Dryer vent for exhaust

H

Hairybuds

Well-Known Member
I have a dryer vent that doesn’t get used that much. Was thinking of taking a 4” in-line fan and some flex duct to exhaust my grow space on an inkbird for humidity and temp. Anyone done this?
 
How big is the space you are going to be venting and how many watts of light are you using? In a 4x4 grow tent with 400 watts of light or more a 4 inch cant move enough air out to keep the heat below 88F and this is in the winter in a basement.
 
perramas said:
How big is the space you are going to be venting and how many watts of light are you using? In a 4x4 grow tent with 400 watts of light or more a 4 inch cant move enough air out to keep the heat below 88F and this is in the winter in a basement.
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I ran a 600 watt HPS in a 4x4 tent and vented with a 4" fan and was able to keep the heat below 88°F. This was in a garage. The only time I had any issues keeping the temp at acceptable levels was in the middle of summer.
 
perramas said:
How big is the space you are going to be venting and how many watts of light are you using? In a 4x4 grow tent with 400 watts of light or more a 4 inch cant move enough air out to keep the heat below 88F and this is in the winter in a basement.
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In basement, 375W, 3.8’x3.5’=12.5 sqft grow space. 7.5x4.5x7.5 room. I’m venting now with carbon filter and it gets to 30C so I’d be adding more venting cfm’s. Spring temps and humidity might be problematic.
 
xtsho said:
I ran a 600 watt HPS in a 4x4 tent and vented with a 4" fan and was able to keep the heat below 88°F. This was in a garage. The only time I had any issues keeping the temp at acceptable levels was in the middle of summer.
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We’re you running a dehumidifier too? I do and I might need to go down to two plants instead of four.
 
Boatguy said:
I use a dryer vent as well, just independent. She would murder me otherwise.
Have my 6" fan dummed down to 4.
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I could do the same, I was thinking of a 6” exhausting with carbon filter and a 4” exhausting outside. Or do what your doing and just leave it as a 6” down to 4” with no filter.
 
My 6" filter/fan feeds into a 4" dryer vent, but it's a short run of about 6 inches of 4" to a 4x6 adaptor, then about 16" of 6" duct to the fan. Space is about 200 ft^3, but only 4' x 3' area used for growing. One 350W light. 1-3 plants max personal. So far - so good, but if I expand at all, and increase cfm, I'll have to make it a 6" vent.
 
I too am using an unused dryer vent for my exhaust air. AC Infinity 6" reduced to 4" at the vent itself. 450w LED, 3'x4'x6 tent; works just fine. Do the math, include all your ventilation 'add-ons' (filter, silencer, etc.) and keep it simple. Basement location, winter temp outside tent (passive make-up air) is at 71F in winter and 75F in summer. I have no trouble maintaining growing temps year round inside the tent using this method. I have hot, humid summers and cold, dry winters. Depends on multiple factors; it can be done. My ideal set-up would be to duct it through the roof just like a plumbing vent. Then, if any odor leaks whatsoever, it's above the roofline. However, the dryer duct from the basement works just fine. If nervous about odors, toss one of those urinal cakes in the last couple feet of the exhaust duct before it goes outside for added 'insurance'.
 
I’m about to come spring/summer and another 2 lights. I just run the ac on vent in the winter. 10in fan, ducting through the big hole I knocked out over the tents’ room’s door reduced to 6 at the hole the landlord cut in the kitchen floor for a dryer vent(literally just a hole straight into the crawl space. I don’t have a dryer so it’ll beat the piece of wood over the hole I have weighed down with a spare ballast to keep my cats in.

keep it up riu yall just giving me good ideas today. Bout to start taking back the mean things I’ve said.
 
Cynister said:
I too am using an unused dryer vent for my exhaust air. AC Infinity 6" reduced to 4" at the vent itself. 450w LED, 3'x4'x6 tent; works just fine. Do the math, include all your ventilation 'add-ons' (filter, silencer, etc.) and keep it simple. Basement location, winter temp outside tent (passive make-up air) is at 71F in winter and 75F in summer. I have no trouble maintaining growing temps year round inside the tent using this method. I have hot, humid summers and cold, dry winters. Depends on multiple factors; it can be done. My ideal set-up would be to duct it through the roof just like a plumbing vent. Then, if any odor leaks whatsoever, it's above the roofline. However, the dryer duct from the basement works just fine. If nervous about odors, toss one of those urinal cakes in the last couple feet of the exhaust duct before it goes outside for added 'insurance'.
Click to expand...
Better off with some ona gel than the urinal cake I think, but also solid idea. Now to figure something to block critters getting in through the ducting
 
Lenin1917 said:
Better off with some ona gel than the urinal cake I think, but also solid idea. Now to figure something to block critters getting in through the ducting
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I had a similar problem, easiest fix for me was to put the filter on the other end. Also freed up some room in the tent.
 
