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  1. #1
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    Adjusting motor sheaves

    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 insulation.

    My question is what level of oversight and training happens in the T&B part of our industry to make certain this does not happen?

    Are balancers supposed to follow a protocol where the sheave must be replaced with a smaller part because the sheave can no longer be adjusted so that the speed can be set without causing a failure? Who would replace the sheave? The balancer or the service tech?

    How is this situation handled by your company?
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist
    Member, IAEI

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  2. #2
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    Jun 2014
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    This is why I refuse to complete a commissioning until after the balancer is done. If I'm signing my name on the warranty form then I want to be the last one who touched the unit.
    This frequently annoys the office, but I'd rather be yelled at for doing too good a job rather then explaining why the new unit is all torn up
    I havent failed. Ive just found 10,000 ways that wont work. - Thomas Edison

    Its not whether you get knocked down, its whether you get up. - Vince Lombardi

    "In this house we obey the laws of thermodynamics" - Homer Simpson

  3. #3
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    Sep 2007
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    edmonds wa
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    What i usually see, is a case of who does not want to pay for fixed size pulley after the supposed balance. Also it is not uncommon to have the new RTU shipped with the med static drive kit for who knows what reason. That then goes back to no one wants to pay for the correct solution to repair it.
    UA Local 32

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  5. #4
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    My approach was to exclude all sheave changes when bidding a job. The reason is that not knowing the equipment you can't really put a price on the sheaves and don't know how many if any will have to be changed. When a sheave change was needed I told the contractor I was working for the sheaves and belts needed and they furnished them. I didn't charge for the installation because most sheave changes only take 15 to 20 minutes. There is no oversight that I know of except commissioning that will prevent sheave adjustments outside of the adjustment limits. The installing contractor should be contacted and informed of the problem and ask to pay for the fix. The balance company should pay for the fix.
    Your complaint is valid and in some cases has done enough damage that the fan had to be replaced.
    Most chains contract the balancer directly and the cheaper the better.

  6. #5
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    Thread Starter
    ...all of this makes T&B irrelevant for this customer type.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist
    Member, IAEI

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  7. #6
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    Feb 2004
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    Food fight. The end result of job plans that don't define who will do what. Some plans will spec the responsibility for replacing sheaves. Most often it's the T&B co. when it happens.
    It's also good insurance for someone not changing the fan speed.
    I have seen where the electric contractor stated the plans didn't spec that he was responsible for disconnects. W/o actually stating who was required he said he wasn't doing it. Here's the fun part. The mechanical contractor had no one employed that could read elec specs. so he went ahead and paid for the disconnects and the install.
    Lesson learned: If it's not in print someone will fight over it.
    I should have played the g'tar on the MTV. MK

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

    SMW Lu49

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  9. #7
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    Nov 2001
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    In my experience most of all the skilled testing in start up's have gone by the way side...for years. I can site case after case where I was asked to start & test, including some balancing, of newly installed systems where most everything, commercial, industrial or residential, was installed by people who know how to bolt things to walls, floors, roofs & everywhere else but had not idea what the boxie thing did.

    Called to a local Federal building as the ceiling mounted HP were not working. Found all of the original blower packing still packing inside the blowers but the install company had them turned on for over a week. All the motors were so hot I could not touch them.

    Addition to a local elementary school to set up controls & set up individual air handlers hidden in the loft of each new class room. The controls were a joke themselves but each air handler still has the wooden shipping blocks on the blower motors & none of the sheaves had been set. In the process of completing the first two the install contractor told me to stop as they were exceeding the man hours on that job. Obviously I told him none of the air handlers were going to work as the motors were still sitting on the shipping blocks so they could not be adjusted and the belts were all loose since they had not also been adjusted including the tension on the belts.

    I left. Never got called back & I betting to this day no one has ever correct the situations in this job & the others that I see. It's get on the job, bolt it down & leave.
    "The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
    - Alexis de Toqueville, 1835

  10. #8
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    DeltaT,
    I have run into the same things and worse when told the facility was ready to balance. I have also seen buildings that have operated for years with HVAC systems completely out of whack. I was asked to TAB the fans in a federal building that the HVAC had been operating in for years but wasn't told why they wanted it done. These were really big fans and when testing I discovered the three fans in the first penthouse tested would not track each other thus wouldn't share the load. That's when I found out why they wanted TAB. They had just spent $10,000 plus rebuilding the mechanically controlled variable pitch vanes on the fans. The problem was the vanes had pneumatic controlled actuators with mechanical linkage and were all fed a signal from a single pneumatic controller. The fans had first class factory installed flow stations and all they had to do was use the velocity pressure on the fans to get them to track.
    There are buildings everywhere with problems that need competent balancers but will not address the problems unless they get a lot of complaints and then they look for the low dollar not competency. I had a lot of calls where the balance absolutely had to be right but never got one of those jobs.

