Multiple fans for an air cool setup

[InjectTruth]

What's up everyone. You can check out more details about my room here https://www.icmag.com/ic/showthread.php?t=268407

Im wondering if it makes more sense to use one super powerful fan on the exhaust end of a duct run or if multiple smaller fans throughout the run are more efficient.

Also, If you have multiple fans, do they have to all be the same CFM? It seems to me that if i had a 1500cfm exhaust fan and a 600cfm intake on the duct run that the intake fan would actually be limiting the air the larger fan can pull. Is this a correct assumption? Or do the cfm's magically get added together?

Ive been calculating according to the Ventilation 101 thread, and since I will be running somewhere between 3200 and 4000w, I need between 1000 and 1300cfm for a delta T (temp rise above ambient) of 10F. There will be several bends in the ducting so this needs to be accounted for.

Should I go with a 1800cfm fan (or larger?) on the exhaust, or go with 1000cfm on the intake and 1000cfm on the exhaust?

One thing that caught my attention in the vent 101 thread was the mention that more than 1 air exchange in teh room itself per minutes stresses the plants? This is really news to me, as I was always under the assumption that if temps and humidity is in check, you cant really move too much air. Sorta like light.

With this in mind it seems more prudent to run a super high CFM through the duct run to try to keep the temp rise as minimal as possible, so I can exhaust the room with a simple 6" 450cfm fan, for a single air exchange every 4-5 minutes (14x18x7 = 1764 cu. ft.)

 

[InjectTruth]

bump

 

[Skyrancher]

I'm no HVAC pro, so I can't comment on adding CFM's.

I can say that using 2 smaller fans to cool your lights will be more efficient. Use 1 fan for each string of 4 lights in a row and exhaust straight out if able. That will cut out all the 90 degree bends. Just one 90 degree bend greatly reduces efficiency and airflow.

Larger fans require larger ducting, which gets expensive and difficult to find over 10". Look at mixed flow fans for more CFM's in smaller fans. Vortex and Fantech are a couple brands.

More later. Phones out of juice.

 

[Skyrancher]

Im wondering if it makes more sense to use one super powerful fan on the exhaust end of a duct run or if multiple smaller fans throughout the run are more efficient.

Also, If you have multiple fans, do they have to all be the same CFM? It seems to me that if i had a 1500cfm exhaust fan and a 600cfm intake on the duct run that the intake fan would actually be limiting the air the larger fan can pull. Is this a correct assumption? Or do the cfm's magically get added together?

One thing that caught my attention in the vent 101 thread was the mention that more than 1 air exchange in teh room itself per minutes stresses the plants? This is really news to me, as I was always under the assumption that if temps and humidity is in check, you cant really move too much air. Sorta like light.

With this in mind it seems more prudent to run a super high CFM through the duct run to try to keep the temp rise as minimal as possible, so I can exhaust the room with a simple 6" 450cfm fan, for a single air exchange every 4-5 minutes (14x18x7 = 1764 cu. ft.)

Had a look at your plans. Very ambitious setup. Nice !!

You say, "In that space, Im hoping to run 8 - 10k". I assume you mean this is your total lighting for veg and flower? If it is only for flower, I would consider more cooling.

But back to your question. You have 2 lines of 4 lights to cool. I would suggest using 1 fan on each line of 4 lights for a couple reasons. With 1 fan on each run of 4 lights, you could cut out the 2 180 degree turns, which will kill your airflow and efficiency. The less turns, the better.

The other reason is that cooling 8 lights in 1 run will not cool the last 4 lights very well, which could lead to premature bulb failure and over heated plants. At best, the last 4 lights will have to be further away from your plants to prevent scorching or bleaching.

About mixing fans, I don't understand the dynamics, but would not mix different cfm fans. Look up Galahad here on ICMag. He is an HVAC pro who is very knowledgable and helpful. He would know the answer to this question.

As for air exchange rate per minute stressing plants, I defer to DHF, a veteran on the forum. "forget about blowin air ON the plants instead of around em.......and why ?.....

Blowin directly on the plants causes increased transpiration and excess nutrient uptake that in turn shuts the plants down from eating , and then stored nutes ensue causing ph to drop and ppms to soar with lockouts and imbalances right around the corner."

