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Type: Posts; User: ceng

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  1. Replies
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    we are trying to get input from BAS, if the...

    we are trying to get input from BAS, if the nozzals are the right size. Thanks for all the input. I will get all of you posted.
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    Hi, we have 2 2-cells bac 1500 cooling towers,(...

    Hi, we have 2 2-cells bac 1500 cooling towers,( total 4 cells). each cell 1125 gpm, 3 tower pumps, each 1500 gpm. Right now, one pump with all cells are fine. When we turned the last two cells one,...
  3. Replies
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    3,453

    mechdesigner4controls, thanks for all the input....

    mechdesigner4controls, thanks for all the input. They are very helpful. For my system, we have both economizer and wheel. So I am not sure if we'll have such a complex whell control. We won't have...
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    Thanks for all of you. It seems we are on the...

    Thanks for all of you. It seems we are on the right track. We have the filters on both oa and return and we have the by-pass damper on both the path of the wheel. Once again appreciate all of your...
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    why if we shut down the wheel, we'll ruining the...

    why if we shut down the wheel, we'll ruining the wheel? I am not good at wheel at all. Is this for freeze?
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    For Ahus serving classroom, gym, offices under...

    For Ahus serving classroom, gym, offices under north ohio public school systems, it requires those units have both heat wheel and economizer. Any one familiar with those? How those are controled?...
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    1,149

    we had the same problem on a 150 Carrier chiller...

    we had the same problem on a 150 Carrier chiller before. The second loop won't be on. It turns out there was a thermostat on this circuit was dead. As I am not expert on chiller, I don't know exact...
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    i heard lon has to use some special chips....

    i heard lon has to use some special chips. Backnet is just a potocol, which is very open. I do see Backnet has more market share now. But we use Lon more THe reason is we deal with lots of building...
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    I don't think it is very hard to write a standard...

    I don't think it is very hard to write a standard control sequence. You can find them either in books or by the contruction document. I do believe the start up, trouble shooting part is the key....
  10. Thread: BIG DILLEMA

    by ceng
    Replies
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    5,976

    i am not sure if you have a bigger pie of the...

    i am not sure if you have a bigger pie of the bussiness in your town than the other guy. If this is the case, let things go seems make sense. We don't want people to be desperate, do we? If you are...
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    i have done this calc. to size the expansion...

    i have done this calc. to size the expansion tank. basically you should have a chart, which tells for every size of pipe, how much volumn is there per foot. you should be able to find the chart in...
  12. Replies
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    835

    i have done this calc. to size the expansion...

    i have done this calc. to size the expansion tank. basically you should have a chart, which tells for every size of pipe, how much volumn is there per foot. you should be able to find the chart in...
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    Thank you for all of your input. I have been...

    Thank you for all of your input. I have been confused by this for long time..
  14. Replies
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    please advise what's the difference between those...

    please advise what's the difference between those two control valves. Thanks!
  15. Replies
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    ashrea publishes a rule for places like church,...

    ashrea publishes a rule for places like church, if it is just used for less than 2 hours, and your turn unit on and off one hour before and after, you can cut the oa 50%.
  16. i have seen no guideline for different velocity...

    i have seen no guideline for different velocity on supply and return. it really relates with where you put ductwork(ceiling, shaft?) which kind of system you have(high low pressure) and the function...
  17. If you don't have a discharge section, your...

    If you don't have a discharge section, your discharge opening would be around the same size of the centrifugal fan discharge. Centrifugal fan needs the velocity to generate the pressure. That might...
  18. Replies
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    Taco has a new system generating software and...

    Taco has a new system generating software and they are giving our free demo. cd. you might give a try. depends on your system, you might have good amount of accessories to add on.
  19. Thread: Need your advice!

    by ceng
    Replies
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    826

    ashrae on-line library has a good amount of books...

    ashrae on-line library has a good amount of books you can use. for the drawings, i don't know where you can get. most companies see it as a copy right. If you have friend working in this field, she...
  20. Thread: Gas piping chart

    by ceng
    Replies
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    1,720

    most of the stuff I bought are made in China,...

    most of the stuff I bought are made in China, that helps prevents me from red check book..
  21. Thread: boiler piping

    by ceng
    Replies
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    917

    seems you have secondary and primary loop. If I...

    seems you have secondary and primary loop. If I pictured what you are seeing right. did the design provide you a flow diagram to follow?
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    this is airlock i normally see in my projects....

    this is airlock i normally see in my projects. corridor, airlock and lab. airlock has two doors, one to corridor and one to the lab. see if the lab is controled to be negative(-), the corridor is...
  23. Replies
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    psu104, I am not sure what you are doing. When I...

    psu104, I am not sure what you are doing. When I am balancing an airlock, normally, we will count the doors connected with the airlock, rule of thumb, one door 100 cfm. If this is a positive airlock,...
  24. Thread: mixed air stat

    by ceng
    Replies
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    968

    I don't think this sensor is a mixing air stat....

