I’ve installed hundreds of fart fans. When you go to the store and press the test button like at Menards who happens to carry this Panasonic fan it is quiet as F. That’s because there is no back pressure. A 3 and 4” insulated flex line will cause some back pressure the fan struggles to push the air and you can hear the turbulence aka: vibration clear as day. Now reach up there and disconnect that flex pipe and quiet as ever. We always put a 4 to 6” adapter on the fan and pipe it outside using rigid where possible. Yes you can buy 6” exhaust vents. This eliminates almost all back pressure and vibrations
Dude I could watch your videos all day. I'm sitting here working from home, working my very corporate healthcare data job, on my 3rd hour of you videos lol. You're a great teacher.
Yes, finally! Not enough has been said about this fan. Here in GA all the time I come across old dingy fans with their venting “pipes” just laying buried in the attic’s insulation. Old, older or newer houses - same thing. When I renovate or replace I use insulated flexible hose and drive it into the attics roof gable. I also install at the end short piece of pipe (for the sake of a sturdier and level install) with one of those plastic louvered vent covers to prevent any bugs or pest taking a ride in my pipe. Works like a charm. For all that 150CFM is not enough there is a even stronger model (230CFM) as well. Thanks for suggesting this one a while ago Steve! 👊👍💪
The Panasonic fans are a game-changer in terms of quiet. They’ve been around for a while…we had dinner with the project team for that product at PCBC back in the late 90s. I don’t remember if they were rolling it out that year or just had an “coming attractions” but it was literally 10% of the noise of a typical Broan/NuTone etc.
I will have to ask my wife which model she purchased. But I told her to get 110cfm MINIMUM for our 85sq ft bathroom. I installed it (no light in the exhaust fan!) And now our mirror doesn't even fog over. It drops the temp in the room when it's on. Love it!
TIP: use a soffit exhaust vent only if you do not have a vented soffit! If you have a vented soffit the moist air will get sucked right back up into your attic space.
Nice work. Radiant floor heat also helps dry out the bathroom. If the vent fan is on a timer, and the radiant floor heat is working correctly, there will not be moisture problems. Also, as you know, the ceiling has to be painted with a vapor barrier type paint.
Radiant heat helps move moisture from liquid water to water vapor…but the moisture is still there just as higher relative humidity. You still need to move just as much air to expel that moisture out of the room.
@@HBSuccess Yes, radiant floor heat is not a substitute for a vent fan. Depending on amount of moisture. I am the only person who uses my bathroom, and I never need to run the vent fan or even use a bath mat. Everything dries out quickly even though the temp is set modestly.
A 6” flex pipe can go 25ft with 80cmf. Using a solid pipe can be an issue if you’re not going straight up. Otherwise it needs to be slopping down to the outside. It will drip right out of those solid pipes. Thats why I went with a 25ft insulated 6” and a 100cfm fan.
Our old house never had bath vents but I want to add them when I remodel. They are stacked, with the 2nd floor bath having access to the roof via the attic. The main floor bath is right below it … I don’t know that I necessarily want to punch through the side brick to add the vent for that one? I would not be opposed to running the main floor vent up through the wall of the upstairs bath and meetup with the 2nd bath’s vent … and just run an attic fan on both baths whenever either bathroom is used. I’ve seen it done but there’s not much info out there on that.
I made the mistake of installing one in a guest bath because the steam from the shower kept setting off the smoke detectors in the adjacent bedroom and hallway when guests opened the door and this fan had high CFM. After not hearing it because it's so quiet, my wife made me put them into the other guest bathroom, the master bathroom and the master bathroom WC. A simple project turned into an entire weekend 🙄
I am currently looking to lay a vent from an existing bath fan that I thought vented outside. I was concerned about pest intrusion however. Will these grates on the end really keep roaches and such out?
As you know the goal of these fans is to "exhaust" air from a room. Because fixed pipe has a smooth interior surface it offers the best airflow due to having minimal interior resistance. The spiral flex with its kinks, twists and turns creates unwanted airflow disturbances within the pipe which reduces the CFM capacity of the fan. That said, if your exhaust pipe run is short and relatively straight, say 3-6 feet, then flex will work. However, when you have a longer run fixed pipe is the always the better option "if you can work with it" within your ceiling/attic space. If your fan to vent pipe runs thru the attic or any 'unconditioned space" then you definitely want to use insulated pipe in those areas to prevent condensation. (i.e., An exhaust fan will pull cool air-conditioned air from the bathroom which in turn will cool the exhaust pipe. A cold pipe running thru a hot attic will sweat!)