Hairybuds said:
We’re you running a dehumidifier too? I do and I might need to go down to two plants instead of four.
Click to expand...

I've ran a small dehumidifier in the tent and was still able to keep the temps in check. A 600 watt HPS puts off significantly more heat than a 375 watt LED. Ambient temps are going to be a factor and I run my light at night when it's cooler so the intake air is going to be at its coolest when the lights are on.

I don't know your setup or when you have your lights on but running in the evening or finding a way to pull in cooler air could make a difference in your temps.
 
CWF said:
My 6" filter/fan feeds into a 4" dryer vent, but it's a short run of about 6 inches of 4" to a 4x6 adaptor, then about 16" of 6" duct to the fan. Space is about 200 ft^3, but only 4' x 3' area used for growing. One 350W light. 1-3 plants max personal. So far - so good, but if I expand at all, and increase cfm, I'll have to make it a 6" vent.
Click to expand...

Sounds almost the same setup as mine. I will try the same thing out.
 
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Cynister said:
I too am using an unused dryer vent for my exhaust air. AC Infinity 6" reduced to 4" at the vent itself. 450w LED, 3'x4'x6 tent; works just fine. Do the math, include all your ventilation 'add-ons' (filter, silencer, etc.) and keep it simple. Basement location, winter temp outside tent (passive make-up air) is at 71F in winter and 75F in summer. I have no trouble maintaining growing temps year round inside the tent using this method. I have hot, humid summers and cold, dry winters. Depends on multiple factors; it can be done. My ideal set-up would be to duct it through the roof just like a plumbing vent. Then, if any odor leaks whatsoever, it's above the roofline. However, the dryer duct from the basement works just fine. If nervous about odors, toss one of those urinal cakes in the last couple feet of the exhaust duct before it goes outside for added 'insurance'.
Click to expand...

I’d love to run through the roof too, I have an extra vent on the roof but being that the grow is in the basement I can’t connect to that one. Wish I could. Your basement temps are a bit higher than mine, they usually are at 65F. What gets me is humidity, in the summer it can reach 65%, now add plants and it’s more. What humidity do you encounter in the summer?
 
xtsho said:
I've ran a small dehumidifier in the tent and was still able to keep the temps in check. A 600 watt HPS puts off significantly more heat than a 375 watt LED. Ambient temps are going to be a factor and I run my light at night when it's cooler so the intake air is going to be at its coolest when the lights are on.

I don't know your setup or when you have your lights on but running in the evening or finding a way to pull in cooler air could make a difference in your temps.
Click to expand...

65F and I run during day, I suppose I could run at night, that would drop it by a few degrees, that might just be the ticket!
 
xtsho said:
I've ran a small dehumidifier in the tent and was still able to keep the temps in check. A 600 watt HPS puts off significantly more heat than a 375 watt LED. Ambient temps are going to be a factor and I run my light at night when it's cooler so the intake air is going to be at its coolest when the lights are on.

I don't know your setup or when you have your lights on but running in the evening or finding a way to pull in cooler air could make a difference in your temps.
Click to expand...

What about pulling in cool air from outside? Or is that a no no with introducing pathogens?
 
In summer the inside air I'm pulling into the tent runs about 65% - 75% RH, winter tends to be 25% ish. Temps with my set-up are no problem, they almost take care of themselves. I just have to watch the humidity closely in summer & winter because the RH is too extreme on both ends. Spring & fall are easy, comparatively speaking.
 
I did a quick ball-park CFM test on my extraction setup today. I used a duct anemometer to measure ft/min at the intake of the fan (6" AC Infinity 6S) with filter disconnected. The fan output goes into 16" of straight 6" flex to a 6"x4" adaptor, then into the 4" dryer vent. I expect the net cfm will be lower when I install it later during stink production. CFM = FPM * 0.2 sqf (approx using 6" dia round duct)
Speed -- FPM -- CFM
1 -------- 290 ---58
2 -------- 463 --- 93
3 -------- 624 --- 125
4 -------- 773 --- 155
5 -------- 933 --- 187
6 ------ 1066 --- 213
7 ------ 1249 --- 250
8 ------ 1449 --- 290

Grow space is about 12 sqf, 96 cuf. I will run on 2-3, 5 and above is noisy, 7-8 are ridiculously loud.
 
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