    I don't think this sensor is a mixing air stat. it is more likely to be discharge. the engineer might want to modulate the damper and the dx coil stage to get the desired discharge temp. Are there...
  25. Replies
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    triton99: if gladstone is asking the flow rate,...

    triton99: if gladstone is asking the flow rate, it is 3 gpm/ton,what I said 3 gallon/ton is for column. YOu have to have enough volumn in a chilled water system for the chiller control function...
  26. Thread: propeller fan

    by ceng
    Replies
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    1,750

    those are new 125 hp compressor located in the...

    those are new 125 hp compressor located in the mech. room. no wall can be used. roof is the only option and there is not a big piece of roof. we have both supply and exhaust fan. I am planning to use...
  27. Replies
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    if you are asking the volumn of the system, the...

    if you are asking the volumn of the system, the rule of thumb of controlling the chiller is 3gallon/ton. McQuay has very detailed formular you can use.
  28. Thread: propeller fan

    by ceng
    Replies
    12
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    1,750

    We have 3 indoor air compressors each needs...

    We have 3 indoor air compressors each needs 16,000 cfm to cool and the compressor itself does not give much external pressure. The pressure drop won't be big, so a propeller fan seems fit this well....
  29. Thread: propeller fan

    by ceng
    Replies
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    1,750

    please advise if I can install a propeller in the...

    please advise if I can install a propeller in the ductwork. Have I had to make the flange myself around the propeller fan then transit to the ductwork as needed?
  30. Replies
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    Brent, would you explain why you don't think it...

    Brent, would you explain why you don't think it will work? I have seen it Ashrae show and thought it was a decent product. Our firm has started to put it into our prjects. Your input is appreciated!
  31. Replies
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    we have been using this boiler on quite amount of...

    we have been using this boiler on quite amount of projects. It has been working well with good tech. support. The only down side I have known is a burned out burner due to the uncleaned mech. room...
  32. Replies
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    You may consider cpvc.

    You may consider cpvc.
  33. Thread: universal inputs

    by ceng
    Replies
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    918

    Please advise really what universal inputs mean?...

    Please advise really what universal inputs mean? Is it the same as analog input? Thank!
  34. Replies
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    you can try Dectron website, but I have hard time...

    you can try Dectron website, but I have hard time to locate the rep before. If you are in the midwest, I can give you a rep cotact information whose office is close to cleveland.
  35. Thread: vav control

    by ceng
    Replies
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    1,034

    Incontrol, for this case, we'd like to use...

    Incontrol, for this case, we'd like to use modulate terminals. And phoenix is too expensive. I have contacted our contrator. Basially he was saying we can use pressure sensor to control the cfm with...
  36. Replies
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    actually EMI is able to work down to 0 deg too. I...

    actually EMI is able to work down to 0 deg too. I believe this one is cheaper than Mr. Slim. You may want to watch for the distance between the outdoor unit with indoor. I think Mr. Slim has better...
  37. Replies
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    Mr. Slim has the low embient option down to 0...

    Mr. Slim has the low embient option down to 0 Deg. We have used it for data room, elevator mech room or other place needs cooling whole year round. It has been working really well.
  38. Replies
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    985

    twc pipe, what I post here is not related with my...

    twc pipe, what I post here is not related with my first post.
  39. Replies
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    we normally try to specify belt drive,just for...

    we normally try to specify belt drive,just for balance purpose. And for long run, if you have to add some air on this fan, you have better chance to keep the existing fan, just use a longer motor.
  40. Thread: vav control

    by ceng
    Replies
    8
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    1,034

    The control will be Andover. Thanks for all the...

    The control will be Andover. Thanks for all the recommendations. I am wondering which will be easier, just tracking the cfm, let the general exhaust controller do the math or by the pressure sensor..
  41. Thread: vav control

    by ceng
    Replies
    8
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    1,034

    All we know vav boxes are controlled by...

    All we know vav boxes are controlled by temperature sensor. I am wondering if I can control the box by indoor pressure sensor to maintain a slighly negative pressure indoor. I am working on an open...
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