dehumidifier and mini split

[randomgrower420]

how is it recommended to setup a dehumidifier and a mini split. I want them working together.

Im ordering a quest 105 and a 2.5-3 ton mini split.

do you set the quest at set point and the mini split humidity higher than that? example quest at 62% mini split at 70%

Im assuming the quest is going to be a more efficient dehumidifier than the mini split AND that setting the mini split at target is only going to make the minisplit work more than it needs to.

Is there a good controller for this? something that would manage enviroment (dehumidifier, co2 and possibly night exhaust and a heater)

Im gonna spend a while searching but if anybody wants to discuss.


Thanks

 

[Granger2]

I have my AC set where I want the temp kept, and my dehu where I want the RH kept, and forget about it. I monitor temp and RH with other devices, and they're always fine. Good luck. -granger

 

[Subcooled]

If the dehu is sized properly, you won't see much water removed by the a/c when room rh is kept below 60%. Water is removed when air is cooled enough to condense on the evaporator coil. With a room at 50%rh, air must be cooled at least 11C (20F) before condensation (moisture removal) begins.

 

[TheCapn]

how is it recommended to setup a dehumidifier and a mini split. I want them working together.

Im ordering a quest 105 and a 2.5-3 ton mini split.

do you set the quest at set point and the mini split humidity higher than that? example quest at 62% mini split at 70%

Im assuming the quest is going to be a more efficient dehumidifier than the mini split AND that setting the mini split at target is only going to make the minisplit work more than it needs to.

Is there a good controller for this? something that would manage enviroment (dehumidifier, co2 and possibly night exhaust and a heater)

Im gonna spend a while searching but if anybody wants to discuss.


Thanks

Did you ever get your Mini Split and quest 105? I just got the same set up. I'm at my witts end trying to get humidity down. It can't get the humidity under 65 during the day (82 degrees). ~55 at night (70F).

I'm going to open up a new thread on this and see if I can get some help.

 

[queequeg152]

whats the issue? just set your dehumidistat where ever you want it.

is the dehuy running constantly? is it undersized?

 

[TheCapn]

whats the issue? just set your dehumidistat where ever you want it.

is the dehuy running constantly? is it undersized?

HI quee and thanks for your repsonse. It is oversized. I have the Quest Dual 105 in a 4 x 600W room with 4 large plants. I have a Mr slim mini-split and the room is sealed, with the exception of the doors needing new weather stripping.

Problem 1:
Even after sealing the room, the dehu cannot keep up. It can't get the humidity under 60% during the day or under 47% at night. But I think I've solved this problem. What I've figured out is... if you have ANY water in the room that can see air (for example, a reservoir with a 6" open service port) as the dehu dries the air, the water in the res will start to evaporate even faster. So the dehu runs constantly, pulling water out of the reservoir. A vicious cycle. I have 4 small reservoirs in the room. I am changing my growing style slightly so no water is exposed to air. I've changed two of the 4 reservoirs and it's already making a difference.

Problem 2:
Again, my room is sealed. I have a 1" hole in the wall near the floor that I have taped up with duct tape. If I remove that tape, and put a flame near the hole, I can see that air is coming OUT of the room! I thought maybe my home air con was trying to suck air out. I turned off the home air, turned off the mini split, and turned of any circulation fans in the room. The flame still shows that air is coming out of the room. Even with the hole taped up, air must be leaking out of the room, and this is seriously stinking up the house! The only thing I can think of is: the cool air in the room is dense, and the air in the basement is warmer (lighter) and the dense air is trying to get out to less dense area. Does that make any sense? I have been reading up on hot air / cool air and from what I understand, cool air is more dense.

Any help from experienced growers with sealed rooms is appreciated.

 

[queequeg152]

id suggest first monitoring the amount of water your dehuy is pumping out... is there any way you can collect it in a container?

regarding the room... how did you go about sealing it? did you disconnect the supply air feeding this room? if not your ac is presurizing the room to some extent. without a path for this pressurized air to return, the room accumulates some amount of pressure.

you can detect this with one of the more accurate static pressure gauges... but i would not reccomend that. to much money for a simple experiment.

yes cold air falls... i suppose if your subfloor is leaking air into the basement you could draw air inside this way. but it solunds like this hole you speak of... is leaking air out of the room, not into the room?

