How to even out temps in grow room

[Bigrick31]

My current room is 18' wide 4' deep and 5' tall. I have an 18,000BTU window AC installed in the middle of the room. It does a great job of keeping the air in the middle of the room nice and cool but the far ends of the room are usually 10 deg higher than the center. To combat this I first bought a Vornado fan


http://www.target.com/CR1-0074-06-V...archRank=target104545&sr=1-6&searchPage=1&rh=

It helped a little but didnt solve the issue. I then bought a 745cfm 8" inline fan which I installed directly over the top of the window AC hoping it would suck in coold air from teh center ofthe room. It the front of the fan then T's out to 4" ducting where I installed diffusers in 4 locations in the room

again in hopes that it would suck in cold air from the center of the room and spread it out evenly throughout the entire room. But still the temps arnt even. If I want the far ends of my room to be 75 I have to set my AC for 69 then the center of my room is at 69 while the far ends are 75. Im really not sure where to go from here I figured the inline fan would solve everything for sure but seeing as it didnt I could use some help on the best way to go about evening out the temperature of the entire room. Anyone have any recommendations?

 

[Buzzsmirk!]

hi rick, i would suspect the structure u have is not well or not at all insulated is it??

u could line the walls with the foam board they sell at HD/lowes for about 10bux a sheet
4x8

how well is ur (growhall) LOL sealed??? hot air will quickly defeat a good a/c system if enough can get in the space.

u could try two smaller a/c units installed on the ends of the growhall

18,000 BTUs for a 360 cubic foot space should cool like a meat locker!!!

either ur a/c is defective OR u have severe insulation issues

are u cooling ur lights??? are your balllast(s) OUT of the grow space??? they " make"heat
get em out of there if they r in there.

hope this helps!!
BUZZ!

 

[Bigrick31]

hi rick, i would suspect the structure u have is not well or not at all insulated is it??

u could line the walls with the foam board they sell at HD/lowes for about 10bux a sheet
4x8

how well is ur (growhall) LOL sealed??? hot air will quickly defeat a good a/c system if enough can get in the space.

u could try two smaller a/c units installed on the ends of the growhall

18,000 BTUs for a 360 cubic foot space should cool like a meat locker!!!

either ur a/c is defective OR u have severe insulation issues

are u cooling ur lights??? are your balllast(s) OUT of the grow space??? they " make"heat
get em out of there if they r in there.

hope this helps!!
BUZZ!

The "Grow hall" is in an attic and is well insulated though there are minor leak points where air can escape which I am working on sealing up. First the Entire room is built out of 7/16 OSB the inside is completely covered in 3/4" Rigid foam insulation thats what makes up the white walls you see in my second pic in my first post. The roof of the room uses R30 pink insulation with a layer of 3/4" rigid foam on top of it. The doors are where the minor leaks are. Since its in my attic there are a lot of studs I have to contend with so rather than fight them I just worked with them I have 9 insulated doors on my room. Again 7/16 OSB with 3/4" foam make up each door. Then to help seal the door I put a thin strip of wood on each side of the door inside the grow room with weather stripping to help create a good seal around the door but since the door is only plywood it tends to bend a little letting some air leak out regardless of how much weather stripping there is. I have some gate latches that I am going to use to suck in the center of the doors where they bow.

heres some pics

As for my lights I use 90 watt LED UFOs they do create some heat but nothing compared to that of an HID fixture unfortunately there is no way for me to vent them.

 

[Bigrick31]

Heres more pics of the room just so people can get an idea of how it was built and how the "hall" works

This is before the doors were in stalled. The doors sit between the vertical studs you see in these pics

 

[cbp420]

You are half way there, make a plenum that will fit over the cold air out of your unit, attach that to your duct with diffusers and you will now have a central AC unit. You still might have hot spots and make sure that the air is moving through the ducts to the end. Good luck.

 

[FrijolElVerde]

Hola Bigrick31, You might try changing your fan setup so that the intakes are at the ceiling at the far ends and the discharge is at floor level in front of your AC thus mixing your warmest air with the coldest air. Just call me the Master of Crazy Ducting- look at what I'm building, HAHA!!!
Best of luck on solving this problem.

