Let's figure out a way to vent my minisplit...

So I have an underground room, with a small walkway/lungroom/hallway between the grow room itself and the wall outside. It's pretty much like this... Walk into the room from the outside, your in the lungroom, then you walk into the grow room from there..

I have a 26,000 btu minisplit cooling my 4000 watt grow. In the cooler months it does an amazing job keeping things cool, however now that the days are getting warmer it does terrible. All of my lights have to be dialed down to the lowest setting which is around 600 watts just to keep it around 83 degrees... this is ridiculous.

What I have come to figure out is that it must be that my lungroom is getting far too hot with the minisplit sitting inside of it to allow the AC to function properly. I have no frozen coils, no pipes, etc to indicate low freon... I think simply put that the compressor is getting to hot... I know this is not a great idea, actually its a terrible idea but I dont have a choice period. There is no way I would be able to get away with sitting the mini split unit outside, it would give it away for sure...

Now i do have a little ventilation in there, I have a 6 inch phresh filter connected to a 440cfm fan sitting on top of the ac unit sucking out the air, however it's still ridiculously fucking hot in there and I belive this is what is causing my AC to not function properly... can anyone confirm?

So, I have thought about building an enclosure around the exhaust part of the ac untit, cutting a hole in the top of the box I build and directly sucking the air out that way.. or, I have also considered maybe upgrading to an 8 or 10 inch inline fan to do the job better and vent it out rather than the 6 inch 440cfm.

Is this what is causing my ac to not cool the room properly? The air coming out of the unit is cool but definitely not cold. It has to be the compressor over heating and hopefully I have not already damaged it.

Any ideas???

You are on it. Building that exhaust sounds like THE thing to do. If that helps some....then maybe take further steps with fan you mention to get temps down more in lung.

For sure extreme ambient temps will cause compressor performance issues.

TintEastwood said:

You are on it. Building that exhaust sounds like THE thing to do. If that helps some....then maybe take further steps with fan you mention to get temps down more in lung.

For sure extreme ambient temps will cause compressor performance issues.

Click to expand...

I ordered a 10 inch inline fan, so I'm gonna get some CFMs pulling hard, the 6 inch doesnt really cut it. Now i know for sure that it's the compressor getting too hot and not allowing the unit to function properly. Left the door open lastnight to the entrance and what'ya know... Temps stayed a steady 78 degrees, cause i was allowing fresh air to mix with the AC unit... That is nearly a 20 degree difference. Also had all 4000 watt lights cranked up to super lumens as well as 2 315cmh's...

I think were off to getting this sorted out now!

Good deal. 10inch.....wow that should pull. Must be awful loud if running at full throttle.

I use a Sensibo for remote management of my AC. Wifi dealio.

I've been thinking about running a water cooled system, possibly intograte a peltier chiller I'm thinking of building. But if you pull the light heat out with just a water cooled system or might be enough. Just toss on a big enough radiator system and pump it outside of.the box and away from the split.

I’ve seen people build box around window units and pull with a fan seems like your on the right track.

How are you making up the air thats being sucked out of your lung room? A 10" would create huge neg pressure that might affect the grow room...

psychadelibud said:

So I have an underground room, with a small walkway/lungroom/hallway between the grow room itself and the wall outside. It's pretty much like this... Walk into the room from the outside, your in the lungroom, then you walk into the grow room from there..

I have a 26,000 btu minisplit cooling my 4000 watt grow. In the cooler months it does an amazing job keeping things cool, however now that the days are getting warmer it does terrible. All of my lights have to be dialed down to the lowest setting which is around 600 watts just to keep it around 83 degrees... this is ridiculous.

What I have come to figure out is that it must be that my lungroom is getting far too hot with the minisplit sitting inside of it to allow the AC to function properly. I have no frozen coils, no pipes, etc to indicate low freon... I think simply put that the compressor is getting to hot... I know this is not a great idea, actually its a terrible idea but I dont have a choice period. There is no way I would be able to get away with sitting the mini split unit outside, it would give it away for sure...

Now i do have a little ventilation in there, I have a 6 inch phresh filter connected to a 440cfm fan sitting on top of the ac unit sucking out the air, however it's still ridiculously fucking hot in there and I belive this is what is causing my AC to not function properly... can anyone confirm?

So, I have thought about building an enclosure around the exhaust part of the ac untit, cutting a hole in the top of the box I build and directly sucking the air out that way.. or, I have also considered maybe upgrading to an 8 or 10 inch inline fan to do the job better and vent it out rather than the 6 inch 440cfm.

Is this what is causing my ac to not cool the room properly? The air coming out of the unit is cool but definitely not cold. It has to be the compressor over heating and hopefully I have not already damaged it.

Any ideas???

Click to expand...

Are you talking about a mini split- inside mounted evaporator coil unit and the condenser unit to be placed outside? Or are you talking about a portable ac? With the hoses for ventilation?

Gquebed said:

How are you making up the air thats being sucked out of your lung room? A 10" would create huge neg pressure that might affect the grow room...

Click to expand...

Leaving the entrance to the door cracked atm from the outside into the lungroom. I will likely make intake holes in the outside wall to pull fresh air from point a to point b.

