Airflow CFM Measured with a Hot Wire Anemometer!

[@acservicetechchannel]

The E-Book, Paperback and Quick Cards: www.acservicetech.com/store The Paperback, Quick Cards at Amazon: www.amazon.com/shop/acservicetech Support the Channel- www.patreon.com/acservicetech Tool List- www.amazon.com/shop/acservicetech Related Videos: HVACR Temp Rise Formula to Measure Airflow CFM: kzbin.info/www/bejne/l5ikl4lpjtaVbbc HVAC Delta T Explained! What Temperature Should it be?: kzbin.info/www/bejne/b52nnWiZm6uGsNU Tools Used in This Video: STA2 In Duct Hot Wire Anemometer: amzn.to/31LFdG9 UEI DL479 Multimeter with temp sensor: amzn.to/2jtsUbJ ST4 Dual Temp Reader: amzn.to/2uk1QFm Tools I Use Are Linked Below! 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Shop through Amazon! Your Purchases through Amazon provide a means for channels such as mine to earn advertising fees from all purchases after clicking through. Prices are the same as normal- www.amazon.com/shop/acservicetech

[@sportsman042002]

When you do the heat rise and use the heat strips is the actual heat pump supposed to be running to or just the strips? Thank you for all your videos I have learned a lot from you.

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[@stuzman52]

One of the best demonstrations of how to measure CFM. I like where you take the measured air and compare it to the CfM formula is comparing the real and math worlds. Great video Craig and keep up the good work, 😀👍

[@jdere31760]

Great job, you even showed how to do the math and check air flow by temp rise method! Who would dislike this video?

[@acservicetechchannel]

I appreciate that!

[@garypoplin4599]

6:20 - It looks like you’ve practiced to near perfection on this process. Spot on 11s each traverse!

[@FooDaki]

i always heard how hartd its to measure airflow at a job , this is an incredible tool ... thank you

[@jaimegutierrez9930]

Thank you for the videos your a legend

[@derrickgarcia303]

Good demonstration.

[@jimbola77]

excellent video partner thank you for sharing!!!!.

[@acservicetechchannel]

Glad to help Jimbola77. I hope things are going well for you!

[@kanive1566]

How would you do this if it was flexible duct? Can you drill holes in the flexible duct and plug them just like you did with the ducts in this video? Or would it be different?

[@zekenzy6486]

Great video. Thank you for sharing . Could you do video for heat pump winter inspection ? how to know Heat pump is work good in winter?

[@acservicetechchannel]

Ze Kenzy thanks for letting me know what you would like to see!

[@tommyhummer2762]

How does this compare to a flow plate? Is it as accurate?

[@theairconditioningguy]

I've yet to do this. Thanks for the info!

[@acservicetechchannel]

Glad to help!

[@biblebloopers946]

What if I want to measure a specific duct going into a room? And what if it's flex duct? How do you measure that?

[@goobermcgoobs7589]

Take off register select what size duct you’re measuring and move back and forth for 15 seconds across the duct

[@gadgethunter5732]

it would be nice to see you include the units of measurement and how they add to or cancel each other out so you arrive at the value you are working out. I always found it very useful when writing exams to include all the units when working through the formulas. Maybe an advanced version of the video. Or possibly that is already addressed in your books? Other wise excellent presentation. I will recommend your channel to my peers and apprentices in the industry.

[@ore-georgecicovic6533]

Great video like always. Have one question. How to messure CFM if unit is working only on cooling and no heat strips for amps reading since ams on blower are to low. Thanks

[@Behuman0627]

Grt video sir... Can you pls clear a doubt do we have to enter duct size to get directly reading in CFM !!!

[@sportsman042002]

Do you have it on just fan or is the Ac running when you do this test?

[@Sctronic209]

Do have a video testing a gas furnace cfm? Nice seeing it being demonstrated.

[@acservicetechchannel]

Not yet but I would like to, thanks!

[@thewallstreetjournal5675]

You can determine the BTUs of a gas furnace. With the formula. (3600 seconds in an hours / Time it take your gas meter to measure 1 ft of gas. When only your furnace is running. ) Times BTUs in a ft of gas close to 1000 BTUS per ft. = BTUs per hour. Use the BTUs per hour in the top of the fraction in the formula on 8:26. The number 3.414 is just a conversion factor for watts to BTUs. {(Sec/hour) / (sec/ft) } ( BTU/ft)= BTU/hr

[@Mik.heckhaus]

does this formula work for gas furnaces? also, how would this work if checking a/c airflow?

[@paulmorrow8372]

This can also be tested using a gas furnace. You use the BTU’s on the name plate of the furnace. With the delta T method, airflow is always tested using the heat. If your blower is multi speed, like most, you want to swap the leads to have the blower motor run at the “cooling” speed when the heat is on. This is normally accomplished by swapping the heat and cool connectors on the control board. You are looking for 400 cam per ton of cooling.

[@smacleod69]

How about doing a demonstration on a return system with a 2 foot return box and flex duct attached. My readings are way off! example 16x25 box. With 2-12 inch flex for 2.5 ton system with a 3 ton blower. My anometer reading 1600 cfm! How the hell does that add up!

