Intake question

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Fr3nzy

Fr3nzy

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Planning on running 4" pvc into crawl space for intake. But not a fan of the stale air. I'm aware It can be treated with uv light but couldn't I just pull air from a vent. Saying house temp is maintained year round. It will be 4 90s around 50' long and upsized to 8" in room for the 500cfm fan. Room is 4x9.6x7.6. Giving me total of 291.8. Does anybody know the loss per 90 in 4" pipe. Also wondering if a 4" fan in front would help.
 
Anthem

Anthem

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Check the web for free flow verses fan power. I think that free flow is something like 2 1/2 times the duct size to equal forced air in normal conditions. No way is a 4" with all those restrictions going to be able to keep up with an 8" fan. You are going to have to do some research to figure out the CFM needs and the restrictions that a 90 degree bend put on the system. It should be obtainable on the web.
 
Fr3nzy

Fr3nzy

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8 in on speed control, just need 70ish cfm output but didnt think a 4 would do it. And free flow brought me to next thought. Room is ultra sealed. If I vented wouldn't it cause suction through. I'll have a look. But is pulling out of the house sufficient enough?
 
chemistry

chemistry

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I suck my air from with in the house, and expel it outside into the open air, or I risk blowing the smell of a full grow through my house, I'd be single by week 5 of flower otherwise. lol
 
Fr3nzy

Fr3nzy

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chemistry said:
I suck my air from with in the house, and expel it outside into the open air, or I risk blowing the smell of a full grow through my house, I'd be single by week 5 of flower otherwise. lol
Click to expand...
Haha, ya I'm venting straight up and out with 8", it's a out building so needed good climate controlled air without adding a ac in there. Room is very well insulated.r25 walls r38 ceiling.
 
jaguarlax

jaguarlax

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Fr3nzy said:
Planning on running 4" pvc into crawl space for intake. But not a fan of the stale air. I'm aware It can be treated with uv light but couldn't I just pull air from a vent. Saying house temp is maintained year round. It will be 4 90s around 50' long and upsized to 8" in room for the 500cfm fan. Room is 4x9.6x7.6. Giving me total of 291.8. Does anybody know the loss per 90 in 4" pipe. Also wondering if a 4" fan in front would help.
Click to expand...


i have been running these cheap dehumidifiers in my closet, they have UV lights built in... just a thought...
https://www.amazon.com/Dehumidifier-Electric-Dehumidifiers-Basements-Bathroom/dp/B07Q5KTRXZ
 
mk23tas

mk23tas

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Fr3nzy said:
Planning on running 4" pvc into crawl space for intake. But not a fan of the stale air. I'm aware It can be treated with uv light but couldn't I just pull air from a vent. Saying house temp is maintained year round. It will be 4 90s around 50' long and upsized to 8" in room for the 500cfm fan. Room is 4x9.6x7.6. Giving me total of 291.8. Does anybody know the loss per 90 in 4" pipe. Also wondering if a 4" fan in front would help.
Click to expand...

You are asking an engineering question that requires a lot of math. Take a look at this document, it will give you all of the formulas you need. I found one without calculus ad uses simple algebra.
 
Fr3nzy

Fr3nzy

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Step one, and my crude carbon filter 🤣 had faint light coming out roof vent so that is its main purpose till I get one ordered. Also starting to get cabinet ready to germ seeds in top, veg In bottom, and flower in the room. But we will see lol. Exhaust fan is ran on a temp control. Still think a speed control is the way to go, easy fix. Also I wanna space the light off the shelf seemed to gain a bit of heat over time. It will have doors plus vent and thinking like a USB humidifier? If anybody has ever used one for seedlings that will be in a 1x2x1.
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