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  1. #14
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    I realize the first post to this thread has probably been certified a long time ago, but I help write questions for the NEBB exams so I've got a bit of insight. I can't go into details of the exams, but I can confirm that the tests are now done through Kryterion testing sites, or paper tests at NEBB seminars. Candidates that review and understand the material in the recommended reading material will likely be fine. I couldn't share the pass percentage even if I knew, but I think it's safe to say most failures are the result of the candidate either not preparing or suffering from test anxiety.

  2. #15
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    Brent you are correct I was certified a long time ago. I think the written test when I took it was appropriate to determine understanding of the fundamentals. I have stressed on this site many times the importance of knowing and thoroughly understanding the fundamentals. If you don't know the fundamentals and how they apply all you are is a hood holder and have no business having a certification. Some think the intent of the test is to limit the number of people that get certified. I don't think that is remotely true. I don't think the practical exam is necessary. There are so many DDC balance programs it is possible to test on one the candidate has never seen. I assume the practical includes balance of DDC controlled VAV'S. The control contractors only share the bare essentials with balancers and it takes a while to learn everything you need to know.
    I'm retired but am glad you posted and glad to hear the test has been improved.
    No man can be both ignorant and free.
    Thomas Jefferson

  3. #16
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    I've known some of the men who helped write the early exams, and while they were really knowledgeable, they would occasionally get the answers to their own questions wrong because they're human and there wasn't much of a review process. The gentlemen proctoring my practical exam is still involved in the business, so I'll be respectful, but I think it's fair to say that it could've been done better. Whether or not the testing format is better now is probably debatable, but without a doubt the questions are better reviewed and have clear answers.

  4. #17
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    I think the practical exam is very difficult to structure. I only remember one of the questions on the written exam that didn't have a correct answer when I took it. The answer was as simple as it gets. Elevations were given on piping before and after a pump and they were looking for static head on the pump. It was a simple addition problem and a review before issuing the test would have almost certainly caught it. I was also certified in S&V. The annual test at one point got way above taking readings. The time it took to answer the questions got ridiculous. I wrote NEBB and told them that and warned that the tests were encouraging giving advise and we shouldn't be doing that. Surprisingly enough they agreed and modified the tests.
    No man can be both ignorant and free.
    Thomas Jefferson

  5. #18
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    One of the writers of the early exam presented me with a question that went something like the following, although in diagram rather than description: There's an open water tank that measures 10' diameter and 10' tall. The tank is filled with 8' of water. What's the pressure at the bottom of the tank?

    Of course, 8' seems like the obvious answer, but he calculated the volume of water, how much it weighed, then divided that by the area of the bottom of the tank and came up with answer that wasn't 8'. I mean, the math idea was right, just a mistake made in rounding or one of the steps due to over-complication. Anyway, it's part of the reason I was happy to volunteer with question writing.

  6. #19
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    Thanks for that Brent. I was never able to figure out why the question I referred was on the test and even more wondered how come the answer was wrong. I would never have figured that out.
    No man can be both ignorant and free.
    Thomas Jefferson

  7. #20
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    Quote Originally Posted by WAYNE3298 View Post
    Brent you are correct I was certified a long time ago. I think the written test when I took it was appropriate to determine understanding of the fundamentals. I have stressed on this site many times the importance of knowing and thoroughly understanding the fundamentals. If you don't know the fundamentals and how they apply all you are is a hood holder and have no business having a certification. Some think the intent of the test is to limit the number of people that get certified. I don't think that is remotely true. I don't think the practical exam is necessary. There are so many DDC balance programs it is possible to test on one the candidate has never seen. I assume the practical includes balance of DDC controlled VAV'S. The control contractors only share the bare essentials with balancers and it takes a while to learn everything you need to know.
    I'm retired but am glad you posted and glad to hear the test has been improved.
    In my opinion the practical exam is very necessary , as one purpose of the CP is to be able to teach others how to balance . I know many engineers who could pass the AABC exam and the written portion of the NEBB exam who couldn't balance a dog house . Funny engineer story …..we were 20% low on air on a decent size AHU . The engineer wanted us to prop the fan access door open with a soda can ( end to end ) and see how much it would increase . I said "so what is this going to prove?" He said " then we will know if we can get the air or not ". I said , "So if we get the airflow are we leaving the soda can here or is someone going to stand here and hold the door open?" .

