My Room Layout: Opinions?

[philbu]

Hi,

I've got about one more week of vegging my scrog and am trying to get the layout right for flowering.

The room is 10x10x8 (800 cu ft)
(2) 4x4 tables
(1) 1000w light each table.
(3) 6 inch, 530 CFM fans

the carbon can will hang from ceiling, its fan will blow through the lights and out through the attic. The intake fan will be mounted to the floor's heat register and draw air from the much cooler crawl space.

My main question is do the placements of the carbon filter/fan, intake and exhaust fans make sense or are they the best way? That, and I hope the 3 fans are strong enough to do the job.

Thanks much for opinions/suggestions! : )

phil

 

[sensibuds]

Pull the air through the can and lights from the attic if possible.

 

[philbu]

Thanks for the reply. The air in the attic is hot (california summer). I was hoping to draw nice cool air into the room from the floor (crawl space, fan 2) and avoid an air conditioner. That cooler room air would then be sucked into the canister (hanging from ceiling on opposite side of floor intake) by fan 1. That would scrub the smelly room air *and* then be pushed through the ducting (yellow) through the lights and out the attic with help from fan 3.

 

[rives]

A couple of things to consider that may or may not work in your installation.

If you set the light cooling loop up so that it draws from outside, pressurizes the fixture, and dumps outside, you wouldn't need a carbon filter on that loop since it wouldn't have smelly air in the loop. Any air that leaked from a poor seal on the hood would leak fresh air into the room rather than pulling smelly air into the loop. A furnace filter or HEPA filter should be put on the inlet to keep dirt out of the fixture.

Dumping moist air into the attic can start mold going in very short order - if you can duct it over to a gable vent and blow it straight outside it would be much better.

The crawl space is going to warm up to ambient temperature pretty quickly if you are pulling 500 cfm of air through it. It certainly won't be as hot as air from the attic, but it will be whatever temperature the air is where the basement vents are. The fan cannot pull a vacuum on the crawl space - any air pulled out of there has to be exchanged with air coming in from the outside.

 

[philbu]

A couple of things to consider that may or may not work in your installation.

If you set the light cooling loop up so that it draws from outside, pressurizes the fixture, and dumps outside, you wouldn't need a carbon filter on that loop since it wouldn't have smelly air in the loop. Any air that leaked from a poor seal on the hood would leak fresh air into the room rather than pulling smelly air into the loop. A furnace filter or HEPA filter should be put on the inlet to keep dirt out of the fixture.

I think I understand. But that would mean I need another intake from outdoors into the room, in addition to the crawlspace intake? There is one window to the room (spare bedroom), now blocked with foam sheeting. Would have to cut hole in foam and mount fan just inside or outside of the hole to blow outside air through ducting and the two lights. Sorry, thinking aloud here.

My other concern is smell coming from that room into the rest of the house. I suppose a bead of calk around the inner door frame might make a good seal when the door is closed.

Dumping moist air into the attic can start mold going in very short order - if you can duct it over to a gable vent and blow it straight outside it would be much better.

Quite correct, I've already cut the exhaust hole in the closet ceiling, close to light #2. Duct is going through the hole into attic and over to the gable.

The crawl space is going to warm up to ambient temperature pretty quickly if you are pulling 500 cfm of air through it. It certainly won't be as hot as air from the attic, but it will be whatever temperature the air is where the basement vents are. The fan cannot pull a vacuum on the crawl space - any air pulled out of there has to be exchanged with air coming in from the outside.

This is an interesting consideration, hmm. I get the concept. Was hoping to avoid the whole air conditioner thing.
Great input, much appreciation.

 

[rives]

My other concern is smell coming from that room into the rest of the house. I suppose a bead of calk around the inner door frame might make a good seal when the door is closed.

If you can avoid the fan at the air inlet (at the crawlspace) the other fans operating by them selves will pull a negative pressure on the room so that no smelly air escapes into the house - all of the airflow would be the other way. The fan at the crawlspace will try and put positive pressure on the room, forcing dirty air out of any available crack.

 

[philbu]

That's an answer to a question that's nagged at me for awhile, could I eliminate that fan. I've seen plenty of references to low/high pressure, but stuff doesn't always sink in until it's time.
By cutting out that fan, would there be any significant impact on the rate of air exchange in the room? I read how air has to be replaced every minute, or every five minutes, or whatever.

thnx

 

[rives]

If you have equal volume fans at the inlet and at the outlet, theoretically your airflow is unchanged. Each one is moving the same amount of air, so the net gain is zero. If they were operating in parallel (both blowing in or both blowing out) then their volumes should be doubled.

Reality, of course, is a bit different. If you have a restrictive inlet, putting a fan there is going to help boost the volume that the exhaust fan can move. However, if the outlet is restrictive, then the inlet fan can get the upper hand and put positive pressure on the room, causing smelly air to escape.

If you can get the lights on a different air circuit than the room air and have a free-flowing inlet, then you should be able to approximately double the air volume because the fans are working in parallel and the volumes add up. Your design has the fans in series, with each one feeding the next, and so your maximum airflow is whatever the smallest or least efficient fan is capable of moving.

 

[philbu]

I understand the airflow options, now, and have an idea how to move forward. Kudos to you for your knowledgeable assistance, rives, guess that's why you're a mentor. : )