have i got enough ventilation

[ganjawarrior]

My grow room is 14 foot long 6.5 foot wide and 7 foot high. I have a 6" tt150 inline fan as an exhaust and a 4" passive hole bringing fresh air in from outside is this enough?

To be honest my grow room is a shed outside and i dont really like passive holes because it means having holes in the side of my shed and they let alot of light out. Is there another way to get air in maybe i could have a fan bringing air in that way i could block the light by using ducting? If i could have a fan bringing air in what size should it be because i dont really understand the negative pressure thing to be honest and dont wanna get it wrong? THANKS :confused2: :bong2:

Nearly forgot i am running 4 600 watt hps lights.

 

[pcduck]

Well to begin with 4 600 watt hps is not enough light. Most grower try to have 5000 lumens/sqft. You need 455,000 lumens and your 4 600's are only giving you 380,000 lumens depending on the bulbs used.

Not sure what a tt150 inline fan is, do you have a link we can look at?
But without knowing the cfm's I would say no, this will not be enough to cool the room. I would look at an inline centrifugal fan that has a rating of at least 637 cfm's.

 

[Locked]

Pc is right...not enough light. You are almost another 600w short. 85,000. I think 600w HPS go 90,000.

 

[The Hemp Goddess]

If your inlet is only 4" for a room that size, I am going to hazard a guess without even knowing what kind of inline you are running and say, "No, you do not have enough ventilation."

You can make light traps (similar to sink p-traps or s-traps) to keep both the inside light out during flowering and the light inside from escaping.

I didn't find much info on your fan. It appears to be 415-450 cfm, but the cfm drops so sharply with any static pressure that I believe it is a duct booster fan and not a stand alone fan. However I could be wrong. How warm does your space get? I am thinking also that the fan is not nearly large enough to cool 5 600W lights.

Negative pressure means that you have more outgoing air than incoming air--this is why we pull the air through the space with an exhaust fan rather than blowing air into the space. By having negative pressure, you keep the smells of the grow room from sneaking through to the outside. You can stand right next to my flowering space and not be aware that it is full of plants almost ready to harvest. Rather than adding an intake fan, you should have more passive inlets and more exhaust. Even if your fan is operating around its max of 450 cfm, you are only exchanging your air about every minute and a half or so.

Remember when figuring intakes and exhaust that every time you double the diameter of a circle, you 4x the area--a 6" hole has twice the cross sectional area of a 4" hole, an 8" hole 4 times the area.

 

[ganjawarrior]

My room aint too hot to be honest its just right 25-27 celcius when lights are on and 19-21 celcius when lights are off. But the reason i was asking if i had enough ventilation was because i wanted to know if i was replacing enough fresh air with a 4" hole. The temperature is alrite at the minute because the weather is alot cooler here where i am. How many more 4" passive holes will i need and if i get a centrifugal inline fan as an exhaust how big of one will i need?

I might sound stupid THG but when you say a p-trap or s-trap do you mean make an s bend in some ducting from my passive hole?

Also lights are not a problem ive got two spare so i will put them up there should be plenty of light then.

 

[The Hemp Goddess]

Basically, yes, only I use 4" plumbing fittings rather than ducting. All sinks have P-traps or S-traps (older homes)--look under a sink. S-traps look like an S. P-traps don't much look like a P though. You probably do not need a double bend, like an S.

I personally like to exchange the air in my space 2-3 times a minute. If your fan is working at max pressure it takes about a minute and a half to exchange the air in your space. I think you need more intakes and a larger or another exhaust fan.