VIVOSUN Quiet Register Booster Fan for 𝟒" 𝐱𝟏𝟎" Holes, Cooling Heating Vent with Intelligent Thermostat Control, 10-Speeds Increase Airflow Booster Fan for Bedroom & Attic, Matte White

Very good product! We use it to pull air from our wood heater in the basement, we have tried a couple of other brands, but they do not rate like this one. Simple to use, very well built, and it moves a lot of air. We do not use it in a vent, but i can see how un-obstructive it would be to the air coming from the HVAC Large opening for the air to pass through, and runs very quietly compared to the others we have. We will be replacing the other brands with this one. :)

For the the money it works well. Really helps to keep the air circulating which does help the furnis to be more efficient.. I have one in three room and together I feel a difference.

Bought this for the vents in a couple rooms in my house, that have poor vent performance. Didn't realize that the inside dimensions of my vents are all 3" by 10", though, so they didn't fit (the inner dimension of your vent does indeed need to be 4x10 to work with these). Plugged it in to test out the performance any way, and: - VERY quiet - Fan seems pretty strong Hard to say exactly how it would have performed if it fit into my vent (and they don't make a 3x10 version that I could find) but worth giving a try if you do have 4x10 vents!

This actually works. When the furnace is on it increases the flow of air into the room and when furnace is not on it continues to pull the warm air into the room to the preset parameters. I’m not waking up at night to turn on my heating pad or electric fireplace. It did take several tries to change from Fahrenheit to Celsius. You have to press the up/down buttons at exact same time and it will eventually switch over. Very pleased with this purchase.

We installed one of these in each of our kids' bedrooms, where the doors are closed and the air conditioning and heat from the furnace are less effective than in the rest of the house. IT WORKS!! All we had to do was place them and plug them into an outlet. Super easy. They automatically start when the furnace comes on, whether for the air conditioner or the heat - you set it for hot or cold. We were shocked at what a difference they made.