Page 2 of 2 FirstFirst 12
Results 14 to 25 of 25
  1. #14
    Join Date
    Feb 2016
    Location
    Louisburg Kansas
    Posts
    1,514
    Post Likes
    BBeerme,
    Did that make her mad?
    Did you read my response to water flowing around the world? I thought that thread was interesting.

  2. #15
    Join Date
    May 2014
    Location
    Bay Area California
    Posts
    18,410
    Post Likes
    I was speaking in the generic sense. I've never been tasked with doing an official commissioning. But have been sent out many a time with a balance cone and told to fix the problems. Used to be when I saw a mess of wire flex, I'd try to explain to everyone that the job was not done proper, and they'll never get the airflow that they want or the system was designed for.

    Now I just say it is doing the best that it can do, because I've learned that no one wants to pay for reducting. There are exceptions of course, but this is just typical commercial office space.

    I did see your response to the garden hose question. I knew instinctively that friction loss could not increase to the point of no flow. Just didn't know the technical jargon.


    Quote Originally Posted by WAYNE3298 View Post
    BBeerme,
    Did that make her mad?
    Did you read my response to water flowing around the world? I thought that thread was interesting.

  3. #16
    Join Date
    Feb 2016
    Location
    Louisburg Kansas
    Posts
    1,514
    Post Likes
    You are correct friction loss will diminish flow a lot but cannot stop all water flow. Vertical head can stop all flow which to some sounds like a contradiction because friction loss develops friction head but friction head goes down as velocity is decreased.

  4. #17
    Join Date
    Mar 2017
    Posts
    3
    Post Likes
    I hope your boss understood the situation and is better than I was at getting the problems corrected.
    My retort to contractors like that just made them more pissed off.
    My Boss always has our back. She is actually one of the best bosses I've had.

  5. #18
    Join Date
    Aug 2013
    Location
    N/A
    Posts
    304
    Post Likes
    We did an install at a retail store, and the balancing co. came in, and TIGHTENED the belts so much, they BROKE a friggin' shaft on a 2 HP motor.
    BRAND NEW UNIT! Literally wasn't in place 72 hours.

  6. #19
    Join Date
    Feb 2016
    Location
    Louisburg Kansas
    Posts
    1,514
    Post Likes
    I have never seen belts tight enough to break a motor shaft. Do you know how he got them that tight?

  7. #20
    Join Date
    Sep 2007
    Location
    edmonds wa
    Posts
    4,182
    Post Likes
    I would think belts that tight, would pull the bearings out of the fan first. Seen that more than a time or 2.
    UA Local 32

  8. #21
    Join Date
    Feb 2004
    Location
    New Mexico
    Posts
    8,164
    Post Likes
    Quote Originally Posted by obieone View Post
    We did an install at a retail store, and the balancing co. came in, and TIGHTENED the belts so much, they BROKE a friggin' shaft on a 2 HP motor.
    BRAND NEW UNIT! Literally wasn't in place 72 hours.

    This is where "loss failure analysis" needs to be applied. Like how much shear load is necessary to break the shaft etc. What I can imagine is a loose sheave cutting through a shaft. Seems a belt would break before a shaft.
    Anything built to code is built to the minimum legal standard

    You can be anything you want......As long as you don't suck at it.

    SMW Lu49

  9. #22
    Join Date
    Feb 2016
    Location
    Louisburg Kansas
    Posts
    1,514
    Post Likes
    I'm betting on a factory defective shaft. I saw a contractor replace a belt that was worn and stretched. He didn't adjust the new belt because he was in a hurry. The new belt was so tight that when it dropped into the sheave it almost sounded like a shotgun blast. A month later no noticeable damage was done. Sooner or later bearing damage or some other damage had to happen.

  10. #23
    Join Date
    Sep 2007
    Location
    Southern CA
    Posts
    1,021
    Post Likes
    Quote Originally Posted by timebuilder View Post
    Lately, I have found several problems related to the adjustment of motor sheaves on new equipment installed and commissioned by others for chain stores I service.

    It seems that the sheaves were adjusted open so much to reduce air flow that the belt would get stuck in the bottom and break, whipping around and damaging the insulation
    I have the perfect solution.
    When i first started out, i would often find myself asking the guys i worked with 'have you ever heard of....' and they were continually annoyed by things like superheat, subcooling, FLA, and so on that they had never heard of, especially since i was using these unheard of things to demonstrate their incompetence. Like this: 'have you heard of superheat? If you dont have any, your compressor slugs liquid and breaks'
    So to give me a taste of my own medicine, one of the guys decided to trip me up.
    'You ever heard of setting motor amps by slip?'
    'No, can't say that i have... why dont you show me sometime?'
    So we go to a pm call, and he goes to a belted blower that was working fine and closes the sheave all the way and starts the motor. Then with an amp clamp that clearly shows the motor overamping, he loosens the bolts holding the motor down and kicks the motor to make it slide until the belt slips enough to bring the amp draw down.
    'Consider yourself educated' he says with a satisfied grin.

    This completely eliminates the problem described...your belt cannot get stuck if your sheaves are completerly closed.
    Last edited by numbawunfela; 11-12-2017 at 05:05 AM.

  11. Likes GoCougs liked this post
  12. #24
    Join Date
    Sep 2007
    Location
    Southern CA
    Posts
    1,021
    Post Likes
    Quote Originally Posted by WAYNE3298 View Post
    A month later no noticeable damage was done. Sooner or later bearing damage or some other damage had to happen.
    Another coworker taught me a good hard lesson on that. I had recently replaced belts and pulleys on 4 squirrel cage condenser fan motors on a 100 ton chiller. My co-worker decided about 4 mos later it was all wrong and the belts all needed tightening since they were clearly too loose. He was trying to use a torpedo level to see if there was too much sag in the belt.... anyhow his perfectly tightened belts strummed like a guitar string. I know this because he strummed them for me to teach me that this is what you are shooting for. He was VERY proud of himself and eager to show how wrong I was.
    About 6 weeks later there were a motor failure and a new set of blower bearings....
    I sure learned my lesson. :-)

  13. #25
    Join Date
    Aug 2002
    Location
    Southold, NY
    Posts
    15,133
    Post Likes
    *
    Attached Images Attached Images

  14. Likes kdean1 liked this post
Page 2 of 2 FirstFirst 12

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Related Forums

Plumbing Talks | Contractor MagazineThe place where Electrical professionals meet.