# Air flow measurement...



## hvaclover

I was curious as to what particular methods of air flow measurement other guys use to ensure proper CFM on spring A/C Tune Ups.

Seems when the time comes you need every second you can grab just to keep up with the volume of calls. Air flow measurements can slow a guy down if he isn't as nimble as others at using the instruments and interpreting the results.

I am trying to find a way to tweak my own procedure as I go to each register and take a volometer reading. The sum of all the airflow tells what the system is doing.

Anybody got some time saving tips?


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## beenthere

I don't include a room by room air flow check with a standard PM/MA.

Just a check at the air handler/furnace itself.


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## JohnH1

I take 4 static readings before and after fillter and evap. I have some general blower charts from NCI training I went through if MFG chart is not avalable. If a problem then I will go further.


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## Nascarwc88

Carrier makes an r-22 superheat calculator, that also has an airflow measurement on it. Not sure if their 410a has one on it or not.


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## beenthere

Double check that air flow chart.
It may be for a TXV system.


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## scooter

hvaclover
I am only curious but how much do you charge for your a/c tune ups and what else do you include.
what are of detroit do you work in most often


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## hvaclover

i leave that all behind when i come here same as all the other guys in my generation.

Why do you have an interest in me and not one of the other pros?

it's no secret I am not the most approachable guy on this forum. Makes me suspicious when someone i have not established a rapport with asks such personal stuff.


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## beenthere

Either because no one else checks room CFM on a PM/MA check.


OR, he has a thing about being bitten in the neck. :laughing:


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## hvaclover

i check CFM on all my annal inspections. And if i have to pull a blower wheel I lube the shaft with Vaseline before i put it in.:001_tongue:


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## hvaclover

beenthere said:


> Either because no one else checks room CFM on a PM/MA check.
> 
> 
> OR, he has a thing about being bitten in the neck. :laughing:


I don't get it.:blink:


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## beenthere

hvaclover said:


> I don't get it.:blink:


You attrack the golth people.


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## hvaclover

beenthere said:


> You attrack the golth people.



Goths are intellectual burn outs who do nothing but play music, chain smoke and generally don't give a poop about anything. Vampire Covens consist of bright, energetic, gainfully employed guys and girls who role play a romantic version of the vampire life style.


ME? I just dig the hell out Christopher Lee, and have since I saw him in the original Dracula.

I use his avatar cause I like the guy:yes:


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## beenthere

hvaclover said:


> goths are intellectual burn outs who do nothing but play music, chain smoke and generally don't give a poop about anything. Vampire covens consist of bright, energetic, gainfully employed guys and girls who role play a romantic version of the vampire life style.
> 
> 
> Me? I just dig the hell out christopher lee, and have since i saw him in the original dracula.
> 
> I use his avatar cause i like the guy:yes:


lol...


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## Yuri

I don't do CFM measurements. Not because they are not important but most of the ductwork I see is not properly sized so what is the point of checking CFM. If the equipment is working properly and the customer is satisfied I leave well enough alone. I can customize the equipment so it performs well, is not too noisy etc. Most techs don't know how to do CFM checks anyway. Unless there is a huge problem we reuse the existing ductwork and make it work. Lots of it was originally from oil furnaces and is large. We don't get more than 50% RH so dehumidification is not a huge concern.


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## scooter

We are in a similar situation with duct but not so much from oil but more from 135,000 btu furnaces and duct installed in 950 square foot houses!
With new customers we do a comfort concern and if there is no problem with circulation as far as the customer is concerned then we dont do a full scale balance.
In Swartz Creek MI, there is an Amana dealer, Garno Brothers. Brian Garno has a side buisness from his main buisness and all he does is air flow balancing. he does it for residential and commercial and if you have any questions about balancing and any possible shortcuts or procedures I strongly recomend that you contact him.
He is always happy to help other dealers/techs and will share any info he has with you. He is also heavy into combustion analasis.
Scooter


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## coolmen

As a NCI certified tech. I check every job with my testo 510. I do this so i KNOW EXACT cfm and can then sell the homeowner on the ductwork repairs. I all so carry the more advanced testo 435 meter and only use the tsi hood on major balancing and testng reports.


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## mechanicalDvr

coolmen said:


> As a NCI certified tech. I check every job with my testo 510. I do this so i KNOW EXACT cfm and can then sell the homeowner on the ductwork repairs. I all so carry the more advanced testo 435 meter and only use the tsi hood on major balancing and testng reports.


 
You check every job? Is that on your time or on the customer's time? Sounds pretty expensive when the customer wants to pay as little as possible if at all for a preseason start up.

None of the companies I have ever worked for want to do much more than look at the filter and start the unit up and check the charge on a preseason, unless it is an actual service contract. One of th elast places I worked had a $49 preseason special in the tv guide section of the local paper, for that price the boss wanted us to say hi and look at the unit for a possible sales call referral.


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## mechanicalDvr

hvaclover said:


> i check CFM on all my annal inspections. And if i have to pull a blower wheel I lube the shaft with Vaseline before i put it in.:001_tongue:


 
I wouldn't want to check any air flow on an "annal inspection" at least not without a gas mask.


