Serious Cooling Issues - Flower Tent

GrumpyToker

GrumpyToker

Well-Known Member
You need a 400 watt HPS for that tent size

You need the 6" fan inside the tent in the upper top corner.

Leave the suction end open of the 6" fan or install a carbon filter here.

On the other end of the fan run a short 1 foot or so of ducting to the first side of the cool tube.

On the other side of the cool tube run another few feet of ducting out the side of your tent venting into your room.

This will pull cool air from the sides of the tent into the tent and use that air to cool the lamp

Cheers
 
since1991

since1991

Well-Known Member
I dont care what people say online.....use them inline exhaust fans PULLING air out of the hoods. Its just silly having them blow over. Ideally for multiple aircooled hoods is to have fans at the beginning and end of the duct lines doing both but if you only have one fan....use it correctly...use it to pull air out. And have it close to your exit hole as possible.
 
riffraff8

riffraff8

Member
@GrumpyToker - as I mentioned my 600W has a switch on the ballast for 50%, 75%, and 100%. My intention was to buy a 400W for this tent when I started, but the 600 was maybe $10 more and can be dimmed, so I bought that with future grows in mind. I never have it above 75% (~450W).

To everyone else, I got the problem solved with your suggestions! It was running 9F above ambient on the 50% (~300W) setting, with my vortex on full blast. It's now running 4F above ambient on that setting, with the vortex at 2/3 power, which means I can turn the light back up to 75% again and not have an issue.

What I did was:

6" carbon filter -> short length of duct -> cool tube -> short length of duct -> vortex -> short length of duct -> window

I then took my 240CFM booster and hooked it up with a 6" to 4" coupler onto the 4" carbon filter. This is my backup carbon filtration for when lights are out, and runs 24/7. It does provide negative pressure, but not nearly as much as having the vortex hooked up like this now does.

I now have the added benefit of never leaking any cool tube air back into the grow chamber from any small leaks in the ducting, as it's sucking until it gets outside the tent.

So, what have I learned?

#1, that I'm sorry to @Resinhound for not trusting his advice sooner
#2, that I still have no actual proof that the fan runs more efficiently when sucking (I now believe that it does, but this experiment didn't prove that definitively as I changed other variables), BUT that using the vortex for both the cool tube and the grow chamber air is definitely far more efficient than using a sealed cool-tube run that contains no tent air, and a separate fan/filter for the tent air. This is really the main thing that changed, having the vortex work hot air out of the top of the tent AND the cool tube, as opposed to just the cool tube with a separate fan for the hot air at the top of the tent
#3, carbon filter drag is far less of a match for the vortex than it was for the 240CFM booster.

Downsides to the new setup:
#1 I think I'm going to go through carbon filters much faster, as well as filter covers.
#2 My humidifiers will be running much more often to keep it at 40% RH in there. This also means more mineral buildup on the carbon filters.

Upsides:
#1 and most importantly, the plants are happy
#2 I was able to remove the tiny 100CFM booster from my setup, and am still able to use both carbon filters.
#3 I can use my light on 75% (~450W) again, whoohoo!
#4 More air being carbon filtered means a safer grow (smell-wise)

Moral of the story is if you only have one big inline fan, use it for everything, not just one thing. If you have more than one, than you can probably have the separate cool-tube run and grow chamber air exhaust as I was using before. Thanks again to everyone that helped out!
 
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VegasWinner

Well-Known Member
riffraff8 said:
Hi all,

I've been running a flower tent (2' x 4' x 5' high) for about a month, and am constantly on the verge of it overheating. I've done a ton of research, built out all my fans/ductwork in the best way I can think of. yet I still constantly feel like my plants will overheat any minute I step out of the house. Here's the setup:

The tent is in a closet. The closet doors are removed, so it is very open, almost as if it were just sitting in the room. There is air conditioning in the room, and while it can occasionally get up to as high as 77F in the room, it is generally about 72-74F on average. My understanding is that with proper ventilation I should be able to keep the tent just a few degrees warmer than the room. I would be happy with a constant 80-82 in the tent, however it keeps broaching 84, even hitting 86F on occasion. That really makes me nervous for my plant's health.

