Dehumidifier? Worth it?

NotTheFeds

Active Member
Hey guys using a spare bedroom to grow,
Have a rk150 can fan extractor fan w carbon filter venting straight outside

Now my question is about dehumidifers

Do I place it in the grow room ?
The negative pressure from the exhaust fan is sucking fresh air in thru bottom of door at quite a rate ( theres a butt load of suction when closing the door it's like it's trying to open it )

Will a dehumidifer in the grow room even do anything if it's sucking that much fresh air in 24/7?

Or am I best to get a larger dehumidifer and dehumidify the house ( where the air is taken from?)

Don't want to waste my hard earned money on a smaller one then have to go buy a bigger one!

From South East QLD Australia so always humid here!

Appreciate your inputs!
Cheers
 

budman111

Well-Known Member
I have one in my room last 2-3 weeks of flower and gets a couple of liters every day so I would advise if you're in humid climate
 

Cvntcrusher

Well-Known Member
I ran a comparison of two PE fem photos treated the same way from seed to harvest. ONLY difference was one was fed chemical fert the other liquid organic nutrients.

I cheaped out on my dehu and ended up getting stalk rot (ez fix with peroxide and better dehu) but if you're question is are good dehumidifiers like a 30pint or bigger worth it?

If you have a chance at higher humidity then YES you absolutely need a good dehumidifier.
 

Cvntcrusher

Well-Known Member
But BE PREPARED TO KEEP UP WITH WHATEVER YOU RUN THE RUNOFF HOSE TOO. AND they do put off a decent amount of exhaust heat. So be prepared.
 

NotTheFeds

Active Member
I have one in my room last 2-3 weeks of flower and gets a couple of liters every day so I would advise if you're in humid climate
Hey mate thanks!
I Know I need one just Not sure how effective it would be inside the grow room itself
 

Rurumo

Well-Known Member
You keep it inside of the room that your tent is in, fyi, not in the tent itself. So the tent pulls in the dehumidified air from that room, and vents it back out. Sure, if you vent outside, you will be pulling more air into the "lung" room from someplace, I'm assuming some other part of your house. But a 30 pint (or larger) dehumidifier will have a pretty huge impact on the RH in that room. I have one in a 400 sq ft space and if I leave it on 24/7, I empty a 5 gallon bucket of water everyday, which sort of freaks me out if I think too hard about it. I could just stick the hose directly into a drain, but I'd rather dump that water out in my yard since I have a tiny septic tank.
 

NotTheFeds

Active Member
You keep it inside of the room that your tent is in, fyi, not in the tent itself. So the tent pulls in the dehumidified air from that room, and vents it back out. Sure, if you vent outside, you will be pulling more air into the "lung" room from someplace, I'm assuming some other part of your house. But a 30 pint (or larger) dehumidifier will have a pretty huge impact on the RH in that room. I have one in a 400 sq ft space and if I leave it on 24/7, I empty a 5 gallon bucket of water everyday, which sort of freaks me out if I think too hard about it. I could just stick the hose directly into a drain, but I'd rather dump that water out in my yard since I have a tiny septic tank.
No tent in room. If that makes a difference,

I was just worried with the air exchange putting it in the room wasn't going to do fark all. I'll see if I can hunt down a larger 2nd hand quality dehumidifer as the big ones are pretty expensive new!
 

rmax

Well-Known Member
Will a dehumidifer in the grow room even do anything if it's sucking that much fresh air in 24/7?
I think you are on to something.

I looked up the RK150 can fan and it is 261CFM. If your grow room is 32.625 sq.ft. the volume of air should be exchanged every minute. How large is the room? All the air in a 10x10 room is exchanged every three minutes with your fan.

You mention venting to outside which means the make-up air is coming in from the outside. In this case I don't think you'll be able to reduce the inbound humidity much. In your case I'd have several fans mounted everywhere.
 

NotTheFeds

Active Member
I think you are on to something.

I looked up the RK150 can fan and it is 261CFM. If your grow room is 32.625 sq.ft. the volume of air should be exchanged every minute. How large is the room? All the air in a 10x10 room is exchanged every three minutes with your fan.