Realbax said:

Are you talking about a mini split- inside mounted evaporator coil unit and the condenser unit to be placed outside? Or are you talking about a portable ac? With the hoses for ventilation?

Click to expand...

I am talking about a 26,000 btu mini split, definitely not a portable.

@Gquebed

Basically, when you walk into the hallway "lungroom", the mini split sits right there to the right, which is the end of the right side of the hall. To the left, there is about a 14 for walkway. Couldnt I just drill an intake hole somewhere to the left and it pull the air from that intake hole instead of pulling my cool air out of the grow room itself?

I notice when I open the main entrance door and leave it open, the way i have it temporarily set up now, it works to cool the the unit down enough to be efficient. However this is only temporary till my fan arrives and I can build something different. Anyway, I notice it allows the odor to get out and I can smell it which is a HUGE no no... I cant be letting odor escape. When the door is closed, it doesnt smell at all. I have a 6 inch fan and filter scrubbing the inside of the room, I have another 6 inch fan/filter sitting on top of the ac unit in the lungroom, which is exhausting hot air the best it can from the ac. But when that door opens, odor somehow escapes.

Y'all need to help me get this straightened out ASAP! Lol.

psychadelibud said:

@Gquebed

Basically, when you walk into the hallway "lungroom", the mini split sits right there to the right, which is the end of the right side of the hall. To the left, there is about a 14 for walkway. Couldnt I just drill an intake hole somewhere to the left and it pull the air from that intake hole instead of pulling my cool air out of the grow room itself?

I notice when I open the main entrance door and leave it open, the way i have it temporarily set up now, it works to cool the the unit down enough to be efficient. However this is only temporary till my fan arrives and I can build something different. Anyway, I notice it allows the odor to get out and I can smell it which is a HUGE no no... I cant be letting odor escape. When the door is closed, it doesnt smell at all. I have a 6 inch fan and filter scrubbing the inside of the room, I have another 6 inch fan/filter sitting on top of the ac unit in the lungroom, which is exhausting hot air the best it can from the ac. But when that door opens, odor somehow escapes.

Y'all need to help me get this straightened out ASAP! Lol.

Click to expand...

A 10" inline fan is pulling probably 1000 cfm of air out of your lung room. That will keep it cool in there for sure, but if there is no intake air coming into to that room you will have huge negative pressure, which will suck air out of your grow room, which is why you can smell it. So... you need to get an intake of air into the lung room at the same rate as the out put. Balance it and air wont be sucked out of your grow room.

I wanted to do a mini split inside too, but i would've had the same prob as you and no way to correct it so i didnt do it.

Gquebed said:

A 10" inline fan is pulling probably 1000 cfm of air out of your lung room. That will keep it cool in there for sure, but if there is no intake air coming into to that room you will have huge negative pressure, which will suck air out of your grow room, which is why you can smell it. So... you need to get an intake of air into the lung room at the same rate as the out put. Balance it and air wont be sucked out of your grow room.

I wanted to do a mini split inside too, but i would've had the same prob as you and no way to correct it so i didnt do it.

Click to expand...

Why would I have to have 2 fans of the same CFM? Could I not just do it like this???

Intake---Duct---Box/AC---Filter/Fan---Exhaust?

Would that work?

Or it could be passive, instead of having a duct running from intake hole, I could just let it pull the air and then out?

Not sure if you have seen them or not, and hopefully someone can chime in on this... But they make an "inline" carbon filter now. I'm not sure how well they work, they do cost a little more than your normal filters but they are made by Phresh which tells me they should be efficient.. Anyone know anything about them?

Here is a pic...

(if I'm still understanding) I would want a speed controller on the Mini-split heat box exhaust fan. That way you can adjust rpm/cfm to kinda match the cfm's of heat being blown out the back of the Mini-split.

I just watched this and learned a few things about scrubbing.

TintEastwood said:

(if I'm still understanding) I would want a speed controller on the Mini-split heat box exhaust fan. That way you can adjust rpm/cfm to kinda match the cfm's of heat being blown out the back of the Mini-split.

I just watched this and learned a few things about scrubbing.

Click to expand...

Yeah I think I am definitely gonna add a speed controller to it. Actually, I might should have went with an 8 inch instead of a 10. I may have been over thinking it, just a hair.

I think a lot of the reason too that my odor escapes when the door is opened, is that the exhaust of the AC unit is right beside the door and it pushes some of it out. That AC blows pretty dang hard, which allows some of the smell to be pushed out before getting sucked up through the carbon filter... Wish I knew the CFMs of the fan on the AC.

That is a good video too btw.

psychadelibud said:

Or it could be passive, instead of having a duct running from intake hole, I could just let it pull the air and then out?

Click to expand...

You could go passive... but youll need a big fuckin hole.

Gquebed said:

You could go passive... but youll need a big fuckin hole.

Click to expand...

That's true...

How about having the intake hole, to duct, into the box I am going to build around the AC. Then using one of those inline filters, have the filter connected to the top of box, then fan pulling air through the duct, into the box, through top of box/filter, then to the outside?

@Gquebed btw... what strain is that in your avatar?? Those are some wicked looking spears!