How much air conditioner do I need for...

How much air conditioner do I need for an 8x13 room with 1200 watts of COB LED and 630 watts of CMH?

Will 5,000 be enough? 8,000? Should I step up to the smallest mini split I can find at 9,000? Bigger?

I know the math for HPS. But LED and CMH are newer technologies that run cooler, so I'm not sure.

This is the design phase of a new room for me, btw.

Use the math for hps because overkill is desirable in cooling.

4000 btu per 1000 watt bulb. So rounding up 8000 btu would be plenty for your cooler running lights.

outside temps in summer?

insulation r factor?

my self here in ali for 8 x 13 room i am using 15,000 and dialing down using controller.

if you can afford higher btu cooling and higher seer factors.

For a room that size, figure that you'll likely save on air conditioning if you use air cooled hoods with insulated ducts and keep the ballasts outside of the room. With or without an exhaust fan, you can still use outside air to cool the hoods, even in a sealed room. It would cost less to cool a grow tent than a whole building, so the room design and insulation all matter. Insulation up front is worth the investment if you'll be working against outside weather. If you use the lights at night you might also save on cooling.

Mengsk said:

For a room that size, figure that you'll likely save on air conditioning if you use air cooled hoods with insulated ducts and keep the ballasts outside of the room. With or without an exhaust fan, you can still use outside air to cool the hoods, even in a sealed room. It would cost less to cool a grow tent than a whole building, so the room design and insulation all matter. Insulation up front is worth the investment if you'll be working against outside weather. If you use the lights at night you might also save on cooling.

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a lot of his light is in cob LED and there isnt much you can do on the air cooling front there, he could use watercooling blocks for computer CPUs though and remove a lot of heat from them that way

Probably easier to describe in more detail what I've got going on and am planning.

I'm currently in a studded out basement that has pink styrofoam on the walls but no drywall. I have a 25'x 12.5' area set aside as my "workshop". In my workshop, I built an 8'x8' room that I currently grow in. It's got a cabinet that I use for a mom/clone/small ass veg area, and the rest of the room is used for flowering. (4'x8' under 1800 watts of LED)

It's too damned small for my big ass! And only having access to one side of the plants is a huge pain in the butt. If I want to do anything with them, I have to pull 3-4 plants out of the way to get to the one against the far wall. Therefore, it's time to build that flowering room I want and is easier to manage.

Which means it's time for a redesign. Which includes finishing the workshop. That means I need to finish the electrical, add plumbing for a sink and drain, then insulate and drywall the walls. My current grow room will have to come down during this, but will going right back up with some minor modifications. Mainly semi-sealing it up. This room I know I can get away with a 5,000 btu window unit built into the wall, but I'm not sure if I need to (see below). I'm not too concerned about air or light leaks because it'll be just a veg room.

The flowering room will be insulated on the wall that it shares with the foundation, but that's all I've planned for. If it is in my (and the plant's) best interest to insulate all 4 walls, I will. But I don't think it's necessary when the basement stays between 60 and 72 degrees year round. My bigger concern is the humidity swings. (low 20% in winter, as high as 60% in the summer depending on the outside temp and rainfall situation.)

The flowering room will have a pair of 315 CMH lights on a light rail moving over a 10'x30" table. Flanking the CMH's, I'm going to run 2 9' long COB "rails" with 600 watts on each rail.

Both rooms will dump air into the workshop at least once a day. (I may keep the veg room how it's situated now with a fan constantly pulling through a scrubber and dumping into the basement. I will need to add more passive intakes though, as I cannot turn the lights all the way up without cooking the room.) The workshop will then dump carbon scrubbed air either into the basement or into the garage, I haven't decided which yet. The basement would be easier. But I think the garage would be a better idea for fresh air movement throughout the whole house. (thoughts?) Third option is to vent the area into the attic through a closet on the main floor. But doing so would be a pretty big undertaking and I don't plan on staying in this house for more than 5-6 years.

If I vent into the garage or attic, I would add an ozone scrubber to the system. The garage gets opened up a couple times throughout the day, it's not insulated at all, and I'm pretty sure it's not too sealed up from outside. So I'm not too concerned about ozone build up. If it does become an issue, it would be pretty easy to add an exhaust fan to the garage.

If I vent to the attic, I would go ahead and do a roof penetration and exhaust all the way outside.

CO2 injection will be in the flower room, though I haven't decided how yet. 20 lb. CO2 tanks are a bit more conspicuous than a 20lb. propane tank. (I do not live in a free state. Yet.) Flip side of that is do I want to deal with the heat (and possible carbon monoxide from incomplete burning) generated by a burner?

Keep in mind this is a mental exercise at this point. I'm still 6ish months away from starting construction. And it really hinges on what happens in November and our local governor's race. Our current one stays, prohibition will continue. He get's ousted, and we'll be legal within 3 years. Which mean's I'll be building a greenhouse instead of building out the basement.

Lester Beans said:

Use the math for hps because overkill is desirable in cooling.

4000 btu per 1000 watt bulb. So rounding up 8000 btu would be plenty for your cooler running lights.

Click to expand...

I've been in the trades for most of my working life. I know that you want to size your air conditioning correctly because too small will never stop running, and too big won't cool and dry the air effectively.

Would the 9,000 btu mini split be too much? That's what I would prefer to run because of the sealed room.

I would think that would work just fine. It wouldn't have to run constantly.

See the AC sticky in this forum. -granger

With circulation fans in the flower room it is simple to calculate the volume or ppm of CO2 to use. But without a meter the flow rate or time between turning the fans on are guesstimated. You might be able to get larger tanks at a welding supply place or food service supply like soft drink refills. Running a sealed room with air conditioning just to use CO2 may or may not be a waste. Running all those accessories - a/c, de/humidifier, chiller, indoors during hot weather can get very costly. Better to grow outside then use the lights in winter.