Model # WHFS24M

Internet #100018252

Store SKU #432659

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

Master Flow

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

  • 10-year parts limited warranty; 5-year labor limited warranty
  • Direct drive motor delivers superior, low-vibe operation
  • Maximum house size for optimum performance: 2500 sq. ft.
$245.00 /each

Frequently Bought Together

Product Overview

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 allows 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. This 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.

  • Powerfully moves air at a rate of up to 4500 CFM
  • 1/4 HP permanent split-capacitor motor helps move hot air out of your home
  • Direct drive motor design offers low vibration
  • 2-speed pull chain switch control for easy operation
  • Includes automatic ceiling shutter in white
  • Can be installed with no joist cutting
  • UL/UL Canada listed




Warranty / Certifications

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Customer Questions & Answers

Can this fan be connected to a variable speed control?

Asked by: stuntmanmike
I installed a whole house fan with a two speed pull chain split capacitor motor about 12 years ago in my house. It was not this model but was what Home Depot was carrying at that time. The instructions also stated that the warranty would be voided if one was installed. I left the pull chain in the high "on" position and installed a wall mount variable speed control rated for a ceiling fan. I always start the fan on high and never turn it down too low. I judge the "too low" by visual observation of louver position. I have never had any issues with the operation of the fan.
Answered by: JGGH
Date published: 2017-02-11

Can this unit be mounted on a wall?

Asked by: Dale
I have this same fan mounted in a wall of my shop although it is not recomended to be mounted this way mine was used when i got it and it lasted aprox. 9 years. the rear bearing is a shielded ball bearing and the front is a bronze oil light bearing.. mine just siezed up this month because there is no way to oil the bronze bearing on the front.. so yes it can be done but the make fans designed for wall mounting and this is meant for a ceiling mount so that the ball bearing in the rear of the motor can act as a thrust bearing and all the front )blade end) is only there to keep the rotor centerd in the stator
Answered by: Scott
Date published: 2017-02-11

can I put this fan in an attic window?

Asked by: westmainmusic
No, this fan is only approved or designed for Horizontal installation only. Please call MasterFlow Technical Services at 800-211-9612, M-F 8A-5P EDT, for any additional questions.
Answered by: Master Flow
Date published: 2016-09-20

how to turn off and on manually

what kind of switch do you use to turn it on and off. it doesn't come with switch and you have to wire one in. so what would I use?
Asked by: carmen
This product comes with a pull chain switch. It can be converted to a wall switch operation by adding a BWS2 wall switch. Please call Technical Services at 800-211-9612, M-F 8A-5P EDT, with any additional questions.
Answered by: Master Flow
Date published: 2016-09-05
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Customer Reviews

4500 CFM 24 in. Direct Drive Whole House Fan with Shutter is rated 3.6 out of 5 by 85.
Rated 4 out of 5 by from I bought this fan to use in the shop fan works great but I was disappointed with the store. I ord... I bought this fan to use in the shop fan works great but I was disappointed with the store. I ordered it online and picked it up from the store when I did it was open so I asked why and they said they open it to make sure it is good. so I thought nothing of it and took it home 2 weeks later I am installing it and figure out it has been installed and brought back but I didn't figure it out till I had it mounted and figured out the pull chain switch was broke and the spacers where cut already. since I was doing the wall mounted switch and I already had it mounted and live 45 miles away, I didn't return it but if you have a open box or re-taped than beware.
Date published: 2016-12-13
Rated 4 out of 5 by from 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!
Date published: 2011-06-25
Rated 5 out of 5 by from 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!
Date published: 2014-05-05
Rated 5 out of 5 by from Easy to install and works well. The fan is easy to install as long as there is a joist running the right direction, or as in my case running the wrong direction down the hallway but fortunately right in the middle. Otherwise you have to do some cutting and framing. The instructions are not terribly clear, but after reading them a few times I figured it out. It works well. Of course there is noise from moving so much air through the ceiling. But in our case we just need to run it a few minutes in the evening to push hot air out of the attic and pull in the cool evening air, which we are fortunate always to have even on the hottest days.
Date published: 2016-05-17
Rated 4 out of 5 by from Best value for my money Yes, these fans are noisy. I looked at buying a Tamarack or Quiet Cool, but I would have paid 4 times the money for 1/4 of the CFMs. This fan's noise is the sound of a powerful, well-built motor. Nothing rattles or shakes. The 4500 on high is powerful enough to pull doors shut. We only run it on low, which is all we would ever need for our 2500 sq.ft. house. This fan can be installed without cutting through joists, which was a big help.
Date published: 2016-07-19
Rated 3 out of 5 by from 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.
Date published: 2012-05-21
Rated 2 out of 5 by from 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.
Date published: 2012-05-09
Rated 1 out of 5 by from 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.
Date published: 2011-11-06
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