# How much heat does a 600 watt light produce?



## sampson456 (Jul 14, 2012)

How much heat does a 600 watt light produce? I mean, the tent will be in a 8*9' room with 9 ft. ceiling. The bedroom door will be closed for security reasons. If I am venting the hot air from the tent into the room itself how much will it raise the temp in my bedroom? Just trying to get an idea of how much the light is going to affect the temp in the room. Maybe I dont even need an AC if I just run the lights mostly during the night with cool air being blown into the room? Will it heat up the hallway area outside my room because of the air flow under the door? My roomates dont mind me growing but if it makes the usptairs area really hot and starts affecting them they might start having problems with it.


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## bostoner (Jul 14, 2012)

first off you can't just let the heat sit outside the tent. It will eventually build and you will be heating the air in the bedroom and hallway eventually. If your pulling the air from the room for the plants it will heat and reheat the same air and you don't want that. You need to get rid of the hot co2 depleted air into another room, the attic or outside. Sucking air in is more efficient that blowing air through. So I'd just exhaust out somewhere and have a passive intake to bring in cool air from the room. When I doubled my exhaust it ran my intake fans too fast because of the pulling. I pulled them out an made the intake holes bigger and it helped a lot.


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## JASON79 (Jul 14, 2012)

sampson456 said:


> How much heat does a 600 watt light produce? I mean, the tent will be in a 8*9' room with 9 ft. ceiling. The bedroom door will be closed for security reasons. If I am venting the hot air from the tent into the room itself how much will it raise the temp in my bedroom? Just trying to get an idea of how much the light is going to affect the temp in the room. Maybe I dont even need an AC if I just run the lights mostly during the night with cool air being blown into the room? Will it heat up the hallway area outside my room because of the air flow under the door? My roomates dont mind me growing but if it makes the usptairs area really hot and starts affecting them they might start having problems with it.


a 600w hps on with widows and out side doors shut in the winter could keep a flat warm by it self 

the heat for a 600w seems unreal 

in the spring it will increase a small grow room 5-10 degrees Centigrade with a 5" fan in and a 6" fan out of the room


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## Slipon (Jul 14, 2012)

I got a 600W HPS pootlight 



so no cool tube or anything .. 

my grow room is located in a spare bedroom (12 sq meters) 
the room is 1/3 of the bedroom so 1x3 meters and celing hights as you can see on the pics (is from when I build it) 

Im in Denmark (scandinavia) so we realy dont have that hot temps .. summer peak at 90F .. but that like a week maybe .. 
mostly 80-85F and even that is like 2 month a year .. fall/spring we got like 50-60F and wither we got snow ..

I mostly have around 70-75F inside my appartment (fairly new so good ventilation but no AC as its rarly in Denmark .. we use heaters )

when I turnd on the HPS in the room it did only take it 10 minuts to build up to +90F 

gott a 100mm outtake ventilation (187M3/hr) 

View attachment 2255463


and it did a ok work ... got it down to 85-88F or so (10-13F more then outside) 


got a fan blowing at the HPS



so I could keep it around 85F at plants top .. summer temps so I was ok with it .. just desided to runn it at night .. witch got it down on 82F or so 

but then the smell got wors and I had to mount a carbon filter .. 



that did take some of the effect from the vent. and with realy high summer temps right now I was right back up on +88F 

so had to upscale to a 6" ventilation (290M3/hr) .. 

got it down on 84F or so .. 

also made a 6" tube runn from my passiv intake over my bedroom window to my intake of my grow room and got a cheap bathroom ventilation

View attachment 2255490

to help pull could/fresh air/Co2 in .. 

so now I can mostly keep it around 82F with fresh air/co2 .. can even smell it in the room and my girls seems to enjoy the fresh air from outside .. and I enjoy not haveing to keep my windows open all the time .. 

but as you see its a strugle .. I did`t quite know what to expect either .. 

so I would realy consider it a lot and do a lot of research fist .. maybe a 250W would be a better choise for you ? maybe you have money and can get a nice cool tube and have a window near to get fresh air in ? maybe you live in Sahara and then I would forget it or go with fluorescent/LED use the money on a good fixture insted of 10 ventilations and ACs .. ther is a lot to consider .. 

hope this help you get a picture of what to expect ..


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## sampson456 (Jul 14, 2012)

bostoner said:


> first off you can't just let the heat sit outside the tent. It will eventually build and you will be heating the air in the bedroom and hallway eventually. If your pulling the air from the room for the plants it will heat and reheat the same air and you don't want that. You need to get rid of the hot co2 depleted air into another room, the attic or outside. Sucking air in is more efficient that blowing air through. So I'd just exhaust out somewhere and have a passive intake to bring in cool air from the room. When I doubled my exhaust it ran my intake fans too fast because of the pulling. I pulled them out an made the intake holes bigger and it helped a lot.


Do you think a good window fan blowing air in the bottom of the window then exhausting the air out the top of the window would work? (There is an upper window and lower one so its about 5-6 ft. tall window) Would it keep things cool enough? It probably gets in the 60s at night and thats when i could have the lights on most the time.


