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  1. willard3

    Duct bracing requirements

    >>>We are talking just some quick info for the very early portion of a project. No design will be performed based on it. I can't tell you how many times I have heard this bad advice and wind up trying to fix something a structural engineer did not understand. Hire an HVAC Engineer
  2. willard3

    Single duct several diffuser

    You are plainly looking fo0r free Engineering with this post.
  3. willard3

    Determine right pressure setpoint

    You should hire an HVAC guy before you screw this up.
  4. willard3

    Single duct several diffuser

    You should hire an HVAC guy to do this rather than screw it up.
  5. willard3

    Hvac docs on control algorithm

    What are you trying to control? You are going to have to understand what you are trying to accomplish and this information is not included in your post
  6. willard3

    Ventilation Exhaust Air under Door?

    This is a code violation. The corridor is an exit during a fire and you don't want to pull smoke from an office and put it in the corridor.
  7. willard3

    Soffit Chase for Ductwork Run on 7' Ceiling

    I concur that local codes will probably dictate ceiling height.
  8. willard3

    Off-coil temperature and airflow effect on total cooling capacity

    As CFM decreases, sensible heat ratio may also change, ie, wet bulb performance may change
  9. willard3

    Off-coil temperature and airflow effect on total cooling capacity

    CFM X 1.085 X delta T = BTU/hr If you lower CFM, BTU/hr will decrease
  10. willard3

    Heating Crawl Space?

    The crawl space has access to soil moisture that may condense when the wet bulb is high outdoors. Wood structure does not like moisture. If you have now or will have any piping in the crawl space, you will be glad you heated it depending upon outside conditions. In Fla, no: in NY, yes. It's also...
  11. willard3

    WSHP Diversity - Central Equipment

    You should read ASHRAE on water-source heat pump diversity factors. ASHRAE says that, after night setback, boilers and chillers will have to run at total load conditions, ie, no diversity.
  12. willard3

    Automatic Lubricators

    Maintenance free bearings is an oxymoron. Anything that rotates needs maintenance. I agree that auto oilers are false security as the mechanic will not check the machine for other problems.
  13. willard3

    Calculated CFM higher than stock equipment

    The CFM per ton is quite variable depending upon the occupancy of the space it serves. Dry bulb and wet bulb variations will influence the CFM per ton.
  14. willard3

    Carbon steel pipe - Is corrosion an issue?

    Water treatment and a strainer are a good idea. In my house, we have carbon steel piping from a thermosyphoning water system that's 115 years old and it is fine.
  15. willard3

    ROOM ACH RATES, VAV

    I don't know where you are, but I would check your local hospital HVAC code for this information
  16. willard3

    What is the best Economical HVAC Equipment

    As I frequently point out to clients, the cheapest cooling system is a block of ice and a fan. What is the best choice for a particular building is frequently not the least expensive
  17. willard3

    Heat Pumps not performing at low temperatures

    I can't count on my hands the number of times I have had to supply some conventional heat in buildings with air-to-air heat pumps. Apart from the efficiency, which is drastically reduced at low temperatures, air to air HP are meant for climates where delta T is quite low. If you have -13F, the...
  18. willard3

    Hot air ducting with in-line axial fans

    There may also be a "system effect" that can be calculated from SMACNA publications.
  19. willard3

    Manual Volume Dampers on Return and Exhaust Ducts

    If you need to balance, and all air systems should be balanced, you need dampers at all outlets/inlets.
  20. willard3

    Minimum angle for vent hood

    There is no minimum angle, but any angle will have an associated pressure drop which you find in SMACNA manuals.

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