Another dehumidifer question

[primitive]

So after getting 2 LG 65 pint units running 24/7, the RH still won't go below 65%.

So I think I have no choice but to grab one of the big pricey ones people use in sealed rooms. My research so far has led me towards the Evolution 115 pint and the Santa Fe Classic 100 pint, but I'm still looking around.

Does anyone have any recommendations? This problem is driving me nuts, if I can't get this down I'll have either gray hair or no hair before long

 

[nouvellechef]

Yeah something is off. I use a smaller one and maintain whatever I decide. Usually 40%. It's in my pics on the Rez. I found by placing it at the end of my room the air is being pushed toward by the fans, it runs much more efficent. Not even close to 24/7. So. Hmm. Give some more details.

 

[primitive]

I'm growing in coco, ebb&flow, flooding only once or twice a day. Ventilation is a 10" max fan w/ 10" duct for exhaust, controlled by a thermostat to keep temp ~77. Two passive 6'' intake holes in the wall to what is essentially an open crawl space. 4 16 inch oscillating fans to move the air, plus a wind machine style fan at the back of the dehumidifiers to help move the dry air around. RH in the crawl space is usually around 75%, outside air fluctuates from 65%-100% throughout the day, often raining.

Before hooking up drain hoses to the LG units they would fill completely every 6-7 hours. Without them, RH shoots up to 88%.

 

[ozzydiodude]

IMO I would block off 1 passive intake turn the other into a fan intake controled by the same thermostat as the exhaust. That way you are not moving air in and out the passive holes adding humidity at all times. This allows you to dehumidify just the air moving in the room.

 

[2Dog]

I need new windows..my house gets humid! A few grows from now I may be able to afford to do the whole house! I think that will help with my humidity probs a lot. Until then i am thinking about a dehumidifier and lots of fan usage/air flow.

 

[primitive]

IMO I would block off 1 passive intake turn the other into a fan intake controled by the same thermostat as the exhaust. That way you are not moving air in and out the passive holes adding humidity at all times. This allows you to dehumidify just the air moving in the room.

That makes sense to me, though I forgot to mention that I've got a layer of washable poly-fiber filter and a layer of carbon filter sheeting in each intake also, held in place by a plastic duct grate. They're at the top of the pic below. I don't think much air moves through them without the exhaust fan on, with my hand next to them I don't feel anything.

I will try blocking one to see if that makes a difference. Would you mind explaining how adding an intake fan would help though? I mean, is it the idea of it obstructing free air flow when the exhaust is off, or are you thinking that it would cut the amount of time the exhaust fan would need to be on by cooling the room faster? As it is the exhaust fan typically cycles on for ~10 seconds then off for ~30 to keep the temp right.

Would adding some ducting to drop it to floor level make a difference? I put them just above table height with the idea that if colder air comes in at floor level and heat rises the freshest air might stay low if entering low.

 

[BBFan]

Awesome looking grow you've got going on Primitive. Ladies seem to be doing well but it must be nerve racking having the rh so high.

There must be something else going on. Other than those 2 passive intakes the room is sealed? How many cubic feet you got that those 2 units can't handle it?

a wind machine style fan at the back of the dehumidifiers to help move the dry air around

Doesn't the dried air come out the front of the unit? It does on my unit.

Is your floor concrete? If so, maybe a moisture barrier is needed? Tough to accomplish at this point I know, but maybe something can be done. Does the air outside your grow space also have as high rh?

Again, looking good. I hope you get the situation figured out. Good luck with it.

 

[ozzydiodude]

Would you mind explaining how adding an intake fan would help though?

It give you control over the air coming into the area. Adding new air only when air is being exhausted should help the dehumidifers by giving them time to pull the moisture out of the air in the room.

 

[legalize_freedom]

With 65-100% humidity outside your home your going to be fighting that humidity forever. I think you should reroute your intakes so they are pulling air in from another room.. In that room is where you want your dehumidifier so that the dried out air is coming into your grow room..

With that much humid air moving through the room your dehumidifier will never catch up

:yeahthat: I think this makes the most sense, have your intake pulling from the room next to it, granted you will need another fan, as it will have to be an active intake, but it should do the trick. Then just control the RH in the room that the air is being pulled from, and exhaust the old air outdoors, or into your crawl space or whatever.

I don't know what your temps are but a heater will help dry out the air also, but if your room is already hot, then this idea is useless.

 

[primitive]

With 65-100% humidity outside your home your going to be fighting that humidity forever. I think you should reroute your intakes so they are pulling air in from another room.. In that room is where you want your dehumidifier so that the dried out air is coming into your grow room..

With that much humid air moving through the room your dehumidifier will never catch up

I'd have two options if I went that route:

1. I could slap some 6'' ducting between the intakes and the laundry room and put a dehumidifier up there. I'd really like to avoid cutting holes in the living area though.

