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:
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). 
The code is available from the "Source Code" section.
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).
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. 
Making the slide cover: Glue the foam board for the cover 
The wood on the sides will be used to attach the drawer slides 
Make sure everything is square and level 
Glue and clamp 
Attach V-Seal weather stripping 
Install drawer slides. These need to be installed as level as possible. 
The cover installed. Notice the space between the top of the wood. This is for the starting collar. 
The cover should fit tight and square in the back of the box. 
Install the starting collar for the duct work. 
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. 
Make sure to use glue 
Screw in a piece of wood that will be used for the threaded rod. 
Screw in threaded insert 
The threaded rod was slightly smaller than the bearing hole so I used a plastic wall anchor as a shim. 
Install cover and limit switches 
Here is what the motor, Arduino, etc looks like 
I shimmed the motor and board so if they heat up there won't be a fire :) 
The relay and current sensor in the fan electrical box 
A blurry picture of the final install 
The LCD 
| Name | Size | # Downloads |
|---|---|---|
| Whole House Fan Model.skp | 407.39 kB | 2882 |
| Name | Size | # Downloads |
|---|---|---|
| WholeHouseFan2.2.ino | 28.15 kB | 2605 |
@lis610 I have found with a 499K resistor the range is reduced to about 1.2m in a ABS box.
With a 1Mohm it was about 3m, I do not have many high value SMD resistors to experiment with but the lower the value the lower the range.
Just tried with a 333K and it operates about 0.8m in free air.
@lis610 said in 
Insulated Whole House Fan:
I am using RCWL-0516 Microwave Radar Sensor for on/off the display. This sensor is very sensitive. I just want to activate the display in a close range. Any suggestions?
You could try the XYC-WB-DC radar sensor. This one allows the sensitivity to be adjusted by changing a resitor value. Here's a Youtube video about it:
Modifying a XYC-WB-DC Microwave Motion Sensor for use in a Sonoff SC – 19:09
— Blair Thompson
I'm waiting for mine to come in from China, so no first hand experience yet on how these sensors work.
@lis610 said in Insulated Whole House Fan:
RCWL-0516
https://www.rogerclark.net/investigating-a-rcwl-9196-rcwl-0516-radar-motion-detector-modules/ shows some possible ways to read something other than a digital output of motion at 5 to 7 meters.
It doesn't look like there is a simple way to just make it less sensitive.
I am using RCWL-0516 Microwave Radar Sensor for on/off the display. This sensor is very sensitive. I just want to activate the display in a close range. Any suggestions?
Looks great @lis610 !
Display. I used old case from iPod. Sprayed a little red paint and top it with black. Push button at the bottom of the case.
Can you add additional code; Close the cover if Fan does not start and display error that fan has no power. Thank you.
@lis610 Awesome! Congratulations and great job for not giving up. That was a lot to tackle for a first project! Nice enclosure to house everything. Looks way cleaner than mine 
Finish! Thank you for all your help!
In the beginning, I connected the DHT sensor to Pro Mini A0 and separate power supply (5V) and ran DHT Example sketch and eading was "nan". Want to mention that all other wires (FAN setup ) attached to Pro Mini as well. Then I disconnect Pro Mini from setup and connect DHT to it (GND, VCC, and A0) got numbers by running DHT Example. Connect everything together (motor, display, radio) and connect DHT to Pro Mini (GND, VCC, and A0) turn on and got zeros for Temp and Hum. Got frustrated and left for a walk. When I come back, Temp: 85 and Hum 52. I was not patient enough. It takes 5 to 6 min for Temp to show on display. I also tried to connect DHT VCC to the external power supply 3.3 and 5 V, but leave GND connected to Pro Mini and it works.
