usually not within 5 years on new equipment. Multiple failures of those same parts tells me either:

    1. There is some kind of wacky electrical problem on your system (have a pro measure high voltage and low voltage supplying the unit and check for any issues.)

    2. An inexperienced tech is throwing parts at a problem waiting for the solution to materialize.

    All in all, everything you are telling me points toward poor installation and inexperienced technicians. Now this is just my conclusion drawn from what I see here, and may not be the case. I would strongly advise seeking out another authorized Trane dealer who will honor the warranty and get a second or third opinion. There may be problems with return air, but based on what you are telling me I am suspicious and would want more information before I spent the kind of money a job like your proposed solution would cost.

    When the other service company arrives, provide them with all the information on the prior repairs, but dont mention the other companies proposed solution. That may bias the diagnosis. Show the prior problems and ask them to determine and propose a solution. They may see something the other company missed.
    It's not rocket-science...

    It's electromechanical thermodynamic engineering

  6. #6
    Join Date
    Dec 2010
    Location
    Down by the river
    Posts
    1,664
    Quote Originally Posted by HVACTechNC View Post
    Something smells fishy... Capacitors replaced for poor return air?

    Does your zoning system have a dump zone or a bypass damper of some sort? Running 2000 CFM through only one zone could cause a variety of problems.

    Improper return air can also cause issues, but not really like the ones you are talking about.... Here is my best answer on your questions:

    1. Bad TXV and a bad evaporator coil tells me one of three things (in order of most likely)

    1. Poor installation. Non-condensables are in the lineset and ruined your TXV. Possibly sludge if the new system is a R-410a system and they re-used the old lineset and did not flush it properly.
    2. Inexperienced technician who saw a problem and started throwing parts at it.
    3. You are one of the unlucky few who got a unit that was built at 4:50pm on the last day before a holiday and was thrown together by people thinking about beer and cookouts instead of making quality equipment.

    2. Adjusting CPH (how many times the system will run a cycle in an hour) doesn't have anything to do with anything best I can tell. Those settings should be made at the thermostat and the control board on installation, and the fact that they were not also points me in the direction of poor installation as the fundamental root cause of your problems.

    3. Start capacitors and start relays are purely electric and should have nothing to do with TXVs and coils. They do fail, and occasionally need to be replaced, but usually not within 5 years on new equipment. Multiple failures of those same parts tells me either:

    1. There is some kind of wacky electrical problem on your system (have a pro measure high voltage and low voltage supplying the unit and check for any issues.)

    2. An inexperienced tech is throwing parts at a problem waiting for the solution to materialize.

    All in all, everything you are telling me points toward poor installation and inexperienced technicians. Now this is just my conclusion drawn from what I see here, and may not be the case. I would strongly advise seeking out another authorized Trane dealer who will honor the warranty and get a second or third opinion. There may be problems with return air, but based on what you are telling me I am suspicious and would want more information before I spent the kind of money a job like your proposed solution would cost.

    When the other service company arrives, provide them with all the information on the prior repairs, but dont mention the other companies proposed solution. That may bias the diagnosis. Show the prior problems and ask them to determine and propose a solution. They may see something the other company missed.
    don't know exactly what year model coil we are working on but there was a service bulletin about a bad txv. I just replaced mine and it's an 08'.

    If he has poor duct design combined with oversized system, this unit banging compressors on and off could and will do what he is describing.
    It's hard to stop a Trane. but I have made one helluva living keeping them going.

  7. #7
    Join Date
    Feb 2003
    Location
    garland, texas
    Posts
    671
    So you have a 5 ton in an upflow position? Is it in a closet with the only return space being under the unit or do you have a pier and beam house with a ducted return system. What size was your previous unit?

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