9,000btu mini split enough?

L

Lund-o

Well-Known Member
sealed room about 8x12.. less than 2k watts of quantum boards. 50pint dehumidifier that doesn’t run constantly. Room has been getting up to 95f with ac set to 76.. trying to figure out if fans are messing with the thermostat but don’t want to completely shut them off.
Should that be enough to cool it?
 
It should be enough to cool it, but I'd upsize it, I'd say eventually you will add more lighting so I'd go ahead and go up another size or two, nice things about mini splits are that you can oversize them and they will still only run as hard as they have too(as long as you get a inverter compressor model and most of them are). The jump in size from a 9k btu to a 12k or 18k btu shouldn't be that much maybe a couple hundred bucks and it will allow you to add more lighting when you decide to do so(your only at 20.8 watts per sq ft.)
Make sure to spec your unit for low ambient cooling if that is an issue where you live, some models won't cool when temps drop below 50 degrees or 30 degrees depending on brand and model. Some like the daikin will shut off when outside temps hit 50, but they have a built in feature called facility setting and it requires cutting a jumper in the outside unit that will then allow cooling down to 5 degree outside.
 
Apalchen said:
It should be enough to cool it, but I'd upsize it, I'd say eventually you will add more lighting so I'd go ahead and go up another size or two, nice things about mini splits are that you can oversize them and they will still only run as hard as they have too(as long as you get a inverter compressor model and most of them are). The jump in size from a 9k btu to a 12k or 18k btu shouldn't be that much maybe a couple hundred bucks and it will allow you to add more lighting when you decide to do so(your only at 20.8 watts per sq ft.)
Make sure to spec your unit for low ambient cooling if that is an issue where you live, some models won't cool when temps drop below 50 degrees or 30 degrees depending on brand and model. Some like the daikin will shut off when outside temps hit 50, but they have a built in feature called facility setting and it requires cutting a jumper in the outside unit that will then allow cooling down to 5 degree outside.
Click to expand...
Yeah I know I should’ve went bigger but little too late for that. Maybe next year. It cools down to 0f and heats to -4f outside temps. At this point trying to figure out why the thermostat isn’t kicking on when it’s 90f in the room.. gonna try wiring a thermostat in so it’s in a different spot in the room.
 
Sounds like you have a problem with the AC unit. Was it professionally installed? Does it blow cold air?
 
Renfro said:
Sounds like you have a problem with the AC unit. Was it professionally installed? Does it blow cold air?
Click to expand...
I installed it, but a friend who is a professional vacced it down and all that. Yes it blows cold air, the unit works fine
 
what specific model air conditioner did you put in
some other things--
how close to the ceiling did you install the split?
where is your condensor located?
what temp incoming and outgoing for the split? (roughly)
 
Last edited:
Nizza said:
what specific model air conditioner did you put in
some other things--
how close to the ceiling did you install the split?
where is your condensor located?
what temp incoming and outgoing for the split? (roughly)
Click to expand...
Gree vireo 9000 115v
I forget, I will measure but I went by their recommended min.
Condenser is outside, with the proper amount of space from building to condenser.
I’ll check temps in and out when lights are on tonight.
 
Therefore, a 1,000W HPS grow light (1,060W with ballast loss) generates 3,617 BTU per hour heat. A 500W LED grow light (550W with driver loss) generates approximately 1,877 BTU per hour heat. A 315W CDL grow light (335W with ballast loss) generates approximately 1,143 BTU per hour heat

that is some random ass info google gave me.
however saying u have 2000w could be approx 2000 btu X 4 so 8000 btu's + that dehumidifier and stuff running maybe you are just within the constraints of the capacity of this unit.

some other questions too

are u using fans to extract and add fresh air or is this sealed? are you using co2 and what PPM?
Is the unit running when your room is at 95degF or not? and is it Cooling inlet temp vs outlet temp (delta temp) this will help to see if it is a temperature reading error with the unit.
 
you have to remember, everything from circulation fans, to dehumidifiers, and also pumps generate heat. This is what you will have to figure when sizing the unit; however 95 F seems a little high UNLESS this is during vegetative cycle.
If that is the case you must realize too; it is coming to the end of the summer, temps may go down
with co2 u can run 80-90 f sealed
non co2 70-80f vented

also with summer going away temps will drop a little
also with changing to blooming you have 4 hours less of light. from 18/6 to 12/12 that is 33% less heat which may put you right where u need to be when you need to be.
A little less light is always an option too. If you can dim your boards if your A/c is working correctly is another option. Also you can vent your room for now then conceal it in flowering if using additiional co2 + a/c
 
Nizza said:
Therefore, a 1,000W HPS grow light (1,060W with ballast loss) generates 3,617 BTU per hour heat. A 500W LED grow light (550W with driver loss) generates approximately 1,877 BTU per hour heat. A 315W CDL grow light (335W with ballast loss) generates approximately 1,143 BTU per hour heat

that is some random ass info google gave me.
however saying u have 2000w could be approx 2000 btu X 4 so 8000 btu's + that dehumidifier and stuff running maybe you are just within the constraints of the capacity of this unit.

some other questions too

are u using fans to extract and add fresh air or is this sealed? are you using co2 and what PPM?
Is the unit running when your room is at 95degF or not? and is it Cooling inlet temp vs outlet temp (delta temp) this will help to see if it is a temperature reading error with the unit.
Click to expand...
Sealed, c02 goes from about 1500/1700 down to 600ppm every 2 hours. Unit is running but at that temp the air coming out isn’t what it should be. When lights go out the air coming out gets much colder..? Or at least feels it.
What do you mean inlet outlet (delta)? Freeon temp?
 
it is most likely a freon leak then or undercharge.
how was the refrigerant piping ran to the units?
4 flare joints?
open the insulation look for oil~ if you see oil it is likely a leak. Also leaks can happen on coils. This is not something to rule out.

