Insulated Whole House Fan


Not sure how much interest there will be in this project but I thought I'd post it in case there are any other people out there that want to make a whole house fan. This projects is for an insulated (R30), automated (using MySensors of course) whole house fan. The purpose of the fan is to vent the hot air in your house out of the attic while drawing cooler air from outside into the house. I live in a climate with hot days and cool nights so this works great for me. The problem is most attic fans that aren't $1,000+ don't have any insulation so during the hot days they allow your house to heat up much faster than it should. So, I decided to see if I could build one, and automate it of course. :)

Here is a short video going over the functionality:

Wiring diagram

![enter image description here]( Whole House Fan Wiring.png "Wiring")

I ended up not having enough space in the code for the SD card but this is how to wire it up if you did want to use it. You can also just leave it wired like this even if you don't use the SD card. Alternately you can use the yellow pins on the other side with the same connections and resistors (except for the SD wiring). ![enter image description here]( TFT SD Card Wiring Diagram.png "LCD wiring")

Code Notes

The code is available from the "Source Code" section.

  • Most things that may need to be customized (motor stall values, close timing etc.) are at the top
  • The LCD uses the Adafruit_GFX & Adafruit_ST7735 libraries. You will need to download these and add them to your libraries folder (or use the Library Manager).
  • The code is too large to have debugging enabled and the LCD. Comment out debugging after you are finished testing.

Parts List

Click on the BOM tab at the top Note: Some of these things are probably only sold in the USA but hopefully it will give you something to base it on if you're in another country


Here are some pictures from the build. I have also created the box as a 3D rendering in SketchUp (.skp) so you can get the dimensions of the box or if you want to make any customizations. The file is available on the "Design Files" tab.

It's important to get the box and drawer slides as square and level as possible so the cover operates as smooth as possible (then you don't need a big motor).

![enter image description here]( 20160328_195043.jpg "The box")

I cut 1/2" strips of wood at 45 degree angles that will be used to help seal the slide. Install these perfectly level otherwise the cover won't close properly. ![enter image description here]( 20160403_122134.jpg "45 degree wood strips")

Making the slide cover: Glue the foam board for the cover ![enter image description here]( 20160403_123741.jpg "Glue the foam board for the slide")

The wood on the sides will be used to attach the drawer slides ![enter image description here]( 20160403_124107.jpg "Cover")

Make sure everything is square and level ![enter image description here]( 20160403_124220.jpg "Cover")

Glue and clamp ![enter image description here]( 20160403_130443.jpg "Cover")

Attach V-Seal weather stripping ![enter image description here]( 20160405_065123.jpg "Weather stripping")

Install drawer slides. These need to be installed as level as possible. ![enter image description here]( 20160406_193144.jpg "Drawer slides")

The cover installed. Notice the space between the top of the wood. This is for the starting collar. ![enter image description here]( 20160406_205837.jpg "Cover installed")

The cover should fit tight and square in the back of the box. ![enter image description here]( 20160406_205918.jpg "Cover installed")

![enter image description here]( 20160406_205935.jpg "Cover installed")

Install the starting collar for the duct work. ![enter image description here]( 20160407_212040.jpg "Install the starting collar")

Hollow out a slot in the foam so a piece of wood can be inserted. This will be used to attach the wood used for the threaded rod. ![enter image description here]( 20160410_091719.jpg "Hollow out foam")

Make sure to use glue ![enter image description here]( 20160410_094741.jpg "Use glue")

Screw in a piece of wood that will be used for the threaded rod. ![enter image description here]( 20160411_200534.jpg "Attach wood")

Screw in threaded insert ![enter image description here]( 20160412_202703.jpg "Screw in threaded insert")

The threaded rod was slightly smaller than the bearing hole so I used a plastic wall anchor as a shim. ![enter image description here]( 20160412_202641.jpg "Shim")

![enter image description here]( 20160617_202956.jpg "Shim")

![enter image description here]( 20160412_202730.jpg "Shim")

Install cover and limit switches ![enter image description here]( 20160420_062238.jpg "Limit switch")

![enter image description here]( 20160617_202936.jpg "Limit switch")

![enter image description here]( 20160618_122304.jpg "Limit switch")

Here is what the motor, Arduino, etc looks like ![enter image description here]( 20160618_145532.jpg "Electronics")

I shimmed the motor and board so if they heat up there won't be a fire :) ![enter image description here]( 20160420_055633.jpg "Electronics")

The relay and current sensor in the fan electrical box ![enter image description here]( 20160618_120509.jpg "Fan electronics")

A blurry picture of the final install ![enter image description here]( 20160626_214027.jpg "Finished")

The LCD ![enter image description here]( 20160621_201413.jpg "LCD")


Design Files

NameSize# Downloads
Whole House Fan Model.skp407.39 kB1514

Source Code

NameSize# Downloads
WholeHouseFan2.2.ino28.15 kB1303

Bill of Material

13013 CFM Quiet Cool Fan
116 in. x 12 ft. Insulated Flexible Duct
116 in. Starting Collar
1Strap for fan mounting
115/32 OSB - 8' x 4' sheet (for fan box)
1Insulation (I used a 4' x 8' sheet)
116" Air Intake Grill (needs to be cut)
1V-Seal Weather Strip
116 in. Full Extension Ball Bearing Side Mount Drawer Slide
11/4" Pillow Block Ball BearingEbay:
11/4" Threaded Rod
1Construction adhesive for insulation
11/4 in. Threaded Insert
1Arduino Pro Mini
1ACS712 - 30 Amp (for Fan)
1ACS712 - 5 Amp (for cover motor)
11 Channel 5V Relay
1L298N Dual H Bridge Stepper Motor Drive Controller BoardEbay: Dual H Bridge Stepper Motor Drive Controller Board Mod...
11.8" TFT LCD DisplayEbay:
51K Resistors
14.7k Resistor
1Microwave Radar Sensor 4-8M 180°Ebay: Microwave Radar Sensor 4-8M 180°LED Lamp Smart Switch ...
1Momentary push button switchEbay:
2Limit switchesEbay:
24.7uF Capacitors
2.1uF Capacitors
1Small wire for attaching duct to fan
1600RPM DC Motor
11/4" fuel line (for coupling to threaded rod)


Sensors & Actuators

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