BTU enclosed room help

[TheAfficianado]

Hi,
I am on page 23 of Ventilation 101 so I am doing the reading, but my particular difficulty has not been addressed.

A) I live in a place with excellent central AC and I can keep house ambient temps as low as 65 degrees if necessary

B) There is a single floor vent into bedroom

C) My original idea was to place a removable flower tent inside the room- thus a room inside a room.

D) Two part cooling: 1) Cool tubes with straight ducting through tent- no scrubbing; 2) flower chamber air movement with scrubbing

E) Grow room would SUCK air through carbon filter

F) There would be an ozone Air Tiger in bed room, and several ozone Jrs. around house

G) the bedroom size is probably 12 w x 12 l x 7 h

In reading, everyone has the luxury of venting their lights outside or into an attic. I don't have that luxury. I realize that once a cool tube is vented, the exhaust-- though clean of smell-- is 20-30 F degrees higher temperature than ambient intake.

If that bedroom door is closed, it will not take long for the ambient passive intake of both the lights and flower chamber to rise faster than the central AC can cool it, especially if the AC is using a thermostat for a different room in the house.

Even though there would be several feet of space around the tent, there would not be much clearance between the tent top and ceiling where hot air rises.

Some may say that the obvious solution would be A) LEDs or B) a window unit in a room on a house with central AC (at least it is a south facing room!)

I would leave the bedroom door open, but I have cats who I absolutely know would climb the grow tent and destroy it, and also, despite intake filters, I don't want cat hair on my bud. I sorta wanted a clean room, and a possible vacation location away from the cats.

I doesn't mean I can't put the cats outside and open the bedroom door and place a box fan and exchange the bedroom ambient air with household 68 F air.

I've run a 400 watt HPS flower room before and I know they can warm up everything, and here I wanted at least 600 watt HPS.

Basically I was wondering if anyone has any experience with the amount of BTUs or heat generated by 600 watt and 1000 watt HPS and how much ambient circulation was required of ambient air without the capability of moving 20-30 F degree hot air out of the space entirely through an attic or window.

I mean it may be doable if i just exchanged the bedroom air by opening the bedroom door every hour for fifteen minutes with a box fan.

I've looked at LED's store bought and home made, they are the ultimate solution for my condition, but it would be far easier to get one or two harvests before the end of the year to help offset the cost of a permanent LED solution for next year.

But sometimes beggars can't be choosers, and this is the design phase. So this is why I am asking with my ambient venting problems, what the largest HPS light could be.

Any thoughts would be appreciated.

 

[TheAfficianado]

I've had access to this thread: https://www.icmag.com/viewarticle.php?articleid=1477


But it is for internal flower chamber temp control, not external chamber temp control

How much cooling do I need?

This is a common question, and though individual spaces vary, there are some formulas and considerations to help you come up with a figure. Essentially we need to add up the BTU's of heat produced, and counter it with at least the same amount of cooling BTU's.

The first consideration is for the ambient air temperature. If you live in a desert, or any place that routinely sees 100 degrees F+ temperatures, your cooling system will need to be larger than that for someone living in a sub-Arctic climate. When sizing cooling systems, go for the slightly larger option if living in a hot climate.

Calculating how many BTU's are needed to cool the empty space is more difficult, but according to user 00420 at ICMag.com, the following formula will be a good start:

Room Area BTU = L x W x 40 ( H = 8foot + 5btu per foot after that)

If you have a wall that is facing the sun add in for the extra heat

Sun facing wall BTU = L x H x 40


A non-air-cooled 1000W HID light will generate roughly 4000 BTU of heat per light, so a 3000W grow would need a minimum of 12K BTU of cooling just to counteract the heat from the lights. Again, if you live in a hotter climate, it would be good to have a slightly larger unit so it doesn't have to run constantly.

Air-cooling HID lights with ducted hoods and fans is a good way to remove approximately 50% of their heat, while only sacrificing 2% of the light due the the glass lens. For best results air should be pulled from outside the grow room, filtered with a simple dust/bug filter, then pushed through the duct work and lights with a centrifugal fan, and back outside. Keeping duct work straight is essential! A single 90 degree bend in the duct work will cut airflow by 60%! Seal the ducts and hoods with aluminum foil tape to prevent leaks, and clean the glass regularly of accumulated dust to keep light transmission levels high.

Gas-fired CO2 generators can create massive amounts of heat, but fortunately have a BTU output rating on their box. Add this figure to the BTU output of your lights.

Dehumidifiers can create quite a bit of heat as well. Check with your dehumidifier's manufacturer for a heat output rating in BTU's, and add it to your total.

HID ballasts, both magnetic and digital also produce heat. If these units cannot be located outside of the actual growing area, add another 1500 BTU per 1000 watts of ballasts and add to your total.

The insulation and sealing of the room will also affect how much heat it absorbs, and how much cooling is required just to cool the empty room. Uninsulated metal buildings get extremely hot due to the radiant heat of the sun, and can exceed ambient temperatures as the building cooks in the summer heat. Conversely, a tightly sealed basement with good insulation will remain cool even during a heat wave.

Timing of lighting schedules also plays an important part in cooling a grow room. Since most areas are hotter during the day, and electricity is often less expensive in the evening, most growers choose to run their lights at night to take advantage of the Earth's natural cooling. Whether you're drawing in cool outside air for cooling, or running a sealed room with an air conditioner, the lower outside temperatures will make both scenarios more feasible. Air conditioning condensers (the part outside the building) work best if not running in direct sunlight, as they have to exchange the heat from the grow room with the outside air too!

So now you should have a good idea of how many BTU's of cooling you need, but what system is best for you to provide that cooling?