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Recent content by ChasBean1

  1. ChasBean1

    Pump head in closed system

    RegiSTR, great question and you are absolutely right. Gauge readings even in a closed system should be corrected based on difference in height of the gauges (P = rho * g * h). But there are exceptions depending on how the gauges are piped. There are often 2 or 3 pipes to a common gauge for a...
  2. ChasBean1

    Questions regarding Fan Performance Curve

    Close, but you're overthinking it. Contrary to popular belief on this issue (and possibly others), size does not matter. That's the beauty of a fan or pump curve. Stick them in any system regardless of sizing of inlet or outlet pipes or ducts, they will only produce the flow that the total...
  3. ChasBean1

    AHU air flow filter

    SAK9, likewise, thank you! You and the crew of other usual suspects have been doing so well that I logged out and haven't been back on for a bit. Hope you are well! Odds are I won't have frequent logins but will stop in every now and then to stir the pot...
  4. ChasBean1

    Question on Makeup Air for hazardous Exhaust System

    Snickster articulated well on this - but the whole meaning of these 184 words of mechanical code is "Make sure the contaminated room is not positively pressurized to abutting spaces by appropriately balancing supply and exhaust airflows." I prefer my 19 words, but things that are...
  5. ChasBean1

    Questions regarding Fan Performance Curve

    No good for me. And I hope it would be no good for most people. Take a 1000 cfm fan designed at 4" TSP. The fan shutoff head (or dead head) is say, 6". These are numbers for typical systems. The 4" TSP is only meaningful if it is the outlet static minus the inlet static. Now let's say the...
  6. ChasBean1

    Supply Air Duct Condensation Temperature

    The cooling coil: DX or chilled water? That matters. Infiltration: the space should be slightly positive. For a negative space, you can count on the duct sweating, especially if temperature control is cyclical.
  7. ChasBean1

    Removing expansion tank after system is hot

    The air separator is all about minimizing corrosion and keeping you from having to burp the system. 6 months? Should be fine. The expansion tank should not be ignored, even if you need a temporary location. If the system stays hot the whole time, all good. If the system cools down, might be...
  8. ChasBean1

    Glycol Corrections

    Do you think your friction loss calcs are so accurate that you would need to correct selected pump head based on a slight change in density due to 25% glycol? No. Heat transfer is de-rated a bit with a glycol solution so go slightly larger on heat exchangers and a smidge larger on pumps, but...
  9. ChasBean1

    AHU air flow filter

    Filer airflow is the same is AHU airflow. Velocity is the key - size the filter bank large enough to be under about 500 fpm (~2.5 m3/s).
  10. ChasBean1

    Open Parking Garage Ceiling - Freeze Protection Heating

    Tough to tell with the givens. What is above? Is this to make the above floor not cold, or protect pipes from freezing? Should be dry sprinkler system in the garage. Also consider making CUH-1 an electric unit (ECUH-1) to eliminate the long HW pipe run.
  11. ChasBean1

    Questions regarding Fan Performance Curve

    Total pressure is the sum of static and velocity pressures (usually), but fan curves are no good if they account for velocity pressure. The curve is simply the static pressure at the outlet minus the static pressure at the inlet.
  12. ChasBean1

    Controlling the water circuit

    Ummm, DP means differential pressure. You want to control the pump to a constant “flow” at “DP2?” No. Control the pump speed to maintain the differential pressure (like, "DP") at “DP2.” The 3-way valve will maintain minimum flow at what you call “DP1” to keep the chillers happy. I tried, but not...
  13. ChasBean1

    ESP For Fan Located at roof

    You're all messed up. Everything cancels. It's all about friction losses. See me after class.. Lol
  14. ChasBean1

    Unoccupied hours temperature setpoints?

    John 187, if the government starts mandating what off-hours temperatures should be, please sign me up for a different government.
  15. ChasBean1

    Thoughts on negative pressure after balancing a Venmar X24 ERV?

    Dgoodyear, the “best of your abilities” needs to improve. Sorry to be blunt. “I know that the fan tables with the unit provide a way to measure air flow across the core to facilitate balancing fresh and stale air flows.” CB: What? “I have also used the anemometer to do an 50 point average...
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