 

[TheCapn]

id suggest first monitoring the amount of water your dehuy is pumping out... is there any way you can collect it in a container?

regarding the room... how did you go about sealing it? did you disconnect the supply air feeding this room? if not your ac is presurizing the room to some extent. without a path for this pressurized air to return, the room accumulates some amount of pressure.

you can detect this with one of the more accurate static pressure gauges... but i would not reccomend that. to much money for a simple experiment.

yes cold air falls... i suppose if your subfloor is leaking air into the basement you could draw air inside this way. but it solunds like this hole you speak of... is leaking air out of the room, not into the room?

>>>is there any way you can collect it in a container?

I could, yes but I have not so far. It produces almost a constant trickle, so I know it is really pulling water out and working well.

>>>how did you go about sealing it?

The room is a room I built, inside a room, in the basement (no hvac ducts). I screwed "quiet board" to the rafters, then waferboard on top of that. The walls are also waferboard and quiet board. Everything sealed with silicone. One wall is concrete, which is painted with dry lock, and then a coat of white primer paint. I used to have the room air ducted but I have sealed up the holes. I don't see how any air could be getting in or out. The only thing I can think of, is that air is getting in around the door jams. It is so difficult to make a sealed door. Ideas?

>>>like this hole you speak of... is leaking air out of the room

Yes, air is coming OUT of the room. And I promise you, there are no vents pushing any air into the room. Again, it's not a lot. You can't even feel it with your hand. But when you hold a candle to the hole, you can see the flame really blow one way. NO DOUBT, air is coming out.

Maybe the air in the basement is cooler than the air at the top of the doors, and cool air is getting in there, and then coming out the bottom. arg. so frustrating.

 

[queequeg152]

wafer board. lol i had to google that.

down south, and in most of the usa we call this stuff OSB? waferboard makes total sense though...

anyway... yea the air flow sounds tiny. it could easly be caused by simple gradients of air temperature across the hole.

regarding air sealing the door... a sweep and jamb seals like you mentioned will help. check under the trim(if there is any) and make sure the jamb is foamed into the rough opening. if it is not, its a huge air leak.

i mentioned collecting the condensate because it would rule out a malfunction in the dehuy(nice dehuy btw).

the only other thing to check would be your basement construction? is this an old house?

old basements are shitty without membranes and without drains and adequate drainage rock around the foundation walls.

you COULD conceivably be pulling in moisture from the slab underneath. did you paint or otherwise seal this slab?

you might check local rainfall recently, as high amounts of soil moisture in a poorly build basement can cause significant humidity even if no water is pooling or running down walls.

do you know if this basement has a perimiter drain? you should see a sump outside or inside somewhere. perimiter drains are usually not allowed to be gravity drained to the street for some reason... so you should have a sump pit somewhere on your property.

thing is though... even a badly sealed basement isnt that hard to dehumidify... unless its fricken huge. your dehuy should be able to dry the whole space out rather well, so i suspect its down to your growing system mostly... as it sounds like your room is reasonably air sealed.

keep a close eye on the humidity in the basement as well as in this room. it might help you correlate.

 

[queequeg152]

oh yea and foam under the sil plates if you have not already. ideally they should have sealant underneath them when installed, but if they did not... foam or acoustical sealant works fine.

 

[TheCapn]

>>>wafer board. lol i had to google that.

ha. yeah I call it OSB too but some people have to google OSB. ha ha ha

>>>basement construction? is this an old house?

From the 70's. I have see mortar in the sill plates and I have covered that with "great stuff" foam.

>>>you COULD conceivably be pulling in moisture from the slab underneath. did you paint or otherwise seal this slab?

I painted it with garage floor paint but it is pretty crappy and much of it has worn off.
>>>do you know if this basement has a perimiter drain? you should see a sump outside or inside somewhere. perimiter drains are usually not allowed to be gravity drained to the street for some reason... so you should have a sump pit somewhere on your property.

Yes I do have a sump pump. But I think you could be on to something here. If the floor or wall is sweating, that would explain it.

Maybe I should try an experiment an put some plastic on the floor. If the floor is damp, would I find water driplets on the floor (under the plastic) after some time?

As far as the doors, I made them myself. They are light proof but not air proof. I'll need to figure out a way to seal them.

