I learned a lot. I learned fancy test equipment is available to see how your unit is running. I learned that lower head pressure, whatever that is, is better. I learned that the fan blade needs to be located properly, and I learned raising the fan blade up higher on the shaft makes it work better. That's a lot, so thank you.
I just did this today on mine. Replaced the fan motor last year and only option was a full sized motor. Looked like the blade was nearly 3 inches below the lip at the top of the unit. Figured that couldn't be good for airflow so wen out, cut the motor body mount bolts down to a couple threads above the nuts, set the fan blade as close as I could get it to the motor body on the shaft and still clear and holy crap - the noise level cut by almost half and the airflow more than doubled coming out the top. Big difference! - can't believe I missed that on assembly but live and learn.
I did the same thing, I put the fan blade at the end of the shaft and jees did it make a hell of a racket you could here it down the street I left it that way till the next day to the thank you's of my neighbors. the next day I cut the bolts that hold the motor till just a few threads were left and slid the fan blade toward the motor and what a difference. That was 4 years ago and now I'm starting to get a rumble moan so I'm going to go back in there and see if I can fix that.
That makes perfect sense when you think about it: All the area below your fan blade is your intake.. So the higher the fan blade is, the more air it's able to intake. I bet if you measured the current to the fan in both positions, it would be pulling more current when the fan was down lower-- due to there being a more restricted intake area. Interesting stuff. I would have never thought it would make such a huge difference. Good to know.
The fan needs to be closer to the top also so that it can pull the air more efficiently through the cooling fins and coil. In order to achieve proper cooling.
I do my best to get a measurement from the fan grill to the hub BEFORE pulling the bad CFM off, then get it as close as I can to that same distance when I install the new one - I figure it was manufactured with the fan blade at the optimal position. If I forget, I just try and get it as high on the shaft as I can with it still clearing the bottom of the motor.
Amazing that there is a guy in your area so clueless to basic physics and aerodynamics, that keeps placing fans that low in the coil. Thanks for your videos, they are so realistic to field work.
Great video, thanks. Were you able to address the loud noise after adjusting the fan blade? You mentioned that it may be the fan blade hub. Is that what it was? My unit just started making this exact same noise this morning.. loud!
@@MiHeatingGuy thanks I actually had it the right way found out it was a leak from the fan blades flying off and hitting the side coils inside, gonna have to get a whole new unit.
Yup, I killed a motor within 2 days by installing the blade leveled to the bottom of the exit. Blade needs to go at least an inch or two above the bottom exit level.
The fan on my unit sits almost a quarter of the way down the height of the coil, but is still set as close as possible to the motor housing. Motor was replaced several years ago (by a dope who didn't know what he was using and banged the hell out of the inside of the coil) while my ex wife was living in my house during our divorce. Only way I have to raise the blades would be to raise the entire grille & motor assembly using some sort of spacers oe bezel, but that would mean several inches. Would that even be advisable?
@@MiHeatingGuy I had wondered that. The top of the housing is only an inch higher than the top of the coil though as well, so would a shorter motor do much if it's only raising the fan an inch or so higher? I did finally give my coil an extensive cleaning a few days ago and that lowered the air temperature in my ducts just a hair more than 5 degrees, which makes a BIG difference.
It can be either CW or CCW, depends on brand and factory setup. I have 2 units, one is CW and the other is CCW. The blades on the two are bending in opposite direction, so both pull air upward. One day one motor was broken, I swapped the motor, found out that. It is not a big deal as you can swith the dirction easily.
It is unbelievable how many people out there work in HVAC and don't have a clue what they are doing. I bet the homeowner is much happier with performance and I guarantee the system will experience more durability as a result.
Thanks for the video. I just replaced a motor and the fan on a 13 year old Goodman. It is shaking the grills in front like crazy. I put it at the same position as the old motor and fan. If If press gently on any point of the top where the motor mounts, it stops. This is the 2nd fan, the first was bent out of the box. Any ideas?
