Heat Buildup

I'm running a 600w Ultrasun HPS bulb, on a Lumatek electronic dimmable ballast (set to 600w), in a cooltube with an open end (nothing restricting airflow except a mesh covering to stop debris from entering, the screen provides negligible resistance.

My grow area is only 2 ft x 5 ft x 5 ft and I have a 550 CFM fan attached to the cooltube. It pulls air from inside the flower room and exhausts it to the outside. My ambient temperature in the room is 68, and even with my fan turned down via speedcontroller I should still only experience 3 degree swing, but temps go up to 82. Anyone have advice? This is even with the door completely open providing almost no resistance to the fan, and I only have 1 90 degree bend in the ducting.

I realize this is a massive fan for a 50cf area, I have it dialed all the way down with a speed controller, and with the doors open it's a 350+SF area.

Anyone know my problem? The air it pulls into the flower area is <70F.

I know 82 is ok but I'd be more comfortable in the 70's so I can account for heat fluctuations.

I've got to be doing something wrong because the math doesn't add up. How can my temps at canopy level be rising so high? The cooltube glass is 14in. from the canopy top (scrog)

GET RID of that bend as much as possible. Also make sure your cool tube is SEALED, and not leaking heat into the room somehow.

One 90 degree bend is alright in HVAC, especially since its a 550CFM fan cooling a cooltube in a 50CF area. I can't avoid it anyway. The end of the cooltube is open, pulling air from inside the flower chamber and exhausting it outside. The ducting is clamped to the cooltube and taped with hvac tape (even though I would think that with 500cfm pulling on it, a few small leaks would really be negligible. If I put my hand over the end of the cooltube it gets pulled onto it I can feel the suction it's very strong.

Not trying to come off like I know anymore than you, but I just don't see how that could be the problem, but then again I don't know what is the problem...

(plus the 90 degree bend is lengthened out as much as I can so it's probably like 75 degrees haha...)

Are you venting to to same area as you are intaking from?

Read above two posts please. It exhausts into my below-freezing garage.

Fix your own problem

It's hard not to come off as a jerk if you don't even read the first 3 sentences of my post where I ask for help, instead of asking questions blatantly answered in my only two posts.

Fix your illiteracy.

Exhausting it "outside", you said? You mean outside of the house right? Simply exhausting to another room inside the house would cause this kind of problem.

Yea it exhausts into my garage which is usually >40F so it would be cooled before ever re-entering the house (if it even does) My thermostat in the house located just outside of the grow room doesnt move from 68 ever...so the intake air has to be that temp. It's actually cooler in the room the flower cab is located because I have the heat vents closed

Make sure that no air is returning to your house from the garage. Crack a window nearbye so that that is definately the path of least resistance for fresh incoming air. Purchase this fan controller. http://aeroponicsnmore.com/climate-control-ventilation-c-23_5/temp-2v-fan-speed-control-variable-idle-setpoint-p-181

If the problem persists, you'll need to get a larger fan (800cfm) and sell the old one. Theoretically, your 400 cfm is enough ... but theory doesn't always work out. Make sure there are no kinks on the exhaust line. If the duct is kinked then your 400cfm is down to 20cfm real quick. Turn it up full blast and put your hand over the exhaust in the garage, is it really pushing 400cfm? If you don't feel a bunch of air, you have found your problem.

I wonder if the radiant heat from the bulb is to much for that small area. You can't cool radiant heat with airflow. You might try to shade your t-stat and see if your air temp is actually less then your reading. If it is maybe just dial down that 600. Im probably just stoned and not making sense, but easy to check out with no cost. Hope this helps.

It's a 550 CFM fan, and even turned all the way down with a cheaper speed control it still throws a ton of air. Turned all the way up it sounds like a jet intake in my grow room. I will check the exhaust point for good air flow, but I am pretty sure I will find hurricane force winds haha. There is no exhaust ducting on the end of the fan, it is simply the end of the fan blowing air into the garage.

The only ducting attached to the fan goes directly to the cool tube, with one (slightly less than) 90 degree bend. I will make sure no air is leaking in from the garage, but once it hits the garage it would be cooled anyway (it's below freezing outdoors and in my garage there is ice on the ground)

What would be my noticed benefits with this style of speed controller that you mentioned? I currently have one like this http://www.google.com/imgres?imgurl=http://www.solar-components.com/Dial_A_Temp.jpg&imgrefurl=http://www.solar-components.com/fans.htm&usg=__INOMjo4J8zUYm1EamUrk46D19Fg=&h=320&w=237&sz=21&hl=en&start=0&zoom=1&tbnid=lTFTS_a3hnK3vM:&tbnh=150&tbnw=111&ei=FQORTefeIom60QGeraWCDw&prev=/images?q=dial-a-temp&um=1&hl=en&sa=N&biw=1280&bih=929&tbs=isch:1&prmd=ivns&um=1&itbs=1&iact=hc&vpx=137&vpy=77&dur=516&hovh=248&hovw=183&tx=114&ty=138&oei=FQORTefeIom60QGeraWCDw&page=1&ndsp=35&ved=1t:429,r:0,s:0

Minigrows saw your post while I was authoring my other, you do make sense but I have a question I don't know if you will be able to answer.

