400 watt club - heat problems

Growver

Growver

Well-Known Member
I need help, my plants are dying from too much heat (and lack of nutes too, though I've recently fixed that). Too often my room is at 34C (which is 93F) with low humidity!!! I have a small room, 3' wide x 6.5' long x 8' high = 156 cubic feet. Light is a vented hood, 400 Watt HPS sealed with glass and it's kept about 12" above the plants.

I have passive intake, active exhaust and 2 standard household fans circulating air. My active exhaust is a 4" inline fan by Tjernlund I found new on eBay, rated at 200 CFM without load. I figure with the ducting and carbon scrubber load I'm maybe getting 100 CFM if I am lucky. The fan is running at full tilt.

Active Exhaust size: 4" round duct = 2^2 x 3.141592 = 12.57" volume exhaust (since "pi x r^2 = volume")
Passive Intake size: I understand it should be 3x the exhaust as a minimum. It is rectangular, 14"x8"= 112" volume intake and has a dust filter which creates minor drag, inlet temp is 22C (72F) from basement.

scrubber -> fan -> duct -> hood -> duct -> exhaust outside

I have tried other duct configurations to get more air moving, including putting the fan at the end of line (pulling air through) but the noise was unbearable at the exhaust end. The fan itself is wrapped in sound insulation and installed inside a sealed box, yet it's still a little loud.

My air intake is at the floor of the room, carbon scrubber is at the ceiling on the far other end of the room. I thought I planned this out perfectly but something is amiss. Still too much heat, the exhaust hitting my hand seems like a small fraction of 200 CFM, maybe I'm not even getting 100 CFM?

What is the solution? Do I need a bigger fan, like a 6" model with more power? How well will that work with 4" ducts? Should I move the carbon scrubber (intake) physically closer to the plants to remove more heat lower in the room? Switch to a cool tube? Add a second inline booster fan? I can't figure out what I did wrong except maybe miscalculate the drop in CFM with the scrubber and all the duct work. The hood seems to take a lot of the CFM, check out my pics.

thanks,
Growver.

CIMG1445.jpgCIMG1447.jpgCIMG1451.jpgCIMG1449.jpg
 
hey man im pretty new to everything but if had to guess i would say that hood is too big for your light and fan it looks like its made for a 1000w. i just got a 400w from htg today just took out my t5 strip and got her setup im running a 400w growbright mh bulb in it with just the cheap reflector "4 sided" reflector i might just turn into a wing and take the ends off to allow better cooling allowing more air to pass anyway im in the northeast and earlier it was probably 87 in my closet with just 2 oscilating fans one aimed out the door right between canopy light and im in a slightly smaller closet than you. yeah i wanna make my own cool tube soon or save up the money for a euro-hood or something ive been having heat issues too and im just getting started.
 
when I started my grow I was in a similar sized closet, to avoid those temps I had to open the door wide open and put a fan blasting the cool air in... but this was early in the grow so I was not fighting the smell.. but what it sounds like your going to have to do is get a exhaust fan that can pull that heat out quicker... basically the more air you can move across that bulb and out of the room the less heat your going to be putting in the room... so not only will you be able to evacuate the hot air faster, but you will be keeping the hood cooler which will put less heat into the room to begin with...
 
i think you just need to throw a fan into the mix, maybe a 2' BOX FAN TO CIRCULATE THE AIR...keep it simple.
 
I've already got two recirculating fans near my air intake (not shown), they are blowing so hard the plants have real strong stems. Plus the powerful 4" inline fan for exhaust. But I can't seem to get the heat out.

I'm thinking a larger inline fan with more power, or maybe a cool tube. I'd like to find the cheapest, most effective route at this point...
 
whats the ambient temp outside of the grow room ? also keeping your ducting as straight as possible and that will help air flow restriction .
 
I think he said it was 72 degrees from the basement... or atleast thats where he's pulling air from... actually ambient air of around the grow i dunno
 
ok after re reading the first post without smoking i got the facts. sounds to me that you need a larger exhaust fan. probably not pulling the air past the bulb fast enough.
 
