Indoor My fan isn't cutting it

[SHRED]

I have a 4" Vortex fan 172 cfm.
My space is about 49 sq ft.
I have tried both T5HO (2-2'x4 bulb fixtures) and a Mars 900w LED fixture. Both produce too much heat for that fan to keep up with effectively. This is even without a carbon filter.
I'm running about 20 feet of ducting which has about 3 bends in it.
What can I do? Get a bigger fan? My ducting runs through drywall so I'd like to stay with 4". Would a bigger fan, reduced down, work?

 

[gmgeoff]

I also have a 4" system, in only a 18sq. ft. area. But I have 6 LED fixtures putting out 735 (true output)watts.
First time I closed it up with them all on, the temp. quickly shot up to 95.
So now I just leave it open all the time. I'm in my attic that's air conditioned so that brings it down. I also had to run two 4" A/C lines into the grow area. I can keep it under 85, but I get temp. swings 70 to 85, not to mention if the plants are high smell, it will go throughout the house (smells good though)

You have about twice the cubic feet that that fan is rated.Since you don't want to change the 4" duct. Maybe putting a strong booster fan in line might help. To what extent I don't know. Maybe someone else on here has used one.
No matter what type of lighting you use. XXX-watt output for all lighting types will give off the same amt. of heat.

 

[Bayes]

IMO, you have an undersized fan for your space AND with the three nineties (with 20 feet of ducting) you have the equivalent of almost 170 feet of ducting. (If I recall correctly, a 90 degree bend adds the equivalent of 50-70 feet of straight ducting. So your 20 feet of ducting with three nineties is the rough equivalent of 170 feet of straight ducting.) Whoa!

I don't think getting a higher output fan and stepping it down alone is going to solve the problem. I think you need a higher output fan AND an inline booster fan because of length of ducting with three nineties. (I have no personal experience w/ boosters, just know a bit about HVAC.)


You might want to use one of the fan sizing "programs" to figure out what size fan you need for your grow space volume w/o the duct run and three nineties.

BTW, I have the same fan with two nineties and 2 feet of ducting (converted wine cabinet).

 

[Bayes]

Just wanted to correct my previous post, I did some research---

I originally posted that a 90 is equivalent to 50 feet of straight ducting. This is probably, almost certainly, overstated. A lot depends on the radius of the bend and whether the interior of the bend is smooth or corrugated. But even in the best of cases, three nineties will add significant additional friction reducing exhaust output.

 

[fweedom]

what are your temps like in the room that your grow space is in? :Sharing One:

 

[wakkytbakky]

got a pic?

 

[SHRED]

I added a booster fan at the intake. It is helping. Here are some pics with some scribbles on them...LOL

 

[SHRED]

what are your temps like in the room that your grow space is in? :Sharing One:

We're having a heat wave now and since my space ins't A/C'ed it in the mid to high 70's in the space with 50-60% RH.

This is with the door off and fans blowing in and around. I'm testing an inline booster fan now (see pics above) and the temps are much better than they were without it and the door closed. I'm testing using the T5 lighting now. Later sometime I will test the LED.

 

[bad dragon bzzz]

why not do away with the 8 feet of ducting and vent into the room in last pic ? in theory if the filter is working correctly smell will be gone,so no need to vent outside.or use the 8 ft of ducking to draw air in from outdoors.

 

[greenjeans]

If it were me, I would try attaching the fan to the carbon filter, putting it at the other end of the system. I would also not have the filter jammed up in the space it is in, but rather let it hang free. Perhaps with some bungees attached to that beam. I'm no engineer, but it seems like the better design is to pull directly from the filter, where you have the greatest amount of resistance, and push through the long stretch rather than trying to suck through the stretch. Also, if the filter is working well, why not just vent into that room and eliminate the long stretch altogether?

Is the air you are pulling in from an air conditioned area? That could help, too.

Good luck!