I was looking at some exhaust fans in Home Depot and noticed that some said you need to install a GFCI. Makes sense because there is a lot of moisture that the fan will have But I also noticed that no one installs one so I’m a bit confused
Panasonic has several modles, with sensors, LED lights, or without and different CFM, I've installed some of the retrofit version, fantastic stuff. Panasonic is the best vent fan. Silent, and lots of air flow. Long life. I replaced 3 rock grinder Broans, , all junk, Panasonic is the way to go. The mounting brackets, are genius. they have different models
Good luck if you're reading this in late 2024. When this video went was originally posted those were your two choices. But... due to the popularity of those Panasonics "Whisper" fan models... Panasonic decided to capitalize on the name and now offer: WhisperCeiling, WhisperFit, WhisperQuiet, WhisperValue, WhisperGreen, WhisperWarm, WhiperChoice, WhisperSense, WhisperThin, Whisper Mighty, WhisperCozy, WhisperRemodel, WhisperRenew, WhisperSuite, WhisperSlim, WhisperVanity and Whisper Recessed. Sheesh... They made the which is better,, whats the difference decision near impossible.
for retrofits, get the ones that say RETROFIT. they have the clever folding support bracket, that slips in from the bathroom, and all you do is enlarge the current hole for the old junk you are removing, and they have an adapter for 3" to 4" if needed
Considering an evaporative cooling fan introduces moisture into a home I imagine it "could" depending on two things: 1) If don't you select the right Panasonic model (Some of their Whisper series include "Humidity Sensing" which will turn it on when it senses a rise humidity). 2) You have a Whisper model "with" the humidity sensor and have it set low. Their humidity sensing fans have a control that lets you dial in at what percent of relative humidity you want before the fan automatically turns on (%RH is adjustable between between 30-80). NOTE: One dilemma / problem/ issue people face with the humidity sensing fans is they are wired so they will come on automatically when it senses a higher humidity level... HOWEVER... this is not the ideal choice for people who use the bathroom to do their business and wish to remove the "smell". For them them best choice is to wire it to a wall switch so they can tun it on and off when needed and forgo a model with humidity control.
My bathroom ceiling is open, so while I am there, I want to change my bathroom fan for a new one, but I have a 3" diameter exhaust pipe, I’m considering changing it for a 4" pipe, which seems to be the standard now, I noticed that the new fans are made mostly for 4" exhaust, but some comes with adapters to fit 3" exhaust pipe. Is it worth the trouble changing for 4" exhaust ? would it be more efficient ?
Basically screwed. If your home is vented with 3 inch like mine, even though the house was built in 2004, I’ve got a foot and a half of what I call hamster cage lining type insulation that was sprayed in there. To try to root around without falling through the ceiling walking on the joist is a challenge. I haven’t been up in the attic looking around, but I did notice most homes, including mine in the neighborhood. Do not have physical vents in the roof or side of the house except for the dryer and the stove vent. It will be interesting to find out how this venting goes. It may be not worth having to make holes in your roof to try to replace 3 inch for 4 inch. Noticing your remark is over eight months old what did you do?
@@aviatortrucker6285 I changed for a 4" pipe. The vent goes through the brick wall, the fan is like 40" from it, so it is no far away. When I removed the old 3" vent, I noticed the hole in the brick wall was already a little more than 4", there was insulation in the gap. Then I put insulation around the pipe inside the wall. At the brick side of the hole, I poured mortar around the pipe, so I have clean 4" hole and it solidifies my brick there. It was easy to do. I installed an aluminum 4" vent with a clapper & a grille against birds. The fan is a Panasonic, quiet compared to the old Nutone.
@@Exoseven like I said, I dread going up there because of the spray insulation. It’s not like our 19 that’s in a bag laying neatly between the joists. I have to see where the 3 inch flex vent hose runs. It has to exit the house somewhere. If I have to change it to 4 inch I will have to see if an existing port or hole is in or near the gable. I have a second bathroom on the other side of the wall for the other two bedrooms, which also has a 3 inch run. I bet those two are put together somewhere and exit through a common duct. I really don’t want to go on the roof as it is dangerous to install a roof mount vent..
