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  1. new2hvac

    Return Fan Required?

    I have seen several different mechanical room configurations...some with a return fan(s) and some without. It seems that most of the larger systems have a return fan. These design variations have led me to several questions and I thought I would pass them along to the pros: Under what...
  2. new2hvac

    Computer room AC unit - vendor?

    I suspect the cost of a new, 15-ton Liebert is about $25,000 - 35,000 depending on the options you require (humidification/reheat, advanced microprocessor, etc.). The installed cost of this unit could be significantly more depending on the amount of condenser water piping or refrigerant piping...
  3. new2hvac

    ASME Rated HW Storage Tank

    I have a storage tank on a boiler loop that is no longer functioning and requires replacement. The existing tank is ASME rated. Question: under what circumstances do you require an ASME rated tank (and the premium pricing)? I found some info that indicates an ASME rated tank is required...
  4. new2hvac

    Fan Variable Freq Drive - Energy Savings

    I'm trying to estimate the energy savings that will be seen by installing a variable frequency drive on (2) 50 hp supply fans. I've reviewed some software provided by a VFD manufacturer, but they only show energy savings of a VFD versus Inlet Guide Vanes and Outlet Dampers (which incidentally...
  5. new2hvac

    Centrifugal Compressor part-load efficiency

    The local Trane rep has been not been very responsive to my inquiries. The 0.5 kW/ton comes from the original installation specs. I base this on a nominal 700-ton chiller with a kW draw of 382. This, of course, does not include the kW of the cooling tower, fans and pumps in the system so the...
  6. new2hvac

    Centrifugal Compressor part-load efficiency

    I'm trying to identify the part load efficiency on a chiller with a centrifugal compressor. I have the installation specs and it appears to be a little over 0.5kW/ton. I don't know if this was measured at full load or some portion of full load. How does decreasing the load affect the...
  7. new2hvac

    Moduline Question

    The model number of the moduline is 37AJ1148-(10-2). Any idea if this is a VAV or CV box? I can't seem to find this model in the literature...
  8. new2hvac

    Moduline Question

    Thanks Tony. Please send info to bkitchens@haynesmechsys.com
  9. new2hvac

    820nm device on 850nm switch ????

    Chances are that the receiver on the 850nm switch will accept an 820nm signal. To be certain, you should look at the spectral width of the transmitter and the range of frequencies the receiver will accept. As long as you aren't pushing the attenuation limitations of the fiber, I don't think...
  10. new2hvac

    Moduline Question

    Thanks for the info. What is required to change a constant volume Moduline into a variable volume moduline? Are all constant volume modulines equipped with a volume regulator? Can this be easily removed if the supply fan has a VFD?
  11. new2hvac

    Moduline Question

    Is anyone familiar with Carrier's Moduline system? Is this a constant or variable air volume system? I've heard it can be either but cannot seem to find any confirmation. If I understand this correctly, the constant volume systems are equipped with a bypass damper that re-circulates the air...
  12. new2hvac

    LIghting Loads

    I don't believe there is an exact conversion because foot candles measure the intensity of the light and some fixtures/bulbs are more efficient than others.
  13. new2hvac

    How Much Cooling is Required

    I'm looking at replacing some swamp coolers with mechanical cooling and am having trouble calculating the cooling requirement. The evaporative coolers are only able to cool the space to about 90 deg F on hot days (outside air around 105 deg F), and they would like it to be cooler. My question...
  14. new2hvac

    Variable Freq Drive on a Fan?

    Is there a significant energy savings when installing a VFD on a variable pitch axial fan? The folks at the VFD company tell me this would be similar to having a fixed blade fan and inlet guide vanes, but I suspect they're opinion is a little slanted. Is there an easy way to calculate this...
  15. new2hvac

    free space optical data links

    In my previous position, we did some testing with a company called Air Fiber www.airfiber.com. They may have just what you're looking for.
  16. new2hvac

    Noise Cancellation

    Are there any commercially available products that can be used for noise cancellation? Specifically, I'm trying to cancel the noise produced by a fan above a false ceiling. It would seem this would be pretty simple technology...wouldn't it be the same as what is being used on noise...
  17. new2hvac

    Data Room Cooling - High Ceiling

    I'm looking at a cooling application in a computer room. The equipment, lights, people, etc amount to about a 40-ton load. This room is about 6000 SF and does not have a raised floor. The room is currently being cooled by the building system which is ducted above the false ceiling...about 15'...
  18. new2hvac

    psychrometric chart question

    That's helpful...thank you. Still I wonder how air at 0 deg F and 0% RH can contain no energy. It must take some amount of energy to heat air from say -10 deg F and 0% RH to 0 deg F and 0% RH. How can you calculate that?
  19. new2hvac

    psychrometric chart question

    If you look at the enthalpy scale on a sea level psych chart, it appears to go to zero at about 32 deg F and 0% RH...following the line, it also appears to be 0 at 30 deg F and 10% RH. I thought the complete absence of energy only occurs at 0 deg K. I'm trying to calculate the heating...
  20. new2hvac

    Indoor pool HVAC Engineering

    There seem to be a lot of variables in indoor pool HVAC engineering. I'm trying to get a clear picture of what's involved. So far, I've identified the following and have questions associated with each... 1) Air temperature should be at or slightly higher than water temperature to minimize...

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