A/C Advice Needed

  • Thread starter BakedasBeans
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BakedasBeans

BakedasBeans

297
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Hey whats going on farmers?

With the weather starting to warm up I am beinging to have my first battle with heat issues(This is my first grow not being inside a house where the temp is constant all year round).

With cold winter temps it was easy.. just go buy a space heater and problem solved:lock:. With the warmer temps I am having a problem deciding which way to go with a cooling unit(Evap coller, Ductless mini-split, Inroom a/c). My issue is with the varation in how much it costs to run each unit. The initial cost of purchase doesnt matter.

I have done some research and heres whats Ive come up with:

*EVAPORATIVE COOLER*
-10,000BTU
-350 SQ FT
-2.1AMPS
-240WATTS
*when run @10hrs/day monthy cost will be around $10*

*IN ROOM A/C*
-10,000BTU
-10AMPS
-1500-2600WATTS
*at 10hrs/day with 2600watt unit will cost $80/mo to run*

*DUCTLESS MINI SPLIT*
-9000BTU
-7-8AMPS
-740WATTS
*at 10hrs/day it will cost $20-25/mo


Now for the room...It is a 4x7x8 room built out of steel studs and drywall. I am using a 600-1000watt air cooled light and a dehumidifier in a sealed setup with co2. The last 2 days the temps have been 92 in the room and 70-75 outside. The grow room is built within a garage.

My first question is which unit would best work for me at an efficient level as I am only growing for personal meds. If its based just on run cost then I know to go with the evap cooler but I also know theres a lot more to it.

With the evap I would have to constantly refill the res.( If i would have to more than once a day I would NOT be able to do that). And I have been told they will only drop the temps 5-10 degrees at best..Is this true?... Also I am unsure of how much humidity it will add. I am in the desert where the humditity hardly gets over 20% outside but ive already hit 98% in my room when my dehuey accedentally shut off...I am emptying the dehuey every other day for perspective.

Now if its between the 2 actual A/C units then I would rather go with the mini split as its 1/4 the cost to run as the in-room. The only issue I can see with the mini-split is I WONT be able to put the condenser outside of the garage. Would I be able to get away with it being in the garage yet outside of the growroom? Or does it have to be outside outside?

As you can I am pulling my hair out over this :icon_dizzy:. Especially since it needs to be addressed ASAP and I have never had to mess with an A/C before. Any advice and help is greatly appreciated! Thanks farmers!!
 
R

RMCG

2,050
48
Go with the mini-split vs the swamp cooler. They cool by adding moisture to the air.

They certainly can cool more than 5-10 degrees, but can only get down as cool as a few * ABOVE the WET BULB temp (not actual temp).

But since you are sealed, you would have humidity build up rapidly.


You can put your minisplit condenser in your garage IF you can do air changes. They do this in mechanical rooms in buildings. Good rule of thumb is 500+cfm / TON of cooling capacity. So, can you actively vent the heat from your garage?
 
BakedasBeans

BakedasBeans

297
18
Thanks for the response RMCG! Ya I figured the sealed aspect of my room would become an issue with the humidy thats why I didnt know if my dehuey would be able to counter it. What is the dry bulb temp??

Actively.. I dont think so. Ill have to look closer but I think the only way to exchange my air that much is to leave open the garage door to the outside which I cant do for obvious reasons. And I wouldnt be able to cut a hole in the wall to vent bacuse up is the crawl space above the house and the side wall is shared with our dining room. So that would be the only way I could put the condenser in the garage?
 
BakedasBeans

BakedasBeans

297
18
Thanks for that link!

Im not sure if I can vent up through a roof vent or not I can definitly look though. I was trying to avoid cutting a hole in the ceiling but if I have to I have to.

How long can the line be between the condenser and the wall unit? If I put it outside I would have to run the line up through the crawlspace across the house and out by my side yard. The way my house/garage are laid out I had to build the room against the shared wall with the house, instead of the wall that goes right outside which would have made it a lot easier for something like this.

So then with the inroom portable a/c i would have to vent it outside as well? Just like the mini split or a window unit?
 
R

RMCG

2,050
48
Max 'lineset' length is determined by the make/model. DIY models are 'precharged' for a certain length (16' -25') I've found Friedrich models that are precharged for 49'. Usually they max out ~150' or so.

Portable or Window unit would need to be vented too. Portables you have much less venting options, so I would dismiss them immediately.
 
BakedasBeans

BakedasBeans

297
18
Cool, ill do some measuring and look into that. It looks like im either gonna have to vent through the crawl space or find a unit that I run a long enough line to the side yard and those seem to be my only 2 options other than dont grow in the garage.

