Stinkyattic ~ The lights, inside fan and exhaust fan are all on 24/0.

Trancefusion5 ~ The fan is always on.

veggie ~ Yup, the A/C is running at night. Our outdoor lows at night only dip into the 80's.

I kinda figured it's a ventilation issue since at night we aren't peeking in on the babies every so often and no one is moving about the house. Last night I tried leaving the zippers at the bottom front of the box open to let in more intake air. I checked it this morning and the temps during the night ranged from 79 to 84. I get that same range during the day with the zippers closed.
McToker Reviewed by McToker on . Why do temps go up at night? I've searched and didn't find an answer. I have a Homebox S (31.5" x 31.5" x 63" - 6.89 sq. ft.). We have central A/C set on 76 F 24/7. I'm running 16 26 watt CFL's and 4 14 watters. The ocsillating fan runs in the box 24/7 as do the lights. The exhaust is handled by a 500CFM fan pulling through a DIY carbon filter. Our plants are still vegging so everything is on 24/0. During the day, the ambient temp inside the box runs from 81 to 84 degrees. At night, the inside temp will get up Rating: 5