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## coolmen

how long does it take to drill 2 to 4 1/4 inch holes and place my digital gage in each of the holes while the system is cooling less then 5 min.
in that amount of time I will know actual readings of air flow and be able to tell the homeowner wherer actual problems are by comparing readings.
I think I would have the upper hand with the homeowner compared to those how dont do it. I tell the homeowner the static pressure test is like checking the human bodys blood pressure to determine sickness. You could add an extra 5 min time explaining trhat to the homeowner so to sell them on duct repairs. being that I am my own Boss and sales man,,I can spend the exrta 5 10 min with the homeowner.


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## G 71

coolmen said:


> how long does it take to drill 2 to 4 1/4 inch holes and place my digital gage in each of the holes while the system is cooling less then 5 min.
> in that amount of time I will know actual readings of air flow and be able to tell the homeowner wherer actual problems are by comparing readings.
> I think I would have the upper hand with the homeowner compared to those how dont do it. I tell the homeowner the static pressure test is like checking the human bodys blood pressure to determine sickness. You could add an extra 5 min time explaining trhat to the homeowner so to sell them on duct repairs. being that I am my own Boss and sales man,,I can spend the exrta 5 10 min with the homeowner.


 4¼" holes, what are you putting in there?:laughing: http://www.dwyer-inst.com/Products/Product.cfm?Group_ID=78&sPageName=Specs


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## Yuri

Unless they have a problem 99.9% of my customers will say it worked fine for all these years and you are trying to sell me something I don't need.

Hey G, we did a job today, G71, PCO, XC13, General Humidifer and a HRV150 all in one old house. Salesman made a killing. Probably a $15,000 or more job.

I'm in the wrong dept.


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## mechanicalDvr

coolmen said:


> how long does it take to drill 2 to 4 1/4 inch holes and place my digital gage in each of the holes while the system is cooling less then 5 min.
> in that amount of time I will know actual readings of air flow and be able to tell the homeowner wherer actual problems are by comparing readings.
> I think I would have the upper hand with the homeowner compared to those how dont do it. I tell the homeowner the static pressure test is like checking the human bodys blood pressure to determine sickness. You could add an extra 5 min time explaining trhat to the homeowner so to sell them on duct repairs. being that I am my own Boss and sales man,,I can spend the exrta 5 10 min with the homeowner.


Ok now can you show me a calculation that gives you total cfm using static pressure at the furnace/airhandler and how that relates to delevered cfm from the system to the building?


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## mechanicalDvr

G 71 said:


> 4¼" holes, what are you putting in there?:laughing: http://www.dwyer-inst.com/Products/Product.cfm?Group_ID=78&sPageName=Specs


 
I think he meant (2 or 4) 1/4" holes.


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## mechanicalDvr

Yuri said:


> Unless they have a problem 99.9% of my customers will say it worked fine for all these years and you are trying to sell me something I don't need.
> 
> 
> 
> I agree with this completely (one of many reasons I avoid resi work).
Click to expand...


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## coolmen

G 71 said:


> 4¼" holes, what are you putting in there?:laughing: http://www.dwyer-inst.com/Products/Product.cfm?Group_ID=78&sPageName=Specs


 With a 4 1/4 " hole We can continue to use the hand method:blink:


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## G 71

mechanicalDvr said:


> I think he meant (2 or 4) 1/4" holes.


 That would make more sense. To me at least.


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## coolmen

mechanicalDvr said:


> Ok now can you show me a calculation that gives you total cfm using static pressure at the furnace/airhandler and how that relates to delevered cfm from the system to the building?


 The test will give cfm output of the equipment as well as duct work issues only.When I install a piece of equipment. I will adjust fan speed that will give me the best cfm out put wth out having extremly high static pressure. Most seam to think that just because a furnace comes in high speed cooling that that is where it is to be left.With so many poor duct systems out there We can only do so much.
Once I Know the unit is putting out 1200 cfm then I can test output of each register using my TSI flowhood. I would only do this test when customer balanceing complaint.

Next week I will be replacing a furnace and adding A/C.
She does not want to pay extra for enlarging the 12pc. 4 " supplys
When the systm is compete and running. She and I will do a static test together to show the results. The ranch will run forever to cool and have extremly high static/noise/stress on the motor and most emportant less efficiency. Im hoping to convienve her that she need this repaired.


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## RoBoTeq

hvaclover said:


> i check CFM on all my annal inspections. And if i have to pull a blower wheel I lube the shaft with Vaseline before i put it in.:001_tongue:


And you claim to not be approachable:shifty:

Sounds more like you like to back into parties wearing union style longjohns to me:thumbup:

You sure we haven't met?


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## hvaclover

Only if you are into Greek Methology


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## CalvinS33

I learned what I needed from this few days ago but I just made an account so I want to say thank you. My cheers goes out to you guys here tonight as I listen to George Thorogood's "I drink alone" lol. Cheers!


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