Last idea... If I go with an evap unit, its going to creat too mch humidity in a sealed room for my current dehuey to remove. Correct? Now if I CANT find a way to make the mini-split work would I be able to just cut holes and switch to intake/exhast and use the evap or would it still be too much humidity?

Oh and i have an 8x8 room the attached to the 4x7 with a dividing wall. Its the same build style as the 4x7. Is there anyway I could utilize that with the whole venting issue Im facing with the mini-split.
 
R

RMCG

2,050
48
My locale (CO) has very low ambient humidity too.

I will be putting in a swamp cooler to drop temps (temporarily) until I seal the whole thing up, but I have roof vents/fan.

If you go intake/exhaust vs sealed room, where are you going to vent the hot air?
 
BakedasBeans

BakedasBeans

297
18
damn, good question. I guess it would end up being sealed within a sealed. If I went intake ehaust I would use the in room evap cooler. The one I looked at needed no venting at all so by hot air do you mean from inside the room? I was thinking of using the intake/ehaust to counteract the humidity issue I would have more than the excess heat because with that setup the exhaust air would be colder than the air in the garage. Would that not work?
 
R

RMCG

2,050
48
So just exhaust into your garage?

Evap coolers don't need ducting, but they do need a water source, figure .7lt/hr usage.


What are your garage temps? esp. during summer?

One of a few things would happen, your garage humidity level will skyrocket, the garage temps will skyrocket or your humidity inside the growroom will skyrocket.

Carbon filters don't work well when in a humid environment either.
 
BakedasBeans

BakedasBeans

297
18
Ya I would just be exhausting into the garage. The one I looked at had a 5gal res so at .7lt/hr I should only have to refill every other day or so which is no prob at all.

This will be my first summer living at this house but not in this city. Our summers are normally pretty hot (nevada). They average in the 90's and see some tripple digits around august. So the garage would probably runn a little warmer or right around that.

But if its say 94 outside and 98 in the garage is it the airfloiw that would make the difference in the opperation of any of these units? Cus the temp obviously is gonna close to the same.
 
BakedasBeans

BakedasBeans

297
18
Sweet thanks for those links! I just checked them out and it says for my area the average wet bulb temp was 58 at it peak(this is the second link you posted).

The first link says the "high temp" is 95* MD, 61MWB. THe "high wet bulb" is 63WB and 87* MDB.

So if im understandning this right the wet bulb average is somewhere around 60* and the dry is 95*? So 60* would be as cold as I can possible get with an evap cooler here? And as the humidity in my room would rise the temp would also rise from that 60* starting point correct?

If im right with that last paragraph then how would I figure the maximum humidity I can have and keep my room around 78-80?
 
CannabisJohn

CannabisJohn

1,063
113
Ya I would just be exhausting into the garage. The one I looked at had a 5gal res so at .7lt/hr I should only have to refill every other day or so which is no prob at all.

This will be my first summer living at this house but not in this city. Our summers are normally pretty hot (nevada). They average in the 90's and see some tripple digits around august. So the garage would probably runn a little warmer or right around that.

But if its say 94 outside and 98 in the garage is it the airfloiw that would make the difference in the opperation of any of these units? Cus the temp obviously is gonna close to the same.

The condensing unit adds 20-30F to air it takes in to cool the refrigerant. With most garages the garage will be 10-20F warmer than outside especially since most garages are uninsulated or poorly insulated. So you must vent the garage very well if condensing unit is placed in garage. So on a 90F day outside your garage will be 100+ and air from condenser will be 120+. Your temps in garage will skyrocket quickly. I would exhaust and supply garage if you put condenser in the garage.
 
Cort

Cort

1,444
163
You cant run an evap in a sealed room.

Evap cooler takes dry air and pulls it through wet pads cooling the air 10-30 degrees depending on humidity and temps. The process is like having a fan on a wet towel, towel gets cool and the moisture is transferred to the air. The more humid the less an evap it cools. You need a constant supply of fresh dry air to make the cooler work.

If you tried to run the evap is a sealed room after a while all you would have is a big fan blowing your hot 90-100RH air around.
 
I

Indicated

29
3
Seriously, forget the swamp cooler . it will never work for your setup..your room isnt that big and you only have the one 1k lamp thats vented..keep it simple and install a wall shaker a/c..but no matter WHAT you use your going to have to keep the condensing air temps in the garage below 90. and thats going to mean the air has to be changed somehow.. the mini split is more efficient because its a 240volt compressor there are 240vac wall a/c's out therethat are that small but you may have to special order it..12,000 btu is PLeNTY for that size space..I have 1k in a 6x6x8 room and only have 230 cfms coming from my central a/c and exaust the room through the light to the attic and i can get the room as cool as i want to year round, granted its indoors but the point is 6,000 btus will do it but nobody makes a 240vac that small that i know of but freidrich makes a 12,000 240vac and its a good machine
 

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