The tent is run at a constant 40% RH for flower. This is maintained with a humidity sensor/controller/humidifier combo, as the room RH has been 25-30% outside the tent.

The tent is running one 600W HPS bulb, hanging about 2.5 Ft above the canopy. The ballast has a dimmer switch with settings for 50%, 75%, and 100%. As I'm having these temperature issues, I've never been able to run it on 100% (full 600W), and have been running it on 50% (a little over 300W draw) just to keep it from overheating. Even at that setting, it gets too hot too frequently for my comfort zone.

The cool tube is a 6" diameter. I have a 449CFM vortex fan hanging just outside the tent that is pushing. It pushes through about half a foot of the 6" duct work into the tent to the cool tube, through the cool tube, and out the other side of the tent. It then has about 3 more feet of the 6" ducting out the other side, with no major bends, to a window where it exhausts. That window also houses my AC unit, so the venting happens on the side next to the AC. I have this fan turned to max (the full 449 CFM), though I would love to be able to turn it down slightly on the dial for noise purposes. I have checked all the ductwork and the seams from the vortex to the window, and no air is leaking from the system.

Additionally, I have 2 carbon filters mounted to the ceiling of the tent, a 6" iPower, and a 4" iPower. The 6" does most of the filtering, the 4" is just a backup because I had it lying around. The 6" is pulled (after the carbon filter) with a 240CFM can fan, also on a dimmer but set to full. The 4" is pulled with a tiny little 100CFM can fan that barely moves any air after the drag from the filter, but does still push a little clean air. As I said this is just a backup for me, I know I shouldn't expect much from such a tiny can fan. Each of my carbon filter lines run about 2.5 - 3ft of duct work total, and vent back into the room. While their exhaust is the same temperature as the tent, they don't move enough to warrant window exhaust IMO, and don't add much to the room heat that the AC can't take care of. The tent uses passive intake through all the flaps by the floor, and does retain negative pressure nicely when I have the 240CFM can fan on full (it always is!)

Aside from all that, I have 2 small clip-on fans inside the tent that are keeping the air moving in there, and blowing between the canopy and the light.

Even with all that running on full, and my poor 600W light dimmed to ~300W with the ballast switch, I'm still seeing 75F in the room and 85F in the tent right now.

One more thing, I have a mesh bug screen on the vortex that keeps dust from collecting on my light. The bug screen does fill with dust about once or twice a week and I slurp it out with a vacuum because it does drastically reduce the vortex performance if left dusty for multiple weeks. I make sure to maintain this, as well as my AC filter at least once a week with the large volumes of air being moved.

So my question is, what gives? Why are some people able to bring their tent temps down to within just 2-3 degrees hotter than ambient? Moreso, how are they doing it with smaller inline fans and less air being moved? I've been constantly making small improvements as I notice issues, but at this point I don't see any obvious change I can make to get the temp to drop those 5-6 precious degrees. I will say that when I was running this as a veg tent with far higher humidity for young growth (60-70%RH), I was able to keep the temp no higher than 82F. Of course this is a function of the humidity, so having a dryer 40% for flowering does mean a hotter tent. I'm hoping that someone has advice or improvements that will help counteract the higher temps. Thanks!
Click to expand...
Reverse fan. Fans pull air efficiently designed that way. Heat is no problem. Filter will stay clean exhaust outside if possible. Intake low separate fan. Exhaust high with carbon filter and muffler. I design hvac systems. I run my systems the way I described. My fans have never been replaced.
Peace
 
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VegasWinner

Well-Known Member
when you push air through a filter it gets dirty fats. when you pull air into a filter it works better and does not foul as quickly.
 
riffraff8

riffraff8

Member
Gotcha gotcha. Yea even in the ignorance of my initial setup, I would never think about pushing through a filter. Too much opportunity for smell leaks, sounds like it might blast carbon everywhere, and the fabric sock filter that wraps around the outside would become fairly useless, dirtying your filter much faster.

I had only been pushing through my cool tube run, and sucking through my filters, but now it's all sucking and it works great.
 
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