Tjernlund DB-2 Duct Booster, Increases Heating and Cooling Power, 275 CFM

I'm very happy with this fan. If you can cut ductwork, the install is easy. Its very quiet, I'm getting no vibration and very little noise, even when standing next to it. Feels like it doubled the airflow down the 6" pipe it's on, but if you have more than a room or two, you might need something bigger. Its heavy enough for it's size to feel well built. My furnace puts out air as hot as 165 degrees, this is the only fan I've seen able to handle heat that high.

Thos really does make a difference in how much heat or air blows out of vents. It works well so far.

This was easy to install as I had a bunch of clearance and its fairly quiet all though it does vibrate pretty good so keep that in mind you will likely need to damped that, I used foam rubber and a ton of aluminum tape.Cons:No electrical, you will need to run wires to this blower as it didn't come with any, that added cost to my project and hassle as most other boosters come with a plugExpectations:After reading the other reviews prior to buying I set my expectations to an appropriate level, this will not blow as hard as in inline boaster, which I would have used if the run I was trying to boast would have been circular instead of square, but it does help. I put this on a run that went to up upstairs and split into two rooms, after installing this booster the output of the two vents was improved and nearly the level as my other vents.The specs say its has 275cfm flow which it simply didn't for me, when I measured the air flow 1 foot from the blower I was getting 155cfm, the vent goes straight up 20 feet to my upper floor and at the junction point between my two registers I was getting 71cfm so if your going to be using this to push air from your basement to your upstairs keep that in mind.This is great for a vent that has a medium-low airflow issue and you are trying to increase it lets say 15-20%, this fan helped to keep my children's room cooler

I installed this identical blower in my parents house about 15 years ago. Used during both Heat and A/C operation. You cut a rectangle in line in the duct. It stays 90% outside of the duct with just the baffle and bottom of the squirel cage dipping into the duct. This is nice because if you have times that you don't use it, it won't restrict the duct's regular air flow. Be sure to face it in the correct direction. I installed it centered in a square duct near the end of the supply that later branches off supplying air to a register down stairs and another one up stairs. Plenty of air for two ducts and very quiet. I would say that with it being mounted in a 12 inch square air duct is an advantage over a smaller duct. I am sure that it is moving quite a bit more air than the 275 cfm rating. The air that it speeds down the duct pulls or induces additional air along with it. Naturally the two ducts it branches to later are smaller. The motor is fully enclosed and thermally protected. You have to have the motor out in the ambient air, not insulated or blocked off as it would quickly overheat and shut down. The old one needs replacing now and I am happy to be able to get the same product.

This fan may be O.K. for a single room duct. In my square duct feeding three rooms, it makes only a small improvement in air flow. It is a bit noisy, and it took time to install. The flanges are set for a round duct, and are difficult to bend for a square duct. The electrical junction box is much larger than necessary and blocks access to one of the mounting screws so that a screwdriver cannot be used. Wiring is straight forward with connections for a hot lead, neutral, and ground. I used this blower with a pressure switch from this company. The switch is wired, as any single pole switch, with the hot lead only.

I bought two of these fans at the main trunk which is split directly in the middle of the hvac unit. I placed one on left and one on the right about 2' from where the duct T'd. We utilized a 120V Ductstat (Found at Menards) so we didn't have to rely on using the power from the hvac unit. We simply utilized an old 15A cord that plugged into the ductstat and used 1/2" steel flex to the other duct booster fan and viola. The fans only go on when the AC temp rises above 3 degrees monitored and controlled by the Ductstat. The fans do have a weird noise but over the past few weeks it seems to diminish or we probably got used to it. After 9 years I figured out that the ductwork was oversized and there wasn't enough CFM, therefore my home couldn't provide cold air fast enough as the house filled with hot air. Glad to say an additional 180 CFM on each trunk line did the trick. The house stayed at 74 degrees while it was 100 outside.... keep in mind the house is almost 100 years old, no insulation in the walls with ceiling a little over 9'..... so keeping it 74 in the summer is a challenge.

The fan on our sump pump went out and this was a perfect replacement and easy to install

I was not impressed with the amount of air movement.Also having to bend the side tab was difficult because the motor gets in the way for square duct installments.Sent fan back and opted for individual ducted fans and got much better air flow.

Installed in less than 1 hr, runs great. Have it connected with the furnace blower motor, comes on at right time and shuts down with the furnace. I have it mounted in the main trunk of a side split, far bedrooms were cool, bow it is even throughout. My guy wanted me to changed up all my trunk sizes, much easier and cheaper fix installing the blower.

the blower runs very quiet

Booster works awesome

I tried using this to increase air flow from the a/c in my basement to my second floor master bedroom. Unfortunately, there just wasn't enough air flow to make a noticeable difference. Also, the unit made a slight humming noise -eventually it became annoying- which could be heard in the bedroom.

I bought 2 of them. 1 is good but the other one is noisy. It is winter and very cold last fast weeks. I will took too much time to return and get back a new one, I am not very happy. They should inspect,test and make sure this item is quite in use before sending to the buyer. Hopefully my review will be read by my sender and if possible send me a quite one and I will be happy to return the noisy one that I have from them.