The manufacturers should provide the holes in the furnace body and the cased coil boxes for these measurements. I'm sure there has been heat exchanger penetrations and A coil penetrations too because the tech didn't drill in the right place.
+ritewayguy I agree bud. It would cost the manufacturer an extra buck for a hole and plug. I have punched a hole in the coil before,,, not pretty! It happened on a Friday afternoon at about 3 pm. in an occupied doctors office.
Excellent video. If for no other reason than you show the types of probes used. I.e. "static" probes (with holes perpendicular to airflow), as opposed to using "impact probes", hole is parralell to airflow. Front hole on pitot tube. The SMACNA Testing, Adjusting, Balancing Manual 1993 edition. Chapt 5. Page 5.9. Shows fan TOTAL pressure being measured with impact tubes on the suction side of the blower and discharge side of the blower. This is an unremarkable measurement, resulting in TOTAL pressure difference. (Therefore, Velocity pressure will be consistent, assuming blower assembly chamber doesnt change dimensions). But for measurement of fan STATIC pressure, using the same impact tube on the suction but a static probe on the blower discharge. Thus not measuring the difference of blower suction STATIC to discharge STATIC but the suction TOTAL to discharge STATIC. I dont know why this is the case but i have found it on other reference materials as well. Your method using both STATIC for blower suction and discharge would seem to be a more accurate method. Again well done.
The problem is with the charts for air flow that deal with cfm and pressure drop. This is revelant for a new coil or system. What about a blower wheel or evap. coil that is somewhat dirty? The chart would be completely wrong. Most units over time aren't completely clean.
aren't even remotely clean is more like it. Rheem is the only company besides Carrier (sometimes) that has these charts. Unfortunately the install manual and these charts are long since gone. Every one of these types of air videos always use the Rheem and they are only about 10% of whats out there, namely because they are much more expensive than say a Goodman or Nordyne or Ducane ..... and the funny thing is there isn't much in them besides a contractor, capacitor and maybe one pressure switch.....
Art Rose, There is a lot of useful information in this video and some of the techniques and procedures covered things that were left out of other videos. Why don't you put out a video of your own and show the rest of us how you solve these issues. No instructional video is going to be perfect and wasting everybodies time trying to pick apart the accomplishments of others is not helpful to anyone. david
It's should be a simple theory of what the product data means and how it would be obtained. A megnahelic in 2014 ?? Get a digital manometer and perform a proper duct traverse if you really want to know accurate Cfm. To many installation and factory faults will get you misleading information .
I disagree. Duct traverse techniques are useful for airflow balancing on large commercial duct systems, but that technique requires a minimum of 8 feet of straight duct with no elbows or takeoffs before the test ports and 10 feet of straight duct after the test ports with no elbows or takeoffs. This is rare on residential systems and requires more drilling, measuring, math and resealing. If you check with your favorite equipment manufacturer, you will see that they endorse the static pressure measuring procedure shown here.
There's so much wrong or missing here.... Sorry, "accurate" airflows are not achieved using this method, or these tools in this manner. You should learn the proper methods for performing a duct traverse. Wrong size mag. Need to use a pitot static tube. Need to use equidistant Vp readings. Wet coil, duct work complete, filters installed, etc.. SqRt of Vp x 4005 x SqFt = Cfm Please come back to school and we can teach you the correct way to do this.
+Art Rose A minimum of Sq. or Rect. duct traverse readings are 16 and a max of 64. When spacing's are laid out accurately, and all of your readings are recorded, then you can average all of the readings for a system total. It has been in my experience the duct traverse cfm is + or - 5% to the static pressure chart cfm when performed correctly. It takes a skilled technician to perform these tests. The video is based on the manufacturers testing instructions and are accurate if DONE CORRECTLY.
A Pitot tube gives TOTAL pressure and you can subtract static to obtain velocity. If velocity is really what he's trying to find then the traverse method would need to be employed for accuracy. With the static pressure probes he's using in this video it seems he can do this with the charts provided from the manufacturer to match their static pressure tests to determine their results of airflow. What are your thought on airflow derived from temp rise formulas?
All you can go to hell, my boss doesn’t give a shit about any of this and I have to do exactly what he just showed in about 5mnts with drilling and readings, along with adjusting the blower wheel before tanking up .
Size and space of installation can make getting a suitabley long enough run of ductwork to carry out a duct traverse difficult. This is a good preliminary method for a serviceman to see what is going on. If his readings are low, and fan amps are down, coils and filters are clean etc, then he can proceed with a more intrusive investigation.
your 0.1 inch measurement on a 3 inch gauge could be out by 0.06 inches either way according to the 2% accuracy of that gauge. Your reading would be between 0.04 to 0.16 inches. Not very accurate even if the pressure drop curves were accurate which they probably aren't. Your 1200 CFM should be somewhere between 900 and 1500 CFM. Accurate, I think not.
+Colin Genge Yes , I would definitely agree with you. A mag gauge (if used) should be sized to hit the middle to high end of the scale for the most accuracy.
This is great,
This is a short example of how to measure static pressure for techs in the business...
Thanks. You explain it very clearly. And the production is great too, I like the sound effects.
hey you need to do more videos....this was great!!!!
Good video , and very helpful as a refresher.
Very nice, good work.
very helpful Video , Thank you
How can I get someone to come to my home to check the airflow?
I must be missing something, why is the airflow increasing when static pressure goes up for the coil?
Total airflow is not increasing, but you can sure bet that the velocity is increasing almost exponentially. That is also why it was getting louder.
