Is their much of a difference in cooling between 8" cooling tubes and 6"?

[Rabbi]

Just wondering because access to 6"ducting and etc seems alot more accessible out here where I live. If in a pinch I could easily hit up homedepot if I needed 6" ducting or clamps but if I needed 8" stuff I would have to order online. Not a big deal to order online or anything if the 8" makes a noticable difference but I guess that's what the question really comes down to, how much of a difference is there?

 

[the gnome]

Just wondering because access to 6"ducting and etc seems alot more accessible out here where I live. If in a pinch I could easily hit up homedepot if I needed 6" ducting or clamps but if I needed 8" stuff I would have to order online. Not a big deal to order online or anything if the 8" makes a noticable difference but I guess that's what the question really comes down to, how much of a difference is there?

try an hvav supply house
hey should have 8" in stock.
an 8'' over 6" is 25% larger so yeah, there's that much mo better cooling

edited for:
25% is in relationship to linear measurement not diameter... I think?
btw gnomes suk at math

 

[Rabbi]

try an hvav supply house
hey should have 8" in stock.
an 8' over a 6" is 25% larger so yeah, there's that much mo better cooling

Thx gnome, 25% is quite large. How many 1000watt lights/8"tubes should one go per inline fan(hope that makes sense) and how many cfm's should the fan be?

example: if I wanted to run 8 x 1000watt/8"tubes how many inline fans would I need and how many cfm's each fan?

 

[the gnome]

well, i have 1 grow all open bulb,
another gro for the last 4 yrs is 2 1000w bulbs on 6" cooltubes
with a elicent 150B inline that is 309cfm
it does the job but still need AC in summer down in florida.
I wish i would have gone 8" in retrospect.

someone else should be along to answer you Q on cooling 8000w w/ducting.
if your doing those numbers definitely go 8"

mucho luck amigo

 

[The Meadows]

While 8" is 25% larger than 6", the 8" can move nearly twice the air a 6" can move. The area of an 8" hole is 50 sq in while the area of a 6" hole is 28 sq in.

 

[Rabbi]

While 8" is 25% larger than 6", the 8" can move nearly twice the air a 6" can move. The area of an 8" hole is 50 sq in while the area of a 6" hole is 28 sq in.

Good to know, thx Meadows.

Do you think an 8" 600cfm inline fan would be good enough for four 8"tubes/1000watts?

 

[The Meadows]

Do you think an 8" 600cfm inline fan would be good enough for four 8"tubes/1000watts?

Hard for me to say. There are too many variables involved for my simple mind. The biggest variables:

For every cubic foot of air that you exhaust, a cubic foot of air must be replaced. What's the temperature of the replacement air? The area cannot get cooler than the replacement air temperature.

Moving air thru objects creates friction which slows the air down. Bends, unsmooth surfaces, etc. all slow the air down. A fan rated at 600 cfm may slow to 100 cfm or slower with enough drag.

 

[Rabbi]

Hard for me to say. There are too many variables involved for my simple mind. The biggest variables:

For every cubic foot of air that you exhaust, a cubic foot of air must be replaced. What's the temperature of the replacement air? The area cannot get cooler than the replacement air temperature.

Moving air thru objects creates friction which slows the air down. Bends, unsmooth surfaces, etc. all slow the air down. A fan rated at 600 cfm may slow to 100 cfm or slower with enough drag.

Yeah I hear ya. thinking maybe I'll go with something a little stronger just be safe. Thx for the help.

 

[Rabbi]

Starting to think maybe going with 2 fans per 4 lights. One for push, one for pull. Would be nice if I could just go 2 fans per 8 lights(one straight line) but I imagine things would start getting pretty warm after the first few lights I bet.

 

[GSPfan]

8" is more than 25% bigger than 6".
3.14 x 6 x 6 = 113.04
And
3.14 x 8 x 8 = 200.96.

Therefore 8" is 1.7 times bigger than 6".

Edit: your supposed to use radius not diameter but the 1.7x bigger will remain the same.