Cool Tubes and Ventilation

Hi all, I am trying to understand just how effective cool tubes are suppose to be. I will describe my set up...(though not growing anything at the moment)

Grow box is approx 36in Tall,16 in Deep, and 36in long.

Setup is somewhat similar to the sunlight sheds mini cab.

Cooltube is attached to 250w hps and is vented by a 150cfm inline duct fan. About 4ft of 4in hose on exhaust side, and about 2 feet on intake side of cool tube.

For cab ventilation I have a dayton 105 cfm 4in fan located near the top of the cab, and a 4 in hole on bottom for negative pressure.

Ambient air temp is 75-76F while cab is always 7 or 8 degrees hotter. So approx 83F.

Inside the cab I have an oscillating fan which is necessary to keep the temp at 83F. Without this fan, the temp will rise to about 87F.

Now, I thought cool tubes are suppose to help keep the cab cooler than that. What temps should I be expecting? What temps are others getting in their cabs?

Sorry for the long post. I wanted to provide as much detail as possible.

Thanks!

Do you have fans in your cool tube ventilation?

The inline duct fan is connected to the cool tube. It is not used to vent the cab. Only to cool the hps.

The cool tube is drawing air from outside of the cab...through ducting...attached to one end of the cool tube...through ducting again...then out of the other side of the cool tube to the inline duct fan.

The other dayton fan is used to bring air into the cab via negative pressure.

Are you venting the air from the light outside? Just want to make sure you aren't sucking the hot air back in to your cab is all....

Yes, air is vented to the outside. I suppose I didn't describe it well enough. The setup is pretty much identical to

Mini Cool Cab Turn Key System

I am not advertising their product, but the design is pretty much like this.

The only thing I can think to suggest would be to make sure it is sealed.

I have 3 cool tubes in a row and I can't pull them apart with the fan on because of the suction...

It really should be cooler, I can touch the glass tube and it is just warm - not hot.

It has to be leaking somewhere to have temps high like that, a bare bulb would run temps like that.

Thanks for the info, I will double check the sealing. What temp range is normal?

I like to keep it inbetween 75F and 80F - mine run cooler than that, I usually have to turn on a heater.

What is your room temp? I am trying to see how much difference it is between the outside and inside temps.

I had the min caddy with 400w and cooltube. the only way I could get the temps down
was to back it up next to my A/C window unit. the cool air came in to the intake fan. I only use it now to veg a mother. Not the best setup.

Hey Buds, i have really been fighting with these temps. Perhaps a small'ish box and HPS don't mix very well. What do you have instead?

I can't see how the temp could really go that much below 80 because even though the cool tube is cooler than a naked bulb, it is still a bit warm.

I had planned on making my own mini cool cab as well:

https://www.rollitup.org/grow-room-design-setup/19305-first-cabinet-setup-first-grow.html


However, I ended up taking advice from others on the forum, and converted my closet into the grow space I wanted:

https://www.rollitup.org/grow-journals/20770-first-grow-northern-lights-x-8.html

If you can find other storage for the things in a closet, I would convert one into a grow groom. Just a little more space will mean a big difference. When I made my cab. the temps were like you described, mid to high 80s, and that was if I left the door cracked. When I moved the setup to the closet, the temps now stay around 75.

I think I may have to section off an area of my closet. I can do it, but was wanting a somewhat stealth factor. It was also an interesting project to build.

On this same note, has anyone here had any ventilation issues with the hydrohuts? I wonder if that may be easier.

Hydrohut Mini, Deluxe hydroponic hut & Original hydrohut are variety of hydrohuts

The mini in particular.

where are you pulling the air from? just outside or the grow box or outside of the house? what is the temp of the air your pulling from?

is your inline fan pulling air across the bulb or pushing it?

Inline fan is pulling cool air from outside of box (inside of my room) through cool tube across bulb and out. Inline fan is on outside of the box. All done via 4in ducting. Ambient air is 75F. Grow box is always roughly 8-10 degrees warmer.

Seeing as how the hydrohut is similar in design, only larger, I was wondering if there were heat issues with that as well.

Thanks for all of the replies! You guys are awesome!

1 thing is for sure, somethings not right lol. i cant tell you exactly what but ive got 3 cool tubes all running off 4" duct work. ive got 3000 watts worth of bulbs in a 12'x8'x6'(LxHxW) room. i know mine is bigger than yours but you shouldnt be haveing temps that high. my flowering room stays around 80 with all the lights on and the outside temp being high 80s.
pic would really help. how is your other fan ran? pushing air out of the room or pulling in?

this is as close to what it sounds like you have that might help.
https://www.rollitup.org/grow-journals/21856-noobs-guide-doin-right-1st.html

well as the owner of the thread you referenced, i can tell you that my problem stems from the fact that i am pulling my filter air from the top, through the cooltube and out the top again. so essentially i am pulling warm air through the cooltube, which limits its effectiveness. i just need a couple things from the dePOT to fix that.

actually, i would recommend the hydrohut. it is a very well built unit, and seems like it will last for years. it is easy to set up everything in there, and there are several options for ventilation and cooling.