The manufacturers should provide the holes in the furnace body and the cased coil boxes for these measurements. I'm sure there has been heat exchanger penetrations and A coil penetrations too because the tech didn't drill in the right place.
+ritewayguy I agree bud. It would cost the manufacturer an extra buck for a hole and plug. I have punched a hole in the coil before,,, not pretty! It happened on a Friday afternoon at about 3 pm. in an occupied doctors office.
can you do it again in high definition I could see a thing
Excellent video. If for no other reason than you show the types of probes used. I.e. "static" probes (with holes perpendicular to airflow), as opposed to using "impact probes", hole is parralell to airflow. Front hole on pitot tube.
The SMACNA Testing, Adjusting, Balancing Manual 1993 edition. Chapt 5. Page 5.9. Shows fan TOTAL pressure being measured with impact tubes on the suction side of the blower and discharge side of the blower. This is an unremarkable measurement, resulting in TOTAL pressure difference. (Therefore, Velocity pressure will be consistent, assuming blower assembly chamber doesnt change dimensions).
But for measurement of fan STATIC pressure, using the same impact tube on the suction but a static probe on the blower discharge. Thus not measuring the difference of blower suction STATIC to discharge STATIC but the suction TOTAL to discharge STATIC. I dont know why this is the case but i have found it on other reference materials as well. Your method using both STATIC for blower suction and discharge would seem to be a more accurate method. Again well done.
thanks . helpful
The problem is with the charts for air flow that deal with cfm and pressure drop. This is revelant for a new coil or system. What about a blower wheel or evap. coil that is somewhat dirty? The chart would be completely wrong. Most units over time aren't completely clean.
aren't even remotely clean is more like it. Rheem is the only company besides Carrier (sometimes) that has these charts. Unfortunately the install manual and these charts are long since gone. Every one of these types of air videos always use the Rheem and they are only about 10% of whats out there, namely because they are much more expensive than say a Goodman or Nordyne or Ducane ..... and the funny thing is there isn't much in them besides a contractor, capacitor and maybe one pressure switch.....
instead of drilling a hole can you simply take the reading where the limit switch is at
Good video
Wouldn't a smaller than 3/8" hole suffice?
Art Rose,
There is a lot of useful information in this video and some of the techniques and procedures covered things that were left out of other videos. Why don't you put out a video of your own and show the rest of us how you solve these issues. No instructional video is going to be perfect and wasting everybodies time trying to pick apart the accomplishments of others is not helpful to anyone.
david
I like how he says know where to drill right after he drills a hole into the condensate pan. 😂🤣😂🤣😂
It's should be a simple theory of what the product data means and how it would be obtained. A megnahelic in 2014 ??
Get a digital manometer and perform a proper duct traverse if you really want to know accurate Cfm. To many installation
and factory faults will get you misleading information .
I disagree. Duct traverse techniques are useful for airflow balancing on large commercial duct systems, but that technique requires a minimum of 8 feet of straight duct with no elbows or takeoffs before the test ports and 10 feet of straight duct after the test ports with no elbows or takeoffs. This is rare on residential systems and requires more drilling, measuring, math and resealing. If you check with your favorite equipment manufacturer, you will see that they endorse the static pressure measuring procedure shown here.
El K-Bone no vale Pee Pee...😁
U put me to sleep!!!
night night. Don't forget your boppy and binky
There's so much wrong or missing here.... Sorry, "accurate" airflows are not achieved using this method, or these tools in this manner. You should learn the proper methods for performing a duct traverse. Wrong size mag. Need to use a pitot static tube. Need to use equidistant Vp readings. Wet coil, duct work complete, filters installed, etc.. SqRt of Vp x 4005 x SqFt = Cfm Please come back to school and we can teach you the correct way to do this.
I agree. this is so many levels of wrong.
+Art Rose A minimum of Sq. or Rect. duct traverse readings are 16 and a max of 64. When spacing's are laid out accurately, and all of your readings are recorded, then you can average all of the readings for a system total. It has been in my experience the duct traverse cfm is + or - 5% to the static pressure chart cfm when performed correctly. It takes a skilled technician to perform these tests. The video is based on the manufacturers testing instructions and are accurate if DONE CORRECTLY.
A Pitot tube gives TOTAL pressure and you can subtract static to obtain velocity. If velocity is really what he's trying to find then the traverse method would need to be employed for accuracy. With the static pressure probes he's using in this video it seems he can do this with the charts provided from the manufacturer to match their static pressure tests to determine their results of airflow. What are your thought on airflow derived from temp rise formulas?
All you can go to hell, my boss doesn’t give a shit about any of this and I have to do exactly what he just showed in about 5mnts with drilling and readings, along with adjusting the blower wheel before tanking up .
Size and space of installation can make getting a suitabley long enough run of ductwork to carry out a duct traverse difficult. This is a good preliminary method for a serviceman to see what is going on. If his readings are low, and fan amps are down, coils and filters are clean etc, then he can proceed with a more intrusive investigation.
your 0.1 inch measurement on a 3 inch gauge could be out by 0.06 inches either way according to the 2% accuracy of that gauge. Your reading would be between 0.04 to 0.16 inches. Not very accurate even if the pressure drop curves were accurate which they probably aren't. Your 1200 CFM should be somewhere between 900 and 1500 CFM. Accurate, I think not.
+Colin Genge Yes , I would definitely agree with you. A mag gauge (if used) should be sized to hit the middle to high end of the scale for the most accuracy.
Oh for crap! Know it all.