# Temperatures



## getnasty (Apr 15, 2012)

I need to get my temperatures in check, and quickly. I got the new light hung up in the closet last night before the lights flipped off. The temperatures in the closet, though, and running in the low 90s. I didn't think adding 200W to my closet was going to boost my temperatures that much! I've got all my ducting setup and sealed, and the exhaust air is coming out fairly well. But my room stays in the high 80's/90's.

Now, my switch is dimmable. 50%, 75%, and 100%. Is dimming it down going to reduce the heat put off of the light at all? 

Is my room running at this temperature throughout flower going to harm my plants? Does heat stress induce hermies? And is it for certain going to happen if I leave the temperatures alone?

I don't understand. The hood is air coolable. My last one with a 400W MH wasn't. I figured an air-coolable hood would prevent my temperatures from increasing this much. Is there anything I can do to get the temps down?

As of right now, my exhaust is setup like this:

Filter -> 6-4" reducer -> Fan -> aluminum ducting -> light -> aluminum ducting -> exhaust

It's set up this way because I have no other way to set it up that I can see. I know it's more efficient to suck air through the light than it is to push air across it. But the hood that came with the light is huge. Barely leaving enough room for me to attach the ducting. In fact, we've kinda mashed it so that it can fit, but still attach, and still allow plenty of air in.


Answers to the above questions, much appreciated. I need to get the room back in check quickly. They just got flipped, and I'm transplanting them tomorrow, I believe. I don't want them going hermie because of temps.


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## Hushpuppy (Apr 15, 2012)

The high temps shouldn't causer hermies normally. That is typically caused by light intrusions during dark periods. The problem with high temps is heat stress will kill the plants if it is too much. Are you certain that the ambient temps are actually that high? If your thermometer is setting in direct light it will read higher than it should as it is being heated by radient energy as well as ambient energy. 

I can't swear to this but if the ambient temp is actually as high as you are reading then you may have to go to 6" hose and a larger exaust fan. What kind of exaust blower are you using and how many CFM is it?


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## Hushpuppy (Apr 15, 2012)

Dimming the light will defeat the purpose of getting a higher wattage light, and will possibly reduce the life of the bulb. How big is your grow space?


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## 4u2sm0ke (Apr 16, 2012)

:ciao: *getnasty*

what size is this closet?  cubic feet

what size is your exhaust fan?....can you run ac unit in the room the closet is in and pull that cooler air through the lights?


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## The Hemp Goddess (Apr 16, 2012)

Don't use the filter unless/until you need it.  The fan does not need to be in the grow room--mine is in my crawl space.  I have never found pushing air through the light to work very well at all.  I'm a little confused on your set up...you have room on one side of your light for a filter AND a fan, but not enough room on the other side for just a fan?  Is your light in the center of the room?


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## Hushpuppy (Apr 16, 2012)

Yeah, I agree. I would think if you don't have a lot of room on the inside of the grow-space that you can just as easily attach the fan in line outside the grow-space so that it pulls the air out of the space. That is how I have mine and it works quite well.


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## getnasty (Apr 16, 2012)

This morning, after the lights had been on for an hour, the temperature read 79 degrees. I had originally had the digital thermometer right under the light, and moved it per HP's post. The ambient temperatures that I'm reading now are closer to the low 80's.

Also, for stealth purposes, I need to try to keep the fan inside the closet. My concern with the design of my exhaust setup, is that the fan is before the light, not after. Therefore, it's pushing air across the light, instead of dragging air across it, like I've read here is the preference.


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## getnasty (Apr 16, 2012)

Oh, and that little guy that's getting no light isn't a concern of mine. When I transplant the others, I think I'm just doing to pull it, being that I accidentally lopped the top off of it, and it's not going to pull much in the way of bud anyways.


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## The Hemp Goddess (Apr 16, 2012)

I don't see why you can't move the fan to the discharge side and connect it right before the ducting goes through the wall.  There appears to be enough room.


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## OGKushman (Apr 16, 2012)

lol duuuude!  you are blowing pressurized air into your HOT hood and the hood is leaking heat back into the grow. its a viscous cycle. 

You need to SUCK the heat out. And filters can be blown into if you want to put it outside the room and save space.

Suck from the light and blow into the filter. THis is what I did years ago and dropped my temps 10-15 degrees.


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## OGKushman (Apr 16, 2012)

Oh i just noticed your filter is 4 inch and the fan is 6? that is going to hold that fan back by A LOT. you got some ducting issues to fix, then your heat problem will disappear. 

Good luck!


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## bwanabud (Apr 16, 2012)

OGKushman said:
			
		

> Oh i just noticed your filter is 4 inch and the fan is 6? that is going to hold that fan back by A LOT. you got some ducting issues to fix, then your heat problem will disappear.
> 
> Good luck!


 
Spot on OG


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## getnasty (Apr 16, 2012)

OGKushman said:
			
		

> lol duuuude!  you are blowing pressurized air into your HOT hood and the hood is leaking heat back into the grow. its a viscous cycle.
> 
> You need to SUCK the heat out. And filters can be blown into if you want to put it outside the room and save space.
> 
> Suck from the light and blow into the filter. THis is what I did years ago and dropped my temps 10-15 degrees.