If I shade the thermostat and the air temp turns out to be lower, doesn't that mean that the plants in direct light under it would still be experiencing the radiant heat and temperatures of 82+?

Edit: After re-reading your post I inferred that you meant there IS no way to deal with the radiant heat and that the ONLY solution is dialing down to 400w? Am I correct in reading what you wrote?

infinitescrog said:

Minigrows saw your post while I was authoring my other, you do make sense but I have a question I don't know if you will be able to answer.

If I shade the thermostat and the air temp turns out to be lower, doesn't that mean that the plants in direct light under it would still be experiencing the radiant heat and temperatures of 82+?

Edit: After re-reading your post I inferred that you meant there IS no way to deal with the radiant heat and that the ONLY solution is dialing down to 400w? Am I correct in reading what you wrote?

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Ok first off this is my thoughts on radiant heat on plants(again just my thoughts), if your temps are still in a acceptable range in direct light and lower in the shade then I would not worry as long as plants dont show stress. but if temps are out of range say 100+ then I would dial down the bulb. Another thought... what is your box lined with? Mylar for example reflects radiant heat and may be part of your problem and maybe not lol. Again hope this helps.

It's a closet w/ flat white paint and panda film white side in for the whole door. And yea temps are usually O.K. they sit at 82 i have my thermometer sitting on the scrog screen in direct light. It got up to 94 one time and I don't have any idea why, usually never passes 82 so I'm OK now, just a little leery to leave them alone for a night or two, ya know?

Mounted on the wall, a few inches above the screen when the thermostat is not in direct light it reads in the mid 70's.

I am going to make sure that the exhaust area isn't having positive pressure created in it thus weakening my fan as well. This IS a legit hvac metal inline fan, not a "duct booster" btw.

Im curious if you were to open you garage door a bit(the big one) and cracked a window in the room with your closet will your temps come down? If you have a newer house its likely its sealed so well your simply not getting enough air to move to start with. If its an older house then most likely that's not the problem. I think another person eluded to this but I thought it was worth plointing out.

minigrows said:

Im curious if you were to open you garage door a bit(the big one) and cracked a window in the room with your closet will your temps come down? If you have a newer house its likely its sealed so well your simply not getting enough air to move to start with. If its an older house then most likely that's not the problem. I think another person eluded to this but I thought it was worth plointing out.

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Sounds like the only other thing it could be.. worst come to worse and your still worried cut back your light a notch. See how it does, but going from what i know ( LITTLE ) that temp should be good. I dont understand how you could have such a huge spike with that turbine moving that much air.

ItsJohny said:

Sounds like the only other thing it could be.. worst come to worse and your still worried cut back your light a notch. See how it does, but going from what i know ( LITTLE ) that temp should be good. I dont understand how you could have such a huge spike with that turbine moving that much air.

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Yea the temps are fine but I was curious why they were as high as they were. If I open the window in the room the closet is in, yes the temps in the closet drop but the air it's pulling in is <40 degrees most of the time and <0F some times so it gets cold REAL fast. (I left it cracked one night and awoke to a reading of 49F)

infinitescrog said:

It's a 550 CFM fan, and even turned all the way down with a cheaper speed control it still throws a ton of air. Turned all the way up it sounds like a jet intake in my grow room. I will check the exhaust point for good air flow, but I am pretty sure I will find hurricane force winds haha. There is no exhaust ducting on the end of the fan, it is simply the end of the fan blowing air into the garage.

The only ducting attached to the fan goes directly to the cool tube, with one (slightly less than) 90 degree bend. I will make sure no air is leaking in from the garage, but once it hits the garage it would be cooled anyway (it's below freezing outdoors and in my garage there is ice on the ground)

What would be my noticed benefits with this style of speed controller that you mentioned? I currently have one like this http://www.google.com/imgres?imgurl=http://www.solar-components.com/Dial_A_Temp.jpg&imgrefurl=http://www.solar-components.com/fans.htm&usg=__INOMjo4J8zUYm1EamUrk46D19Fg=&h=320&w=237&sz=21&hl=en&start=0&zoom=1&tbnid=lTFTS_a3hnK3vM:&tbnh=150&tbnw=111&ei=FQORTefeIom60QGeraWCDw&prev=/images?q=dial-a-temp&um=1&hl=en&sa=N&biw=1280&bih=929&tbs=isch:1&prmd=ivns&um=1&itbs=1&iact=hc&vpx=137&vpy=77&dur=516&hovh=248&hovw=183&tx=114&ty=138&oei=FQORTefeIom60QGeraWCDw&page=1&ndsp=35&ved=1t:429,r:0,s:0

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The speed controller I mentioned above is fantastic because it is temperature controlled. It's also Day/Night sensitive. So you can set it to 70f degrees and the fan will pur along at whatever idle speed you want, but when the room hits 70f the fan will ramp up and draw in max air. This will keep your room at a perfect temperature without you having to constantly adjust your fan speed. It's not on/off like most controllers, it's variable speeds with a nice constant idle (you set the idle).

The idea mentioned above about opening the garage door is a good one. Check the exhaust duct in the garage, you'll be surprised at how much a little ducting can restrict a so-so fan. Also, it's not only about the temperature of the return air. It's the Co2 levels. Fresh air from outside the house will have more Co2 that any air mingling and returning from your garage.