duct booster fans

[Tim]

I have a bonus room over my garage upstairs, which is at the end of about a 40' run of 12x8 duct (furnace is downstairs on opposite end of house). My heating is zoned (up and down), but the only way I could get any real airflow to the bonus room was to close down way too far on the branch duct dampers upstairs.

I installed a fantech FX8 8" inline fan as a booster fan, controlled by a thermostat in the bonus room (using an Argo AR822 relay). I used sound isolation mounts (rubber plate form mounts from Mcmaster Carr), and the fantech neoprene mounting clamps to connect it to the fuct work (prevents transmission of sound).

It works great, and I cannot hear the noise of the fan when standing in the room directly below it. It provides alot of air, and has solved my heating problems.

I read some previous posts on this board talking about too much noise or ineffective fans. This solution works great.

[Joseph Meehan]

I am glad it works for you. Many people report little success with booster fans in general. I would have to say that they are not a good substitute for a well designed system. For that you need a professional how knows and cares about what he is doing. Having said that in my current home I had one room that was always too cool or hot. I would have preferred to rebalance the system for the start, but it has too many other issues and they are just going to wait until I am ready to do it right. I did add in in-line booster fan and it is controlled by the furnace. It does work well, but I will replace it and redesign the ducts when I need to replace the furnace - AC.

[boden]

Why wasn't it sufficient to just use FanTech's neoprene compliant couplings? I'm about to install a FX8 blower in my basement for a cooktop down draft exhaust and would like to keep it as quiet as I can reasonably do. FanTech also has an in line muffler that I'm curious about.

Boden

Tim wrote:

[TURTLE]

This is Turtle.

i'm in the HVAC business and will say rarely will i ever see a fan booster fan ever work out. i'm glade to hear your problem was solved with this booster fan.

TURTLE

[trader4]

Count me as happy with a booster fan. I have an upstairs bedroom that is at the far end of the duct run and only served by small round ducts that run from the end of the basement run all the way upstairs. I added a booster fan near the end of the duct run in the basement and it made a noticeable difference in summer cooling. It didn't entirely solve it, but it helped and the cost/benefit was worth it.

[Tomes]

Me too. We have a room between the main part of the house and the garage and have a booster fan in the duct to that room. When it is off the room is cold now and when it is on it is fine. No problem, no worries. Tomes

[Tim]

turtle posted:

booster fan ever work out.

I have heard that frequently, and between that and reports of too much noise I was hesitant to go for this solution. The cost of replacing a long section of duct with 12x10 or larger was prohibitive, so I figured I would give the booster fan a try.

Part of my problem is that between the furnace in the basement and the duct upstairs, my duct makes a total of (count them) 8 90 degree turns. Trying to make this into a straighter shot would be pretty difficult.

boden posted:

It probably would work just fine if you suspended the fan from them (like they show in their brochure). I wanted to mount it more securely, so used the plate form sound isolation mounts. Probably overkill, but I do alot of work with vibration dampened equipment, and I was trying to ensure that no noise would be transmitted through to the ceiling joists.

[TURTLE]

This is Turtle.

For every 90 degree elbow you put in a duct work, it restricks 1/27 th of the air moving through it. Put 27 -- 90 degree elbow in a ductwork line and it will be a plugged up air ductand no air will move through it.

TURTLE

[CJT]

I don't think that's how the math works.

[Goedjn]

By my figuring, you'd actually get closer to 36% of the original flow.

[Bubba]

Ok Terry ........................I just gotta say With a statement like that............ That is one of the silliest, goofiest, dumbest, bird brain things Ive heard in quite sometime. I must of missed that class? When you drink, you shouldnt type. :-) Bubba

[Joseph Meehan]

TURTLE wrote: ..

Actually it will be 36.096% of the air will be going through. See a elbow by elbow account below. :-)

0.962963 0.927298 0.892953 0.859881 0.828034 0.797366 0.767834 0.739395 0.71201 0.68564 0.660245 0.635792 0.612244 0.589568 0.567733 0.546705 0.526457 0.506959 0.488182 0.470102 0.45269 0.435924 0.419779 0.404231 0.38926 0.374843 0.36096

[CBHVAC]

Figure it correctly, and you need to figure in whats called TEL, and for every 90, its another 5ft added to it, then you take your ductulator, and see how it figures with your friction co-efficient and see how bad you killed flow.