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  1. #1
    Join Date
    Jun 2008
    Location
    Carencro, LA
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    50

    Whats with Trane blowers?

    Yesterday for the third time in less than a year I had to go to a job in which a blower in a Trane commercial air handler simply flew apart, and make a temporary S.A. feed from a temporary unit into the duct for the downed air handler. All three units have been of different tonnages and all over the 100 ton range. The one I went on yesterday was actually the second blower they put in that particular unit. When the first one went, they were able to get it fixed within a day or so. But then a week later, that one went also which is where the temp. unit came in 'cause they have to wait a week for this next one to come in. The first unit this happened to the shaft actually sheered in two. Is this a strange co-incidence or has anyone else been hearing of stuff like this happening?

  2. #2
    Join Date
    May 2004
    Location
    Rapid City, SD
    Posts
    7,415
    I'm assuming we're talking squirrel cage style?

    I've heard of them blowing apart in residential stuff, even seen a few here and there. Every one of them was from poor duct design and air flow issues.

    Not 100% sure, but here's my story.

    You restrict the air flow enough, the wheel cavitates, this increases the motors speed since there's no restriction, spinning too fast causes the blower to come apart.
    "If you call that hard work, a koala’s life would look heroic."

  3. #3
    Join Date
    Jun 2008
    Location
    Carencro, LA
    Posts
    50
    Quote Originally Posted by amickracing View Post
    I'm assuming we're talking squirrel cage style?
    All squirrel cages. I haven't started working on units yet, but how do you rectify the issue of cavitating without changing the duct size from whats already installed? Slow down the motor speed? How would you remedy the airflow issues after slowing the motor if that turns out to be the solution? Maybe add some extra turning vanes in the down stream of the duct to keep from having to adjust the motor rpms?

  4. #4
    Join Date
    May 2004
    Location
    Rapid City, SD
    Posts
    7,415
    That's where experience and "gut feeling" comes into play (correcting duct issues).

    Sometimes it's as simple as adding a couple runs, sometimes you'll have to add vanes, possibly hard pipe it if there's a lot of flex.

    One system I worked on had duct for a 2 or 2.5 ton unit, there was a 4 ton installed. The house called for a 2 ton. So even the equipment can be the issue.
    "If you call that hard work, a koala’s life would look heroic."

  5. #5
    Join Date
    Oct 2007
    Location
    Austin Texas
    Posts
    1,818
    The only Trane sqirrel cage I've ever had to change out was in a 15 ton RTU. I have a 480 ton dx air handler at my site with 4 60 HP blowers all turning their own Trane squirrel cage. That unit has been there since 1978. I've been there for almost 12 years. The only thing we've changed has been a couple of blower shaft bearings and a couple of motors. Maybe VFDs could help. Since putting them on my motors, we stopped destroying flex duct on startup.
    Nemo me impune lacessit.

    How much blood do I have to bathe in to get clean?

    Don't look down on anyone unless you're helping them up.

  6. #6
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
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    4,494
    i recently changed out a blower wheel on a 75 ton Intellipak rooftop unit (for 75 tons it has 2-22 inch diameter forward curved fan wheels). we did it mostly "just in case". the installing contractor tried to balance the wheels, due to lots of vibration, at start up. 27,000 cfm design and since a small portion of the floor was being used, it was only running an estimated 4,500 cfm...that is not even on the curve chart! unit was probably running in fan surge and they thought that it was fan unbalance. we replaced everything (fan wheels, bearings, shaft, etc.) just in case. then we balanced everything.

    this contractor says that they find lots of Trane wheels out of balance and have to balance almost every single one...i don't think so!!! we removed a large portion of the supply duct and now we are moving some air...bye bye fan surge.

    i have never seen a fan wheel come apart before (at least not with good reason).

    what type of unit is this running on?

    good luck.
    "If you pull one more stunt like you just pulled with Tommy, you won't have to get on a plane because I will personally kick your ass from here to Korea!" - Best of the Best

  7. #7
    Join Date
    Jun 2008
    Location
    Carencro, LA
    Posts
    50
    Jayguy, I didn't look at the model number or anything on the unit. I'm just a duct man for now. The first two units that this happened on was about fall of last year. One was 2 year old install and the other was about 5-6 year old install. The one I did last week, the hospital maint. guy told me it was a 7 year old install. These three were the first time I had heard of it so I was wondering if it was a fluke or a newly occurring trend. Hope it's just a chalk up to bad duct design.

  8. #8
    Join Date
    May 2004
    Location
    Rapid City, SD
    Posts
    7,415
    Forgot to mention.

    Make sure all the damper (fire/smoke) are open too. Make sure there was no recent failure of them.

    A control company (not the one I work for) was messing with the dampers one day and closed a bunch off. This fan system the building had was a beast... blew up many a feet of duct lol
    "If you call that hard work, a koala’s life would look heroic."

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