DHF also has his 10 Commandments of Growing....#3 is, "III. Thou shalt exchange thy air 2x a minute."

Hope my limited knowledge helps.

Have a good grow

Rancher

 

[the gnome]

thanks for that skyrancher,
do you by chance kniow where to find all of DHFs *commandments?

 

[Catfish Billy]

I would venture to guess to look back at any of the 100's of posts he has made. Pretty sure he regurgitates them often...

 

[Skyrancher]

thanks for that skyrancher,
do you by chance kniow where to find all of DHFs *commandments?

Yes, I do...To avoid hi-jacking the thread, I'll PM the 10 C's.

 

[InjectTruth]

Thanks for the answers, fellas.

Skyrancher - feel free to post that list right in here. DHF is a pro who has helped me many times. Always willing to lend a hand.

I hear what you are saying about independent runs. Im tryin to avoid cuttin holes in the wall, but am starting to get over that.

The pressure is gettin to me and I may just set the tents back up for the winter. I know it works and sure its a tighter space to try to pull numbers from, but every run up till the summer heat shut me down got better and better.

Then I could just throw an extra light in the extra bedroom, and another in the soil room after i straighten it up to try to up my numbers for now.

Its really gettin to me, but I'll figure it out. I just can't afford any mistakes/ learning curve right now. We shall see.

 

[Skyrancher]

The 10 commandments

"I. Numbers shall dictate thy yields.

II. Thou shalt use no less than 50wpsft.

III. Thou shalt exchange thy air 2x a minute.

IV. Thou shalt pull all lateral suckers from thy main branches.

V. All fan leaves shall be removed from thy plant by the harvest moon, starting after thy plants have finished stretching.

VI. Bare bulbs rule, all others drool.

VII. Thou shalt wash thy illicit drug profits with "rent to own" houses.

VIII. Everything that isn't green shall be covered in reflectix.

IX. Thou shalt monocrop to dial every last gram out of thy bitches.

X. Thou shalt take 2x the cuts needed and keep only the strongest and fastest rooting.

And they all rejoiced, for life was good and the harvests were plentiful... "

 

[DHF]

The 10 commandments of the Book of DHF

"I. Numbers shall dictate thy yields.

II. Thou shalt use no less than 50wpsft.

III. Thou shalt exchange thy air 2x a minute.

IV. Thou shalt pull all lateral suckers from thy main branches.

V. All fan leaves shall be removed from thy plant by the harvest moon, starting after thy plants have finished stretching.

VI. Bare bulbs rule, all others drool.

VII. Thou shalt wash thy illicit drug profits with "rent to own" houses.

VIII. Everything that isn't green shall be covered in reflectix.

IX. Thou shalt monocrop to dial every last gram out of thy bitches.

X. Thou shalt take 2x the cuts needed and keep only the strongest and fastest rooting.

And they all rejoiced, for life was good and the harvests were plentiful... "

by DHF

NOT by DHF..... For the record.....Bobblehead posted that shit with his sarcastic ass in HL45`s thread , but.....

For the most part all the rules are from time tested and proven methods/techniques for dialage .....

After Bobble`s post about the 10 commandments , I came back with the additions of what he left out , but pretty sure all those posts have been deleted in the Love Machine thread......anyways....

I didn`t create "DHF"`s 10 commandments in post form , but I stand by each and every 1 as the way shit works if yas pay attention to detail.....

Peace.....DHF..........

 

[coldcanna]

The 10 commandments

"I. Numbers shall dictate thy yields.

II. Thou shalt use no less than 50wpsft.

III. Thou shalt exchange thy air 2x a minute.

IV. Thou shalt pull all lateral suckers from thy main branches.

V. All fan leaves shall be removed from thy plant by the harvest moon, starting after thy plants have finished stretching.

VI. Bare bulbs rule, all others drool.

VII. Thou shalt wash thy illicit drug profits with "rent to own" houses.

VIII. Everything that isn't green shall be covered in reflectix.

IX. Thou shalt monocrop to dial every last gram out of thy bitches.

X. Thou shalt take 2x the cuts needed and keep only the strongest and fastest rooting.

And they all rejoiced, for life was good and the harvests were plentiful... "

Bahahahahahahah, I spent months and months reading thousands of pages and everything I ever needed was right here, they should make all the new members read that before your profile is up! Freakin brilliant!