Yes... its worth changing especially if you have the room and opportunity to swap it out. FACT: The larger the pipe - the more efficient the fan. My problem was the distance from the fan to the exterior wall is 15 feet which is not ideal for flex pipe due to the resistance if creates. I didn't have enough room (very tight attic clearance) to maneuver the installation of rigid pipe so I took advantage of the 6 inch adapter (included with the fan) and ran 6 inch flex. Like yours my old pipe was also 3 inches. I had just enough elbow room to finagle and run insulated 6 inch flex. The venting distance is not ideal but I was hoping by increasing the pipe to 6 inches it will help alleviate some of the friction loss introduced by flexible pipe. My biggest challenge was enlarging the hole in my brick exterior to accommodate the 6 inch vent cap.
You never do soffit vent it should always go out the roof no matter what now some times you can do it out the side of the house but only when the bathroom is in the basement and you go out the joist pocket further more the Panasonic fans are the best on the market.
Installed this today with new 12/2 wiring on its own 20 amp breaker to a decent single pole 20amp switch and it keeps tripping the breaker.... Can't figure out why. Does it need a special switch or something?
Not necessarily true. The NEC (National Electrical Code) does not require either the bathroom switch, fan or the light fixtures to be GFCI-protected. The exception occurs if/when the fixtures installed is designed for and installed "in" the shower stall, it that case those units do require GFCI protection to meet UL requirements.
Love your channel. You mentioned the model you got was adjustable from 110-150. The one you linked is 80-110. Did you change to the smaller model or just link the wrong one? Only reason I ask is my bathroom is similar size with 9ft ceilings and I have a 110 CFM fan on a small 3-4ft exhaust run out the side of the house and it can’t keep up with the moisture.
Sorry, yeah I should have clarified that. The adjustment switch has both readings on there. This one is the 150 www.build.com/panasonic-fv-1115vq1/s1428189
Im no expert but through my exploration in this subject, You’re supposed to vent your fans through the roof. I thought I heard its code on all new construction in many states. I have the roof mounted vent and insulated tube purchased. Just have to install it. This Old House episode.
Yes, depending on the model you select and providing you have adequate vent piping. Different models have different CFM ratings (identifies how many Cubic Feet of the fan will exchange per Minute of air ) e.g., If your room is 10ft by 15 ft then a 150CFM fan would exchange all the air in the room once every minute. The higher the CFM the more air (smoke) it will pull out. Panasonic actually makes a WhisperCeiling model rated at 390 CFM, it sucks in air like a tornado... but its pretty darn loud.
I’ve installed hundreds of fart fans. When you go to the store and press the test button like at Menards who happens to carry this Panasonic fan it is quiet as F. That’s because there is no back pressure. A 3 and 4” insulated flex line will cause some back pressure the fan struggles to push the air and you can hear the turbulence aka: vibration clear as day. Now reach up there and disconnect that flex pipe and quiet as ever. We always put a 4 to 6” adapter on the fan and pipe it outside using rigid where possible. Yes you can buy 6” exhaust vents. This eliminates almost all back pressure and vibrations
@dumbcarguy - I'm having this exact problem. Unfortunately the ceiling is all closed up. What options do I have at this point? It's very loud.
Dude I could watch your videos all day. I'm sitting here working from home, working my very corporate healthcare data job, on my 3rd hour of you videos lol. You're a great teacher.
One of the best remodeling videos I’ve ever seen. From A-Z install, upgrades, sources. Loved it.😊
Yes, finally! Not enough has been said about this fan. Here in GA all the time I come across old dingy fans with their venting “pipes” just laying buried in the attic’s insulation. Old, older or newer houses - same thing. When I renovate or replace I use insulated flexible hose and drive it into the attics roof gable. I also install at the end short piece of pipe (for the sake of a sturdier and level install) with one of those plastic louvered vent covers to prevent any bugs or pest taking a ride in my pipe. Works like a charm. For all that 150CFM is not enough there is a even stronger model (230CFM) as well. Thanks for suggesting this one a while ago Steve! 👊👍💪
The Panasonic fans are a game-changer in terms of quiet. They’ve been around for a while…we had dinner with the project team for that product at PCBC back in the late 90s. I don’t remember if they were rolling it out that year or just had an “coming attractions” but it was literally 10% of the noise of a typical Broan/NuTone etc.
