The fan laws question is on the HVACR master exam yet i am unable to find them in either of the books that are aloud to be used. Which book are the fan laws in?
These methods are taken from several different sources. I do not know of a single source that would include them all. There is a book that comes close to covering all the methods/laws, "Definitions, Conversions, and Calculations for Occupational Safety and Health Professionals" by Edward Finucane. Finucane's book will present formulas in a slightly different format. I use the same formulas but simplify them. In addition I would recommend "Fundamentals of Industrial Hygiene" by Barbara Plog.
Thanks. Can you tell me why amps on a propeller fan increase with air blocked to it and amps decrease on a centrifugal fan when air is blocked? I do know that air is a load on the centrifugal fan and if removed then amps drop. The propeller. Thanks
Hello Johnny. I'm not an HVAC expert but here is my guess. It is all due to the fan design and how the different designs move air. Axial (propeller) fans work like a screw to create a pressure differential. With Axial fans the inlet side is not as important for its efficiency so a blockage will not increase loading and current draw. Centrifugal fans capture the air as it enters the fan housing and then throws the air forward. It is much more dependent on air supply at the fan inlet. Without air at the inlet the system can become "air bound" and the fan has to work harder to move the air. I recommend talking to a mechanical engineer who specializes in fan design or an HVAC expert who has years of field experience. In addition to what I've just thrown out as a possibility, there are dozens of different variables that can effect how a system moves the air. The phenomenon you describe is also going to be affected by the specific type of centrifugal fan, the blade/impeller design. Hope this helps.
@@JohnnyJr396 Here is a link to a discussion related to your question. A lot of different opinions. Some of the them are probably correct, lol? cr4.globalspec.com/thread/108775/Squirrel-Cage-Blower-Speeds-Up-When-Airflow-is-Blocked
Best explanation and math I have seen for fan laws... thanks
Thank you
The fan laws question is on the HVACR master exam yet i am unable to find them in either of the books that are aloud to be used. Which book are the fan laws in?
Thanks, useful video for me.
Glad it was helpful!
Great video thank you for the excellent lessons, is there a website that you know of where I can print all these laws for reference
These methods are taken from several different sources. I do not know of a single source that would include them all. There is a book that comes close to covering all the methods/laws, "Definitions, Conversions, and Calculations for Occupational Safety and Health Professionals" by Edward Finucane. Finucane's book will present formulas in a slightly different format. I use the same formulas but simplify them. In addition I would recommend "Fundamentals of Industrial Hygiene" by Barbara Plog.
Thanks. Can you tell me why amps on a propeller fan increase with air blocked to it and amps decrease on a centrifugal fan when air is blocked?
I do know that air is a load on the centrifugal fan and if removed then amps drop. The propeller.
Thanks
Hello Johnny. I'm not an HVAC expert but here is my guess. It is all due to the fan design and how the different designs move air. Axial (propeller) fans work like a screw to create a pressure differential. With Axial fans the inlet side is not as important for its efficiency so a blockage will not increase loading and current draw. Centrifugal fans capture the air as it enters the fan housing and then throws the air forward. It is much more dependent on air supply at the fan inlet. Without air at the inlet the system can become "air bound" and the fan has to work harder to move the air. I recommend talking to a mechanical engineer who specializes in fan design or an HVAC expert who has years of field experience. In addition to what I've just thrown out as a possibility, there are dozens of different variables that can effect how a system moves the air. The phenomenon you describe is also going to be affected by the specific type of centrifugal fan, the blade/impeller design. Hope this helps.
@@SafetyProCalculations thanks for taking the time and sharing your thoughts and opinions on that! I appreciate the input
@@JohnnyJr396 Here is a link to a discussion related to your question. A lot of different opinions. Some of the them are probably correct, lol? cr4.globalspec.com/thread/108775/Squirrel-Cage-Blower-Speeds-Up-When-Airflow-is-Blocked
@@SafetyProCalculations definitely a lot of opinions lol. Thanks!