Optimizer For Trane A/C
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  1. #1
    Join Date
    Jun 2005
    Posts
    31
    I have a Trane 14xli R410a system (2.5 ton). It's 3 months old. It has a TXV on the inside coil.

    Furnace is an XL80 2-speed.

    I am a 70 deg person. Part of it is for health reasons.

    I'm having a problem with coil/suction line freezing.

    It has been looked at several times. The pressures/charge have been tested, and the last time it was drawn down and weighed back in.

    It seems to freeze most often when it's milder outside.

    I don't like to open windows due to pollen issues.

    It was recommended that I get an "Optimizer" for the outside unit.

    I'd like to understand more about this. All I know is it's supposed to slow the fan down during milder outside temps, how this helps I'm not sure. That's what I'd like to understand further.

    It's my understanding you can buy an optimizer kit for the unit that has a new ball-bearing fan, thermostatic device and ... ?

    I've searched using google but haven't been able to come up with anything on this. Trane's site search is down.

    Thanks

    -Larry

    BTW... The inside coil used is a "Superior". Is this good equipment ?

    -Larry

  2. #2
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,232
    More air flow not less to avoid freezing! Cooling your home below outdoor dew points causes condensation in the walls and on the ducts. Wet surfaces for days grows mold. Warmer and drier is a better more comfortable strategy.

  3. #3
    Join Date
    Jun 2005
    Location
    New York
    Posts
    207
    Yes, your talking about a motor master for low outdoor temp conditions, it works by operating the outdoor condenser fan to maintain a 90-100 deg liquid temp, some do it to maintain a certain head pressure, liquid line temp is the best way to do it, a ball bearing cond. fan motor is reqiured. In simple terms, it makes the outdoor machine think its warmer out when its not.. Sounds like thats what you need. Teddy, he isnt talking about slowing down the evep fan.

    [Edited by ultratec on 06-26-2005 at 06:51 PM]

  4. #4
    Join Date
    Mar 2002
    Location
    Concord, CA
    Posts
    2,633
    ultra summed it up Larry. You can think of refrigerant (Freon, Puron, whatever) like porridge in the fairly tale. It doesn't want to be too hot. It doesn't want to be too cold. It wants to be just right. Cold temps outside will cause the refrigerant temperature drop. If it drops too low the cooling coil gets too cold. When the coil drops to about 29 degrees humidity will start to freeze onto the coil.

    My only question is what Teddy Bear somewhat (mistakenly) referred to. Namely, what's your indoor airflow? Did they measure it? While an outdoor fan control is a certainly credible solution here, I've seen many systems run in low ambients and not freeze (even though they could have and even should have). Having high enough indoor airflow through the cooling coil goes a long ways to preventing freeze ups. If your indoor airflow is real pathetic then the so called optimizer may not be enough to completely eliminate the problem. In fact, if indoor airflow is real bad then the airflow may be a bigger factor in your problem than your preference for low indoor temps.

    Whatever the solution they and you come up with, I’d hope they’d do it for a song. When a customer comes to me with a VERY specific need and spends thousands on my services to meet that need then my number one goal in designing a new system is to meet that specific need – be it quietness, clean air, low temps or whatever. Pleasing a customer with such a specific need is actually much easier than trying to please someone who has no clue what they really want. The ones that don’t know what they want sometimes want everything. In your case you had exactly ONE important goal. If I fail to meet that goal on the first try the very least I can do is offer the follow-up solution for near cost.

  5. #5
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,833
    Choo Choos can run in 40-50 degree weather w/o fan speed controls. But they do suggest freeze stats on the evap or suction line. The XLi already has a 2 speed condenser fan though it is pretty hard to tell low from high.

    I keep my place 68. Trane XV80 with another brand of cooling system. Never a lick of trouble. I think I'm running 425 CFM per ton with comfort R turned on.

  6. #6
    Join Date
    Mar 2002
    Location
    Concord, CA
    Posts
    2,633
    68 degrees?