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## sampson456 (Jul 14, 2012)

(I wouldnt be sucking the air directly from the window into the tent just blowing fresh air into the bedroom itself with a window fan, then exhausting pretty much directly out the window with ducting?) What do you think?


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## sampson456 (Jul 15, 2012)

Thanks alot slipon that was a lot of help. I kind of lost what you were saying about the 6 inch ducting over your window to a bathroom vent though. The light is a air cooled hood reflector. Would a cool tube work better? It gets pretty cool at night here and should be getting even cooler soon. I think i could do without the AC as far as the plants health if i have good ventilation. It will be a 6" 440 cfm inline duct blower with a carbon filter. Im wondering how hot it will be in my bedroom without an AC. The tent will be in the room that i sleep in so if i am exhausting the air from the tent outside and have the cool night air blowing in from a window fan will it still be hot in my bedroom? I have to sleep in here so i dont want it to be too hot.


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## towlie (Jul 15, 2012)

Sampson. Looks like you're pretty well covered here. Just thought I'd give you a couple equations to help. A 600 watt bulb produces 600 watts of heat (first law of thermo.) It doesn't matter how efficient the light is because it's either giving off light or heat... both of which are energy, and both of which ultimately result in heat. Keep in mind that if you have a 100 watt fan, this counts as energy too. So add up all of your equipment in the room. Just look at the back nameplate. It should have a running wattage rating......................................................................................................................................................................................................................................................................................... 1 Watt = 3.412 Btu/hour... (or 600 watt = 2,047 btu/hr)........................................................................................................................................................................................................... REFRIGERATED AIR CONDITIONING: 1-Ton (of a/c) = 12,000 Btu/hr... (2,047/12,000 = 0.17 Ton) For example, if you air-conditioner is rated for 1-ton, you would need to rob 17% of it's airflow to cool the room. You could also buy a small 1/4-ton modular air-conditioner at Home Depot............................................................................................................................... EXHAUST AIR CONDITIONING Btu/hr = CFM x DeltaT x 0.9 CFM = Exhaust Airflow in Cubic Feet per Minute DeltaT = The temperature difference between your grow room and your air intake temp 0.9 = This is just a conversion constant that is good up to Denver. If you're at see level, your calc's will be slightly more conservative. If you've got the money, I'd purchase a variable speed exhaust fan with integral thermostat controller (you can buy these at most hydro sites.) If you buy a constant speed fan (with no thermostat), you'll have to slow the fan down in the winter or you'll freeze the grow room. The variable speed temperature controller will slow the fan speed down and prevent the room from freezing in the winter. Good luck bro.


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## towlie (Jul 15, 2012)

Damn. I don't know why I couldn't get the above post to format correctly... Wherever you see a long string of periods is supposed to be a new paragraph. Hopefully it makes sense.


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## sampson456 (Jul 15, 2012)

Towlie thanks for the advice about the adjustable fan I will definitly get one since it is the middle of the summer now and will be well into the first part of winter by the last month of the grow. I had trouble following the last paragraph, the exhaust AC btu/hour. What is DeltaT? Another question do you think a 4 ft by 4ft by 6ft grow room is too big for a 600 watt light? thats only around35 watts per sq. ft. that seems pretty low but the only other choice is a tent half the size. I dont really want to build my own and all that for the first time i just want to buy the kit so i can get a good idea of how the tent should be setup then next grow i might just build my own and make adjustments i feel would help.


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## towlie (Jul 20, 2012)

Ya. Sorry about that. I don't know why my post wouldn't format. 

600 watts does seem pretty big for a 4x4x6 room. So long as your exhaust is sufficient, it shouldn't be a problem... I guess one concern I have is that your plant may grow almost 6-ft high. 600 watt is going to be pretty hot, so you're going to want to keep your light about 18-inch above the plant and probably at least 6-inches below the ceiling. If your pot or hydro tub is 12-inches tall, you'll only have 3-feet of usable height for actual plant space. If I'm imagining this correctly... I think if I were you, I'd consider a 400 watt flowering bulb, and a 200 watt CFL. 

Hopefully this post formats correctly:

600 watt = 2,047 Btu/hr (I'll abreviate this as Btuh for simplicity)

Exhaust (cfm) = Btuh/(DeltaT x 0.9)
DeltaT = Temperature difference between your grow room and your exhaust source. For simplicity, I'll assume you want to keep your grow space at 80-degF. Let's assume you can get your exhaust make-up air from your air-conditioned house with the thermostat set at 72-degF. You'll need the following exhaust airflow rate...

DeltaT = GrowRoomTemp - MakeUpTemp = 80-72 = 8-degF
Exhaust = 2,047 Btuh/(8-degF x 0.9) = 284-CFM (cubic feet per minute)

But... Let's assume you're getting all of your exhaust make-up air from the great outdoors. For the sake of this post, I'll assume it gets up to 105 where you live... Obviously you can't cool your grow room to 80-degF with 105-degF air... But if you're willing to let your room get 8-degF hotter (113-degF), you'll need 284 CFM.

Hope this helps.


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