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  1. lukaiENG

    typical hotel room hourly occupation profile

    IRstuff raises a good point, does the hotel has any means to monitor room occupancy? (and integrate into room temperature controls) I have occasionally seen the keycard used to deactivate lighting but I've never seen it deployed to put AC on a unoccupied set back. possible though no doubt.
  2. lukaiENG

    Ventilation

    if only it were that simple... we would all be out of jobs!
  3. lukaiENG

    Variable Speed Drives - "Slowing down the motor?"

    In more basic terms, think about regenerative braking in an electric car. the wheels are slowed down when the EMF generating motion is removed, since the wheels are (initially) still rotating they generate a "back-EMF" in the motor windings which is used to push regenerate some change back in...
  4. lukaiENG

    Brand new air cooled chiller £60k out of order within 10 days

    What sort of vibration are they saying it was? internal vibration on the machine? Was the chiller installed with vibration isolation? did the rotating/reciprocating chiller components have vibration isolation? is the manufacturer recommendation to vibrationally isolate the chiller? What was...
  5. lukaiENG

    Designing a MUA system for a 600 CFM hood fan

    in my jurisdiction, the requirement for needing to provision make-up air was if the KEF is over 400 CFM. If I were you I would select a 400 CFM KEF like I did. We never run KEF past 2/3 speed so I've never had any flow issues.
  6. lukaiENG

    Residential HVAC unit

    you could also have some leaky ductwork or or maybe some vents open off the system to other areas? in my house we have a furnace for the 2nd level which also has some grilles in the basement. I have to close these down in the summer to make sure the cooling goes where it is needed.
  7. lukaiENG

    Whirling Sound 54dB

    it sounds like you may be getting regenerated noise off the grilles or maybe through some torturous duct design. maybe as a test you could remove the grille and see if the noise stops, if it does then you might be able to re-select for a higher free area grille to achieve the same design.
  8. lukaiENG

    ACMV Condensation in the toilet

    Questions: What temperature is set to 24C? the supply temperature or the room temperature? Are all pieces of equipment operational? what is LAT off FCU? Where is the FCU pulling from? possible issues: [ol 1] FCU could be malfunctioning, either not blowing or cooling. Either of these would...
  9. lukaiENG

    RH and DB temperature

    A desiccant system would be one way to deliver this result. the process is pretty much as Emrelug describes above
  10. lukaiENG

    preparing cutsheet packages

    As Willard states, a product specification will normally call out the required documentation, as a baseline, follow this format. Larger projects will have a set of general requirements specifications which will include submittal requirements. For specifications that follow the AIA Master Specs...
  11. lukaiENG

    HVAC seismic design criteria?

    We normally have delegated design verbiage within our specifications, putting the onus on the contractor - if it works with timing this is probably your easiest approach. In my experience the local contractors understand the requirements intimately as they have to deal with them on every...
  12. lukaiENG

    Daikin unit

    Good point above, but I wouldn't treat the catalog performance tables as worst case - these are just at common/standard design conditions which may be more or less stringent than the design need. Always get a selection from your rep at your design conditions.
  13. lukaiENG

    High Amps on Chiller Compressor Motor

    What voltage are you getting at the chiller/components? perhaps the integrity of the electrical connection was compromised leading to low voltage/high current?
  14. lukaiENG

    Could a system exist which doesn't need to vent heat to the outside, but converts it to electricity?

    According to Britannica: At those temperatures, rejecting from the heat sink to atmosphere should be no problem, the household AC might be running a little hard though. [wink]
  15. lukaiENG

    Altitude and Coil Sizing in Trane Trace

    most manufacturers typically have a threshold below which they don't de-rate. Typically around 3000 ft. anything above this and they should most definitely de-rate.
  16. lukaiENG

    SS 316 OR SS 304 OR A2-70 OR A4 70

    According to this website they are basically the same, they have a slightly different composition & are manufactured to different standards (EU vs US I assume) https://www.fastenal.com/products/attribute/600173/5;jsessionid=202C597BAB6E1291E073818CBE01A41B.jvm3
  17. lukaiENG

    Primary/Secondary chilled water system pumping - variable primary - variable secondary

    Variable Primary is a thing. You will want to have a minimum flow bypass in the loop somewhere to ensure that you can pass minimum flow through your chiller. The minimum flow will be dictated by the chiller manufacturer and will me ~40-50% of the chiller nominal design flow. Note, the "chiller...
  18. lukaiENG

    Emergency switch machine room EN378

    What you are suggesting makes sense and will be in the operators best interest. Why are you second guessing yourself? $$?
  19. lukaiENG

    Compressor room ventilation

    Depending on the size of the room and the amount of refrigerant in the largest circuit you may need to treat the room as a machine room which dictates exhaust rates and operation. Refer ASHRAE 15.
  20. lukaiENG

    Daikin unit

    I was really oversimplifying above. Don't expect linear changes if you change the deltaT. As I said in my first response, get selections from your rep

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