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Master Flow

Model # WHFS24M

Internet # 100018252

Store SKU # 432659

4500 CFM 24 in. Direct Drive Whole House Fan with Shutter

This item has been discontinued.
The Home Depot no longer carries this specific product.

$245.00 /each
  • 10 Year Parts Limited Warranty; 5 Year Labor Limited Warranty
  • Direct Drive Motor
  • Maximum house size for optimum performance: 2500 sq. ft.




Model # WHFS24M

Internet # 100018252

Store SKU # 432659

The Master Flow 4500 CFM 24 in. Direct Drive Whole-House Fan is a smart energy saver for any home in a climate where air conditioning costs are a concern. It will allow you to beat the heat by forcing hot air out of your home through your attic space while bringing in cooler outside air through your windows and doors. A Whole House Fan is an important part of a complete home ventilating system! Unit comes with a white shutter and features a low-vibration direct-drive mechanism for reliable performance. A minimum 1100 sq. ft. of attic space with a minimum of 1008 sq. in. of net free area attic exhaust is required for proper operation.

  • Moves air at a rate of up to 4500 CFMs
  • 1/4 HP permanent split capacitor motor
  • Direct drive motor design
  • 2-speed pull chain switch control
  • Includes automatic ceiling shutter in white
  • Can be installed with no joist cutting
  • UL/UL Canada listed
  • Home Depot Protection Plan:

    Home Depot Protection Plan


Cut-Out Left to Right Length (in.) 
27.25 in 
Product Depth (in.) 
Product Height (in.) 
Product Width (in.) 
Amperage (amps) 
Color Family 
Color/Finish Family 
Galvanized Steel 
Product Weight (lb.) 
36 lb 
Voltage (volts) 
Warranty / Certifications
Manufacturer Warranty 
10-year Parts Limited Warranty 5-year Labor Limited Warranty 


