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  1. Waramanga

    Engineers using revit?

    Hi all, Is anyone out there using revit for construction phase engineering? ie fan calcs, pump calcs etc? Seems to have a lot of promise. I am and engineer working for a contractor and our drafting is all outsourced (Revit) and then we do the calcs based on the 2d pdfs of the project. Seems...
  2. Waramanga

    Acoustic insulation in supply & Return Duct up to 3 Mtrs

    Get your hands on insertion loss data for internally lined duct to determine what length of treatment you need. I agree that a mech engineer should be able to handle 90% of HVAC acoustic design situations.
  3. Waramanga

    Help with a Crane D930 valve data!!

    Hi all, I have a job I need to recommission that has Crane valves, specifically D930 model double regulating type (they are branded "John" which I understand was a local Australian company that licensed them to sell in Australia at one stage about 20 years ago). I cant find any data on the...
  4. Waramanga

    Constant pressure variable volume fan calculation

    Yes it will have to be a VSD, just adjust until the flow is correct and ignore the static pressure.
  5. Waramanga

    Pressure Loss Through Symmetrical Wye

    The OP doesn't think this is straight forward clearly. I am not familiar with ASHRAE notation, what is the C value and what formula do you use it in?
  6. Waramanga

    Constant pressure variable volume fan calculation

    I have a constant volume system on a 3 storey building that we are decommissioning floor by floor. Still need the pressure to feed each floors mixing boxes but 1/3 less volume. Change the pulley to suit etc etc..... any ideas??
  7. Waramanga

    Constant pressure variable volume fan calculation

    They assume one variable is changing at a time. Volume proportional to speed, pressure to the square of the speed, I want to keep the pressure constant and change the volume. Which fan law covers that situation Willard?
  8. Waramanga

    Constant pressure variable volume fan calculation

    Hi All, How do I calculate fan RPM required to maintain constant pressure and halve the volume? If I assume constant resistance to airflow in the system its just a proportional relationship ie half the volume is half fan RPM but the system resistance is going down by the square root of the...
  9. Waramanga

    Best Building Automation Control Brands

    Agreed, BAS quality is completely dependant on the local support for all but the most complicated systems in my experience. Around here the installers install for nothing and charge like wounded bulls for service, fitouts etc. The best you can hope for is good service while you are getting...
  10. Waramanga

    stratification question

    If the rooms are not heated then stratification wont happen, if you are heating the room then normal engineering principals apply, whats the point of heating the ceiling eh?
  11. Waramanga

    100% fresh air system various exhaust methods

    Missed that you were after fixed pressures. What is the application?
  12. Waramanga

    100% fresh air system various exhaust methods

    Yes you will need to provide a path for the air to get out of the room and outside. If the resitance path is too great then you will end up with doors that don't open, front doors howling etc. Maybe you should look at heat recovery and a return air fan? usually pays for itself up front.....
  13. Waramanga

    Fan Sizing

    +1 Willard, OP needs professional assistance.
  14. Waramanga

    makeup water system connected to water supply for closed chiller system

    Err, document on the internet?? I think you are in trouble designing the chilled water system if you are struggling with the make-up....ask a local plumbing consultant for advice on this, money well spent mate!
  15. Waramanga

    Theoretical Fan Questions in order to get myself a better understanding of how they operate

    1. All motors for hvac are synchronous, ie they rotate at a speed dependant on the line frequency and the number of poles the motor has. If you have a giant motor driving a tiny fan it will spin at the same speed as the right sized motor on the same fan (assuming the same number of poles. 2...
  16. Waramanga

    Wrong refrigerant charge pressure gauges-High head pressure

    Agreed, gages have different graduations and PT relations on them depending on the full scale deflection of the gage. 410 gages usualy just have that due to the high pressures making other gases not practical to indicate. Also, different oils somestimes......
  17. Waramanga

    HVAC Support Spacings ... can I get farther?

    Add in structural engineer with appropriate expertise and PI
  18. Waramanga

    Constant Primary and Variable Secondary Chilled Water System with bypass decoupler pipe

    One book: Total Hydronic Balancing from t and a...
  19. Waramanga

    HVAC controls guide

    Found it!!!! I went through the history in my web browser and bingo! Thank you, if people have any more links they want to share on this subject?...... http://www.peci.org/ftguide/csdg/CSDG.htm
  20. Waramanga

    HVAC controls guide

    Thanks HerrKaLeun, that wasnt the one but I agree that is a good document from Honeywell. It was more of a consultants guide rather than an installers guide. It was kind of like a best practice for consultants, giving the crucial things they should have in the documentation from controls...

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