negative pressure and a/c?

[Carpet Muncher]

i have an 8" inline and carbon filter blowing up into the attic.. which in the winter was great. however now that the is a/c running, it seem a little wasteful... but i don't know what to do about it?

i tried running it so it recirculates, but even @ 747cfm it didn't handle the odor. the only other option i can think of is to go through the wall and vent into the bathroom, but i'm not sure that would work either.. because i leave the door to the grow room open. (plus i'm not big knocking a 12" hole in the wall.. but i will if it works.)

any ideas or suggestion would be greatly appreciated.. thank you.. CM

[S4v]

What sort of Ac do you have? Wall type or portable? Btu info would be nice as well. You should techically be ducting/routing the output of the AC to an area that can be ozoned or scrubbed. If you're not doing that then thats usually your smell leak in an otherwise closed-off room. For example I route my portable ac's to the Attic and there's an ozone generator up there that works on a timer. Works pretty well so far

If you're handling the routing of the ac's you shouldn't have a problem with your 747 cfm fan doing its job to scrub the room and maintain a negative pressure. But since you do i can only think of 3 reasons that would happen off the top of my head -

1: The ac's fan output has MORE cfm than your fan/scrubber and the fan/scrubber can't clean the room faster than the air is coming in. This will push air thru any cracks in your room and the smell will leak and build

2: The room is too big and its scrubbing, but too slow and small leaks occur and bild (rare).

3: You're scrubbing the room only during 'light-on' times and when lifghts are off your ac's are still pushing air (even tho they're not cooling anything, they push air)

I'm sure there's more but thats what i can think of off the top of my head. Let me know some more details and i'll help you out if i can. Later

[Carpet Muncher]

Sv4.. thanks for the detailed answer, and sorry for leaving out that info.

i have central a/c, and so far the only smell is in the room.. well, actually you can smell it about 6" outside the doorjam the last 2wks of bloom, but that's it. (the door stays open during lights-on.)

also, i'm not using the fan to vent hoods or anything else.. it just sits on a brick on the floor in a corner of the room, and shoots straight up into the attic. set up like this, it creates a neg pressure for the entire interior of the house, (1story) so all the air gets sucked into the attic. when the house is closed up, the fireplace chimney is the passive intake.

also, i don't have the wall/ceilings lined with plastic, so i'm sort of worried about the smell penetrating the drywall. so as soon as i can afford it i'm going to get an ozone gen and do what you said.. stick it up in the attic. i'm also going to put a UPS on it because of frequent power outages due to thunder/lighting storms.. hopefully that will cover it?

[S4v]

Hmm if your door is open during lights on then the recirculating wouldn't work as well. Your problem seems to be number 2 on my list.

During lights on the room technically becomes a HUGE room for 12-18 hours and its just recirculating and pushing the air back thru the open door. The pressure isn't there because the space is too big. The best thing to do would be to hook it back up to the attic so the air will go some place else rather than trying to scrub it. Then kill the smell in attic with a fan/filter or ozone.

If you have smell problems with the fan/filter going to the attic AND the ac going, then the extra air from the ac may just be pushing too much air out for the fan to handle - problem number 1. Your best solution would be bigger/more exaust fans

If you dont live at this place, you may wanna get an ozone generator for the worst smelling area and run it for 30 min or so every other day when the lights are off and nobody is home. Keeps the smells down a lot more than not doing anything and it's relatively cheap for one of those Tiger ozone things. Dunno the exact name off the top of my head. Later man

[hydrorascal]

with your aroma issue ... a nice diy carbon filter or 2 just hanging in the room would be an excellent addition.

[Carpet Muncher]

thanks guys.. currently i have no odor issue.. at all.

and yes, the neg pressure is strong enough that i have to give it a good pull to get the door closed. the intake is the central air vent.

for several reasons, i just don't like the idea of sucking a/c cooled air into the hot attic, and was hoping there was a common solution to this?

also, it's not even hot yet and i can tell the a/c is taking longer to cool the house.. 3yr old unit, functions perfectly..

[plantbuilder]

rheostat

[Old Toby]

I've designed a room about 13'x13' that has AC, 5k watts, 2 scrubbers each with about 500cfm of flow. Because the ceiling is peaked, it has extra headroom on one side of the room. I built a wire shelf 7' off the floor. That is where the scrubbers sit. They suck in the hottest air in the room, through the scrubber, then push through 2 or 3 lights and out into the attic, which also has it's own thermostaticly controlled exhaust fans (3000cfm total attic exhaust). The door to the room will NOT stay open...the pressure is just too much. Also had the AC choked down in the other half of the house so that the flow in to the bloom room is very high....also used insulated 12" ducting and high flow grates. The room will cool down to 62F if the AC runs without the lights. Concrete floor keeps the reses nice and cold. It isn't cheap though....about $6500 retail to get 5 4x4 e&f setup with 5 1k hortilux, scrubbers, meters, controllers, ect....

Tobold Hornblower

[Carpet Muncher]

sounds like the answer is to just go ahead and suck the a/c out.. ok.

thanks everyone for their time, and thanks 3LB for the idea on how to set it up.

[plantbuilder]

lol @ not accepting advice

[The Cannarchist]

"i have an 8" inline and carbon filter blowing up into the attic.. which in the winter was great. however now that the is a/c running, it seem a little wasteful... but i don't know what to do about it?"

I'm not with you CM.

Are you trying to heat the attic in the winter ,from the grow air ,but have to use an A/c to cool it in the summer?( I may be slightly stoned)

[Carpet Muncher]

Canna.. i like it cool in the house (65 or so..) and only heat the vege area.. which is a small area and isolated from the suction.

[The Cannarchist]

Are you in a house or Condo/suite?

[The Cannarchist]

Sorry,not prying...but there are different answers depending....

[Carpet Muncher]

i'm all ears.. wanna sketch?

[Carpet Muncher]

filter.jpg

well it basically worked..

the square at the end of the hallway is the intake for the central air.

[The Cannarchist]

Do you have a "central passage",for vents etc?

Go look at your roof and tell me what you see sticking out the top.

[Carpet Muncher]

yes.. i have tons of passive vents in my attic.
the climate here is very dry.

[kisanth]

CM, sounds like you have a large room that's A/C'd using "central air" for supply and return? And, your scrubbing your exhusted air up into your attic which by pulling out your cooled air is keeping your AC on a lot?

Why not connect your scrubber, minus the inline, to your central airs return and be done with it? This would cool the room while scrubbing the air before it goes back into the rest of the house.

just thinking out loud here.....

[The Cannarchist]

Most bathrooms have an exhaust fan venting to the outside.Is it possible to connect into that instead?

[Carpet Muncher]

K, it's a 10x10 rm, and while i think it could be a great idea, the logistics in this situation would require a lot of remodeling.

great idea Canna, but it has a window.. negating the need <by code> for an exhaust. besides, like Old Toby, i use a 12" insulated duct, and i think most bathroom exhausts max out at 4". and even then, i'd still be sucking out the a/c'd air.

it seems to me that the only other practical place to vent to, would be the bathroom. but <based on almost zero knowledge of VAC> that would only work if the intake to the room was reduced to around the same cfm as the scrubber fan pulls. (iow, reduce the open door to the right sized crack, or cut some holes in the door for passive intake.. with a way to block the light?)


ps.. today i realized (duh) that i could eliminate a lot of the problem by running the lights at night.. so i reset the timer.