Too much heat from HLG quantum boards?!

First-time grower. 8 9-gallon RDWC buckets under 4 QB288s and 4 QB648s. 6” inline fan running through 4” duct to adjacent veg room. Passive 12x12 air intake, as well as a passive 6x18 air return from veg room. Water chiller/epicenter/res also in veg room. I managed to move one driver into the veg room but, the driver for the 4 qb288s is still in the grow room (up high, next to carbon filter). Both rooms are covered in silverboard.

Grow room is 250 cu ft. I’ve calculated I’m introducing 507 watts resulting in 1729 BTU/hr heat output. I want to avoid an AC unit due to difficulty venting outdoors (and electric) but could bite the bullet if it was a necessity. I live in a cold climate and the room is in the basement.
Currently the grow room heats to about 95F with the veg room at around 85F. What should I do?!
Also, I’ve heard you can run CO2 at 1500ppm and get good results at 95-degree heat is that true? I’m all about terps.

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Your 3xhausting into a room that circulates the heat that is exhausted rite back into the tent.

I had issues with heat and I cut a hole in wall to exhaust into a room that doesnt connect to room tent is in.

I bought to small aluminum heat sinks and placed thise on top of the tent. I then ran solid core wire and put the two Meanwell drivers. Plus with how piss poor our AC is I had to buy a 5k BTU window ac that is pointed into the tent. Temp is controlled.

Cool. Appreciate the replies. So if I changed the 4” exhaust to a 6” exhaust and vented into a non connected basement room, would that do it? Or do I still need an ac?

I have to deal with heat and I have seen my canopy temps hit past 105 degrees. South Texas is brutal so you have to get creative.

I don’t know if that will work for you.

If you can exhaust it like this. Close everything else but open one bottom port.


Is the rest of your basement pretty cool? If so, maybe you can use a regular box fan to pull hot air out of the grow room from up high, and cut a return air grill into the wall down low.
I have a 4 x 6 grow closet and a 2 1/2 x 5 tent in a spare bedroom. With both of those grow spaces venting heat into the bedroom, it was getting over 90°F in there. I really wanted to avoid venting through my roof, so I tried this, and it’s been good since.

The fan draws the hot air out, and I cut in a 16 x 16 return air grill with a filter on the opposite side of the wall with the door.

I just bit the bullet and bought an ac. You can get them on craigs list for like 30 bucks. Aint worth fuckin up a thousand bucks worth of weed.

Moving your drivers outside the room/tent/area can help reduce temps. (I think @MrPeat was saying this too).

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Also. I too live a cooler climate and grow in my basement. In the winter I duct the exhaust though a carbon filter and then into the basement outside the grow area. I run a big dehumidifier year round, so this takes out the humidity but leaves the needed heat.
In the summer I vent the grow exhaust straight out a basement window (it’s sealed except the exhaust ports).

How much duct are you running, how many bends, what is fan and filter rated for? I suspect just by running smaller duct you have introduced a significant static load. You could be missing air exchange.

From 4 288 boards and 4 648 boards? Are you running them at half power?

Can you post some pictures of how your ventilation is setup please?

Thanks guys.

I may have messed the wattage math up. Im pretty sure each driver is capable of pulling 600w, so maybe 507w for the both doesn’t make sense. How many watts would you estimate?

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I can’t post pics of the entire 4” run as it’s in the ceiling. It’s pretty gnarly though, so you may be on to something. It’s snakes around other ducting. I would say its about a 5’ run with 3-4 elbows.
My plan at this point is to either eliminate this run and keep all the ducting 6”, or to get a Y duct and add a short 6” run to the existing one.

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Filter: Phresh Filter 6 in x 24 in 550 CFM
Fan: Hurricane Inline Fan 6 in 435 CFM

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Excellent choice, this is filter I use too. How long has it been in service? Should last a while if you’ve had prefilter on, unless it has been exposed to high humidity. Humidity will plug them up pretty quickly.