Grow Tent in Bedroom - Closing Windows due to cold outside temperature?

[greenops]

Hi fellow growers,

I got a 80cm x 80cm grow tent running under dimmable 480w LEDs in my bedroom.
I like to leave the window cracked open at all times for fresh air, but since it's been such a cold winter here, the grow tent's average temperature is at 21C / 70F, RH 45-60%. When I close the window, I can get it up to 25C, which I think the plants would like more.
I have no ducting connected from the window opening to the tent. Air gets sucked in passively from the room and vents into the same room.

My questions.

1) I always assumed I have to leave the windows open for fresh air. Is that a fact? Does it have any negative when I have the window closed at times? That way the grow tent climate would be 25C / 50%rh.

2) Is there a difference if the air gets sucked in directly from outside into the grow tent vs when the air inside the room gets sucked into the grow tent?

3) How important is it to have the exhaust vented outside the room, where the grow tent is in?


Thanks in advance!

 

[flylowgethigh]

I just set up tents inside and have had those questions. IMO, it is best to have a stable lung room temp as baseline. The room has to be cooler than the tent, so drawing in cooler air will offset the heat from the light. If the humidity in the lung room is lower than the 50% you target, then humidity has to be added. I have been hanging wet shirts on one wall of the tent, and that is the best stabilizer of the temp and humidity I have found, as long as air is flowing through the tent. Air needs to flow through, and around inside the tent. The plants will use lot of water, and I didn't want all that moisture in the house. I vent through a wall to the outside, and the intake for the room is through a door that I have a 20" x 25" filter in. Since this is your bedroom, you will have a higher level of CO2 than outside. My tents runs 550-600 with me and the dawgs in the house, and I am flowing air through it, from the end I sleep in to the other end where the tents are (then it goes in the tents and is exhausted outside). One other reason to vent the air outside is so you don't breath the fumes of the soil and plant.

Just things I thought about as I set-up my grow. And oh yeah, the fans which you set the speed are probably better than the ones that vary the speed to control temp and humidity. For AC Infinity that means a T6 is varying all the time, while a S6 keeps a constant flow. Use 2 of the S6 fans (independant control), and you pretty much have airflow under control, and the sound will be a low constant hum. Get one fan to intake and another to exhaust, set them so the flow and tent pressure are good. If the tent is hot, hang a wet shirt or two on a side wall. The shirt cools as it evaporates. I want to control a pump that sprays the shirt with an inkbird. The humidity works out perfect with the wet shirts and internal circulation fans. Don't bother with a room humidifier IMO in the tent. Mine may go in the nursery.

As for breathing in outside air, that also means pollen, spores, etc....

 

[greenops]

Thanks a lot for your reply. And also thanks for the wet shirt tip, I'm going to try it out next time I have humidity issues.

 

[flylowgethigh]

Sweatshirt works better cause it holds more. Temperature is also fixed with the wet shirts. 75*, 50+ % guaranteed as long as the air inside circulates, it's just a pain to re-wet. Like I said, I am gonna automate that process, and I may use a cotton towel as the wick. A "wall of water", hanging on the side of the tent. Catch the drips and funnel them into a plant. External reservoir, pump, inkbird, some nozzles and hoses... Don't wash the shirts in chlorine...

 

[greenops]

That's a cool project man, good luck with that. On the other hand, do you have any tips for keeping the RH down? It's around 50% in the room but reaches 65% inside the tent.