Is there anyone out there ???

I have a 40"w x 43"l x 82 1/2"h,(approx. 82 ft./3) insulated enclosed space inside my unheated outdoor shed. I live in the Northeast U.S.. Winter temps can go well below freezing (32F./0C.) I planned on using a 400w HPS/MH light, My exhaust fan with carbon inline filter is rated for 65cfm. .I have a 28 in/2 inlet opening with damper, Can someone please tell me what my grow room temp will be. And would it be o.k to not have a constant air flow exhaust working ,but hook the exhaust system to a temperature controlled device, that would only come on when temp gets to high inside box.. I was thinking of setting exhaust temp to come on at 70F. and turn off at 78F. Or will grow box ever get up to ideal temp of 70-78F. ????? Getting frustrated with little or no info on this subject. Thanks.

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Originally Posted by POHNNY

I have a 40"w x 43"l x 82 1/2"h,(approx. 82 ft./3) insulated enclosed space inside my unheated outdoor shed. I live in the Northeast U.S.. Winter temps can go well below freezing (32F./0C.) I planned on using a 400w HPS/MH light, My exhaust fan with carbon inline filter is rated for 65cfm. .I have a 28 in/2 inlet opening with damper, Can someone please tell me what my grow room temp will be. And would it be o.k to not have a constant air flow exhaust working ,but hook the exhaust system to a temperature controlled device, that would only come on when temp gets to high inside box.. I was thinking of setting exhaust temp to come on at 70F. and turn off at 78F. Or will grow box ever get up to ideal temp of 70-78F. ????? Getting frustrated with little or no info on this subject. Thanks.

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Well its a hard question to answer, but id think you could rig up the fan with temp controls easy. And im thinking in an hour it will kick on too if its insulated, with out any really good out take, it will get hot in there. Hell just one set of 4 cfl's keep my room up close to 78 degrees. So your 400 will get hot, if you could pull air from the top it would help id think. And use a small heater with a thermostat in it would cover you if it gets too cold. So both working or when needed rather, you would have complete control id think. I live in the same area so i know what your trying to do and sounds like a good idea to me:thumbsup:




:rasta:

This is an almost impossible question to answer unless you have some sort of advanced degree in engineering.

Heat loss/gain varies with the temperature differential (DT..delta tee) between the warm and the cold. Without the exhaust intake issue the amount of heat loss can be calculated on a given DT with each different DT, i.e., higher/lower outside temp....and lets assume it is a constant interior temp. THAT can be calculated quite easily..........unfortunately I cannot remember all the formula for calculating heat loss/gain related to R-value of the shed walls. But it goes something like; DT*?= total heat loss in btu/hr; then divide that by the R-value to get the heat loss per hour...AT THAT GIVEN TEMPERATURE.

BUT, I heat a 2500 square foot house off of the waste heat from 1800 watts of lighting for half a day....until the outdoor temperature drops below 40 degrees, then I have to supplement my heat. My home has very good insulation to retain that wasted energy. There is significant heat from those lights, I would assume just one 400 watt will keep the shed from freezing...using lights during the coldest part of the 24 hour cycle.

Well thanks dude. Anyhow heres my plan... And I am open for advice. PLEASE. Setup: Approx 82 cu.ft space insulated,located inside outdoor shed. (1) 400w grow light (ballast outside of box), (1)65cfm exhaust with inline carbon filter located at top of box exhausting to interior of outdoor shed (I'm thinking this exhausted heat will add warmth to shed area ?. (1) oscillating fan in box, Min. 28-30 sq. in. intake duct with damper located at bottom of box. (1) ceramic cube heater inside box. set to come on at 72F.. I will have 18/6 on light for veg. then set to 12/12 for flower. Exhaust fan will be plugged into a programmable thermostat control outlet set to come on at
78F. and off at 73F. This I am hoping will control the heat produced by 400w light. And that the light will provide sufficient heat inside box when outdoor temps go below freezing... EXPERIMENTING IS FUN

Be careful trusting something that if it goes wrong it kills all....Good luck

Quote:

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Originally Posted by POHNNY

I have a 40"w x 43"l x 82 1/2"h,(approx. 82 ft./3) insulated enclosed space inside my unheated outdoor shed. I live in the Northeast U.S.. Winter temps can go well below freezing (32F./0C.) I planned on using a 400w HPS/MH light, My exhaust fan with carbon inline filter is rated for 65cfm. .I have a 28 in/2 inlet opening with damper, Can someone please tell me what my grow room temp will be. And would it be o.k to not have a constant air flow exhaust working ,but hook the exhaust system to a temperature controlled device, that would only come on when temp gets to high inside box.. I was thinking of setting exhaust temp to come on at 70F. and turn off at 78F. Or will grow box ever get up to ideal temp of 70-78F. ????? Getting frustrated with little or no info on this subject. Thanks.

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Make sure you have a heater for "night time temps" or you will stunt your plants...

Thanks for any and all input.. But also what do you think of the set-up ??