  11. #9
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    Nov 2001
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    Same here Wayne. A number of years back I got a call at an engineering firm full of men & two women. The men complained of the heat in all offices & the imbalance of air to most of the outer offices. The receptionist sat in the front office with a wool sweater on & an electric heater on under he desk. This was during the summer & in the 80's outside. The receptionist ran the office like a nazi & blocked off about 30 to 40% of the supply ceiling air ducts with file folders & shipping tape. She did a professional job...which was a sign of dedication which I was not to mess with. So I went in the main complaining office full of engineers including one lady & asked them why they didn't remove the taped folders from their supply ducts so they could get some air and air conditioning. They all shook just with the thought of having to face the receptionist. And the one engineer lady was from some country that didn't believe in personal cleanliness so I could not even stay in that office myself. She smelled so back I chocked.

    I do talk to the receptionist and those air vents are not to be opened...period.

    So I tell the owners representative this is where the problem is & forget about the entire episode. Plenty of more customers waiting.... A week or so later they ask me to return to finally fix everything assuming the air flow issue was addressed. The owners rep told me that after I left they hired an air balancing company to balance the system & I could see some holes in the package unit where they had apparently inserted their tubes. But I go down stairs & all of the file folders are still on the air supply vents with the employees telling me no one has touched anything since I had been there. I talk to the owners rep about his again & he state that the air balance company could find no wrong with the air flow so the problem must be mechanical..hence I was called back.

    Told the owners rep again that they just spent about $1,100 for an air balance check on this system & that everything was OK according to the air balance guys. Makes a guy think he is crazy with stuff like this happening more & more. Told the owners rep the exact same thing as I told him before & that if someone didn't get the receptionist to allow the removal of all the covered vents than no one could help them. Never heard back from them.

    What a waste of time.
    "The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
    - Alexis de Toqueville, 1835

  12. #10
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    The air balancer should have told them the same thing you did. With the problems they had the total airflow would have been low and the fan static high. You can bet they hired the cheapest balancer they could find. I have seen similar problems many times. The thing that irritated me most was being called in to fix the problems only to find out that someone in the office that had never seen an airflow hood knew more about air balance than I did.
    As an after thought maybe this forum will be most useful for venting frustrations and helping those of you not retired like me to maintain sanity.

  13. #11
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    I was on a job where they lacked sufficient cooling. Did my pre-lim and read all registers. Total read CFM was low. Went to the roof to look over the RTU. Before taking SP's or fan RPM's, I noticed it was not sitting on the curb correctly. I could feel the cold air when I put my hand down there and see the cold area, about a 3" gap.
    So I called the Mech Contractor who we were working for, and informed them of the problem the had, like missing registers, missing VD's, and the RTU/curb issue.

    They complained to my boss that I was finding too many problems. The other balancing companies never have that many issues with their work.

  14. #12
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    SF1.15,
    I was told that several times. Nitpicking, gilding the lily and less often not doing my job were popular complaints. I actually had a general's superintendent and a mechanical contractor in tears complaining they couldn't get paid and it was my fault. I had contractors write me demand letters to balance facilities that couldn't be balanced. The only advice I have is don't sacrifice your integrity or you will be just another balancer. 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.

  15. #13
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    Reminds of the times I pop the ceiling tiles and see everything run in wireflex.

    "Sorry ma'am, the unit is doing the best it can do."



    Quote Originally Posted by WAYNE3298 View Post
    SF1.15,
    I was told that several times. Nitpicking, gilding the lily and less often not doing my job were popular complaints. I actually had a general's superintendent and a mechanical contractor in tears complaining they couldn't get paid and it was my fault. I had contractors write me demand letters to balance facilities that couldn't be balanced. The only advice I have is don't sacrifice your integrity or you will be just another balancer. 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.

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