You mention venting to outside which means the make-up air is coming in from the outside. In this case I don't think you'll be able to reduce the inbound humidity much. In your case I'd have several fans mounted everywhere.
It's a small bedroom, 10ft x 15ft x 7.5ft, so I know the extractor fan is a little underpowered but the suction coming into the room from under the door is unreal. I'm thinking I'll have to upgrade the extractor fan as well! Might have to bite the bullet and buy a large dehumidifer to treat the house so that the air getting sucked in is already treated.. lucky I have a small house I guess!
 

NotTheFeds

Active Member
I think you are on to something.

I looked up the RK150 can fan and it is 261CFM. If your grow room is 32.625 sq.ft. the volume of air should be exchanged every minute. How large is the room? All the air in a 10x10 room is exchanged every three minutes with your fan.

You mention venting to outside which means the make-up air is coming in from the outside. In this case I don't think you'll be able to reduce the inbound humidity much. In your case I'd have several fans mounted everywhere.
Maybe a larger extractor fan first? Ie: more air exchange so less humid air plants are expiring in grow room?
 

NotTheFeds

Active Member
I'll look at getting a larger extractor fan first ( this one was great in a 5x5 tent )

I've already got 2 ,industrial floor fans moving air around in the room so air movement is no issue

Will see if humidity drops with larger extractor fan
( 92% outside humidity at the moment.. 4 weeks of rain wouldn't help either )
Appreciate all your time! Cheers
 
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rmax

Well-Known Member
It's a small bedroom, 10ft x 15ft x 7.5ft,
10ft x 15ft x 7.5ft = 1,125 cubic feet.

Your fan moves 261 CFM (cubic feet a minute). All the air in the room is replaced every 4 minutes.

Since the make-up air is coming from the rest of the house you noticed the suction under the door. If the rest of your house is sealed up, like closed windows and doors, the make-up air is being sucked in through chimneys and cracks/crevasses.
 

Roy O'Bannon

Well-Known Member
how many plants?
It would be easier to control the bedroom climate and have the plants in a tent. Pulling large amounts of fresh air through defeats room conditioning.
Run some co2 bags to offset your room being mostly sealed.
That comment about the carbon monoxide and air leaks is no joke.

I mean you could close the bedroom door, run a window a/c unit and a dehumidifier, little heater if you needed. Keep the room where you want your tent and run that carbon filter setup on the tent exhaust. Leave one of the bottom flaps on the tent open, keep the air moving through the tent, not the room.
 

NotTheFeds

Active Member
10ft x 15ft x 7.5ft = 1,125 cubic feet.

Your fan moves 261 CFM (cubic feet a minute). All the air in the room is replaced every 4 minutes.

Since the make-up air is coming from the rest of the house you noticed the suction under the door. If the rest of your house is sealed up, like closed windows and doors, the make-up air is being sucked in through chimneys and cracks/crevasses.
Hey mate going to price up a new extractor fan today.

The more I think about controlling humidity the harder it sounds! Going to start with.more air exhange. Hopefully this rain goes away and humidity levels return to normal so I can then figure out how much I need to drop it by, if any. I'm hoping the large fans in my grow room are going to be enough late in flower to move enough air around and prevent rot
 

NotTheFeds

Active Member
how many plants?
It would be easier to control the bedroom climate and have the plants in a tent. Pulling large amounts of fresh air through defeats room conditioning.
Run some co2 bags to offset your room being mostly sealed.
That comment about the carbon monoxide and air leaks is no joke.
Only 2 at this stage but I'm thinking ahead.. I have an 8x25l autopot setup. Only using 2 right now as had issues with seeds/delivery..
But when these are done I'm going to use all 8.
I prefer the room as opposed to a tent ( seems a lot easier to keep lower temps )
 

NotTheFeds

Active Member
I don't understand about the carbon monoxide? Grow room is venting to outside? Butt tonne of neg pressure in the grow room. So no air is escaping into the house.. If that's what you mean?
 

rmax

Well-Known Member
I don't understand about the carbon monoxide? Grow room is venting to outside? Butt tonne of neg pressure in the grow room. So no air is escaping into the house.. If that's what you mean?
The Cause of Backdraft
Many appliances in a home, such as a gas water heater, boiler, furnace, woodstove and fireplace, use combustion to function. During combustion, carbon monoxide is produced and released to the outside through a flue or a chimney. However, if there’s more air being pushed out through the home elsewhere, such as an open window, an exhaust fan, or leaks in the ceiling of your top floor, your home will naturally try to replace that air by drawing more in – including from the chimney or flue – in an attempt to balance the indoor pressure.

 
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