I purposely searched out for a somewhat noisy vent fan... gotta cover up the bathroom toilet blasting
I’m with your logic. Noisy fans move air while covering toilet noises.
Same. My dad always puts the quietest fans he can find in his bathrooms. I always find the loudest ones 😅
Yeah, you can also help bring fresh air through all the other windows with a turbocharger
Maybe rather try cleaning up your diet... Problem solved.
Can they make a noise canceling fart fan?
I will have to ask my wife which model she purchased. But I told her to get 110cfm MINIMUM for our 85sq ft bathroom. I installed it (no light in the exhaust fan!) And now our mirror doesn't even fog over. It drops the temp in the room when it's on. Love it!
What size was your vent hose? This one is for 4-6” Most older home is only 3”.
TIP: use a soffit exhaust vent only if you do not have a vented soffit! If you have a vented soffit the moist air will get sucked right back up into your attic space.
Nice work. Radiant floor heat also helps dry out the bathroom. If the vent fan is on a timer, and the radiant floor heat is working correctly, there will not be moisture problems. Also, as you know, the ceiling has to be painted with a vapor barrier type paint.
Radiant heat helps move moisture from liquid water to water vapor…but the moisture is still there just as higher relative humidity. You still need to move just as much air to expel that moisture out of the room.
@@HBSuccess Yes, radiant floor heat is not a substitute for a vent fan. Depending on amount of moisture. I am the only person who uses my bathroom, and I never need to run the vent fan or even use a bath mat. Everything dries out quickly even though the temp is set modestly.
Love our 2-bulb heat lamp on a timer switch in the ceiling of our basement bathroom! 🥵♨
A 6” flex pipe can go 25ft with 80cmf. Using a solid pipe can be an issue if you’re not going straight up. Otherwise it needs to be slopping down to the outside. It will drip right out of those solid pipes. Thats why I went with a 25ft insulated 6” and a 100cfm fan.
should still use teh bracket even in new construction. It's designed to support, and for later maintenance if needed
Our old house never had bath vents but I want to add them when I remodel. They are stacked, with the 2nd floor bath having access to the roof via the attic. The main floor bath is right below it … I don’t know that I necessarily want to punch through the side brick to add the vent for that one?
I would not be opposed to running the main floor vent up through the wall of the upstairs bath and meetup with the 2nd bath’s vent … and just run an attic fan on both baths whenever either bathroom is used. I’ve seen it done but there’s not much info out there on that.
I made the mistake of installing one in a guest bath because the steam from the shower kept setting off the smoke detectors in the adjacent bedroom and hallway when guests opened the door and this fan had high CFM. After not hearing it because it's so quiet, my wife made me put them into the other guest bathroom, the master bathroom and the master bathroom WC. A simple project turned into an entire weekend 🙄
Great Job!!
Can I use this fan in a kitchen, or would the grease and other cooking vapors be problematic? Thanks for sharing
humidity shmumidity, what aboot tird skink removal? I go 3 times the recommended air flow to remove the stink effectively
I am currently looking to lay a vent from an existing bath fan that I thought vented outside. I was concerned about pest intrusion however. Will these grates on the end really keep roaches and such out?
Great info ! Do you like to use flex or fixed pipe from the fan to vent ? Do you like insulated pipe ?
As you know the goal of these fans is to "exhaust" air from a room. Because fixed pipe has a smooth interior surface it offers the best airflow due to having minimal interior resistance. The spiral flex with its kinks, twists and turns creates unwanted airflow disturbances within the pipe which reduces the CFM capacity of the fan. That said, if your exhaust pipe run is short and relatively straight, say 3-6 feet, then flex will work. However, when you have a longer run fixed pipe is the always the better option "if you can work with it" within your ceiling/attic space. If your fan to vent pipe runs thru the attic or any 'unconditioned space" then you definitely want to use insulated pipe in those areas to prevent condensation. (i.e., An exhaust fan will pull cool air-conditioned air from the bathroom which in turn will cool the exhaust pipe. A cold pipe running thru a hot attic will sweat!)
4th option, open the window if you have one. Natural air is cheapest and effective.
I was looking at some exhaust fans in Home Depot and noticed that some said you need to install a GFCI. Makes sense because there is a lot of moisture that the fan will have
But I also noticed that no one installs one so I’m a bit confused
Nice video ,Thk you
I guarantee you’ve reduced airflow about 25cfm with the added static of that flex
Can you please recommend putting a switch and sensor? Can you recommend which one to buy?
