Temperature control in a 5x5 stealth room

Hi all,

I need help deciding on a solution to improve temperature in my stealth grow closet. I'm currently sourcing air from my central a/c supply duct with 4" ducting and an inline fan. I have a 6" fan and carbon filter exhausting air into the attic. The thermostat is outside the grow room, so there is a gap between what I set it and the actual air temperature in the grow room (+/- 12 degrees, depending on time of day and outside temperature).

This setup mostly works in my climate, except in July/August temps in the grow room get near 95F, even with exhaust fan at 100%. I have to set the thermostat to its lowest setting to get the room under 90f, which is very expensive. I just don't flower during that time of year. Ultimately I want temps to be controlled in the 70's to low 80s.

I am considering using a portable a/c unit like this: https://www.amazon.com/dp/B07DQVNSP8/ref=cm_sw_r_sm_apa_fabc_N916FbFNSM0Z0. Are these good? I am planning to vent the exhaust into the attic.

A window unit a/c is not an option, unfortunately.

Any other ideas or experiences with these air conditioners?

123drp said:

I have a 6" fan and carbon filter exhausting air into the attic.

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Thats a big no no. Venting warm humid air into a cold attic will cause condensation and black mold is the likely result. It's a very expensive problem.

Renfro said:

Thats a big no no. Venting warm humid air into a cold attic will cause condensation and black mold is the likely result. It's a very expensive problem.

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To be clear, I actually have the exhaust ducted through the attic so it vents outside. However, I wasn't thinking about condensation so I may revisit how this is set up. Thanks for the input.

Any air you push out of your house has to be replaced. Whether you have an inlet or it comes in through little cracks around doors/windows/etc. Where i live most days are either to humid or to hot or to cold to be sucking any outside air in. What kind of light are you running?

JoeBlow5823 said:

Any air you push out of your house has to be replaced. Whether you have an inlet or it comes in through little cracks around doors/windows/etc. Where i live most days are either to humid or to hot or to cold to be sucking any outside air in. What kind of light are you running?

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I currently have 3 LED lights running, all metered at 700 watts from the outlet. I'd like to add a 4th light if I can control temps better.

Would you recommend venting exhaust back into the house instead of outside? I can do either.

123drp said:

I currently have 3 LED lights running, all metered at 700 watts from the outlet. I'd like to add a 4th light if I can control temps better.

Would you recommend venting exhaust back into the house instead of outside? I can do either.

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It all depends what exactly your doing, what options you have, where you live, etc. If you have a cold basement and can somehow vent to the basement, that would be ideal. That is what I do. Like i say, where i live the weather is shit 90% of the time so pushing tent air outside just to pull shitty outside air back into the house is a terrible idea. Dehumidifier would be running non stop. Furnace would run way more in winter. AC would run way more in summer.

1100w HPS heat straight to the basement.