2. I could move my intakes to the wall the flower room shares with the much smaller veg room and put the dehumidifier in there. But from what I've read you want high humidity in your veg room? Right now I'm just letting the humidity in the veg room hover at ~70%-75% and controlling the mildew with a sulfur vaporizer.

Which sounds like the lesser evil to you?

 

[primitive]

Would you mind explaining how adding an intake fan would help though?

It give you control over the air coming into the area. Adding new air only when air is being exhausted should help the dehumidifers by giving them time to pull the moisture out of the air in the room.

OK. So the idea is that the bulk of the intake fan obstructs air exchange when the exhaust fan is off?

What I was saying about the filter inserts in my post above is that when the exhaust fan is off the intakes already don't seem to have any air exchange. I don't understand how adding a fan( just a metal enclosure filled w/ blades suspended in air) would stop the air flow with the exhaust off any better than the filter packed intake already does. I mean, if you hold a centrifugal fan up to a light you can see light through it.

Though...I can see how that would work if I put a short length of ducting on it with a damper in between.

 

[primitive]

Awesome looking grow you've got going on Primitive. Ladies seem to be doing well but it must be nerve racking having the rh so high.

There must be something else going on. Other than those 2 passive intakes the room is sealed? How many cubic feet you got that those 2 units can't handle it?



Doesn't the dried air come out the front of the unit? It does on my unit.

Is your floor concrete? If so, maybe a moisture barrier is needed? Tough to accomplish at this point I know, but maybe something can be done. Does the air outside your grow space also have as high rh?

Again, looking good. I hope you get the situation figured out. Good luck with it.

Thanks!

The floor was concrete, but now it's got a layer of particle board covered by vinyl flooring.

On my units the dry air does come out the back, yes.

The room is 15x17x~8.

 

[BBFan]

Have you looked here:

hxxp://www.ehow.com/how_5618615_calculate-dehumidifier.html

 

[2Dog]

how many pints of water does the average...ok bad way to ask how many pints of water do you think you would get in a 10-11 room? at 60%? so hard to decide what size someone will need.. I may have to buy one.

 

[zem]

aim your dehumidifier straight at your plants, it will be blowing dry air straight at them, the RH of a room with exhaust intake will not go down many points however that dehumidifier will be blowing dry air. i dont think you'll need another dehumidifier for this grow

 

[primitive]

aim your dehumidifier straight at your plants, it will be blowing dry air straight at them, the RH of a room with exhaust intake will not go down many points however that dehumidifier will be blowing dry air. i dont think you'll need another dehumidifier for this grow

Yeah I had both dehumidifiers pointed at the plants with a wind machine in between to help move the air their direction, but w/ 4 4x4's in an L configuration it didn't cover much of them. I put the hygrometers remote sensor in the area I was blowing towards and it was just a few points lower.

So here's what I'm currently trying: I just moved one of the dehumidifiers into the veg room, unhooked the veg exhaust fan duct so that it blows into the flower room rather than outside, put it on the same thermostat as the main exhaust fan, and closed the two passive intakes from the crawlspace into the main room. So now my main rooms only intake is from the veg room, kinda like what Mindzeye suggested, drawing air from another room with a dehumidifier.

Fingers crossed this will do something.

 

[primitive]

So here's what I'm currently trying: I just moved one of the dehumidifiers into the veg room, unhooked the veg exhaust fan duct so that it blows into the flower room rather than outside, put it on the same thermostat as the main exhaust fan, and closed the two passive intakes from the crawlspace into the main room. So now my main rooms only intake is from the veg room, kinda like what Mindzeye suggested, drawing air from another room with a dehumidifier.

Somehow, after trying what I described above the situation just got worse. The dehumidifier in the veg room brought the RH there down to 40%, and thats the only air now being piped into the main room, which still had it's own dehumidifier running...and is at 75%, worse than when I had both units running in there and intakes from the outside?

***?!?

 

[nouvellechef]

Hmmm. Wish I could help. It's was pouring here in WA in the last weeks of flower for me. Not sure what the humidity was outside. But the DH kept it at whatever like I said before. Sure someone will chime in.

 

[legalize_freedom]

yeah...thats strange, is your veg room alot smaller than your bloom room? Even if it is though, you wouldn't think that it would get worse. Anyway to pull air from the room above it? (I think you said this is in a basement/crawlspace) I know it would require cutting a hole in your grow room ceiling/floor of the room above. I think the room you are pulling the air from needs to be close to the size of the flowering room. Are you sure you are exhausting enough? is your ventilation plugged somehow? Old Carbon filter maybe. They say that humidity over 60% greatly reduces the life of the carbon filter. I dunno man, I hope you get it figured out! I'd hate to see all them beautiful buds get moldy!