[@ivanivanov9949]

Could you, please, answer one fundamental question about Hot Wire Anemometer? There are 2 thermistors in the Anemometer probe. But only one of the thermistors (the upper one) is to be exposed to airflow.The other thermistor(the lower one) must be hidden away from the air flow and it senses only the ambient temperature. Why you put both thermistors into airflow? Do I understand everything right? Please, explain.

[@scottm3552]

When do you make the decision to drill into a customers duct without them getting upset about holes in there nice ductwork?

[@harkamagar201]

How can you do in the round duct. Do we still need to make couple of holes??

[@solvintx]

Great video !!!! Question, Where do we measure cfm when working with flex duct? At the plenums?

[@acservicetechchannel]

Yeah in the least turbulent area. The more turbulent the air, the more incorrect the readings will be, thanks

[@bloombrewingCo.]

What's the difference in tools to measure CFM, on the Fieldpiece SDMN6 Manometer and the Fieldpiece STA2 Hot Wire Anemometer? A manometer measures Atmospheric Pressure and an Anemometer measures Wind Speed. Just a different way of calculating CFM ?? Also, if you had to pick 1, which one is a "more useful" tool ?

[@mackenziegray2090]

STa2 I'd just a anemometer and the sdmn6 is a manometer. you can calculate cfm using a manometer. but it's a longer step. you take the static pressure measurement then you want to square root that number. multiply that number by 4005. multiple your answer by 0.9 (carrier recommendation if you're just measuring one whole to get an average). now you want to get in² of the dimension of the ductwork. multiple length x width and divide that number by 144 and you'll get ft². multiple that number by your feet per minute and equals to cfm. example: 0.2 static 0.45 square root 0.45x4005x0.9=1602fpm let's say 20x20 dimension of duct 20×20=400 400÷144=2.8ft² 1602÷2.8=572cfm

[@Arieldny]

Question, isn’t this formula used to calculate system capacity. Checking the name plate (total btu) I’m confused q=1.08 x CDL x delta T I know you solved for Cfm but then where is Q left in this example ?

[@pizzle1011]

Nice... question though. I noticed from other videos you check this formula/cfm using electric heating. How would you check it with normal gas fired furnace? Is it explained in the book (which I ordered the other day)?

[@pralaypatel7110]

The book does have this video example. I have to admit that it's so much better watching it in a video. Thanks Craig. Please support this channel and the Author. He's been doing excellent work to inform and help everyone for years!

[@acservicetechchannel]

Yes cfm can be determined with a gas furnace and oil heat and the formulas are in the book, thanks! Please let me know what you think of the book after reading it!

[@rhalama1]

How accurate is measuring the heat differential to this method?. I am sure this is the most accurite but i dont want to purchase this instrument. Enjoy your video's.

[@acservicetechchannel]

Temp rise formula is the most effective way to determine cfm but you need a heat source such as strip heating or gas furnace, thanks!

[@300zxdriver]

How about at your individual vents, equal them out?

[@josegmoreno4966]

Where do you take the amp draw if you don’t have heat strips. ?

[@dustinschmidt4584]

Couldn't you use this formula for CFM? BTU(out)/(temp rise * 1.08) = CFM

[@k8aik8ai]

what's the formula for a gas furnace?

[@xtremecomfort7799]

Thanks!!!!!!!!

[@acservicetechchannel]

Glad to help Xtreme Confort!

[@Bryan-mg4gf]

How far down in a return for a roof top unit should I place this probe?

[@mikeamerongen5298]

Where would you take the amp draw reading on a gas furnace ?

[@johnthomas5786]

does the book have instructions for checking airflow/cfm like in this video?

[@shootermcgaven5021]

So Air handler amp draw at the heat strips. Where do you take reading on a gas furnace?

[@sprockkets]

Look at gas meter outside to calculate. I watch the half foot meter for about 1 minute.

[@Bdpjev]

Is there a service tech book for refrigeration

[@acservicetechchannel]

I dont have one on refrigeration at this point, thanks!

[@seek3n]

I thought we are checking heating the whole time until he said 400 cfm/ton of cooling at the end 😂

[@dunckeroo1987]

His electric heater is 100% efficient. But A/C is even more.

[@famousdude1239]

Those cuttings from the unibit....are being sucked into the electric motor! Nothing like a magnet below your cuttings.

[@fuzzyvision1219]

Just imagine drilling 5 holes in a return drop with a vari bit right in from of some ole fart that's the flashlight holding type watching your every move lol...

[@james10739]

None of these are helping me im trying to figout cfm for a window ac and a mini split

[@jeffb8437]

Cfm..... not cfm’s! Otherwise great video

[@acservicetechchannel]

Ha ha yeah, you're right, thanks!

[@workinprogress008]

Attack of the cfm's!

[@davidestrada5488]

This seems like to much work for a little window to diagnose a system

[@jdere31760]

David, I would say a tech in field would check the air flow after finding the following: low suction pressure at the condenser and then go check that the air filter and evap are not clogged. At this point, you would need to check air flow or you would not be covering all your bases and while you are there, check amp draw on the blower motor too.

[@kevinpearce3281]

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