Exhaust Experts Needed.

[Dropastone]

Hey thanks for looking. I'm right in the middle of building my new grow room and I'm looking for some advice on my exhaust setup. Hear is a diagram I put together of what I"m planning on doing and a few pics of what I got done so far.

My main question is will my inline fan be big enough to cool three lights plus the use of a scrubber the way I have it setup? The total length of the grow room is roughly 25 ft long by 4.5 feet wide.

Thanks.

 

[mike91sr]

In short, no it wont be enough. I forget the exact ratio, but 125 feet long and youre going to need a lot more than 530 cfm. I use a 440 for 2-600w lights with a 36" scrubber and less than 15 feet of ducting and its barely enough. In fact, I have my scrubber disconnected right now to lower my temps 2-3 degrees. Granted this is in a cabinet not a basement, but still. Either get a few and make shorter runs or get an industrial size exhaust. Just don't get a few and put them inline. The air is just gonna get too hot running across 3 lights and it's going to radiate back out through your ducting (unless it's insulated).

 

[Bonzi Lighthouse]

Have you considered running T5 HO for veg and 2 x 400w CMH in unvented hoods?

*edit get that horse out of your basement.

 

[Mr.J420]

I like Bonzi's idea of T5's for veg, if you get 2 fans, one for the scrubber and one for the vented hoods maybe? It works for me.

 

[Bonzi Lighthouse]

I see lots of commercial type OPs and many of them use T5 for veg

 

[kappainf]

Nevermind.... I just figured your diagram out. Got confused for a minute, might have been from the bubble hash. Anyways, I think your set up will work great. You may possibly need a bit more air flow. however, I'm sure temps will be do-able with the way you planned, especially if that basement naturally stays fairly cool. Keeps us informed, let us know how it works out, good luck. Looks like you'll have a nice little set up.

 

[Bombhillsnotcountries00]

i dont have an answer for you about your exhaust but i really like your room design and lay out. how many plants do you plan on flowering in there?

 

[chasmtz]

I strongly recommend you rethink your airflow. in order for the exhaust to do anything, you will need a lot more CFM or 1-2 more fans just like the one you have. I would get a 4" fan for intake ~170 cfm, then id go

scrubber>fan>MH>fan>HPS>HPS>fan>outside

They dont move nearly as much air as you want them too with all that resistance. Also, to have a good fresh air supply, you will want an intake fan, trust me.

 

[Dropastone]

Thank for all the responses guys. I must have been stoned when I wrote 125 feet long because it's actually only 25 feet long.

@ bonzi, I do have an 8 bulb T5 HO set up that I have been considering using in place of the 400 watter. Also I've already got all my equipment purchased so the duel 400 CMH with unventilated hoods is out of the question for the time being. Although I have been wanting to try those out for a while now because I've heard nothing but good things about them. Oh and the horse, that's my baby boy and he goes wherever I go.

@ kappainf, yes the basement stays very cool so I'm hoping for the best. I think I'm just gonna have to experiment with a cpl of different setups to see what works best. I'm starting to think the T5 Ho setup would be the ticket to solve any heat issues that may arise.

I may post more updates in here but if you all want to see how this turns out just follow the link in my sig.

Peace

 

[Dropastone]

i dont have an answer for you about your exhaust but i really like your room design and lay out. how many plants do you plan on flowering in there?

Thanks man. I'm gonna start out with only 3 or 4 and see how that goes and may do more down the road.

I strongly recommend you rethink your airflow. in order for the exhaust to do anything, you will need a lot more CFM or 1-2 more fans just like the one you have. I would get a 4" fan for intake ~170 cfm, then id go

scrubber>fan>MH>fan>HPS>HPS>fan>outside

They dont move nearly as much air as you want them too with all that resistance. Also, to have a good fresh air supply, you will want an intake fan, trust me.