I'm not an expert since I'm having issues too. I replaced a condenser fan motor and it's vibrating. Another guy said that the four mounting screws on top might be over tightened. And yes it could be one of the fan blades could be tweaked. Here's the youtube link. I hope it helps. I hope it helps me too. th-cam.com/video/QSDUkmoebYs/w-d-xo.html
However, how about some theory? What is head pressure? Why is lower better? Can it ever be too low? Is lower always better? How does moving the fan blade higher make it work better? Should you always make the fan blade as high as possible? Or is it not that simple?
I'm going to take a stab at answering some of these questions. "Head pressure" is another term for high side pressure or discharge pressure. That being said, if your head pressure is near your low side pressure, you are either low on refrigerant or you might have a problem with your compressor, so, yes, it can be too low, so lower isn't always better. In this case, lower is better because 182 psi means the system is running much less efficient than at 162 psi. How does that work? Well, pressure builds up heat and heat builds up pressure, the point of the condenser fan is to force air through the condenser coil to dissipate heat. Here's a quick demonstration of why the fan dissipates more heat when blade is located closer to the top: Blow on your hand from 1 inch away. Now blow on your hand from 1 foot away. Now, hold your hand as far away from your face as you can and try again. The further away your hand is, the less force you'll feel and the more air flow is lost in other directions. By moving the fan blade as close to the grill as possible, you are forcing ALL of the air to be forced in that direction, and with all of that air coming from outside of the condenser through the condenser coils, thereby dissipating more heat and lowering the head pressure. There might be designs in which placing the blade closer might not be the most optimal, but for a general idea, this is roughly where it should be.
unsure if they do it because they don't know better or a mix of dont care/job assurance/making future sales the bad way, so it works poorly/cooks, then they can sell a new unit :|
Maybe you think we should already know all that, but you're here to teach, right? I have no knowledge, but let me just make something up: The purpose of the fan is to pull cool outside air into the center of the unit, cooling the condensor coils by drawing the air past them. If the fan is too low in the unit, the highest coils on the unit are not cooled in this fashion. Even worse, as the air is passed over the lower coils it gets heated, and then this hot air is "blown" by the fan past the higher coils, not giving them the cooling that is desired. The result is the condensor working at only 66% of what it could, obviously a disaster. The lesson is to locate the fan blade as high as possible on the motor shaft with out having anything interfere with the fan blade.
I had the same problem today. I am the culprit who replaced the motor last year. There was only one supply house open at 5 pm and they didn't have the right motor . The replacement motor was longer than the original and the fan blade was set to deep below the shroud . Again they called me at 5 pm and the compressor was tripping the internal over loads. I went to the depot and bought pvc couplings that were an inch and a half long. Using long screws I mounted the grill higher up and the fan blade position was close to the original setting .No kid can stick their fingers in deep enough to get close to the spinning blade . When the heater breaks customers will wait . When the AC breaks they have no patience on a 90 plus day. Butchery happens when things get desperate and you worry about their comfort. Don't be like me. Use the right parts or don't fix it. I' going to check the unit again if the weather gets hot and replace the capacitor. 16 year old r22 unit
I learned a lot. I learned fancy test equipment is available to see how your unit is running. I learned that lower head pressure, whatever that is, is better. I learned that the fan blade needs to be located properly, and I learned raising the fan blade up higher on the shaft makes it work better. That's a lot, so thank you.
I just did this today on mine. Replaced the fan motor last year and only option was a full sized motor. Looked like the blade was nearly 3 inches below the lip at the top of the unit. Figured that couldn't be good for airflow so wen out, cut the motor body mount bolts down to a couple threads above the nuts, set the fan blade as close as I could get it to the motor body on the shaft and still clear and holy crap - the noise level cut by almost half and the airflow more than doubled coming out the top. Big difference! - can't believe I missed that on assembly but live and learn.
