I bought two of these units to boost airflow in two areas of my home that are quite far from the main furnace and get little cooling/heating airflow. I had previously used another duct booster brand that sat on top of the grate and turned on/off automatically based on the temp of the air from the duct. Those units were really noisy and the airflow was just slight better than just the regular, non-boosted airflow. Didn't really feel much of a temp difference in the rooms. Plus, they died after a couple years of use. This airflow booster unit is quite different. It uses a squirrel cage fan instead of the circular fan found in most other units. The squirrel cage fan creates a lot of airflow. The whole unit also mounts inside the duct outlet so is hidden from view except for the power cord which is very nice from an aesthetic point-of-view. It is quieter than the above-the-grate models, too. These duct boosters really made a temperature difference in the rooms where they are used, particularly in cooling. I could never get the temps below 78-80 degrees F in those rooms during hot days no matter how low I set the thermostat. With these boosters, I got temps down to the thermostat setting which is such a relief in the summer. That made the cost of these units worth it (and in spite of the minor problems. More on those later.). Installation is a snap, too. Just drops in the existing 4x10 inch duct opening. Plug in the cord, turn on the switch and you're up-and-running. That is, if everything is just right - the proper opening size, close-by power outlet, no blockages in the duct opening itself. If all of those conditions exist for you, you will have no problems (other than some airflow noise which may or may not bother you). Otherwise, read on. Besides having the perfect duct opening, there are a few other things you should know about. First and foremost is this unit does not sense temperature to turn itself on and off. In fact, it has no "smarts" whatsoever. It's merely a fan that fits in the vent opening with an on/off switch that controls fan motor. It's either always running or off. Air will flow through it when it's off, but at a greatly reduce rate because of the size of the unit. That's not entirely bad for me. since I normally leave the furnace fan on continuously in very cold or very hot weather to even out temperatures throughout the house. This booster allows me to leave the furnace fan on "auto" since these booster does the job of the furnace fan and, in doing so, saves wear-and-tear on that furnace fan. However, while these boosters are quieter than the above-the-floor units, they are not completely silent when running so you definitely know when they're on. It's not motor noise, though, it's the sound of the rushing of air from the high airflow. That can't be avoided. As for the perfect opening, this booster is fairly bulky (see photos). When properly installed, the entire unit sit quite deeply in the duct opening flush with the floor (wall). You should check the clearance inside your duct outlet below the grate opening before buying this booster. I did not do this and I could not get the unit to fit flush in one the ducts where I was planning to use it. The ductwork opening must be no smaller 4" x 10" for this model (it fits quite precisely in that opening). If there any bends or narrowing of the ductwork inside the duct opening, they may block this unit from fitting flush with the floor or wall. For this booster to drop in cleanly, there must be at least a clean 4" drop into the ductwork for the unit to fit flush. Also, if there is a bend in the ductwork where the main ductwork meets the ductwork outlet (in the floor or wall), the fan opening of the booster must face the opening side of the bend (i.e. not blocked by the metal side of the bend), otherwise the airflow will be blocked. Again, if there any kinks, bends, or narrowing of the ductwork, they may prevent this unit from facing the right direction as well since the motor end of this unit is larger than the other end. As for the grate cover, you must use the grate that is supplied with the kit (see photo). There is less than 1/2" of drop for a grate cover to fit inside the booster face, so normal grate covers won't work. Plus, there has to an opening where the power plug has to go through and for access to the on/off switch. Sadly, I had some nice, decorative covers that I can't use anymore (too deep and they blocked the cord). The grate you get in the kit is a plain, brownish-tan, finned cover. It doesn't fit completely flush, either, and sits about 1/16-1/8 inch off the floor (or wall) when it's in place (see photo). It also fits loosely in the opening without any fasteners which is fine if this unit is on the floor, but if you're wall-mounting this booster, you'll have to figure out how to make that grate stay on the wall. Their grate does allow the cord to plug into the power socket on the booster and the on/off switch is easy to get to. Speaking of the power cord, it plugs in through the front of the grate into a port on the unit (see photo). Unless you hardwire beneath the ductwork somehow (if you are a handy person), you will have a black cord extending quite conspicuously out the grating. Power-wise, it requires 110-120VAC. Fortunately for me, I happen to have wall outlets near my ducts, so it was easy to find power. If you don't have such an outlet, then you'll need to use extension cords or something, to get power to the unit. In summary: Pros: - Great airflow - Relatively quiet (compare to other units) - Significantly boosts airflow in needed areas. - Hidden (mostly) - Easy to install - Well built, all metal construction Cons: - No automatic temp sense to turn unit on and off. - Totally manual on/off, i.e., always on or always off. - Bulky, requires correctly sized opening to fit properly - Not completely silent in operation (airflow noise) - Cord stands out of the unit when plugged in - Can't use custom grate covers - Expensive If I have any more feedback as I use this product over the seasons, I will report back. [UPDATE 5/19/2017] Well, it's been two years since I installed these units and they're still running as good as ever. Never had a failure. I have them running on wall timers (the kind that plug in the wall socket) to turn them on and off at appropriate times (I have them shut off during overnight hours). When the weather is really hot or cold, I let them run continuously, 24/7, non-stop. And they do, without failure.They are far better than any above-the-grate booster that dies after a season or two. I did discover a slight glitch with the power cord. The end that plugs into the blower fits very loosely into the socket in the blower. Just a slight touch will knock it free enough to cut power, shutting off the blower. This could happen for any number of reasons such as vacuuming. Even the slightest nudge will break the connection. I've discovered on numerous occasions that I had unknowingly knocked the cord and cut the power off. You can't tell from a distance because the cord is still standing up in the grate and looks fine. I could tell the blower was off because of change in room temp. I've tried to use electrical tape to hold the cord to the blower, but it's not an elegant solution. I wish the cord had a firmer connection to the blower. Still, both blowers have run like champs since day one, for two years now. Much better life expectancy than I expected. They still make a world of difference in temps in my home.
