Need a proper inline fan

[Padox]

The fan will be more than ample provided the air coming in is below 25c. I don't personally have a carbon filter and there for cant help as far as how much it will restrict air flow but a simple fail safe would be to get one designed for 6in ducting and simply have 6in down to 4in with a premade adaptor and continue the rest in 4in as planned, im sure that would create near no restriction. You truly do need to suck through the filter for max efficiency. when air gets pushed into the filter it bounces back and causes air disturbance and an airlock of sorts, pressure does build up and begin to flow out but slowly. Sucking allows for the full surface area of the filter to be used... As for the 600w bulb heating up, as there is air passing over it from warm up and non stop through the day, the heat really shouldn't build up. Although on the small end of fans.. 175cfm of air passing over a single 600w bulb is a lot, id use a similar volume of air to cool a compressor system on a 8x8x8 cool room

 

[GreatLife4All]

The fan will be more than ample provided the air coming in is below 25c. I don't personally have a carbon filter and there for cant help as far as how much it will restrict air flow but a simple fail safe would be to get one designed for 6in ducting and simply have 6in down to 4in with a premade adaptor and continue the rest in 4in as planned, im sure that would create near no restriction.

Size of the vent out of the filter does not matter.

The fan must overcome the static pressure imposed by the filter. This can be accomplished with a 6" opening or a 1" opening. It can also fail with a 1" opening or a 6" opening. Pressure is not volume. And volume won't help you to overcome the static pressure.

Static pressure conversion to Velocity Pressure is what is important. A fan will produce a certain amount of total pressure - part of that is burned to overcome static pressure - the rest is used to produce an air flow with a certain volume. and the relationships betwen Static, Total, and Velocity pressure are given by this formula:

Total Pressure = Velocity Pressure - Static Pressure​

or, rearranged slightly:

Velocity Pressure = Total Pressure - Static Pressure​

Without getting into specifics, it is easy to see that the higher the Static Pressure - the lower the Velocity Pressure... if you keep the total pressure the same.

Or... the static pressure imposed by the filter must be overcome to produce a flow of air.

From experience, the static pressure of a good carbon filter will cut the air flow rating of any fan. How much can not be predicted based on the info given in this thread. An inline booster fan has very little total pressure. An inline fan has a higher amount of total pressure. One of the specially designed hydro fans for carbon filters have very large total pressure ratings. So each type of fan will see a different drop in the volume of air flow produced.

It takes more energy and better designs to produce higher total pressure ratings - thus the better fans are much more expensive.

 

[DSXJ]

You sir, are very knowledgeable and I have learned quite a bit from you in this thread.

If I could, I would add more rep.

Thanks buddy!

 

[Grow nh]

Don't know if it will help, but I had to swap out my 4"and get the 6" to keep heat down.

My set up. 2.5'x5.5'x6' with 600w light, outside temp 64-68° inside grow room temps would hit high 80's easily .i had 4" fan with filter that I was using with cfl's and really didn't want to buy a new fan so I gave it a shot and temps got to hot even with a 12" and 6" fans blowing air around . Went and got 6" fan with speed controller and temps are much lower now, as of now with 6" fan temp has been 78°-80° with controller on 70℅
Even with 16 23w cfl's temp was maxing out at 82° with my 4" fan.
I had the 4" pulling filter-hood-fan-outside , have 6" same way

I knew I should have got the 6" when I brought my light, oh well what's one more trip to hydro store.

Good luck

 

[DSXJ]

Yea your outside air temp will be much higher then mine

In about another month or so my temperature outside will be -25 to -40 C so that when I run my 12 on 12 off during flower the 12 on will be during the night when no one is awake and furnace is not running. Should keep temps down quite a bit so I'm thinking the cool tube + the 4" fan will work. I noticed you did not state you if you were running a cool tube or not.

When running my 600w @ 100% I get temps of 90-97° and at 50%/75% between 80-90°. Adding the cool tube plus the 175cfm fan for the little area should do wonders, all I have is 3 cpu fans and a regular home fan. The plants thus far are not having an issue with being ran 400watts MH @ 85-90°, even when the temp was 95° I didn't notice much of an issue some strains can handle it from what I've heard. Not like I'm going to run the temp that way the whole time obviously because it's my smoke and not my "Experiment" lol.

Once I get the last of my order in things should come together nicely.

 

[Padox]

Size of the vent out of the filter does not matter.

The fan must overcome the static pressure imposed by the filter. This can be accomplished with a 6" opening or a 1" opening. It can also fail with a 1" opening or a 6" opening. Pressure is not volume. And volume won't help you to overcome the static pressure.

Static pressure conversion to Velocity Pressure is what is important. A fan will produce a certain amount of total pressure - part of that is burned to overcome static pressure - the rest is used to produce an air flow with a certain volume. and the relationships betwen Static, Total, and Velocity pressure are given by this formula:

Total Pressure = Velocity Pressure - Static Pressure​

or, rearranged slightly:

Velocity Pressure = Total Pressure - Static Pressure​

Without getting into specifics, it is easy to see that the higher the Static Pressure - the lower the Velocity Pressure... if you keep the total pressure the same.

Or... the static pressure imposed by the filter must be overcome to produce a flow of air.

From experience, the static pressure of a good carbon filter will cut the air flow rating of any fan. How much can not be predicted based on the info given in this thread. An inline booster fan has very little total pressure. An inline fan has a higher amount of total pressure. One of the specially designed hydro fans for carbon filters have very large total pressure ratings. So each type of fan will see a different drop in the volume of air flow produced.

It takes more energy and better designs to produce higher total pressure ratings - thus the better fans are much more expensive.

Great information there mate, + reps, looks like your knowledge goes deeper than mine. I just figured a filter designed for a 6in fan would be longer and wider and therefore have more surface area and less restriction. A 6in fan wouldn't be able to get its 250+cfm through the filter but a 4in could get its 175cfm. All theoretical for me as I said I work with filters, fans and ducting but never with a great amount of restriction. I also use a 400w HPS so perhaps im underestimating the extra heat. I agree with Grow nh in that a 6in is problem solved but if you have a 4in cool tube, bigger ducting either side will make no difference as the 4in cool tube is a restriction

 

[Grow nh]

I have a cool hood,
My setup is in my basement (unheated), temps outdoors different story winter is coming and temps will -10°to-20° at night.
I did notice the carbon filter did affect the fan cfm output , how much I don't know.

Good luck

 

[DSXJ]

Just thought I would add that my fan and filter has shown up.

With no cool tube or air cooled hood I am running temps from 600watts at 80-85 degrees in my 48x24x58.

The fan was rated at 190cfm and is clearing my room 7 times a minute, there is extreme negative pressure sucking my tent door in.

The positive thing, it's holding steady temps! Mind you my OAT ( Outside air temp ) is probably much lower then the average persons.

GL to anyone who comes across this read!