 

[someotherguy]

hey bro, sorry i can't add anything regarding your current
problem but i wanted to say that i hope you will start a grow
diary thread as i would love to see how you do with those
LED's.

peace, SOG

 

[Buzzsmirk!]

rick, ur pics arent loadin on jy screen so i have had to use my mental imagerey a bit.

if u r usin leds then heat from lighting is not ur problem.

u R in an attic!!! i would have to surmise that heat is leaking into ur space at a bad rate!

make ur space smaller and easier to seal or re examine ur set up!!
"9" doors WTF??? mental image not working att all now
iquess uhave no pathway in the space and uaccess it thru the doors right??

9 doors (homeade doors) are ur problem or most of it IMHO

take some sqaure vinyl gutter downspout material (square tubing 4"x4" approx and fashion a duct system over your cold air supply on the a/c try reducing it to 2 or 3 inch stuff out towards the ends
this evenly disribute the cool air w/o big fans
BUZZ!

 

[Bigrick31]

You are half way there, make a plenum that will fit over the cold air out of your unit, attach that to your duct with diffusers and you will now have a central AC unit. You still might have hot spots and make sure that the air is moving through the ducts to the end. Good luck.

I had tried that once.

Im not sure what happened but this worked for a day then I noticed my AC had shut off and my temps were rising. When I went to investigate I found that the face of my AC was covered in ice and my duct work was really cold I began to think that by boxing in the face of the AC I had somehow caused it to freeze so I removed the plenum and defrosted the AC with a heat gun also my RH is a bit high usually 50-70% working on installing a dehumidifier to keep the RH below 45% so im guessing that may have also helped the face of my AC freeze over. So maybe this time add an 8" intake rather than a 4" and use a dehumidifier?

rick, ur pics arent loadin on jy screen so i have had to use my mental imagerey a bit.

if u r usin leds then heat from lighting is not ur problem.

u R in an attic!!! i would have to surmise that heat is leaking into ur space at a bad rate!

make ur space smaller and easier to seal or re examine ur set up!!
"9" doors WTF??? mental image not working att all now
iquess uhave no pathway in the space and uaccess it thru the doors right??

9 doors (homeade doors) are ur problem or most of it IMHO

take some sqaure vinyl gutter downspout material (square tubing 4"x4" approx and fashion a duct system over your cold air supply on the a/c try reducing it to 2 or 3 inch stuff out towards the ends
this evenly disribute the cool air w/o big fans
BUZZ!

here are some direct links to the pics

http://i22.photobucket.com/albums/b330/Bigrick31/IMG_3062.jpg

http://i22.photobucket.com/albums/b330/Bigrick31/2f324c4c.jpg

http://i22.photobucket.com/albums/b330/Bigrick31/de5eea6b.jpg

http://i22.photobucket.com/albums/b330/Bigrick31/IMG_2025.jpg

http://i22.photobucket.com/albums/b330/Bigrick31/IMG_2026.jpg

http://i22.photobucket.com/albums/b330/Bigrick31/IMG_2027.jpg

Hola Bigrick31, You might try changing your fan setup so that the intakes are at the ceiling at the far ends and the discharge is at floor level in front of your AC thus mixing your warmest air with the coldest air. Just call me the Master of Crazy Ducting- look at what I'm building, HAHA!!!
Best of luck on solving this problem.

Thats in interesting thought though it would require a decent amount of work given my current space restrictions but not out of the question thanks!

hey bro, sorry i can't add anything regarding your current
problem but i wanted to say that i hope you will start a grow
diary thread as i would love to see how you do with those
LED's.

peace, SOG

I might start one on here once I get the room dialed in. So far im happy with the performance of the lights.

