Venting

[KushBlower12]

Ok so im going to run 4 600 watt lights in my den. Its the coolest room in the house and its secluded. My concern right now is air ventilation, I believe its vital and Ill do anything to have supreme flow. I cant intake from the window because it faces the front of the house.

So would it be alright to intake the air from the crawl space under my house since the air is cooler?

Basically, I want to run an air cooled system. Ill have filtered ducting leading from under my house to an intake fan that sucks the air through the ducting and the light hoods and then exhausted through the attic with a carbon filter at the end.

And should I have another fan of equal force at the end before the filter?

2 heavy duty blower fans should generate quite a bit of air flow.

please let me know, thanks guys

 

[The Hemp Goddess]

I pull air from my crawl space. All intakes should have some kind of screening to keep bugs out. And if you have mold in your crawl space, you have it in your home. Those spores do not know they are supposed to stay in the crawl space...

If I understand you correctly, this is not going to work.

crawl space--fan--ducting--light--light--light--light--carbon filter--exhaust through attic

Is this right? If the ventilation to cool your lights is pulling air from outside your grow space and exhausting outside, you do not need a carbon filter on this ducting--there is no air from the grow space getting in. You are going to need a substantial fan to cool 4 600W lights. What brand/type/size fans do you have? How many cfms? How large is your ducting?

Also, you need a continual supply of fresh air coming into your grow space all the time the lights are on. Your plants need CO2 and you need to exhaust the oxygen they expire. I like to exchange the air 3-4 times a minute, but once a minute is probably sufficient. So what is the volume of your den?

You have a couple of options here. Can help you more when we know more about the fans.

 

[KushBlower12]

Thanks Goddess for the great info. Ya that is basically what I was thinking, but I guess I didnt clarify. and you're right - since I'm pulling from the outside and its going through the hoods and right back out, I wouldnt need a carbon filter. Ill change it up a bit.

Intake - 12,000 BTU portable A/C unit with thermostat and exhaust ducting in back (hot air from ac going right back outside)

Exhaust - (2) 6" Growbright Inline fans with 6" ducting through 2 hoods each. Then ducted through the ceiling and into the attic where a carbon filter will clean the scented air. The inline fans push 424 cfm each. Would that be enough you think? My den is roughly 300 sqft.

Thanks!

 

[Old_SSSC_Guy]

I genuflect to the Goddess for her wisdom (grin).

Remember that if the 12,000 BTU cooler is pulling a lot of air and exhausting outward, you need equal to that volume of fresh air intake to the room. Ditto for the inline fans. If are pulling maybe 1000cfm from the room - it has to come from somewhere. If you don't accomodate it air will be sucked in from the house - possibly impacting other vented applicances in the house. If you have electric heat/cooling/hot water its not as much an issue. But if you have gas/propane heat or hot water then you have a problem. Gas hot water heaters are seriously lame in the way most of them vent and running them in a negative pressure space is very bad mojo on the fumes.

Its not the square feet that matters - its the cubic feet. A 15'x20' space is 300sf - but if its 7' high its 2100 cubic feet of air space. So your crawl space intake better be a big sucker (literally). Some crawl spaces are real humid, sucking that straight into the grow might not be a good thing. The light systems will dry the dry as it passes through them, but heat it too.

Don't blow air into ducting - always suck air through it. Its all about the air pressure in the ducting...