View Full Version : How to cool my room

07-25-2011, 11:19 PM
I have two grow tents, one 51.5"Long x 22.5"Wide x 48.5"Tall with a 4 bulb 4' T5 HO (4 X 54 Watts) and the other 98" wide x 55" deep x 79" tall with 2 X 600 Watt HIDs. I plan to vent the 2 600 Watt lights using air drawn and exhausted from the outside (with a 6" centrifical fan) and the T5s vented to the room (4" axial fan). The room is 13' X 13'. I plan to use bottled CO2 to the larger tent. The daytime outside temps here are around 95F but have hit 105F. At night, it will drop to 75-80F. The humidity is 70-95%, even higher at times. The room is now cooled by the central A/C, but I haven't started growing yet. As the outside enviroment is too hot and humid, I can't ventalate the room to the outside. I plan to scrub the air with a 6" carbon filter and centrifical fan. Is the central A/C going to be sufficient or will I need to seal off the room and install a window A/C? How big of an A/C? Bear in mind I only have two 15 Amp breakers to work with. Will running the lights at night help? I will want them on 20 hours and off 4 during veg, so I can only avoid the hotest part of the day.
Sorry for the long post, but I wanted to include as many details as needed.

07-27-2011, 08:23 PM
Anyone out there?

07-30-2011, 08:24 AM
You will have top figure out the btu/hr and it is way lore complicated than your data indicates.

07-31-2011, 05:53 PM
I wasn't getting any replies, so I decided to wing it. I bought a new 5,200 BTU window A/C. I opened up the back of the large tent and sealed it to the wall where I installed the A/C. It's only 234 cubic feet I'm cooling. 2 600watt lights should put out about 4080 BTU. They're both air cooled, so I should subtract, what, maybe 50%? Ballasts are digital and outside the tent. I have a 23 watt UVB lamp I plan to run, maximum, 4 hours a day during the last three weeks of flowering. 23 watts shouldn't make much difference either way. The hard part was light proofing the A/C. The fan shroud is Styrofoam and daylight comes right through it. I found foam safe black paint. Two coats and light was still coming through! I lined it with silver duct tape and that stopped the light coming through the foam, but now light was being reflected from down below where I could reach with a brush or the tape. I put another layer of tape on, this time black Gorilla duct tape. That seems the best I can do. It's not 100%, but it's close.

I'm pretty sure I've voided the warranty on the A/c

The damn wings on the A/C do a very poor job of blocking light or air flow. Lots of silver duct tape! They make a asphalt base/corrugated aluminum tape that is 6" wide for sealing roof vents and such. That might have been a better choice as it supposedly stretches and conforms to irregular shapes. Never have used it myself. Any Roofers out there?

Now I am concerned I may have too much A/C. It may not do a good job of dehumidifying the tent.

What other data is needed?

08-01-2011, 05:40 AM
Solar load, building load, latent load, equipment load and etc.............

08-01-2011, 10:16 PM
Don't know how to calculate solar load. Three sides and roof exposed to air conditioned room. One 8 X 6.5 side is sealed to west facing wall, unshaded. Two 600w HIDs, one 23 watt CFL (UVB). 424 CFM 6" inline fan with about 30' flex duct with 8 90 deg bends. Both ends of flex duct are attached to a twin 9" window fan (1400 CFM total). Attachment is just 6" bulkhead fittings bolted to grill. Window fan is to hide ducts. Only lights, A/C, and one surge arrester in tent. Room containing tent has central A/C. Solar load should be minimal, central A/C takes care of building and latent load. Tent is not sensibly warmer than room it is in with no equipment running. Have 3 hygrometers, 2 with outside temp probes, get different temp readings with all placed side by side. Can't trust any of them. Have CO2 system (bottled gas), so can tolerate higher temps.
Anything else needed?
System keeps logging me out!

08-05-2011, 11:14 AM
Hmmmm, ask a question, get questions for reply. Not much help.

04-13-2014, 11:26 PM
I don't know answer for this.