Continue to Site

Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

  • Congratulations waross on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Recent content by bigAlittlee

  1. bigAlittlee

    Running Cooling Towers "too dry"

    Yes 4 towers each usually at 25% of their design flow, except extreme summer conditions. I don't know if you do care about control valves that much once you add the VFD. I feel running the fans at low speed and using as much surface area as possible would be the optimal scenario. Also...
  2. bigAlittlee

    Running Cooling Towers "too dry"

    So I am doing some retro-commissioning work on an older building that currently wets all 4 cooling tower cells at all times. Control valves do not exist. Single speed fans are sequenced by thermostats in each basin, each of which control their respective fan to operate at varying basin...
  3. bigAlittlee

    VAV system

    I agree with ChasBean on designing around the pressures. You can go to the ventilation and infiltration chapter in ASHRAE fundamentals and look into leakage calculations. These leakage calculations can be pretty intense, and not necessarily that accurate. Not because they can't be accurate...
  4. bigAlittlee

    Sizing an HVAC unit for commercial building

    Ha I Googled Manual J as I don't do residential and found this which I didn't realize was a joke at first. Pretty funny. http://synergyairflowandventilation.com/docs/ManualJSDT.pdf Air Conditioner or Heat Pump Sizing Chart Preparing your sizing chart: 1. Print out this page. 2. Leaving...
  5. bigAlittlee

    Estimating cooling tower energy savings using bin data

    Absolutely. The reset strategy is Twb+5F or 70F (whichever is greater). The out of whack humidity sensors will be replaced for this. The method I ended up using was running numerous 3000 series cooling tower selections with the BAC web based selection software for 2.5F weather bins with CWT...
  6. bigAlittlee

    Estimating cooling tower energy savings using bin data

    A very fundamental to HVAC, though not so simple problem I am trying to solve using a route I wouldn't normally take. Up until now my experience estimating building performance has largely been with using various energy modeling programs, with libraries for equipment etc. Well - I got a new...
  7. bigAlittlee

    Commercial HVAC Humidfication System Efficiency

    Trying to come up with arguments for various methods of humidification in large scale (high-rise building) HVAC systems. I don't know the answer myself and will be spending the next couple hours trying to find it and was wondering if anyone had any good information or opinions on preferred...
  8. bigAlittlee

    Short-Term Ventilation Design

    6-9a is IP 6-9b is SI
  9. bigAlittlee

    Mechanical Room Layout Resources

    In the few years I've been doing MEP work, I've done plenty of sizing and modeling calcs, equipment selection, etc., but until recently I haven't been faced with the task of laying out mechanical rooms. I understand this isn't that hard and it's not that I can't do it, but every time I do one...
  10. bigAlittlee

    Chilled Beam

    I'm not sure if you are implying that you would like to calculate the capacity theoretically and find water and air side Nusselt numbers or what. If that's what you're going for good luck with that. If you are looking for a good source for typical data I would recommend the Trox chilled beam...
  11. bigAlittlee

    Under Slab Geothermal Cooling System

    Right, I wouldn't know what to do if you have a leak. You'd pretty much have to cap it and never use it again I guess. I've spent a lot more time checking out different system types since I first posted, and this type doesn't seem feasible. However, it sounds like because of high water...
  12. bigAlittlee

    Under Slab Geothermal Cooling System

    Yeah? I guess that means if the ground you're standing on is flat then you should assume that the earth is flat too. You should note the difference between "guess" and "estimate." I understand that temperature decreases with depth, then stabilizes, and then increases. Upon further research...
  13. bigAlittlee

    Under Slab Geothermal Cooling System

    I have little experience with geothermal heat pumps, but it is being pushed as an idea for the conceptual design of an upcoming project. I have been recruited to explore the feasibility of such a system and to start I would mostly like to find an example of such a system already in place. The...

Part and Inventory Search