 

[Buzzsmirk!]

rick i have enough info now to say air leaks R def ur problem
if ur a/c is frosting over its a sure sign of excess humidity(leaks)
i m not gonna link on the pics (secuity paranoid i be) no offense to you either rick

it seems to me ur humidty is bad and the RH of hot air (leaked air) is laden w/ moisture
ur evap coil frosts up quickly

i know this is a shitty expensive "prescription" rick ..........u NEED to rethink and/or rework
ur nine doors any warpage = massive leakage = not workin

when growin indoors u r essentiallly "GOD" u must "create" a suitable enviroment for ur plantlife if u have ahot humid attic on the other side of the doors and ur probs r heat/humid ........................................ use ur head................ its thedoors not sealing!

make better doors try sandwiching a 2x2 frame between two thin sheets of OSB wfoam board in the void(s) look very hard at your "frame"(s) u have door frames jambs do you??
if not.................include that in ur rework process

plus once sealed up ur temps will be in check but CO2 avail may be prob...............once again YOU r "GOD" u will need to vent periodically or use co2 enrichment

thats my theory based on the info u given me

GOOD LUCK and good harvest(s) to you

would love ur feedbackon the UFOs i am a HID user myself but the LEDs intrigue me a bit.

my "advisors" at my grow shop tell me LEDs wont match the HIDs abilty to get dense nugs
but i suspect certain strains (genetics) maybe more suited for LEDs than others
BUZZ!

 

[Panama Red]

Rick, a couple of questions;
1)Does the AC unit vent to the outside or into another area of the building?
2)Is the unit set to draw outside, fresh air or re-circulate the room air?

 

[Bigrick31]

rick i have enough info now to say air leaks R def ur problem
if ur a/c is frosting over its a sure sign of excess humidity(leaks)
i m not gonna link on the pics (secuity paranoid i be) no offense to you either rick

it seems to me ur humidty is bad and the RH of hot air (leaked air) is laden w/ moisture
ur evap coil frosts up quickly

i know this is a shitty expensive "prescription" rick ..........u NEED to rethink and/or rework
ur nine doors any warpage = massive leakage = not workin

when growin indoors u r essentiallly "GOD" u must "create" a suitable enviroment for ur plantlife if u have ahot humid attic on the other side of the doors and ur probs r heat/humid ........................................ use ur head................ its thedoors not sealing!

make better doors try sandwiching a 2x2 frame between two thin sheets of OSB wfoam board in the void(s) look very hard at your "frame"(s) u have door frames jambs do you??
if not.................include that in ur rework process

plus once sealed up ur temps will be in check but CO2 avail may be prob...............once again YOU r "GOD" u will need to vent periodically or use co2 enrichment

thats my theory based on the info u given me

GOOD LUCK and good harvest(s) to you

would love ur feedbackon the UFOs i am a HID user myself but the LEDs intrigue me a bit.

my "advisors" at my grow shop tell me LEDs wont match the HIDs abilty to get dense nugs
but i suspect certain strains (genetics) maybe more suited for LEDs than others
BUZZ!

Cool man thanks for the info! ill get to work on sealing everything up 100%

Rick, a couple of questions;
1)Does the AC unit vent to the outside or into another area of the building?
2)Is the unit set to draw outside, fresh air or re-circulate the room air?

My ac is installed like this

I dray in fresh air from outside (through my roof) using an 8" 745cfm inline fan and smaller booster fans along the way. Then I use 8" Ducting to exhaust the back of the ac outside about 8 feet away.

Ive been playing around with the settings on the AC theres a little lever that you can push/pull which blocks a hole in the AC im guessing this allows me to mix or not mix air. I had the hole open guessing that mixes with outside air. I just closed it up though to see if that works any better for me. I bought the AC used on craigslist so im not familiar with all its functions.

 

[Panama Red]

That little lever is exactly what you think it is.
Usually pushed all the way in is re-circulate and that's what you want in this case.
Run it closed for a while and see if the far end temps come down.
If it doesn't a few simple changes will fix it.
Keep in mind that an 'air conditioner' is actually a 'heat exchanger'.
That 'hot exhaust out duct' is just removing the heat from the unit's coils on the outside of the unit not air from the room.
You need to create a bit of negative pressure in the room to get the remaining hot air out and allow it to fill more completely with the cold air.
A small exhaust fan near the ceiling at the hot end (or one at each end since the unit is in the middle of the room) will draw out the remaining heat and opening the lever a small bit will allow the room to cool more efficiently.