I see your logic, unfortunately it won't work that way. The fan can only push as much air there is space for. That's why one matches the fan to the ducting. The reducer actually will raise the airflow noise slightly due to it's increased velocity by being reduced in volume. If it were reversed so that it was a 6" fan going into an 8" duct, the noise would go down.
Also take back the speed controller. It's design will cause premature failure of your fan. You can tell because you'll hear a slight humming. Not many people know about it, you've been hipped. What you do with the info is up to you. The variac is the way to go.
I hear what your saying man! .. I was wondering a few ways to get around this and still get away with using the
8" fan.. firstly I've noticed that the side of the fan that pulls air from the grow-cab actually has a hole thats
6" with an 8" neck ..
so from there back to the reflector is all 6" equipment, minus a 1" x 1" gap at the fan where the 6-8" reducer attaches to the 8" neck of the fan.. Then on the other side of the fan (side blowing to carbon filter) there's obviously an
8" hole but with an
8" neck..
at the moment there will be a reducer attached going 8" to 6" then a 6" Carbon Filter... (
I can see this is where the noise would build up as you said) ...
BUT! if I only used the 6" carbon filter temporarily, until I can get an
8" Carbon Filter (doing away with the reducer on the blowing side) then surly the noise would then be reduced, as opposed to the way its set up now ??
I only plan to use the
cheapy plastic speed controller until I can find a nice
UK version of the
US Variac you showed me for a reasonable price.. (
kinda low on funds at the moment) lol, I am hoping my theory on the install is going to stand up
I think if all components from the left (
sucking side) ie/
6" Reflector > 6" Elbow > 6" Ducting > 6" Elbow > and then
6" to 8" Reducer up to the sucking side of the 8" fan - also a 6" hole (
with an 8" neck) with a
1x1" ring gap around the inner part of the neck where it connects
this whole side is virtually all 6".
If I then on the
right (
Blowing side) the exhaust hole is
8" - connected straight into a
NEW 8" carbon filter ie/
8" In-line fan > 8" Carbon Filter.... I cant see there being a problem with noise.. especially when I get a
Variac
But with the
8" fan blowing through an
8" to 6" reducer and into a
6" Carbon filter.. (
as it will be for now) I can see this is where the noise will occur!,
I can put up with that for a couple of weeks...at least until I have paid the Hydro Store for the 8" fan etc etc... then I will get a
new 8" Carbon Filter and that should (should) eradicate the noise problem...
Phew! .. Sorry if I rambled on a bit there lol...just had my 1st joint of the day and am pretty spacey lol
What do you think of my theory ?? when I think about it I cant see a problem though (with a new larger carbon filter +
8" duct hole) - STELTHY