Calculating Air Flow for Air Handling Units

[@blee597]

Nice training. You make it easy to follow. There are a couple of issues in your content. 1. The static calculation should be a difference calculation 1.5 - (-1) = 2.5 TSP. The second thing is your units on the curve are 1000 so your flow would be 19000 and not 1900. Awesome video. Thanks for sharing.

[@ZenHVAC]

Good catch Bryan! You're right, it should be 19000, I'll correct it soon. I wrote the formula so folks would understand the concept of treating the negative number as a positive. I really appreciate the feedback! Patrick

[@jrh86]

Excellent explanation and video.

[@passiveincome8564]

a very nice explanation this air flow calculation. Thanks

[@ariefsyahrizal3645]

wht about the propeller size ? Does propeller diameter affect the airflows? Suppose I calculated on how much airflows (m³/s) is needed to cool down a certain system, for example a generator. Now how to select a fan out from it ? The rpm of the fan depends on the rotations of the rotor since it'll be installed on the rotor. How to calculate the proper size of the fan to make this schematic works ?

[@passiveincome8564]

1900 cfm / is the chart not starting 5 cFm x 1000? please clear it to me to understand 1900 CFM. thanks

[@ehsan3261]

Hi, thanks for the useful training. For the purpose of my research, I am looking for an equation that I can calculate the air pressure drop due to the existence of heating/cooling coils inside the Air Handling Unit. May you please introduce me such an equation if you are aware of it?

[@ace7709]

I need to measure cfm a rtu or mua do you have a video on that?

[@manojjangir3781]

Can you panel size calculation for ahu, I dedly need it , because I have joined design field help me.

[@victorvasquez5418]

Good job thank you for your help

[@asassasa1899]

Sir, where i can get the curve of static pressure vs air flow, cause at the manual production motor, i cant get it

[@mohtashumahmed351]

I like this video please Make HVAC rekate more videos

[@nobodipchandrapal1058]

Sir, I will use motor-gearbox coupling without using pulley and belt that time how can I calculate the flow rate???

[@carlosbetancourt9228]

If i have a Fan wall, what RPM' should i use?

[@ral153]

Hi Sir Patrick, If my blower is directly coupled to the Fan motor, i will use the Fan motor RPM directly to check the CFM correct? Thanks

[@ZenHVAC]

Correct! Thank you for mentioning direct drive fans, I should have pointed that out!

[@ral153]

@@ZenHVAC thank you sir, this video really helps a lot for us that is new to HVAC. looking forward for more videos. :)

[@hoozdis]

wow! they editied out the snarky comment regarding sheave measuring! please add it back

[@sokachinnarao7694]

Sir, plz explain pipe GPM calculation.

[@ryinfo9461]

why the static pressure is taken for internal? not like roof top

[@ZenHVAC]

Great question Ramzy! They use internal static on built-up air handlers because the unit static changes according to the optional components installed (chilled water coil, heating coil, DX coil, filters, etc) so they use the fan's static curve (internal static) instead of having a different curve for every possible option. Let me know if this helps. Also, what would you like our next video to be about! We'll dedicate it to you!

[@ryinfo9461]

yeah thank you. Can you make a video of how PICV works and other valves

[@ZenHVAC]

Great idea! We'll have it for you in a few weeks!

[@deepshad0w]

Dear Zen, it's very informative. I'm struggling to find someone who would endorse or second your step 4, in which you mention to measure inside diameter of sheave. I have searched hard on internet and in person to several people they all argue it has to be outside of diameter just as in step 3. Kindly elaborate! Thanks

[@ZenHVAC]

Good catch! We should have been more specific on step 4. Measure to the back of the belt if it is an adjustable sheave to be sure you are measuring the functional diameter of the sheave. We really appreciate the question and pointing out how we could have done a better job of explaining! Respectfully, Patrick

[@gustavoportales9199]

Thanks for your video.

[@ZenHVAC]

Thanks for the comment Gustavo, Let us know if there are any HVAC topics you would like us to cover! Patrick

[@gurjantsingh4626]

Nicly explains

[@israrabbasi8229]

excellent sir

[@ZenHVAC]

Many many thanks!

[@TheSpatulaCity]

1:08 There's an air handler, No kidding... lol

[@Tamilsongs2813]

super sir

[@MedinaRR]

Excellent

[@ZenHVAC]

Thanks!

[@TAUFIKCADTUTOR]

good

[@ross1116]

A sheave is a type of pulley. Still a pulley.

[@ZenHVAC]

You are correct! Like a Battle Ship and the Queen Marry are both ships, but different. In the days of old, a pulley was for a flat belt, and sheaves were pulleys for V-belts.

[@vanbavt08ct]

NAME / CAPACITY / SA/ RA / SIZE / Resistors AHU1 120.38KW SA - FLOW: 22680 - SIZE 714x714, RA - FLOW: 20700 SIZE 1300x500, HEAT 380 // PH / 29KW AHU2 122.52 KW FLOW 21600 SIZE 638x638 FLOW 19440 SIZE 1200x500, 380 // PH / 30KW AHU3 137.79 KW FLOW 27000 SIZE 714x714, FLOW 24948 SIZE 1500x650, 380 // PH / 37KW AHU4 184.05 KW FLOW 31320 SIZE 800x800, FLOW 26820 SIZE 1300x650, 380 // PH / 18KW AHU5 110.86 KW FLOW 16920 SIZE 568x568, FLOW 13536 SIZE 1000x450, 380 // PH / 19KW * / First AHU1 wind velocity comparison with AHU3 different wind flow levels AHU1 is smaller than AHU3 4300 cmh but the same wind mouth size 714x714 ** / Comparing wind flow AHU3 with AHU4 different wind flow AHU3 is smaller than aHU4 2000 cmh but the mouth of the wind recovers more than 1500 / 1300mm *** / AHU 3 resistors, AHU4 too small compared to AHU1, AHU2, AHU3 AHU1 120.38KW 380 // PH / 29KW AHU2 122.52 KW 380 // PH / 30KW AHU3 137.79 KW 380 // PH / 37KW AHU4 184.05 KW 380 // PH / 18KW AHU5 110.86 KW 380 // PH / 19KW I summarize so the doctor analyzes help me! I think the designer has made a mistake. If so please help me get one correct answer. Thank you very much! This is my email [e-mail]

[@ponkrapujari679]

it should be 19000 sir I'm from Mangalore india

[@ZenHVAC]

You are correct! I miss spoke during the recording.

[@ponkrapujari679]

I'm a Hvac designer

[@bryanswanson5007]

alot of bad information here stopped watching 2 min in. To correct you on one thing, the motor has a sheave the blower has a pulley.

[@passiveincome8564]

1900 cfm / is the chart not starting 5 cFm x 1000? please clear it to me to understand 1900 CFM. thanks