Need more temperature headroom, is this theroetically a correct understanding/solution?

Right now, I have a 8x8x9 room I DIY'd with two 600watt HPS air cooled fixtures and ballasts (in the room) passive intake, dehumidifier, exhaust, and essentially uses my basement as the lung room.

Pre-Air cooling the hoods, I was averaging 89f in the room with the door closed and had to keep it open during lights on, and keep the A/C uncomfortably low in the house.

I hooked up the air-cooling and now with the door open during the day, and door closed at night I am basically hovering at 75f 55%-60% humidity if I keep my central A/C set to 68.9f. Better, but not there yet.

I need to improve this as I'd like to run the A/C a little less, and be able to keep the door closed and locked. Currently if I close the door, and let the A/C climb to 70f, the room reaches 85-86f. This appears to be no good for HID, but I have no way to run more A/C.

I think I have to go LED, but want as much or more light output. My understanding of LEDs (looking at quantum boards such as Spider Farmer sf4000), is that due to the lowered IR output, the room temp can/needs to run hotter for the VPD to reach the optimum range. This would be excellent for me.

I am wondering, considering a watt of heat should be equal no matter the source, if the 2 sf4000's pull around 1200watts, and I closed up the hole for the air cooling, in the room and kept the door closedm I imagine my room would again reach 89-91f to be realistic (having the lights up 100%).

My concerns:
- With suitable air exchange and movement in the room, and no supplemental CO2, is 90 or even to be safe, 91 or 92 too hot for LEDs?

- If 91/92 is ok, at this higher temperature range, what range should I be able to keep my humidity in to reach the right VPD range throughout the grow?


If my understanding is correct, and this works, It should substantially lower my electrical costs because:

- One less fan used (no more air cooled hood)
- A/C not running all the time, huge savings.
- sf4000 should output more light than my 600 (it appears to replace a 1000warr), so I can likely dim it and save more money and run a bit cooler.
- If humidity needs to be higher at this temp, I can run my dehumidifier less.

I hope this is right, I'm feeling optimistic! Thanks for any feedback or confirmation!

The sf4000 would be more than a 600w hps but less than a 1000w hps as far as light output.
They are 450w each.

85-86 would be as high as I would want it without co2 which would be pointless in a vented space anyway.
You could run higher RH to match vpd chart, plenty of led vpd charts online.

Seems to me though your seeing a considerable temp rise with just a couple of 600 hps.
Which says not enough air exchange or your air your venting is finding its way back into your grow space.

Where is your room in relation to your lung room? Where does new air come from and what fans you running? Make and cfm?

Many guys shutdown grows in summer months
The return isn't worth the investment on personal grows
I guess you can throw cash at the issue or resign to a new plan in the future
No cheap resolution though

I'm not sure I'm hooped yet, I am also willing to turn down the lights if needed, and maybe the thoughts and details might help to get your further opinion on my situatuion. You see I'm even worried about growing in winter when I need to run heat in my house. I knew I would run into these problems, and figured I'd work through the problems or scale down accordingly.

Grow room design info:

- It is 8'x8'x9' but I only grow at most 8 plants in a 4'x8' space, the rest is storage and work area for me while in the garden.

- I run my dehumidified in the room, and it seems to cause temperature spike at lights on/first watering when my house is cool from over night and not enough heat has acumulated yet to trigger the central A/C before the room temp rises, and again at lights off when it is pulling the humidity from the cooling room but not as bad.

- I run a 6" A/C infinity fan and filter through a straight piece of rigid ducting 10ft to my cold air return in my furnace, I tested my returns around the house and they are all still pulling strong. The lung room (basement) air sits at about 19 to 20 degress with A/C running and rises over night (part of the morning spike). I think it's rated at 350cfm. I know this is low, was hoping to get away with it due to growing only a 4x8 space in the room with 8 or fewer plants. This could be replaced, but I was hoping to work on lowering/removing heat sources in the room.

- the intake for the lights and exhaust are into the basement, so this does warm the basement slightlym, but the a/ keeps it cool.
- the exhaust fom the room goes to the upstairs through the cold air intake and is cooled by the A/C.

My thoughts:

- I misread the sf4000, if it is only 450watts, then that would be a drop of 400watts of heat energy in the room from the 1200 I am running now. This alone should drop my room temp a bit I think even without air cooling the hoods.

- If the room an then run hotter and I can then run a higher humidity, the dehumidifer should kick on less throwing less heat.

Still thinking this is a dead end?

Thanks!

I may have overstated the max temp, my peaks hit 90, the average with door closed when running A/C throughout the day and no dehumidifier running is more like 82. I might be answering my own question by having to think through this a little more. I would still appreciate further insight or feedback as buying a really good led light will still be cheaper then trying to get a split a/c unit in there.