Here's one solution. If your HPS ballast is magnetic, go buy a CMH bulb. It burns alot cooler than HPS and will eliminate many heat problems
 
I guess I maybe provided too much information in my first post, and maybe asked too many questions... because most of the clarifying questions everyone is asking me were answered in the first post. But thanks for the help so far guys.

Just wondering how well a 6" fan will work with 4" duct work now... my ballast isn't magnetic I don't think, so I doubt I can change the bulb.

Also, will a cool tube be more efficient than my vented hood?

Thanks...
 
Hey guys i just read this thread for some good info i think its the way im gonna go. Maybe ill be able to pick up a cool tube from michaels but its got good info for every HID noob having problems. it really made me change my mind on an HTG cool tube to fit my cheap ass 400w HTG fixture and im going to pick up the 6" grow bright fan probably from HTG and vent into my attic DIY cool tube or not. Here ya go...

https://www.gardenscure.com/420/lighting/123450-diy-cool-tube.html

Peace
 
go to home depot and look for a bathroom fart fan that has 100cfn or better(CFN-sucking power) my 2x3 grow closet was around 105 F with the doors closed, thankfully i had no plants in there yet, cut a hole 6x6 inches and get a 8in box fan and put it right up against it(put mesh on the outside if you wanna block bugs)do the same thing but cut 3x3in and put a 4 or 6 in fan up against it( again mesh if you want)but face it going out( the larger fan should be the intake) doing all this you dont have to shell out hundreds for a perfect vetalation, after doing this my grow clost doesnt get over 80 even on these warmer days, good luck!
 
I just started my first grow, I have 1 400 watt HPS Bat wing top and a circulating fan next to two opened windows it's a 10x10 room. The only thing I have for an exahst is a cheap 50 cfm bathroom fan x 4" flex tube going thru a hole in my ceiling.
The temp, is 10 Degrees cooler in the room than out side.
 
you have a similar problem i used to have. the active exhaust that you have will not be enough. i had to use a 6' inline fan rated at 400cfm for my 400w hps. connect that to your enclosure it it will suck all the air out. for the intake, i suggest you use the other inline fan(s) you have to bring fresh air in. after that just keep your oscillating fan active to keep a good airflow. that's how i have my setup in a 4x2x5 and keeps the temps at 87 with tent closed
Growver said:
I need help, my plants are dying from too much heat (and lack of nutes too, though I've recently fixed that). Too often my room is at 34C (which is 93F) with low humidity!!! I have a small room, 3' wide x 6.5' long x 8' high = 156 cubic feet. Light is a vented hood, 400 Watt HPS sealed with glass and it's kept about 12" above the plants.

I have passive intake, active exhaust and 2 standard household fans circulating air. My active exhaust is a 4" inline fan by Tjernlund I found new on eBay, rated at 200 CFM without load. I figure with the ducting and carbon scrubber load I'm maybe getting 100 CFM if I am lucky. The fan is running at full tilt.

Active Exhaust size: 4" round duct = 2^2 x 3.141592 = 12.57" volume exhaust (since "pi x r^2 = volume")
Passive Intake size: I understand it should be 3x the exhaust as a minimum. It is rectangular, 14"x8"= 112" volume intake and has a dust filter which creates minor drag, inlet temp is 22C (72F) from basement.

scrubber -> fan -> duct -> hood -> duct -> exhaust outside

I have tried other duct configurations to get more air moving, including putting the fan at the end of line (pulling air through) but the noise was unbearable at the exhaust end. The fan itself is wrapped in sound insulation and installed inside a sealed box, yet it's still a little loud.

My air intake is at the floor of the room, carbon scrubber is at the ceiling on the far other end of the room. I thought I planned this out perfectly but something is amiss. Still too much heat, the exhaust hitting my hand seems like a small fraction of 200 CFM, maybe I'm not even getting 100 CFM?

What is the solution? Do I need a bigger fan, like a 6" model with more power? How well will that work with 4" ducts? Should I move the carbon scrubber (intake) physically closer to the plants to remove more heat lower in the room? Switch to a cool tube? Add a second inline booster fan? I can't figure out what I did wrong except maybe miscalculate the drop in CFM with the scrubber and all the duct work. The hood seems to take a lot of the CFM, check out my pics.

thanks,
Growver.

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