Thanks for all the ideas. On a side note, I hooked up the CO2 this morning (for the first time) before the lights came on and cranked it up from 900 to 1500ppm. I lost about 75ppm every 15 minutes. I am new to CO2 so I don't know if that's good or bad.

 

[queequeg152]

Maybe I should try an experiment an put some plastic on the floor. If the floor is damp, would I find water driplets on the floor (under the plastic) after some time?

you might try this... but be very careful lest you grow mold.

pop open your sump pump and see if its connected to a perimeter drain.
if this thing was built in the 70's... its probably just there to drain flood water though.

regarding co2, ive no experience in this area. you will have to wait for someone more experienced to chime in.

 

[Granger2]

You're better off with a max of 1000 ppm. -granger

 

[TheCapn]

You're better off with a max of 1000 ppm. -granger

Thanks, Granger, I will take that into consideration. The great news is that my room is truly sealed and the CO2 has been running for 2 weeks. I have not even used 1/4 of my 20lb tank. The room is holding CO2 well, And the plants seem to be doing very well.

Here is an update on my progress. I got some 4 mil plastic sheet and covered the entire floor. I left it there for 5 days and there was absolutely no sweat or moisture under it. So I'm convinced my floor is not leaking humidity. Then yesterday, I got some 6 mill panda film and hung it over the concrete wall. After 20 hours, there is no moisture under it either.

I wanted to share this screen shot with you all. This is a screen shot from my "lacrosse alerts" monitor, which shows the last 24 hours of temp and humidity. BTW, if you don't have a monitor like this that will alert you if the temp gets too high, then you're at risk.

Notice a couple things from the screen shot:

1. At night, you see the spikes going up and down. That is where the dehu is kicking on and off. It takes it down to about 51%, then it turns off and the humidity rises to about 57% before it turns on again (it has a dial type humidistat).

2. During the day, the dehu cannot keep up. It keeps the room about 60%, and it never is able to get it down to 51%, where it would kick off. It runs constantly for 12 hours during lights on. I'm ok with 60%, but I don't understand how a $2K dehu can't keep up in a 4x20 room with 4 plants.

3. The humidity drops rapidly about 45 minutes before the lights go out and before the mini split drops the temperature. Look carefully and you can see this. My suspicion here is that the plants know the dark cycle is coming and they start to transpire less, even before the lights go out.

4. My dehu is running constantly during lights on (12 hours) and about 1/2 the time during lights out (another 6 hours). So that is 4.9 amps X 18 hours a day. arg! Check out the night time up and down spikes. See how the dehu gets it down to 51%, and when it turns off, the humidity rises within one hour. Then it turns on again and it takes about an hour to get it back down to 51% (the time from a low spike to a high spike is about one hour)

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My last test is to measure the water coming from the dehu to see how much it is really pulling out. When I look at the drain line, I see a constant trickle so I assume it's running well but this will be the final test.

I wish I could take all the plants out of the flower room and let the dehu run to see what it can really do, but I'm on a perpetual schedule. The plants get so big and can't be moved. I know this post is boring for most people so I'm throwing in a picture of some GDP Purple Dream. This picture was taken at 3 weeks, 4 days.

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[TheCapn]

Not sure why the pictures didn't come through, or why I can't edit my post. Anyway, here they are:

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[merkin Donor]

You might want to check the humidity of the air coming out of the mini-split. I put in a 12,000 btu head against my own better judgement (only running 2,500 watts in the room) and I'm grossly over-sized so the system just idles along. Even though its pulling 2-3 gallons of water a day out of the room it's not performing like it would if it was perfectly matched for the heat load. As for that air coming out of the room you are probably experiencing building stack affect even though its a basement it still acts like a two story building.

 

[queequeg152]

can you delete all that text and junk from that one post?

regarding the dehuy.
it being 2 grand has more to do with how efficient it is... its not built for enormous loads, its probably only equivelant to a couple of those shitty portable dehumidifiers.

they are usually rated at 80 degrees f @ 60% humidity btw. it you are below those figures its capacity will be reduced.

regarding your ac unit.

how much moisture is it removing during the day time?
its a variable speed cassette no? have you tried enabling dehumidification via the thermostat? it should be capable of slowing down the blower wheel such that the temperature drop across the evaporator coil is greater, thereby extracting more moisture.

biggest thing though is your growing system im betting. i cant really judge from that picture, but im guessing there is a shitload of larger plants in there. each of them transpiring a significant amount. its understandable why your humidity reaches 60% during lights on.


might still be a good idea to measure the quantity of water its producing to rule out some absurdly small number.