  8. #21
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    Instead of a practical exam if an engineer wants to be certified he should be required to balance jobs and submit a balance report on the jobs. They could lie and submit a report someone else did but if ask a few questions it wouldn't be too hard to figure out if they knew what they were doing.
    I would have told the engineer to go get a can of soda so we could try his idea and while he was gone would have sped the fan up.
    No man can be both ignorant and free.
    Thomas Jefferson

  9. #22
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    Quote Originally Posted by bradluke0 View Post
    In my opinion the practical exam is very necessary , as one purpose of the CP is to be able to teach others how to balance . I know many engineers who could pass the AABC exam and the written portion of the NEBB exam who couldn't balance a dog house . Funny engineer story …..we were 20% low on air on a decent size AHU . The engineer wanted us to prop the fan access door open with a soda can ( end to end ) and see how much it would increase . I said "so what is this going to prove?" He said " then we will know if we can get the air or not ". I said , "So if we get the airflow are we leaving the soda can here or is someone going to stand here and hold the door open?" .
    Without fan test data, here's a guess of the engineers intent...

    Opening the fan access door is a quick way to find out two possibilities...
    1) if the upstream (to the fan) ahu dampers, ra fans, ductwork, inlets are restrictive
    2) And if restrictive can the present configuration downstream (from fan) provide design cfm.

    And opening the fan access door is a quick, low labor cost way to determine if speeding up the fan will help.

  10. #23
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    If you know the airflow and fan RPM you can easily calculate the new fan speed needed to obtain the desired airflow. All you find out by opening the door is if the fan will move more air with less total static pressure. Of course it will but the total static pressure will go up as fan speed is increased not down. The engineer didn't know what he was talking about.
    No man can be both ignorant and free.
    Thomas Jefferson

  11. #24
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    Quote Originally Posted by WAYNE3298 View Post
    If you know the airflow and fan RPM you can easily calculate the new fan speed needed to obtain the desired airflow. All you find out by opening the door is if the fan will move more air with less total static pressure. Of course it will but the total static pressure will go up as fan speed is increased not down. The engineer didn't know what he was talking about.
    As I said, not knowing fan data, I gave possibilities.

    If the airflow to the fan is restricted, the open door would/may provide design cfm due to reduced TSP.
    Perfect world is to know design TSP as calculated.
    Again, we are talking about a very quick test.
    Also, what if the door is opened and no change is noted? Possible restriction in SA somewhere...fire damper partially closed, system effect due to creative duct transitions that are an abortion.
    If these are present, changing fan speed will not solve the problem.
    Jogas
    Four wheel therapy, my 1968 Camaro is gone and will be missed

  12. #25
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    Static pressure profiles will tell you if you have a restriction and where if you know how to do them. Part of air balance is obtaining fan date. If you open the door fan airflow will increase but that doesn't tell you if or where you have a restriction. If you have a fan curve that dips and recovers and you open the door you don't know which side of the dip in the curve you were on before you opened the door and which side you are on after you opened the door. Opening the door could also put the fan in it's unstable region or in some cases take a fan out of that region.
    Opening the door is a cheap way to screw up.
    No man can be both ignorant and free.
    Thomas Jefferson

  13. #26
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    Quote Originally Posted by WAYNE3298 View Post
    Static pressure profiles will tell you if you have a restriction and where if you know how to do them. Part of air balance is obtaining fan date. If you open the door fan airflow will increase but that doesn't tell you if or where you have a restriction. If you have a fan curve that dips and recovers and you open the door you don't know which side of the dip in the curve you were on before you opened the door and which side you are on after you opened the door. Opening the door could also put the fan in it's unstable region or in some cases take a fan out of that region.
    Opening the door is a cheap way to screw up.
    Agree to disagree.
    Jogas
    Four wheel therapy, my 1968 Camaro is gone and will be missed

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