Recomended air flow for vented hoods?

[slackerbri]

Hello,


I was looking for some knowledgeable info and advice on venting multiple air cooled hoods. Is there a recomended formula of CFM to Watts and/or the total length of of ducting/area cooled? Any info and experience is greatly apreciated.

 

[Guest]

It would be easier to relate to if you could tell us how many hoods you intend to run, their wattage and vent hole size. Different inline manufacturers have different CFM performance for the Same Size when compared to one another.

TyStik

 

[darrinjefferson]

well as long as he has the question posted i will put mine up hahaha.

Im going to do a set up with 2x600watts. they will have aircooled hoods as well. will a vortex 8" with 747cfm be enough to cool them?

thanks for the help

 

[Guest]

You can bet your Bippy it will work, jeez, I use a 10" on 6 x 600 with Plenty of CFM's to spare, and "O" heat issues.

You will be good to go when and if you expand your grow and light system.


Above are 5 x 600 and an 8 tube t5 on a 10" CanFan inline ( not all are visible), also overkill, and no worries.

TyStik

 

[darrinjefferson]

thanks alot for the response ty-stik. i saw that build of yours and i must say it is really impressive. if ya dont mind i got some other questions for ya too.

1- i assume i will be able to run a filter if needed as well with the 8" fan? not planning on running one but if it gets stinky i will.

2- i have heard talk about sealed rooms and such. i am going to have 2x600 in a line...the question is where should i get the air. should i do a sealed system just cooling lights. or should i put a large intake holes in the room to allow air in and then it will be sucked through the lights?

i also will have an a/c unit built into the room so i can use it when its too hot. not sure if this makes a difference.
thanks for your help

late

 

[yamaha_1fan]

when doing a sealed room, most use C02. So the hood coolong needs to be sealed by pulling air from a seperate room, environment, etc, passing it through the hoods, then exhausting outside of the room. Otherwise you would loose your C02

 

[Guest]

Hi Yamaha-1fan, check out these cooling watts/cfm charts. The first one was rescued from the OG HPS users group and the second one is from an electronics company for cooling general purpose electronics. I also have a computer program for calculating air flow through electronic cabinets which verifies the accuracy of these charts.

If you are going to cool multiple hoods a parallel arrangement is superior to a serial one. Let's say the airflow through the hood results in a 20*F increase in ambient temp, and you have 3 hoods, then the exit airflow will be 60*F from the last hood.

 

[slackerbri]

Wow thanks everyone for their input, espically that graph Red, much appreciated.

Myself I am running 2 600's and a 1000 watt all in a serial setup with the 1000w between the 2 600's. I use a Vortex 6" fan and I use Hydrofarm hoods all with glass, 2 Radiants with built in 6" flanges with and a Daystar with built in 6" flanges as well. I run the 600's in the Radiants and the 1000w in the Daystar in the middle of the two. Currently I can run the 2 600's without a significant amount of increase in temp(non air cooled hoods, low 70's) but as soon as I add the 1000w it just starts climbing and climbing into the 80's. I figure no matter what I am going to have a significant amount of cooling when I connect the ducting to the fan. The total run of the ducting including the hoods is aproximately 15 ft and I am setup for pushing the air thru as opposed to pulling.

 

[salgjkhaf]

yo slacker. is there anyway you can pull the air? i'm not too positive about this but i think you might have better air movement if you pull instead of push. and according that chart, the cooling tystik is using would be impossible. 5 600s is 3000 watts and a 10 inch fan only pulls about 800 cfm and that is the load line for a 4 F increase with only a 1000 w light. maybe i'm just confused.

all i know, is that i need a 6 inch. my fan (see below) isnt cutting it.

 

[slackerbri]

Good question about the pulling vs pushing, I wondered that myself and was told at the store where I bought my fan that it didnt really matter too much, just as long as there is air flow. Another question would be how much of a difference does it make to use colder air as opposed to warmer air over your bulbs for effective cooling?

I finally have time to hook everything up in place tonight and see whats up, my aim is to keep my room in the low 70's with 2200w going, wish me luck.