Thanks for your input man but I've done my research and have read and been told that running consecutive fans like that on one run will not increase your airflow and my possibly damage your fans. What I have pictured in my diagram is not set in stone and is subject to change if need be. Also I do have two 60 CFM Hydrofarm blowers that I can add to the setup for extra intakes if needed. Just hoping it's not needed so I can save on the electric bill but I will do whatever it takes.

 

[jdmcwestevo]

if u use an 8 inch valueline 735 cfm would be better. and use a 400 CMH to further lower temps would work better. make sure ur scrubber's cfm matches the fan.

 

[LionsRoor]

Hey thanks for looking. I'm right in the middle of building my new grow room and I'm looking for some advice on my exhaust setup. Hear is a diagram I put together of what I"m planning on doing and a few pics of what I got done so far.

My main question is will my inline fan be big enough to cool three lights plus the use of a scrubber the way I have it setup? The total length of the grow room is roughly 25 ft long by 4.5 feet wide.

Thanks.

I really like the work you've done so far - looks great! Your ventilation system needs a little tweaking... My humble advice (based on real-world experience!): Don't exhaust the lights with room air - and don't hook up veg and flower lights to the same air source. For the flower room lights, use a 6" Vortex-style fan to pull fresh air from outside the room through the lights and exhaust out the room. Run the veg room hood open - 400 watt MH bulbs run cool enough. You can hang this light a little higher too, to generate a bigger light footprint. A 6" Vortex-style fan for your intake, matched with another 6" for your exhaust, will do the trick. Depending on the size of the filter you are using to scrub your zone air, get the appropriate fan and simply attach it to your filter and set it or hang it in your room to let it actually 'scrub' the air... (it's not scrubbing the air if you use it on an exhaust run). Use a HEPA filter on your room intake to keep pests and spores out of your zone. Use a climate controller to fire the intake/exhaust fans as needed. Plug the light exhaust fan into the same timer as your lights.

Again - just my humble opinion based on my own real world success and failures. In general - you need enough fan power to replace the air in your room once every minute AT LEAST. Just do the math to find the best fan size... go bigger than what you calc as ducting and filters, etc will decrease your CFM's. Overhead in your HVAC system is always a good thing. Go as big as you can afford with fans... You can always put speed controllers on em.

Grow well!

 

[Dropastone]

if u use an 8 inch valueline 735 cfm would be better. and use a 400 CMH to further lower temps would work better. make sure ur scrubber's cfm matches the fan.

Optimal range for my scrubber is 265 CFM. If I did go with an 8" inline would it work well with my 6" hoods and ducting?

I really like the work you've done so far - looks great! Your ventilation system needs a little tweaking... My humble advice (based on real-world experience!): Don't exhaust the lights with room air - and don't hook up veg and flower lights to the same air source. For the flower room lights, use a 6" Vortex-style fan to pull fresh air from outside the room through the lights and exhaust out the room. Run the veg room hood open - 400 watt MH bulbs run cool enough. You can hang this light a little higher too, to generate a bigger light footprint. A 6" Vortex-style fan for your intake, matched with another 6" for your exhaust, will do the trick. Depending on the size of the filter you are using to scrub your zone air, get the appropriate fan and simply attach it to your filter and set it or hang it in your room to let it actually 'scrub' the air... (it's not scrubbing the air if you use it on an exhaust run). Use a HEPA filter on your room intake to keep pests and spores out of your zone. Use a climate controller to fire the intake/exhaust fans as needed. Plug the light exhaust fan into the same timer as your lights.

Again - just my humble opinion based on my own real world success and failures. In general - you need enough fan power to replace the air in your room once every minute AT LEAST. Just do the math to find the best fan size... go bigger than what you calc as ducting and filters, etc will decrease your CFM's. Overhead in your HVAC system is always a good thing. Go as big as you can afford with fans... You can always put speed controllers on em.

Grow well!

Thanks for the input man. You have given me some interesting advice. Now I'm off to ponder some different options.

Peace.