 

[TheCapn]

You might want to check the humidity of the air coming out of the mini-split. I put in a 12,000 btu head against my own better judgement (only running 2,500 watts in the room) and I'm grossly over-sized so the system just idles along. Even though its pulling 2-3 gallons of water a day out of the room it's not performing like it would if it was perfectly matched for the heat load. As for that air coming out of the room you are probably experiencing building stack affect even though its a basement it still acts like a two story building.

>>>check the humidity of the air coming out of the mini-split

How do I do that? Hang a meter in front of the output?

>>>you are probably experiencing building stack affect

I was just reading about this and I think you are absolutely correct! I have been diligent about sealing up any cracks, even the tiniest, and this has helped. In addition, I set up a duct booster fan to pull air out of the basement and push it outside, putting a negative pressure in that area, and this has helped too. The odor is no longer present.

 

[TheCapn]

I cannot thank you guys enough for the help here. I'm still learning about running a sealed room. It is not for the faint at heart, or for the budget minded, that's for sure.

>>>can you delete all that text and junk from that one post?
For some reason I can't edit it. Sorry.

>>>regarding the dehuy.
As a last ditch effort, yesterday, I went to home depot and rented a Dri-ese revolution. Hooked it up. Within only 45 minutes the humidity was at 50% (during the day)! I reported this info to the quest people. They said there is no reason the revolution would work better and they are now convinced there is something wrong with the Quest Dual 105. I want to add, over the last two weeks, they have been incredibly responsive, answering emails within hours and very professional along the way. They are shipping out a new unit today. I will know soon if the new one works better.

>>regarding your ac unit.
>>how much moisture is it removing during the day time?
I don't know because I have it running to a condensate pump. But the pump runs frequently so I know it is pulling out water.

>>its a variable speed cassette no? have you tried enabling dehumidification via the thermostat?
Yes I did put it on Dry mode but it didn't seem to make a difference. I will give that a try again and see if it helps any. I have the speed on high right now, in order to help circulate the air.

>>biggest thing though is your growing system im betting. i cant really judge from that picture, but im guessing there is a shitload of larger plants in there. each of them transpiring a significant amount.

Not a shitload; only 4 plants. But let's just say, they are BIG. I average a pound per plant. The room is about 4'x20' and 4x16 of that is complete canopy, wall to wall. Crawling room only.

>>might still be a good idea to measure the quantity of water its producing

Ok I will adjust some things and run out output into a container and see what I get. Then I'll do it again on "DRY" mode and see what happens.

In the meantime, here are 3 of the 4 plants. I don't have a pic of the 4th right now.

This is "planet X" which comes down this Friday. This pheno is OK but nothing to brag about. This is a new strain I tried and it's not for me. It gets way too tall and is nearly uncontrollable (other 5 phenos were all the same). I have to top it a week into flower just to keep it manageable. You can see a lot of light burn on leaves. Still, nice and frosty, dense, nice bag appeal, and great effect. Difficult to get any good size out of the colas.

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And of course the bonkers, frosty, beautiful, infamous Purple Dream pheno I found last year (by GDP). This one has 2 weeks to go.

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The 3rd plant with 4 weeks to go was posted above.

THis is what the Purple dream looks like when it is finished.

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[queequeg152]

i wish i could say i was hopeful that your new unit would work better.... but alas, i dont think i have much in the way of hope.... there could be a number of reasons that that other dehuy performed better than the quest. regardless though hope the new one works out.

regarding measuring the condensate from your dehuy and ac unit.

the easiest thing would be to simply buy a 30 gallon trash can and pump the condensate to it.

i assume you have a drain in the basement... or perhaps a utility sink somewhere? just bail out the water with a 1 or 3 or 5 gallon bucket available inside any paint department at lowes or HD.

alternativly you could rig up a current sensor and data logger to monitor the frequency of the condensate pumps operation. you would just need to measure the volume inside the condensate pump reservoirs to determine the total volume of water per cycle.

if you want to persue the latter i could help you here... but it seems a trash can is the more logical solution unless you are pursuing more long term monitoring.