 

[Albert Hofmann]

I'm going to agree with Ty, as long as your setup is rigid duct, sealed, pulling air not pushing and I prefer no more than 2 lights in a row...you can cool alot of watts with 1 decent fan. Personally, I run 6-600 and 2-1000 hps all cooled by 1 10" vortex and it works quite well.


Intake:

Intake trunk:

Exhaust:

Exhaust trunk:


And if you guys are planning on running several lights and live in a climate that is warm or has a warm summer, you will still need some form of AC. I don't care if you are running 3000cfm through each light, the radiant heat has to be dealt with.

 

[salgjkhaf]

Good question about the pulling vs pushing, I wondered that myself and was told at the store where I bought my fan that it didnt really matter too much, just as long as there is air flow.

i'd trust the people around here way before i trust some hydro store guy tryin to charge me 300% on every items wholesale price

 

[Guest]

Darrinjefferson: With the 8" inline and your lights install the Carbon Filter against the inline and discharge directly outside. In my setup the air comes in from outside via a 10" rigid duct. Running 3 pairs of 600's with each pair having their own hookup to the cool air intake duct, through the hoods and out to another 10" rigid duct that connects to the inline 10". Air flow is adjusted by way of dampers aided by an Infrared Thermometer that a assists in determining flow temps for each pair of hoods.

Fresh air for ventialtion is provided by a filtered 6" inline, on the floor, pulling from outside and discharging into the room. Both the 6 and 10 inch fans are connected to my Cap Controller. When radiant temperatures reach 81F at top of plants the controller turns on both inlines and at 75F turns off.

There is also an 8" 'Carbon 3' filter with matching inline that is timer controlled @ 15 minute intervals.

Summer temps are dealt with via a 12,500 btuh through wall mounted A/C, when needed. As you can see the room is Controlled, it doesn't control me, which leaves plenty of time to grow without having "issues" to deal with. Except during planting re potting and chop the grow requires very little time for general maintenance.

When it is lights on I walk in, check soil moisture, plant health and walk out. Fortunately there is plenty of floor space for the grow which also helps dissipate internal heat during the Fall, Winter and early Spring time.

Basically if all is well the girls, babies and clones are left alone to do their thing without being fussed over and killed with kindness.

TyStik

 

[slackerbri]

so whats the concensus, push or pull the air?

 

[ZoSo]

I don't have a source but i always heard it's more efficient to pull than push air.

Something having to do with the physical properties of it.

I suppose if you have negative air pressure then there would be less resistance but that's pure speculation.

EDIT: Also, if you have any leaks you'll lose less hot air with negative pressure.

 

[slackerbri]

I would think pushing fresh air into the system would be more efficient then trying to pull hot air out because air will pull out of any available space at whatever CFM rating the fan may pull but introducing new fresh air into the system coming from outside at that same CFM may work better but I imagin alot of it has to do with how your system works. Space wise it works better for me to have the fan in a certain place and then exhaust thru where my A/C does.

Please if anyone knows anything otherwise please tell me whats up.

 

[darrinjefferson]

ok so if im not using co2 would it be better to use a non sealed room or sealed room?/ wouldnt i need fresh air right? i dont know why i am confused but if anyone can help i would appreciate it

 

[Albert Hofmann]

pulling air is the most efficient method not pushing....like was stated in several previous posts

 

[Guest]

What Albert said

Slakerbi, try this----hold your hand fully extended in front of you with the flat of your palm in front of your face-----now blow as hard as you can...............not much air gets there, right? Hook up an inline in the sucking mode and it will pull air, lots of air.

This "pushing of air" is what Newbs pick up on and take as fact, nothing could be farther from the truth, wind tunnels being the exception and you aren't running a 1000 horsepower engine on your fan either.

TyStik

 

[darthvapor]

i prefer seperate intake and exhaust plenums rather than inline cooling the lights. I also have my ballast in a box I made for them and that gets cooled too. makes a big difference. I wasnt able to remot mount them. I use passive on the intake and have 5 1000 watters hooked up to a vortex 8". The duct is a straight shot from the room to the fan and vent point 5 feet away. the lights get hooked to the rigid by flexible aluminum dryer vent. room temps went from 92f to 78f with just that modification. The extra money I saved on air conditioning got me to my last amsterdam trip.!!!