Product review (5 stars): This fan has been working great. I read people were having problem with installation
Our dryer has 40ft long vent, it used to take hours, had to be run at least twice to dry, high electric bill, and I had to clean the vent from the lint built up every three months. This fan has been working great. I read people were having problem with installation. I thought it was pretty simple. The manual is only in one page but I thought it's straight forward. Here what I did to get the sensor to work:
1. Open the wall 4-prong plug-in (240V), and test which hot wire is used for the dryer motor. It's either the red wire or the black wire.
2. Remove one hot wire and insert it into the sensor hole. Reconnect the hot wire back to the wall plug-in.
3. Build a new wall plug-in for the fan. Connect the hot wire (black) to T1 of the sensor, T2 to a new plug-in that goes to the wall 110V plug-in. The idea is to use the sensor to switch the hot wire of the fan.
4. Run the dryer without heat. The idea is the sensor is supposed to only sense the dryer's motor and not the heating. If it doesn't turn on the fan, go back to step no 2 above. If you used a red wire previously, now try the black wire. Redo step 2-4.

I attach a picture showing how I tested which hot wire that carries the dryer's motor electrical current. In my case, the red hot wire.