 

[unity]

Cheers brother, points to you for spending some thought on your grow room!
You certainly can cool all those lights with one fan, the problem is that your duct flanges on the lights are too small to accommodate the fan size you need.
A couple of simple rules to follow:
1. passive intakes should be 25% larger then the exhaust size
2. When sizing the fan, don't go by the cfm numbers alone, but instead look at the cfm at a certain static pressure. (cross reference that with the duct performance information at a given static pressure)
OK, let me back up here, do you have a way of measuring static pressure, like a HVAC friend etc.?
3. Your biggest static pressure loss will be undersized duct work, as well as the carbon scrubber (oversize it!!!)
4. The smoother the interior of the duct the more efficient your fan will run. (if flex is used, stretch the shit out of it or oversize it)
5. Twining fans can work in certain situations, but is usually not needed if air distribution is sized correctly. If you twin fans, one needs to be an active intake, the other an exhaust. The active intake HAS to be sized correctly as to prevent positive leaks in the grow space. (you will have odor leaks if the intake is stronger then the exhaust)

What is the largest you can make your intake holes, transition holes, light flanges, carbon filter... You get the idea
It looks like you are handy, the flanges on your lights can be modified depending on the lights you get.

Kind

BTW, I would not run my space like you have got it planed, but if you do, the info I provided will help. I like sealed grow spaces for year around growing in my climate zone

 

[chasmtz]

were not trying to be negative or put your design down, its a matter of having experience with air flow. I'm not an expert but I can tell you without a doubt in my mind that you will need more air flow in those rooms. I must say though that having the coolest air come into flower then go into the veg room in really thoughtful. At first when I saw that you didn't have independent air flow for each room, i was really concerned. Its obviously well thought out, take heed to what everyone is telling you friend, you will be happy you did.

 

[amrcngror]

love the setup, youll get it worked out i bet it does great!!! happy growing friend

 

[Dankster4Life]

Your running 2 600's?

A scrubber rated for more the 265cfm may also have to be considered.I know that isn't some thing ya want to hear as it just means spendin more $.I agree,you will need more air than what you have.

Have you thought about just doing each room separately on the ventilation?Your 2 little fans may be enough to keep a veg room with just the t5 and just use your larger fan with filter in flower?Lot less duct work to.I dunno.........lot's of options.

You are off to a very nice start,jealous of your space as it's just about what i'm wanting myself.When i scroll through the page it looks like your installing some 10" subs in there for the girls.I'm stoned

 

[Dropastone]

Cheers brother, points to you for spending some thought on your grow room!
You certainly can cool all those lights with one fan, the problem is that your duct flanges on the lights are too small to accommodate the fan size you need.
A couple of simple rules to follow:
1. passive intakes should be 25% larger then the exhaust size

Thanks man I appreciate the kind words of encouragement. Passive intake should be fine. It's a 10x8 opening with 6 inch duct for the exhaust.

2. When sizing the fan, don't go by the cfm numbers alone, but instead look at the cfm at a certain static pressure. (cross reference that with the duct performance information at a given static pressure)
OK, let me back up here, do you have a way of measuring static pressure, like a HVAC friend etc.?

You lost me at static pressure and I have no friends with HVAC experience.

3. Your biggest static pressure loss will be undersized duct work, as well as the carbon scrubber (oversize it!!!)

Still lost lol. I've come to the conclusion that I'm gonna just vent each room independently and by another inline fan a scrubber for the veg room. I think that will solve a lot of my problems.

4. The smoother the interior of the duct the more efficient your fan will run. (if flex is used, stretch the shit out of it or oversize it)

Got it, That sounds like some sound advice.

5. Twining fans can work in certain situations, but is usually not needed if air distribution is sized correctly. If you twin fans, one needs to be an active intake, the other an exhaust. The active intake HAS to be sized correctly as to prevent positive leaks in the grow space. (you will have odor leaks if the intake is stronger then the exhaust)

That's why I want to go with the passive intakes because it just seem so much simpler and less expensive at the same time.

