0050206023853

Master Flow

Model WHFS24M

Internet #100018252

Store SKU #432659

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

$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.

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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 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

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Customer Questions & Answers

33 Questions36 Answers

Customer Questions & Answers

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

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3 answers

Can this fan be connected to a variable speed control?

This question is from 4500 CFM 24 in. Direct Drive Whole House Fan with Shutter
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August 12, 2015
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Asked by
Milton, GA
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Home Improvement Profile: DIYer
September 1, 2015
Answer: 
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 Read More
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. Read Less
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Asked by
Novato, CA
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August 13, 2015
Answer: 
I did some research via a quick Google search. Based on what I read, the best I can say is a definite "maybe" (sorry, there were lots of conflicting opinions - even among seeming "qualified" electricians).
Although based on what I read, it does look like a split capacitor motor CAN be equipped with an infinitely variable speed control (conceptually), the biggest question seems to be regarding the start Read More
I did some research via a quick Google search. Based on what I read, the best I can say is a definite "maybe" (sorry, there were lots of conflicting opinions - even among seeming "qualified" electricians).
Although based on what I read, it does look like a split capacitor motor CAN be equipped with an infinitely variable speed control (conceptually), the biggest question seems to be regarding the start load of this particular motor (i.e., when the motor first kicks in, how much is the instantaneous draw?) The switch would need to be rated to handle that load...
I would recommend contacting QuietCool directly. I'm sure that this is not a novel question...(Please post your findings...I'm curious too. I have the two speed switch, but have thought that maybe more adjustment would be nice...) Read Less
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August 13, 2015
Answer: 
Thank you for contacting MasterFlow ... Due to the design of these motors, speed controls are Not Recommended and will void your warranty. PLease call Technical Services at 800-211-9612 with any additional questions.
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2 answers

can I put this fan in an attic window?

This question is from 4500 CFM 24 in. Direct Drive Whole House Fan with Shutter
June 30, 2016
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July 6, 2016
Answer: 
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.
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Asked by
Novato, CA
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July 2, 2016
Answer: 
If it fits, I don't see why not.
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2 answers

how to turn off and on manually

This question is from 4500 CFM 24 in. Direct Drive Whole House Fan with Shutter
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May 17, 2016
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?
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May 19, 2016
Answer: 
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.
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Asked by
Novato, CA
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May 18, 2016
Answer: 
The version I bought had a pull chain that activated a 3 speed switch. If yours is just ON/OFF then I'd use a standard ceiling fan type variable switch. HD has many varieties.
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2 answers

Noise

This question is from 4500 CFM 24 in. Direct Drive Whole House Fan with Shutter
Asked by
Ramona, CA
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September 10, 2015
What is the decibel level of this fan when it is operating?
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September 14, 2015
Answer: 
Thank you for contacting MasterFlow ... The 24 inch direct drive fan was measured at 68 dB (low) and 71 dB (high). Fan noisy can be attributed to several different factors. 1) A narrow hallway will amplify any noise produced. 2) If the attic does not have the correct amount of measured exhaust NFA or if the attic space is not large enough to handle the incoming air from the fan (min. of 1,000 sq feet at Read More
Thank you for contacting MasterFlow ... The 24 inch direct drive fan was measured at 68 dB (low) and 71 dB (high). Fan noisy can be attributed to several different factors. 1) A narrow hallway will amplify any noise produced. 2) If the attic does not have the correct amount of measured exhaust NFA or if the attic space is not large enough to handle the incoming air from the fan (min. of 1,000 sq feet at 4/12 pitch). Please call Technical Service Group at 800-211-9612 to discuss any issues. M-F 8A-5P EDT Read Less
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Asked by
Novato, CA
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September 11, 2015
Answer: 
The quote that I got from HD.com Chat - On full it is roughly 70dB.
If you Google "70dB" it says that "it's the sound pressure of 'normal conversation'."
While this may be true, I will tell you (as I wrote in my review) - this fan (installed in a home in a hallway) is VERY, VERY loud. Almost unusable on high, and downright annoying on low. I recommend that you install it in a "test" fashion - before Read More
The quote that I got from HD.com Chat - On full it is roughly 70dB.
If you Google "70dB" it says that "it's the sound pressure of 'normal conversation'."
While this may be true, I will tell you (as I wrote in my review) - this fan (installed in a home in a hallway) is VERY, VERY loud. Almost unusable on high, and downright annoying on low. I recommend that you install it in a "test" fashion - before you tear up your ceiling, etc. - to make sure that you are OK with the volume.
I ended up going with a QuietCool CL-4700. It is quite a bit more money - but worth every penny in my opinion. Read Less
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Customer Reviews

Rated 3.6 out of 5 by 84 reviewers.
Rated 3.0 out of 5.0 by moves air well standard installation is based on ceiling joist being centered in fan, i had to build a box, not that hard. fan lovers require 5.5" for clearance, so the fan box sits on top of the joists and requires an additional 6" of clearance -- manual suggests 18" or more fan is roughly 28" square.. but not exactly, dimension of the lovers is 27.5" and the other s 28.5" fan has 2 speeds, not quite, not horrible make sure to buy a romex connector, not included August 7, 2016
Rated 5.0 out of 5.0 by Cool Now! Works just fine. Template was just a little too big. Overall works as expected. August 16, 2016
Rated 4.0 out of 5.0 by 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. July 19, 2016
Rated 5.0 out of 5.0 by Works great The unit was well constructed and runs with no vibration noise at all. I had to do a lot of extra framing to get it to fit in an old house. The fan frame allows for that. July 25, 2016
Rated 4.0 out of 5.0 by very good purchase bought this fan to put in my shop wall to draw out some of the heat. so far so good July 12, 2016
Rated 3.0 out of 5.0 by Damaged upon delivery! I ordered a second attic fan, because the first one was damaged. Well guess what, so was the second one. After making repairs, it works great. June 28, 2016
Rated 5.0 out of 5.0 by 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. May 17, 2016
Rated 5.0 out of 5.0 by Great value for the money! Very easy to install and very affordable! If you need a whole house fan at a great price, this is the one to buy! June 28, 2016
  • 2016-08-26 T12:21:57.779-05:00
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