    Well... They say that both the brain and reproductive organs work better at cooler temps. Some of us need all the help we can get.

    Hmm. Maybe that's why I like winter so much more than summer.

  7. #7
    Join Date
    Apr 2001
    Location
    san jose,ca.
    Posts
    5,285
    Boy i better set my t-stat at 50dg.if it helps all that.

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,630
    I keep mine at 70 when home, 74 when at work.



    they should check indoor air flow.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  9. #9
    Join Date
    Jun 2005
    Posts
    31
    Air flow is around 1090. It was actually dropped from the 1380 or so it was originally set to. They felt that a) the airflow was too high for the ductwork I had and was increasing static pressures and b) at the higher speed not enough cooling was being pulled from the coils.

    SP, I believe, was .90.

    Doing anything with the ductwork would be prohibitively expensive. It's a down-flow with all the ducts (12 4X10's) in the floor and run through the concrete slab.

    The return is pretty big, looks like around a 8X16, maybe a bit bigger, with a 20X20 grille.

    If we did do anything with the airflow about all we could do is put a box under the coil case and dump some air somewhere. My guess would be the garage since it wouldn't hurt to put it in there anyway.

    The system has an AprilAire 2200 media filter installed (in operation about 6 weeks).

    I don't think there's any doubt that the supply's are borderline. I just can't reasonably do anything about it.

    They do blow quite a bit of air though. It's not like you can't feel it. It rattles all the curtains nicely.

    The freezing only happens when it's below 70 or so outside, so this seemed like an inexpensive and reasonalble thing to do.

    This system has confused just about everyone that has looked at it.

    -Larry



    Originally posted by Irascible
    ultra summed it up Larry. You can think of refrigerant (Freon, Puron, whatever) like porridge in the fairly tale. It doesn't want to be too hot. It doesn't want to be too cold. It wants to be just right. Cold temps outside will cause the refrigerant temperature drop. If it drops too low the cooling coil gets too cold. When the coil drops to about 29 degrees humidity will start to freeze onto the coil.

    My only question is what Teddy Bear somewhat (mistakenly) referred to. Namely, what's your indoor airflow? Did they measure it? While an outdoor fan control is a certainly credible solution here, I've seen many systems run in low ambients and not freeze (even though they could have and even should have). Having high enough indoor airflow through the cooling coil goes a long ways to preventing freeze ups. If your indoor airflow is real pathetic then the so called optimizer may not be enough to completely eliminate the problem. In fact, if indoor airflow is real bad then the airflow may be a bigger factor in your problem than your preference for low indoor temps.

    Whatever the solution they and you come up with, I’d hope they’d do it for a song. When a customer comes to me with a VERY specific need and spends thousands on my services to meet that need then my number one goal in designing a new system is to meet that specific need – be it quietness, clean air, low temps or whatever. Pleasing a customer with such a specific need is actually much easier than trying to please someone who has no clue what they really want. The ones that don’t know what they want sometimes want everything. In your case you had exactly ONE important goal. If I fail to meet that goal on the first try the very least I can do is offer the follow-up solution for near cost.

  10. #10
    Join Date
    Jun 2005
    Posts
    31
    BTW... The freezing still occurs with the higher CFM speed. Thought I'd better toss that in.

    -Larry

  11. #11
    Join Date
    Jul 2004
    Location
    midwest
    Posts
    2,868
    Higher blower speed will not help if the ducts are to small. You need to measure the return duct and length, 16x8 will not handle the needed cfm for return. I don't think you need freeze stats or low amb. controls, you have a airflow problem.

  12. #12
    Join Date
    Mar 2002
    Location
    Concord, CA
    Posts
    2,633
    So git yer optimizer then and don't pay too much.

  13. #13
    Join Date
    Jun 2005
    Posts
    31
    Now I need to figure out where best to get it from.

    -Larry

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