The proper way to assess this is to use a recovery machine and hook it up to the condensor and weigh out all the refrigerant that was in the system
after or before you find this number, you find the factory charge of the unit, the line length, and the amount to add per additional lineset length
I believe each unit is usually precharged with 25 ' or so and need to be run a minimum of 9'-11' of lineset length. any additional length of lineset after 25' i think you add .22oz of 410a per ft.. I may be wrong but all this stuff can be figured out in the manual. If you really believe the unit isnt putting out cold air during peak hours of its usage I really believe it could be undercharged

if you pull out the refrigerant and it is less than you calculated and you cant find a leak it could have originally never been charged correctly if under lineset/over lineset length

it is rare to find a unit with an issue that is new with problems other than this, but it does happen!

hopefully for you it is just a crappy flare leak and not a warranty process so you can keep on with your grow bro!
 
I also wonder if your condensor is cutting out for some reason like maybe the whole refrigeration process is stopping for some reason.
undercharged/overcharged units can do this because the compressor can overload
 
also i forgot to ask this HUGE question... lol

did it ever work before with the same lights and heat load? if it did and slowly became an issue I would say this is definately a leak issue!
 
Nizza said:
it is most likely a freon leak then or undercharge.
how was the refrigerant piping ran to the units?
4 flare joints?
open the insulation look for oil~ if you see oil it is likely a leak. Also leaks can happen on coils. This is not something to rule out.

The proper way to assess this is to use a recovery machine and hook it up to the condensor and weigh out all the refrigerant that was in the system
after or before you find this number, you find the factory charge of the unit, the line length, and the amount to add per additional lineset length
I believe each unit is usually precharged with 25 ' or so and need to be run a minimum of 9'-11' of lineset length. any additional length of lineset after 25' i think you add .22oz of 410a per ft.. I may be wrong but all this stuff can be figured out in the manual. If you really believe the unit isnt putting out cold air during peak hours of its usage I really believe it could be undercharged

if you pull out the refrigerant and it is less than you calculated and you cant find a leak it could have originally never been charged correctly if under lineset/over lineset length

it is rare to find a unit with an issue that is new with problems other than this, but it does happen!

hopefully for you it is just a crappy flare leak and not a warranty process so you can keep on with your grow bro!
Click to expand...
When I first installed The factory flares leaked, my friend owns a AC company so nitrogen tested it, fixed it, filled it properly.
 
Nizza said:
also i forgot to ask this HUGE question... lol

did it ever work before with the same lights and heat load? if it did and slowly became an issue I would say this is definately a leak issue!
Click to expand...
Yes it did, weirdly enough when I went from a standing oscillating fan to wall mount fans it started.. I have tried moving them, changing where the air blows etc no luck
 
I would have to say it could be a coincidence of going to the wall mount fans and a leak of refrigerant somewhere in the coilsor piping to the coils to cause loss of cooling capacity then. Start there and try to rule out a leak by visually testing first. the next step is weighing out the charge and seeing if that is right, then if that isnt right, testing with nitrogen to find the leak, fix it, then re-evacuate and re-charge

notably it may be a bad factory/product
perhaps looking into reviews on this and seeing if it is worth your time really looking for a leak or not

you could also add a few OZ's of r410a to the system and see if it handles the load a little better the next day.. and if it doesnt take them out. but remember this must be done in liquid form.

if the "factory" flares leaked then I don't really know what to say..
In my experience the head and the condensor both have a convex fitting with male threads and the copper refrigerant line pipe flare is made in the field~ typically is what leaks.

However since this is an off brand I wouldn't be suprised if the problem wasn't at all the copper tubing or the guy's flare job- the product could just be crappy and sometimes when you try to save money with an off brand u get a bad egg maybe this is one of those situations or piping to the coils
 
Last edited:
off to bed tonight bro ill be back around. I do hvac for a living so I can at least point you in the right direction remotely
 
Nizza said:
you could also add a few OZ's of r410a to the system and see if it handles the load a little better the next day.. and if it doesnt take them out. but remember this must be done in liquid form.
Click to expand...
My unit only has the lowside port so I do it running and with a liquid lowside charger on the gauge manifold.

https://www.amazon.com/Imperial-535...argid=aud-801381245258:pla-350589960208&psc=1

That allows the fluid to expand and you have to do it in small burst of a few ounces then wait for the low side pressure on the unit to drop back down before adding a bit more. Refrigerant tank needs to be upside down or have the dip tube.
 
You must log in or register to reply here.

Similar threads

T
mini split vs wall unit ac in sealed CO2 room
Replies
8
Views
778
Drop That Sound
Drop That Sound
W
Mini split advice, wall mount vs slim duct, C&H vs Aircon
Replies
15
Views
2K
watsongreenthumb
W
B
One Mini-Split, Two Rooms?
Replies
5
Views
432
Blazin Budz
B
A
Will insulating a drop ceiling help a mini split.
2
Replies
30
Views
2K
MidnightSun72
MidnightSun72
Pauly1118
MINI SPLIT: how many BTUs needed for 8x8 with 4000w HPS?
Replies
10
Views
383
medicaloutlaw
medicaloutlaw
Back
Top