Panasonic has several modles, with sensors, LED lights, or without and different CFM, I've installed some of the retrofit version, fantastic stuff. Panasonic is the best vent fan. Silent, and lots of air flow. Long life. I replaced 3 rock grinder Broans, , all junk, Panasonic is the way to go. The mounting brackets, are genius. they have different models
Shame we don’t get these sorts of fans in the U.K. 😢
I installed these, but they are difficult to clean the inside.
Great video, thanks for the information!
Which fan is better? WhisperCeiling or WhisperFit and what's the difference?
Good luck if you're reading this in late 2024. When this video went was originally posted those were your two choices. But... due to the popularity of those Panasonics "Whisper" fan models... Panasonic decided to capitalize on the name and now offer: WhisperCeiling, WhisperFit, WhisperQuiet, WhisperValue, WhisperGreen, WhisperWarm, WhiperChoice, WhisperSense, WhisperThin, Whisper Mighty, WhisperCozy, WhisperRemodel, WhisperRenew, WhisperSuite, WhisperSlim, WhisperVanity and Whisper Recessed. Sheesh... They made the which is better,, whats the difference decision near impossible.
for retrofits, get the ones that say RETROFIT. they have the clever folding support bracket, that slips in from the bathroom, and all you do is enlarge the current hole for the old junk you are removing, and they have an adapter for 3" to 4" if needed
Will running an evaporative cooler cause this to turn on?]
Considering an evaporative cooling fan introduces moisture into a home I imagine it "could" depending on two things: 1) If don't you select the right Panasonic model (Some of their Whisper series include "Humidity Sensing" which will turn it on when it senses a rise humidity). 2) You have a Whisper model "with" the humidity sensor and have it set low. Their humidity sensing fans have a control that lets you dial in at what percent of relative humidity you want before the fan automatically turns on (%RH is adjustable between between 30-80). NOTE: One dilemma / problem/ issue people face with the humidity sensing fans is they are wired so they will come on automatically when it senses a higher humidity level... HOWEVER... this is not the ideal choice for people who use the bathroom to do their business and wish to remove the "smell". For them them best choice is to wire it to a wall switch so they can tun it on and off when needed and forgo a model with humidity control.
Shout out to the WAGO LEVER NUTS!!! This is a pro who knows that time and reliability are worth money.
My bathroom ceiling is open, so while I am there, I want to change my bathroom fan for a new one, but I have a 3" diameter exhaust pipe, I’m considering changing it for a 4" pipe, which seems to be the standard now, I noticed that the new fans are made mostly for 4" exhaust, but some comes with adapters to fit 3" exhaust pipe. Is it worth the trouble changing for 4" exhaust ? would it be more efficient ?
Basically screwed. If your home is vented with 3 inch like mine, even though the house was built in 2004, I’ve got a foot and a half of what I call hamster cage lining type insulation that was sprayed in there. To try to root around without falling through the ceiling walking on the joist is a challenge. I haven’t been up in the attic looking around, but I did notice most homes, including mine in the neighborhood. Do not have physical vents in the roof or side of the house except for the dryer and the stove vent. It will be interesting to find out how this venting goes. It may be not worth having to make holes in your roof to try to replace 3 inch for 4 inch. Noticing your remark is over eight months old what did you do?
@@aviatortrucker6285 I changed for a 4" pipe. The vent goes through the brick wall, the fan is like 40" from it, so it is no far away. When I removed the old 3" vent, I noticed the hole in the brick wall was already a little more than 4", there was insulation in the gap. Then I put insulation around the pipe inside the wall. At the brick side of the hole, I poured mortar around the pipe, so I have clean 4" hole and it solidifies my brick there. It was easy to do. I installed an aluminum 4" vent with a clapper & a grille against birds. The fan is a Panasonic, quiet compared to the old Nutone.
@@Exoseven like I said, I dread going up there because of the spray insulation. It’s not like our 19 that’s in a bag laying neatly between the joists. I have to see where the 3 inch flex vent hose runs. It has to exit the house somewhere. If I have to change it to 4 inch I will have to see if an existing port or hole is in or near the gable. I have a second bathroom on the other side of the wall for the other two bedrooms, which also has a 3 inch run. I bet those two are put together somewhere and exit through a common duct. I really don’t want to go on the roof as it is dangerous to install a roof mount vent..
