Saturday, June 8, 2019
Squirrel Cage Window Fan - Foam Core Board

Summertime evenings in Colorado cool down nicely. With the lower humidity here (vs the Midwest) it's nice to open the windows in the evening to cool the place instead of using the air conditioner. A small box fan sat on the ledge until the fan motor bearings failed. I didn't care to replace with the same type of fan and leaned towards a squirrel cage style. A year back I purchased this Lasko cage fan but it mostly sat as I hadn't decided how to use it with the window. Should I make an extended shelf and place the fan near the window or set the fan on the floor and purchase some HVAC air ducting to connect the fan's intake to the window? 

I explored the HVAC ducting with some flexible ducting and quickly decided a shelf mount would be cleaner. Some white "duct tape" with foam core board and spare materials in the garage (plywood, pole, nails) found the project coming together.

The window has an external screen. Since the horizontal blinds are not able to "drop" down to the windowsill I've added white posterboard to cover the lower window area where the blinds can't cover. When the window is to be closed - it slides closed - no matter if the fan is sitting by it.

The extended shelf "clamps" onto the existing window ledge. A washcloth is placed over the window ledge to keep the paint in good condition. The "white" support post below the extended shelf is a wooden rod. I placed a small nail in the top end, extending out about 1/2". The nail "pokes" into a hole in the extended shelf. Should the pole get knocked the nail should keep the pole from being dislodged.

The fan, running on low speed, draws about 48 watts - a low cost option to the air conditioner.

Animation showing the assembly.

Vertical covering to help seal the window above where the fan is pulling air. The goal is to pull air into this window and force it out through the other side of the home for uniform cooling.

Blinds about where they stay.

Extended shelf with the clamp.

Shelf, with support pole, clamped in place.

Foam core board assembly. The angle has the fan directed towards the doorway.

Intake of the fan sitting next to the hole in the foam core board.


So far so good. We'll see how the summer flows.

The window can be slid closed and locked without moving the fan.

This was a first time working with foam core board. It was fun working with it. It offers good structural integrity (for this project). Cutting was crisp with a straight edge and razor blade. The white duct tape makes the project look good.

The computer control / automation side of me thinks that automation might be something to tackle...  Inside air temp, outside air temp, rain sensor, automatic window open/close control. Decision to open the window and operate the fan depending upon temps. If it's raining - turn off fan and shut window. Doubtful those additions would be added but it's fun considering the options.