What is the largest you can make your intake holes, transition holes, light flanges, carbon filter... You get the idea
It looks like you are handy, the flanges on your lights can be modified depending on the lights you get.

Kind

I'm running 6 inches on everything including Hoods, scrubber and duct work. Also as I said before my passive intake opening is 10" X 8" with three 6" holes leading into the flower room which I'm also planning on covering the four holes with a filter. I've already bought everything and there is no turning back now. What I can do is buy an 8 inch inline with 8 to 6 inch reducers for the flower room and use the 6 inch inline for the veg room.

BTW, I would not run my space like you have got it planed, but if you do, the info I provided will help. I like sealed grow spaces for year around growing in my climate zone

I have no co2 yet so a sealed space is out of the question for me at this time but in time I can make co2 happen. Thanks for all the help and info bro, it is appreciated. Now it's time for me to Google static pressure.

were not trying to be negative or put your design down, its a matter of having experience with air flow. I'm not an expert but I can tell you without a doubt in my mind that you will need more air flow in those rooms. I must say though that having the coolest air come into flower then go into the veg room in really thoughtful. At first when I saw that you didn't have independent air flow for each room, i was really concerned. Its obviously well thought out, take heed to what everyone is telling you friend, you will be happy you did.

Hey thanks man. I'm not seeing any negativity here. I'm just looking for some good advice from somebody that has experience. I'm taking all this info in like a sponge and plan to apply it to my setup. Like I said nothing is set in stone and the diagram I drew out is just a guide line to what I'm trying to accomplish and to give people who are trying to help me an idea of what I'm working with.

Thanks for your input bro and it is appreciated.

Your running 2 600's?

A scrubber rated for more the 265cfm may also have to be considered.I know that isn't some thing ya want to hear as it just means spendin more $.I agree,you will need more air than what you have.

Have you thought about just doing each room separately on the ventilation?Your 2 little fans may be enough to keep a veg room with just the t5 and just use your larger fan with filter in flower?Lot less duct work to.I dunno.........lot's of options.

You are off to a very nice start,jealous of your space as it's just about what i'm wanting myself.When i scroll through the page it looks like your installing some 10" subs in there for the girls.I'm stoned

Yeah man after all this great advice I've decided to vent each room independently because I believe it will solve all my problems. I've also decided to run two inline fans with each having it's own scrubber one for the veg and one for the flower room. I'm thinking about (still going over it in my mind) pulling cool air into flower room from the laundry room and vent it outside. Then I'll have to pull cool air in from my passive intakes from the veg room. That should be enough (depending on what size fan I get) to pull all the fresh air in that I need for both rooms and exhaust to the outside as well. I'll probably buy a new 8" inline with a couple of 8 to 6 inch reducers so I can use it with my 6 inch duct work.

Thanks to all for your replies and please speak up if you have anything else to add regarding my new ideas.

Here is a few pics of what I got done today. Building two doors tomorrow.

Peace and happy medicating.

 

[Dankster4Life]

Lookin kick ass bro.Gonna be sweet when all finished.

 

[chasmtz]

i believe that independent ventilation is going to solve your problems as well. I have my flower vent fans controlled by a thermostat(best price I found) I want to get another for my veg room but havent really needed it yet. I have a very strong tendency to go over board and it looks like you do too. I expect you to use some reflective material that will help prevent mold and what not. I would like to suggest a product like THIS I used a product called "Denshield" in my walls, painted the waterproofing on, then wrapped in b/w poly. I am in my basement as well and I think you should use a water tight barrier on your area first. This will allow you better control of temp & humidity. The product linked can be painted and will stick to virtually any surface. I am in construction and have used this product MANY MANY times and am very happy with it, on the job site and in my own home. I am not promoting either website, just USE these products myself and know that they perform up too and beyond what they advertise