How to winterize a whole house fan? Are covers effective?

What does winterization mean?

Winterization is the process of preparing for the winter. In HVAC it basically means preparing your house to stay warm without energy losses during the winter months.

What is the need to winterize a whole house fan?

Whole house fans are very effective in cooling your house during the mild summers without using an air conditioner. However, during cold winters you cannot use these fans, they are nothing but a large hole in your ceiling.

Even though whole house fans are installed with louvers they are not sealed enough to prevent heat from escaping to your attic during the winter season. So while the fan saves you money during the summer season, it is a reason for you to lose money during a cold winter. The loss of heat is enough to add more workload on your heating system, and for it to work efficiently the whole house fan should be winterized.

Do I need to winterize my fan on warm winters?

You don’t have to winterize your whole house fan during warm winters. This depends on the geographical location you live in. If you live in the Southern states of the USA where winters are warmer, your whole house fan need not be winterized. In fact, it is recommended to run a whole house fan on warm winters as they will reduce moisture build-up in the house which will lead to the growth of molds.

How to winterize a whole house fan?

how to winterize a whole house fan

Winterizing a whole house fan is pretty easy, all you have to do is prevent heat from escaping through the louvers of the whole house fan. For this, the solution is simple, insulate the louvers.

There are many methods to insulate a whole house fan. You can either use an insulated, air tight cover from the top, or you can cover the louvers using an insulation board from the bottom.

I prefer to cover the fan louvers from the bottom as it is easy to remove when needed. But it may not be aesthetically pleasing to see an insulation borad attached to the ceiling of your hallway.

Here are a few methods in detail to winterize your whole house fan;

1. DIY winterization from the attic by building a box cover

An easy method to winterize a whole house fan is to cover it with an insulated box from the attic. With a bit of creativity you can easily design a box cover that will stay open by itself when the fan is running. This means the insulation box will remain closed when the fan is not running ie, in the winter.

Here is how to create this box cover;

Things you need;

  1. Rubber foam self stick weatherseal tape
  2. 2 inch Foamular board
  3. Duct tape
  4. Metal tape

This box is made using a 2-inch thick formular insulation board. This one has an R10 insulation rating. First, create a box around the fan with the foam board and tapes. Then make a cover suitable enough to cover the box as shown in the video. Hinge the cover using the tape on one side. The weather seal is used to seal the point of contact between the cover and the box. Since the foam board is very light it will open itself while the whole house fan is working. When the fan is not working the cover will close, and it will provide enough insulation to prevent the heat inside the house from escaping into the attic.

The dimensions of the box will vary depending on the size of your whole house fan. Since the cover opens while the fan is working you don’t have to remove the box even after winter, it will just work as it should. You can also use metallic hinges, and they are the preferred option if you plan to keep this DIY setting forever.

You can also cut the cover in the middle so it opens like double doors. But in this case you may have to add stoppers to prevent the cover from opening more than 90 degrees angle.

2. DIY magnetic cover for the fan louvers

Another method to winterize a whole house fan is by insulating it by using a magnetic cover. You can make this cover by yourself, and you will need the following;

  1. Heat insulation foil
  2. Disc magnets or bar magnets
  3. Duct tapes or a sewing kit

This will work only if the louvers you have are metal not plastic.

To make a magnetic cover, the first step is to cut the insulation foil to the size of the louvers. Then attach the magnets to one side of the foil so that they will come in contact with the metal louvers of the fan. Make sure you add enough magnets to keep the insulation cover in position.

This magnetic insulation cover is a much convenient option than using a velcro cover. It is easier to install and remove, and you won’t have to stick anything permanently on the ceiling.

3. Winterizing the whole house fan with a velcro cover

You can buy this type of whole house fan covers from websites like amazon. Here is a good product. –

In this case, we use velcro to attach the insulation cover to the louvers of the whole house fan. For this first we need to stick the velcro to the insulation cover as well. Here is a detailed video showing this whole process.

There are many more DIY methods to winterize your whole house fan. However, I find the first and second methods more effective and convenient. Which ones do you prefer?

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Charles John

Experienced HVAC technician with 8 years of experience in the industry. Capable of handling all sorts of heating and cooling equipment as well as proficient in operational management, construction-related techniques such as preventative maintenance, electrical troubleshooting and AutoCAD

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