Yes... its worth changing especially if you have the room and opportunity to swap it out. FACT: The larger the pipe - the more efficient the fan. My problem was the distance from the fan to the exterior wall is 15 feet which is not ideal for flex pipe due to the resistance if creates. I didn't have enough room (very tight attic clearance) to maneuver the installation of rigid pipe so I took advantage of the 6 inch adapter (included with the fan) and ran 6 inch flex. Like yours my old pipe was also 3 inches. I had just enough elbow room to finagle and run insulated 6 inch flex. The venting distance is not ideal but I was hoping by increasing the pipe to 6 inches it will help alleviate some of the friction loss introduced by flexible pipe. My biggest challenge was enlarging the hole in my brick exterior to accommodate the 6 inch vent cap.
You never do soffit vent it should always go out the roof no matter what now some times you can do it out the side of the house but only when the bathroom is in the basement and you go out the joist pocket further more the Panasonic fans are the best on the market.
Never say never 😆
I agree with everything except venting through the soffit. It will eventually come back into the attic and create mold on the underside of the roof.
Unless you have eves with no vents. Which is very common these days with foam insulation 👍
@@BathroomRemodelingTeacher In that case yes!
Installed this today with new 12/2 wiring on its own 20 amp breaker to a decent single pole 20amp switch and it keeps tripping the breaker.... Can't figure out why. Does it need a special switch or something?
vent fan should not be on a 20A a breaker, you wired something wrong
I have a Panasonic fan and it’s quiet but it’s always running. Why?
stop chasing it?
there must be a switch somewhere, and always on might actually be good for ventilation, they are so silent. Panasonic vent fans are the only way to go
Soffit vent is a bad idea if you have a ridge vent the soffit is going to suck that hot moist air right back into the roof
Exactly why I said it’s a last resort 👍
Never use a soffit vent for bathrooms
Unless you have too 👍
If over shower it must be on GFCI, otherwise not legit. Why are you not using the bracket? for future
Not necessarily true. The NEC (National Electrical Code) does not require either the bathroom switch, fan or the light fixtures to be GFCI-protected. The exception occurs if/when the fixtures installed is designed for and installed "in" the shower stall, it that case those units do require GFCI protection to meet UL requirements.
@@eltonnoway7864 2023, basically has entire residential environment on GFCI and AFCI easier to do it all, than pick and choose.
even 240V water heaters, dryers, dishwashers GFCI
@@eltonnoway7864 doesn't have to be directly over shower tub, there is a distance requirement, to be GFCI
Soffit vent for an exhaust fan, big no no if it’s a vented soffit.
Correct, but who has that anymore
Soffit vent where it’s cold is a no no. Severe ice build up.
Love your channel. You mentioned the model you got was adjustable from 110-150. The one you linked is 80-110. Did you change to the smaller model or just link the wrong one? Only reason I ask is my bathroom is similar size with 9ft ceilings and I have a 110 CFM fan on a small 3-4ft exhaust run out the side of the house and it can’t keep up with the moisture.
Sorry, yeah I should have clarified that. The adjustment switch has both readings on there. This one is the 150 www.build.com/panasonic-fv-1115vq1/s1428189
they have a 3 position slide switch to select CFM, and the one with LED light has also a selector for it's operation as needed.
This is the most powerful bathroom fan that Panasonic makes. 390 Cubic Feet Per Minute!!!
It sucks like a tornado... but man that thing is LOUD!
Im no expert but through my exploration in this subject, You’re supposed to vent your fans through the roof. I thought I heard its code on all new construction in many states. I have the roof mounted vent and insulated tube purchased. Just have to install it.
This Old House episode.
All of this was addressed in this video
You probably lost about 30% of the fan’s max cfm from the friction of all of that flex duct. Should use rigid duct work.
Wago !!!!
Is it good to suck cigarette smoke???
Not as good as Quitting Smoking brother!
Yes, depending on the model you select and providing you have adequate vent piping. Different models have different CFM ratings (identifies how many Cubic Feet of the fan will exchange per Minute of air ) e.g., If your room is 10ft by 15 ft then a 150CFM fan would exchange all the air in the room once every minute. The higher the CFM the more air (smoke) it will pull out. Panasonic actually makes a WhisperCeiling model rated at 390 CFM, it sucks in air like a tornado... but its pretty darn loud.
Cringed when you popped nails through exposed metal 😳