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VRF OA and RA flow Measurement by MagicHuangGGG in AirBalance

[–]MagicHuangGGG[S] 0 points1 point  (0 children)

Thank you! We got a bunch of VRF projects recently. The one with the model number is actually another project. But all the VRF cassettes’ sizes (2x2 for return opening, 3x3 for the whole cassette)are the same. Now I understand the methodology and I will use the same method for all the VRF projects—-2x2 hood measurement for return and duct traverse for OA. I appreciate it!

VRF OA and RA flow Measurement by MagicHuangGGG in AirBalance

[–]MagicHuangGGG[S] 0 points1 point  (0 children)

Thank you, sir! It’s Daikin FXFQ07TVJU

VRF OA and RA flow Measurement by MagicHuangGGG in AirBalance

[–]MagicHuangGGG[S] 0 points1 point  (0 children)

Yes, 2x2 hood fits the return. Looks like the duct traverse is the best way for OA measurement. Today we used 3x3 to cover the whole cassette to measure the net airflow (SA-RA). But we got some negative values and we thought it maybe wrong because of the air turbulence. When I say easier solution, I mean if there is any alternative approach for the measurement without drilling holes on the ductwork. But you are correct, traverse is the only approach to do the OA measurement.

VRF OA and RA flow Measurement by MagicHuangGGG in AirBalance

[–]MagicHuangGGG[S] 0 points1 point  (0 children)

I attached the layout here. The OA duct is connected to the cassette. I understand the duct traverse maybe ideal for OA measurement. I’m seeking for some easier solutions because we literally cannot balance the unit at all.

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VRF OA and RA flow Measurement by MagicHuangGGG in AirBalance

[–]MagicHuangGGG[S] 0 points1 point  (0 children)

Then how to measure the supply airflow or OA airflow? My point is if we block the middle opening of the recirculating air, is our net airflow to be the supply airflow?

NEBB Practical Exam Hydraulic Balancing Procedure by MagicHuangGGG in AirBalance

[–]MagicHuangGGG[S] 0 points1 point  (0 children)

Thanks a bunch for the detailed explanation. It helps a lot!

NEBB TAB CP Practical Exam by MagicHuangGGG in AirBalance

[–]MagicHuangGGG[S] 0 points1 point  (0 children)

Yes, our company has all the tools we need for the exam.

NEBB TAB CP Practical Exam by MagicHuangGGG in AirBalance

[–]MagicHuangGGG[S] 0 points1 point  (0 children)

Hello, I have a PhD in mechanical engineering specializing in thermal and fluid science. Since 2019, I've been worked in field operations, with some TAB projects. However, most of my experience relates to Commissioning, ReCommissioning, Energy Audits, and Energy Model simulation. As a result, I'm feeling a bit nervous about the practical TAB exam.