I did the same thing, I put the fan blade at the end of the shaft and jees did it make a hell of a racket you could here it down the street I left it that way till the next day to the thank you's of my neighbors. the next day I cut the bolts that hold the motor till just a few threads were left and slid the fan blade toward the motor and what a difference. That was 4 years ago and now I'm starting to get a rumble moan so I'm going to go back in there and see if I can fix that.
Well i could only go about another 3/8" but that made the difference, no more noise. Thanks man.
@@prmayner happy to help
That makes perfect sense when you think about it: All the area below your fan blade is your intake.. So the higher the fan blade is, the more air it's able to intake. I bet if you measured the current to the fan in both positions, it would be pulling more current when the fan was down lower-- due to there being a more restricted intake area. Interesting stuff. I would have never thought it would make such a huge difference. Good to know.
The fan needs to be closer to the top also so that it can pull the air more efficiently through the cooling fins and coil. In order to achieve proper cooling.
Do you check the amp in the motor if there is any difference in the location of the blade?
Thank you
Very good video..
Is there ever a reason to lower it or should you always have it up higher? Why is it adjustable
I do my best to get a measurement from the fan grill to the hub BEFORE pulling the bad CFM off, then get it as close as I can to that same distance when I install the new one - I figure it was manufactured with the fan blade at the optimal position.
If I forget, I just try and get it as high on the shaft as I can with it still clearing the bottom of the motor.
How do you know what size
Surprised the subcooling did not go up with higher blade placement.
Amazing that there is a guy in your area so clueless to basic physics and aerodynamics, that keeps placing fans that low in the coil.
Thanks for your videos, they are so realistic to field work.
+Jeff S hey thanks for your comments I really appreciate them keep watching thank you
Very good demostration!
I replaced the fan blade but now the unit won’t start.
Good video, Lennox had re-call on fan shroud , was told to remove it.2001-2005 Will stop noise too.
+Michael Lee Mike that's good information I will have to check into that I was not aware of that thanks for your support keep on watching
whiiirrrrrrrrrrrrr
Great video, thanks. Were you able to address the loud noise after adjusting the fan blade? You mentioned that it may be the fan blade hub. Is that what it was? My unit just started making this exact same noise this morning.. loud!
I have a question is the fan blades supposed to blow up and out or downwards and in? I think I installed my blades the wrong direction but not sure
Up
@@MiHeatingGuy thanks I actually had it the right way found out it was a leak from the fan blades flying off and hitting the side coils inside, gonna have to get a whole new unit.
Thanks for doing the demo. Some really good information here.
+LEO ASHRAE hope I could help thanks for watching
Yup, I killed a motor within 2 days by installing the blade leveled to the bottom of the exit. Blade needs to go at least an inch or two above the bottom exit level.
The fan on my unit sits almost a quarter of the way down the height of the coil, but is still set as close as possible to the motor housing. Motor was replaced several years ago (by a dope who didn't know what he was using and banged the hell out of the inside of the coil) while my ex wife was living in my house during our divorce. Only way I have to raise the blades would be to raise the entire grille & motor assembly using some sort of spacers oe bezel, but that would mean several inches. Would that even be advisable?
Sounds like the wrong motor
@@MiHeatingGuy I had wondered that. The top of the housing is only an inch higher than the top of the coil though as well, so would a shorter motor do much if it's only raising the fan an inch or so higher?
I did finally give my coil an extensive cleaning a few days ago and that lowered the air temperature in my ducts just a hair more than 5 degrees, which makes a BIG difference.
nice little demo , very important
Great info.
Enjoyed the demo. I think a UFO got in there. Lol
Good video, it answered a big question I had 👍
Nice experiment
Looking down should the fan turn clockwise or counterclockwise?
It can be either CW or CCW, depends on brand and factory setup. I have 2 units, one is CW and the other is CCW. The blades on the two are bending in opposite direction, so both pull air upward. One day one motor was broken, I swapped the motor, found out that. It is not a big deal as you can swith the dirction easily.