Rated 3.6 out of 5 by 73 reviewers.
Rated 5.0 out of 5.0 by Works GREAT!!! Although I have only had this fan installed for several days, I LOVE it! I decided to go with the 24" fan because my house is less than 2200 sq. ft. and I was told that if there wasn't adequate ventilation, the 30" fan would/could make excessive noise. I'm not sure if people have difficulty installing the fan, but the way I did the install makes the fan seem "quiet". The fan noise is very comparable to a traditional box fan. I truly do not mind the noise it makes. I also put the fan on a 60 min. max timer. What I have been doing is setting the timer anywhere from 30-40 minutes, with a couple of windows open down stairs and one or two open up stairs. This cools the house down extremely fast. I am so glad I decided to put a whole house fan in our home. You should do it too! You won't be sorry! May 4, 2014
Rated 5.0 out of 5.0 by Good fan I didn't follow the directions, This is what I did and the fan is quiet. My house is 2300 sqft and it pulls the air thru nicely. I open the windows about an inch in the bedrooms and other rooms I want air to come in from the outside. My attic has vents on both ends of the house and affords plenty of exit space for the fan exhaust air. I got these Ideas off the internet and found them to be absolutely correct. First I mounted the fan in my attached garage ceiling. The fan will pull air from your home and into your attached garage ceiling. You don't have to mount it in the house. You will not get that central fan noise in the house that way. We have a screen door in the kitchen that goes to the garage. The air flows out thru the screen door. The next thing I did was to build a box for the fan to sit in on top of the ceiling joists. I cut the center joist and boxed it in. Then built a frame to hold the fan on top of the joists. I cut lengths of pipe insulation to fit on the fan wood frame. The glue on the insulation seam holds the insulation on the frame.$1.79 each for 2 insulation tubes at HD. The frame, is snug to the insulation but not tight. Hence when the fan runs, it is not vibrating on wood to wood contact. All you hear is the fan blade turning like you would any fan. There is a pull chain to turn it on and off. It is a 2 speed fan. I run it on high. I used the same size wood the ceiling joist were made of, to box in the joists where I cut one out. I used 2x4 s to make the box on top of the joists. I used a sawzall to cut the sheetrock, and the center joist. If you bridge across the top of your joists before you cut the center joist, you will not get any sag from the two ends of the cut joist. All will be strong after you box them in. I attached a wire and a plug on the fan wire to power the fan. I plugged it in to a receptacle in the attic. The pull chain is right outside the kitchen door in the garage. August 17, 2013
Rated 5.0 out of 5.0 by This fan really works great. You can feel the air stream by you and it cools down the house in no time! It is amazing how many people do not know what a Whole House Fan is. Even contractors. It is a very efficient way to replace the air in your house and attic just by running this fan for about 15 minutes once the air outside is cooler than the air in your house. This fan was not the biggest, but it seems to be built really well. I am very impressed! August 20, 2013
Rated 3.0 out of 5.0 by Good Product I had installed the 24" direct drive whole house fan. The Product was good , I have a 2300 sq. ft. house and it moved enough air to cool it down in just a few minutes. As for the installation of the fan ,if you are mechanically inclined then don't read the directions. The only thing you need is the cutout measurements. The directions are only there to confuse you. Go to YouTube and you can see a better idea on how to do it. The noise level isn't that bad, you got to expect some noise just with the the blades moving the air and cooling down the house. The noise is out weighted with the benefits it has. Just think of a night when someone burned the toast or your cooking the fish or the broccoli and it stinks-- just open the window, turn on the fan and no more smell ---it's great !!! Another good suggestion that a friend passed on to me was to paint the inner boxed in area ( the area between the under side of the fan and the top side of the shutter with BLACK paint--so when you look up into the attic through the shutters you can't see anything except black and darkness. March 23, 2015
Rated 4.0 out of 5.0 by Loud, but effective I have owned several homes with whole house fans ... this is the loudest one I have heard. However, if you have a hallway to the garage or other out of the way location, it is not too bad. If you go with the standard "over joist" mount, plan on cutting up two two by fours to build a base around the joist, and if you have blown in insulation, plan to cut up two six foot one by tens to build a box that extends above the fan to hold back the insulation. It takes only a few minutes to draw cool air through the entire house. Only wish is that the low speed would be lower. Even low still creates quite a breeze through the house! June 25, 2011
Rated 3.0 out of 5.0 by Blows a lot of air, noisy This fan has worked fine for me for over 10 years. It blows a lot of air, but I wish it were quieter. When you are close to it, you can't hear anything else. The motor finally burned out a winding. The exact replacement motor is only available from the manufacturer of the fan, which is a big disadvantage. Replacement parts should be generic and easily available, otherwise, the fan blows no air at all. If I was starting from scratch, I would look for a quieter fan with a motor that is easy to oil and replace. This is the second one I have bought and installed. The bottom line is that it blows a lot of air, lasted me over 10 years of intense use every summer, and the price was reasonable, but you have to accept that it is very noisy. May 21, 2012
Rated 2.0 out of 5.0 by Noisy Unit/High Decible Level even on low speed Home Depot is fine. The unit however, is very loud, even on low fan speed. It was unexpected that the fan noise would be this loud since I was replacing with an identical unit (the old unit: the low fan speed noise level was acceptable - the bearings wore out, thus the replacement). Once I/you install the replacement unit and discover the noise/decible level it's too late to return without severe effort: time, sweat, reinstallation cost, etc. May 9, 2012
Rated 1.0 out of 5.0 by Too Loud I spent a good bit of time installing this fan in the house I just bought. Upon completion of the project I was ready to test the new fan. It works is the best I can say about it. I have a whole house fan in my previous home and wouldn't think of not having one in this house. After turning this one on I was very disappointed in noise level. I walked outside to the street and could still hear it. I won't buy another of this brand. It's loud, what? It's Loud, what? IT'S LOUD. November 6, 2011
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