Originally Posted by J_P_A I'm not a fan of the Panasonic fans. I finally broke down and pulled the 490 cfm version I had out. I suppose it's still to be determined if the noise I'm hearing is a direct result of the Panasonic design, of if it present with inline fans in general. At any rate, I would plan to put the fan as far from the room as possible. In my case, the fan makes a low frequency broad spectrum rumbling that is very difficult to dampen out.
I'm hesitant to make any recommendations because I'm not familiar with your climate. A house without central air is a completely foreign concept to me these days. That said, if you can find enough space to use both of those fans as exhaust fans, that may well be enough volume to keep the room cool. If you're planning to keep the door open when there is more than two people in the room anyway, having one fan on the supply and one on the return may be enough to keep the room comfortable with two people.
I don't remember for certain, but I think that can has a 6" inlet and outlet. You need to plan on upsizing the duct to an 8" or 10" to keep it quiet. You are shooting for 250 feet per minute. If you use a 6" it's going to be loud!
I think Tim has the right idea. You need to do some testing to see just how much air you will need to move to keep the room comfortable.
These are the 340 cfm models, so not sure if they're smaller/less noisy than your bigger one... We shall see! Yes, they have 6" connections and I agree on upsizing the duct runs.
Is there a way to calculate what size/length of duct I need to go with in order to hit the 250'/m number?
Also, is there some sort of calculation I can perform to pick the right vent size within the room so that it doesn't whistle?
Originally Posted by thebland
Do what you can to lower that noise floor.... Ideally to below 30 db. 50 db is really, really high! Did you measure near a furnace or such?
At your current noise floor and your max output, that's a pretty limited / crappy dynamic range.
Shouldn't be a huge issue as I'm sure you're sealing this room off from the rest of the basement.
What do you mean about a limited/crappy dynamic range?
The frequency graph was a snapshot in time of what my bedroom is like during normal sleeping times. The 50dB is as measured from about 2" away from my wife's ear as she slept (held the phone by her head without her knowing...). We leave a small fan running on my nightstand through the night as a white noise for better sleeping, even during the winter so it's truly 365/year. I can't sleep without a fan running since I was an infant. My wife has taken on the same "issue" and can't sleep without it on. Anyhow, the 50dB's is considered a max across the frequency spectrum as indicated by the full FR plot (the highest dB is around 42 in that plot so not sure where the 50dB's comes from using the other iPhone app)... You will also notice that there aren't any LFE's going on and so anything below 80Hz is going to be my challenge. But with testing I'll be able to determine how to handle it if it doesn't work with just complete decoupling the walls and ceiling and a single layer of 5/8" rock. My only option however will be adding more mass, but I'll cross that bridge when I get there, but at least I'll be performing some testing before finishing the room.
Originally Posted by Expat444
Looks good, can you tell me what you used to measure your noise floor?
I used two iPhone apps:RTA LitedB Volume
Although most likely not all that accurate, they will give me a point of reference as a baseline and a Δ in testing.
After doing some more research and receiving a PM back from the Black Cat theater owner, I think my purchase of these two fans will be adequate for my room. I just need to dampen them and figure out the duct run and sizing. After giving it some thought and envisioning how the room will be used, this should do the trick. Here is why...
When my wife and son are sleeping it will just be me in the room. My thoughts are that with just me inside and the door shut, I can enjoy a movie without needing to run the fans. This will lower the need to dampen the fans on the other end (adjacent room). I will obviously still want to dampen them so they aren't noisy within the HT though.
When my wife and son are with me in the room, we can run the fans, which should be enough to keep it comfortable. If not we can turn on the AC unit(s) within the adjacent room in the summer or open a window in the winter. If that isn't enough, we'll find something else to do!
When there are others with us we can run the fans and if it becomes uncomfortable we can open the HT door. If that still doesn't cut it we can turn on the AC unit(s) in the windows of the adjacent room. If that doesn't cut it, then my whole house would be uncomfortable anyhow!
When it got above 90 degrees this past summer, my basement was nice and cool. We run window AC units in the upstairs bedrooms and two on the first floor to cool the open floor plan (kitchen / living / dining). My thinking is that since my basement was already cooler than my upstairs while running AC units to maintain 68-72 degrees, I should be okay with my plans.
Now who can point me in the right direction to duct design? I'm willing and have the tools to build my own ducts using MDF and liner........