You never even said weather it was better or worse for a layman to know 🙄
What application are you using on your tablet to measure the head pressure?
Great video brother
+Israelhvac thanks john
It is unbelievable how many people out there work in HVAC and don't have a clue what they are doing. I bet the homeowner is much happier with performance and I guarantee the system will experience more durability as a result.
Thanks for the video. I just replaced a motor and the fan on a 13 year old Goodman. It is shaking the grills in front like crazy. I put it at the same position as the old motor and fan. If If press gently on any point of the top where the motor mounts, it stops. This is the 2nd fan, the first was bent out of the box. Any ideas?
I'm not an expert since I'm having issues too. I replaced a condenser fan motor and it's vibrating. Another guy said that the four mounting screws on top might be over tightened. And yes it could be one of the fan blades could be tweaked. Here's the youtube link. I hope it helps. I hope it helps me too.
th-cam.com/video/QSDUkmoebYs/w-d-xo.html
Amazing video now I can fix my moms.
nice info
However, how about some theory? What is head pressure? Why is lower better? Can it ever be too low? Is lower always better? How does moving the fan blade higher make it work better? Should you always make the fan blade as high as possible? Or is it not that simple?
I'm going to take a stab at answering some of these questions. "Head pressure" is another term for high side pressure or discharge pressure. That being said, if your head pressure is near your low side pressure, you are either low on refrigerant or you might have a problem with your compressor, so, yes, it can be too low, so lower isn't always better. In this case, lower is better because 182 psi means the system is running much less efficient than at 162 psi. How does that work? Well, pressure builds up heat and heat builds up pressure, the point of the condenser fan is to force air through the condenser coil to dissipate heat. Here's a quick demonstration of why the fan dissipates more heat when blade is located closer to the top: Blow on your hand from 1 inch away. Now blow on your hand from 1 foot away. Now, hold your hand as far away from your face as you can and try again. The further away your hand is, the less force you'll feel and the more air flow is lost in other directions. By moving the fan blade as close to the grill as possible, you are forcing ALL of the air to be forced in that direction, and with all of that air coming from outside of the condenser through the condenser coils, thereby dissipating more heat and lowering the head pressure. There might be designs in which placing the blade closer might not be the most optimal, but for a general idea, this is roughly where it should be.
@@danielfranklin9062 Hey ! You got a love heart from the video author. I'll take that as his endorsement of the accuracy of what you wrote.
unsure if they do it because they don't know better or a mix of dont care/job assurance/making future sales the bad way, so it works poorly/cooks, then they can sell a new unit :|
Maybe you think we should already know all that, but you're here to teach, right? I have no knowledge, but let me just make something up: The purpose of the fan is to pull cool outside air into the center of the unit, cooling the condensor coils by drawing the air past them. If the fan is too low in the unit, the highest coils on the unit are not cooled in this fashion. Even worse, as the air is passed over the lower coils it gets heated, and then this hot air is "blown" by the fan past the higher coils, not giving them the cooling that is desired. The result is the condensor working at only 66% of what it could, obviously a disaster. The lesson is to locate the fan blade as high as possible on the motor shaft with out having anything interfere with the fan blade.
I had the same problem today. I am the culprit who replaced the motor last year. There was only one supply house open at 5 pm and they didn't have the right motor . The replacement motor was longer than the original and the fan blade was set to deep below the shroud . Again they called me at 5 pm and the compressor was tripping the internal over loads. I went to the depot and bought pvc couplings that were an inch and a half long. Using long screws I mounted the grill higher up and the fan blade position was close to the original setting .No kid can stick their fingers in deep enough to get close to the spinning blade . When the heater breaks customers will wait . When the AC breaks they have no patience on a 90 plus day. Butchery happens when things get desperate and you worry about their comfort. Don't be like me. Use the right parts or don't fix it. I' going to check the unit again if the weather gets hot and replace the capacitor. 16 year old r22 unit