Didn't realize a 4" filter would hold back a 6" fan. I don't know what you mean by pressurized. The room has 3 passive intakes and the room the closet is in, is cooled with a 5000BTU air conditioner. I'll have to work on getting a new filter if the heat continues to go up. Right now it's stable at 82 degrees.


Any idea's on setting the exhaust up a little more efficiently but getting the filter and fan off of the ground? I need the space for the big girls to thrive and get enough light to all their banches.I can't cut holes in the walls and would prefer not to in the ceiling, but may be a posibility. I rent this property.

In regards to the room's dimension's, I have plenty of headroom in excess of 7' and the floor space measures 2.5' x 4'. 9sq ft, roughly.


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## OGKushman (Apr 16, 2012)

The fan is blowing air into the light, this makes a positive pressure in the hood. The heat from the fan and the bulb is now being pushed out every crack in the hood. None of them are completely sealed. Rather then worrying about how sealed it is, suck the air from the hood. 

Put a digital thermometer on the hood now. Then put the fan after the hood (not before it how it is now) and watch the hood temps fall. Put the filter after the fan (wherever you have to) and blow into it and temps will fall more. Put a panty hose on the hood and leave it open at the sucking in side. It will clear hot stale air from the top of the grow and give you a ton of more floor space.

I can post a pic if u still need.


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## OGKushman (Apr 16, 2012)

Pic 1: hood to roof
Pic 2: open hood (no pantyhose lol)
Pic 3: vortex sucking heat out and blowing into carbon filter


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## getnasty (Apr 17, 2012)

I like your set up, my friend, but unfortunately, I can't be cutting into walls here. I'm not handy enough to repair them before I move out, and if one of the other tenants in the triplex (who share the attic space) need to have cable or electrical work done, I don't want to have to explain why there's a fan and filter up there. 

I would basically need to move the fan to the left side of the closet, as THG mentioned, and keep the filter where it's at. for now. Problem is, that's doubling up the amount of space in use on the floor. One side for the fan, one side for the filter. Doesn't leave me with very much space for ladies to sit in.

So, I'm thinking about putting in a corner shelf on the filter side, and raising it up off of the floor. This way I can use the ventilation I have the higher up I need to move the light. But I'm puzzles as for the fan. there's not enough space to put it on the left. I almost have to put it up above the light, suspended. So, my question is this:

How much reduction in airflow is there per bend in exhaust ventilation? My fan is 400CFM, I believe. It's the GrowBright 6" fan from HTGSupply. I'm in a 9 sq ft area. 63-ish cu ft, I believe. The closet's around 7 ft high. This fan should be plenty to pull out air with a couple bends in the piping, shouldn't it? I have a plan, but I must have turns in my exhaust in order for it to work, and my concern is diminishing the pull to the extent that it's worthless having the fan in there in the first place.


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## getnasty (Apr 17, 2012)

*And filters can be blown into if you want to put it outside the room and save space.*


Completely msised that earlier. That's a great idea and free's up the right side of the hood! Pantyhose ftw!


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## OGKushman (Apr 18, 2012)

Intake on the ground sucks out cold air. Better to hang the filter by a stud in the ceiling at or above the light. 

Heat rises grasshoppa.


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## getnasty (Apr 18, 2012)

Im thinking about keeping an open end on the right side of the hood with pantyhose slipped over the end and secured. Then putting the ducting and fan above the light on the other side. Thing is, I think i'm going to need to use a Y splitter. Attach the fan to one side, and the filter to the other, then on the fan side, run ventilation to a ducting hole cut in the top of the closet. Thing is, i'll have 2 openings from which air is being sucked from. Is that going to be too much for my fan?


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## getnasty (Apr 20, 2012)

Anybody have any input on whether the two openings as opposed to one, would work with my 6" fan as described above? Im thinking it may be my only option. Unless, of course, I filter outside of the closet, but i'd prefer not to.


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## OGKushman (Apr 20, 2012)

i use Y splitters all the time...it slows down the suction big time, some rooms can handle it.


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## The Hemp Goddess (Apr 20, 2012)

getnasty said:
			
		

> Anybody have any input on whether the two openings as opposed to one, would work with my 6" fan as described above? Im thinking it may be my only option. Unless, of course, I filter outside of the closet, but i'd prefer not to.



When I do that, I make my openings 4" openings that go into a 6" wye.  Two 4" holes have about the same area (12.56 sq in x 2) as a single 6" hole (28.26 sq in).  I am not sure that this is going to work in your case, though.  You need the resistance to be pretty equal, or the opening with the least resistance will get the majority of the air flow.  You want to try and keep everything "balanced"--same length of ducting, same amount of turns, same resistance, etc.


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## Hushpuppy (Apr 21, 2012)

Hey this is just my opinion but I don't see the need or function of using a wye splitter for that space unless you are intending on getting 2 filters. I thought about what may work for you as I have the same size grow space. This is a crude picture of the space with the fan suspended from the ceiling and connected to the wall so that it is pulling all the inner space air, It also shows the light being suspended with the filter being either suspended directly above the light or actually laying on the light. Even though you have some serious bends in this setup, the fact that the fan is pulling the air (by way of the centrifugal blower creating vacuum) changes the dynamics of the airflow action. This should allow proper airflow without causing any problems, and regular flex hose should work. The only issue that I would see is the smaller carbon filter. I would get a 6" with more air contact surface to allow for more air volume to be pulled in.   Hope this helps


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