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Type: Posts; User: tnhikr44

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  1. Replies
    4
    Views
    1,193

    In a situation like this I certainly would not...

    In a situation like this I certainly would not recommend lowering the space temperature set point. If the unit will allow you to place the fan on continuous run mode I would try that first. Keep the...
  2. Replies
    1
    Views
    828

    My thoughts are you are correct on your wild...

    My thoughts are you are correct on your wild guess. With a bunch of air bypassing, but with the system still calling for cooling, the supply air temperature is likely to drop well below normal...
  3. Technically, general air changes have no...

    Technically, general air changes have no stipulations regarding filtration. If the room happens to be a negative pressure room, the general air changes are calculated by the exhaust leaving the room....
  4. Replies
    20
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    2,166

    I want to give kudos to BenControllin here. These...

    I want to give kudos to BenControllin here. These are contract documents we are talking about here, and every avenue must be taken before any changes are made.
    Based on the information provided, I...
  5. Replies
    10
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    1,156

    heatingman, I can appreciate your desire...

    heatingman,

    I can appreciate your desire to get more involved with controls. I wish more 'mechanical' guys did. Dead serious. But as a 20 plus year test and balance technician I cannot help...
  6. Replies
    21
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    37,970

    The typical CO2 set point I see is 900-1000 ppm....

    The typical CO2 set point I see is 900-1000 ppm. You have measured a high of 775, and my high was around 650. In both instances we would be able to maintain a level between 900-1000 with additional...
  7. Replies
    2
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    1,497

    I have balanced many "pool packs", but have only...

    I have balanced many "pool packs", but have only witnessed a few that actually worked in all load conditions. Higher end chilled water/ hot water/ electric reheat systems in upscale hotels and such....
  8. Replies
    21
    Views
    37,970

    The industry standard that we use is 400-450 ppm...

    The industry standard that we use is 400-450 ppm CO2 for fresh air. Technically it is 392 ppm. And although I have tested 'fresh' air at higher levels than that, never have I ever seen it above 650...
  9. Replies
    21
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    37,970

    If the task is to simply lower the CO2 to below...

    If the task is to simply lower the CO2 to below 1000 ppm and maintain that concentration, with no regards to temperature or humidity, I think it would be rather simple. A 100% outside air variable...
  10. Replies
    14
    Views
    2,433

    Many single phase motors have changeable...

    Many single phase motors have changeable rotations. There are several spade connectors under a removable wiring plate on some. Change this spade to here, move that spade to there and bingo ... it...
  11. Replies
    15
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    3,381

    In your opinion, what would be the benefit in...

    In your opinion, what would be the benefit in running a flex only duct system?
  12. Replies
    15
    Views
    3,381

    Sheet metal has been the industry standard since...

    Sheet metal has been the industry standard since the beginning of the industry. Sheet metal with flex take offs came around later. Total flex is the lazy mans way. Not to say that it will not work,...
  13. Replies
    18
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    2,357

    Although probably out of your price range, I...

    Although probably out of your price range, I would suggest a Shortridge ADM with an airfoil for velocity readings. It is the least angle sensitive device I have used. For a cheaper option I would go...
  14. Replies
    9
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    2,226

    Not knowing the application (type of facility),...

    Not knowing the application (type of facility), the amount of required outside air and calculated loads it is hard to say. I am no engineer, but at nearly 4 cfm per square foot (based on 400 cfm per...
  15. Replies
    5
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    839

    That seems like a large delta to me. Assuming...

    That seems like a large delta to me. Assuming your longest duct run is 100 feet, and your air velocity is 500 fpm, it takes 11 seconds from fan to grille. That is about one degree per second. That is...
  16. ChippyTX, Not to sound like a jerk, but...

    ChippyTX,

    Not to sound like a jerk, but either you can afford to keep a reasonably even temperature throughout your house or you cannot. If you can, set the T-stats at the same temperature and...
  17. Replies
    8
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    2,454

    That is a very awkward way to introduce make up...

    That is a very awkward way to introduce make up to a pressure critical building in Florida. Actually, that is awkward no matter where you are at, but especially in Florida. Based on the picture, I am...
  18. Replies
    20
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    7,219

    In this day and age of commissioning and LEEDS...

    In this day and age of commissioning and LEEDS certifications, the 'drive by' balancing or 'Denny's reports' are a thing of the past. Those who 'pencil-whip' reports these days will not last long.
    ...
  19. Thread: cfm

    by tnhikr44
    Replies
    14
    Views
    1,897

    just_opinion, 1. As I stated previously,...

    just_opinion,

    1.
    As I stated previously, size and velocity are relative. On that return duct you mention the typical velocity will be somewhere between 500 f.p.m. and 1000 f.p.m. on nearly...
  20. Thread: cfm

    by tnhikr44
    Replies
    14
    Views
    1,897

    just_opinion, Not trying to be an ass, but,...

    just_opinion,

    Not trying to be an ass, but, in my opinion you have it completely backwards.

    1. Size and velocity are relative. If the system is large the ductwork is large... but the velocity...
  21. Replies
    4
    Views
    3,018

    Madtrumpeter, By a high velocity sysyem do...

    Madtrumpeter,

    By a high velocity sysyem do you mean that there are small supply grilles installed, creating a "jet"effect at the grilles? Or are you talking about small ducting (due to restricted...
  22. Several people have mentioned economizer...

    Several people have mentioned economizer controls, which is
    an important factor in regards to energy consumption. But no one has really mentioned required ventilation. In most commercial bldg.'s...
  23. Replies
    15
    Views
    1,908

    Perhaps I am misunderstanding you, but if you are...

    Perhaps I am misunderstanding you, but if you are truely going to use an automated system you need sensors, not T-stats. That is assuming that you want your temperature controls functioning via a...
  24. Replies
    6
    Views
    1,182

    You could, but I am not sure it would be received...

    You could, but I am not sure it would be received well. In the past we have somewhat clashed in regards to sequences of operation and such. The casino hotel job in Cherokee comes to mind, along with...
  25. I think this is a very valid point and should not...

    I think this is a very valid point and should not be overlooked. As previously pointed out, "over" filtration will cause reduced airflow, which in turn will cause reduced performance of ANY filtering...
  26. Replies
    6
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    1,182

    I gotta ask... is Rick or...uhm... whats her...

    I gotta ask... is Rick or...uhm... whats her name... Darla or Stella or something or another still working there??
  27. Replies
    7
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    8,357

    This statement is DEAD on!! I have seen it too...

    This statement is DEAD on!! I have seen it too many times. The design engineer will spec a residential furnace with a max. operating static of 0.5" then slap on an "A" type D/X coil on top then...
  28. Replies
    24
    Views
    3,669

    Over the years I have seen many problems when...

    Over the years I have seen many problems when airflow is reduced on D/X systems. Even with hot gas by-pass or hot gas re-heat low load conditions seem to cause problems. On VAV systems it is...
  29. Thread: Fan Sizing

    by tnhikr44
    Replies
    4
    Views
    1,587

    Not a fan manufacturers task... a units...

    Not a fan manufacturers task... a units manufacturers for sure, but a fan is just a fan. All static losses must be taken into account. Reducing airflow from a fan is always much much easier than...
Results 1 to 29 of 44
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