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 Kine
Registered: 11/25/08
Posts: 374
Last seen: 14 years, 10 months
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 HID heat... 
#242714 - 06/24/09 10:27 PM (15 years, 5 months ago) |
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How much more heat would a 250 have over a 150? I want to do a small stealth grow but dont want heat problems. I know a 400 was a bitch, but if its only a 3-5 degree diff; i might as well pick up the extra lumens and such and just beef the fan up a bit...
thoughts.
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 Data
That Guy
Registered: 08/12/08
Posts: 4,038
Loc: Southwestern US 
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Re: HID heat... [Re: Kine]
#243359 - 06/26/09 10:53 PM (15 years, 5 months ago) |
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well I have no real experience with HID's, but its kindof a thermo problem...since the wattage is how much energy you are adding to ur system...which is being converted to heat and light...and the light is getting absorbed by the plant and the surrounding surfaces...the light going to the plant gets bound up in chemical energy and some heat...and all of the light getting absorbed by the surroundings is converted into heat...now all of the waste heat that gets generated by the filament can be carried out in an air-cooled light design...leaving only the radiant heat (IR mostly) from the light that is heating the actual growspace.
This heat produced in the growspace is then removed by heat transfer across any walls or ceiling/floors, absorbed by the vaporization of water(mostly from the plant itself during transpiration), but more than likely the heat is transferred to the air by either conductive heat transfer or vaporization of water...and then removed from the system via a fan...with fresh, lower humidity, lower temperature air.
so the questions i have for you are:
-is the light air-cooled?
-is the exaust for the air-cooled light exhausting back into the room? or out of the room?
-what are the basic dimensions of ur grow area (L,W, and H)
-What is the current temp and relative humidity in ur grow area
-what kind of exhaust fan are you running?
-what is the temp and RH of the fresh air coming into ur grow area?
-are you running a carbon scrubber on your exhaust fan, or is relatively obstruction free?
If you can get me this info...i can probly set up a calculation for the change in air temp you would see when you upgrade to a 250W light.
Otherwise I'm sure someone with more experience with this than me might come along and help out...just trying to reason it out since nobody else is answering.
Peace,
agmotes165
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“The Universe is under no obligation to make sense to you” -NDT
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Kine
Registered: 11/25/08
Posts: 374
Last seen: 14 years, 10 months
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Re: HID heat... [Re: Data]
#243395 - 06/27/09 12:34 AM (15 years, 5 months ago) |
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That would be great! But my room is going to be designed for the light; bigger light = more plants... thus, bigger room. Its for a stealth, so i also dont want masses of heat being transfered... that shit can get wicked in small areas sometimes. I may have seperate smell/heat exhausts; or more convienently just vent the room...
So i guess im looking for some one who's used both... i've delth with 400, seen a 150, but never felt it. I want to know; open air; how much hotter a 250 is then a 150.
Thanks tho.
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Data
That Guy
Registered: 08/12/08
Posts: 4,038
Loc: Southwestern US
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Re: HID heat... [Re: Kine]
#243417 - 06/27/09 08:11 AM (15 years, 5 months ago) |
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well, that being said...i looked up a 150W and 250W HPS lights...and for the 2/3 increase in electricity use...you get a jump from 16000 lumens output to 28000 lumens of output, or a 3/4 increase in total light output...so if you are shooting for a luminous intensity in the direct sunlight range...or 33000 to 130000 lux, lets say 35000 for the time being...then with a 150w, you could effectively light .45 square meters, or about a 2.25x2.25 foot room...versus the same lux rating given 28000 lumens, would work out to .8 meters squared, or about a 3x3 foot room...so working it out as a function of head space...you get 3.5 cubic feet of extra air per foot of height of the room...so use that to calculate how much extra air you get based on ur room height. so say if ur room has an 8 foot ceiling...then you would go from 40.5 cubic feet to 72 cubic feet of airspace...or a .77% increase in air space...so given the variables...even if you increased the wattage coming into the system by 2/3 (which given the 3/4 increase in light output...you wont be putting 2/3 more heat into it) and staying with the same light intensity...the increase in air space would more than adequately distribute the extra heat given off...but thats making a lot of assumptions...but those are my rough estimates...
hope this helps a little
agmotes165
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“The Universe is under no obligation to make sense to you” -NDT
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ethnoguy
E to the G
Registered: 04/21/08
Posts: 429
Loc: your momma's house
Last seen: 15 years, 4 months
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Re: HID heat... [Re: Data]
#243430 - 06/27/09 09:46 AM (15 years, 5 months ago) |
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Whats the sqft and cf anyway?
EG
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Kine
Registered: 11/25/08
Posts: 374
Last seen: 14 years, 10 months
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Re: HID heat... [Re: ethnoguy]
#243582 - 06/27/09 07:52 PM (15 years, 5 months ago) |
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EG; refer to my second post... lol.
Im building it all around the light... i care about heat dissapation. I cant be having an apartment with the AC cranked windows open and massive fans making noise all day trying to keep the house cool... Having previously worked with a 400; im not going that route till i can utilize the space a 400 can light. So im just worried about keeping heat down, cause i dont know of a way to litterally make heat dissapear; just move it to somewhere else; so i want to do the least of that with in reason.
If you've ever seen pipedreams bub closet; thats kind of my idea now. Have a mother/clone, and utility chest; then another flower room that will be linked; but not directly...
Its really hard to explain. The best thing would be to get ahold of a 150 and 250 and use my IR temp gun to get readings... but i can only get a 400 and 1000!  But its a slow going project... just a question that im not easily finding an answer to...
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