Negative Pressure Causing Damage

Okay I'm really hoping someone can help me out here.. There's a few ways I was thinking of dealing with this, but I want the easiest and cheapest ideas first. I have a 12x20 ft sealed grow room (1680 cubic ft) and am using a Whynter 14,000BTU dual hose ac unit (ARC-14SH). This thing is exhausting way more air than it is intaking. To the point where my vinyl flooring is parachuting and stretching / ruining it. I was under the assumption no dual hose air conditioners create negative pressure until I started doing some googling. If I do not take care of this quickly I'm afraid it's going to cause damage to the wood as well. The floor is plywood underneath the vinyl and I even feel the nails starting to raise.. It's bad. I also have a small hole in the ceiling where my light fixture is and it's sucking large amounts of hot air through the attic as well. I know I need to seal this soon but the main concern is eliminating the pressure. There is an extra air intake panel on the back of this unit which comes with a carbon filter. I am unable to tell if this intake is just being blown back out of the fan or if this is creating the extra exhaust air. Check out the unit on Amazon - https://www.amazon.com/Whynter-Portable-Conditioner-Heater-ARC-14SH/dp/B002W87P9C

I am against the whole "passive" air intake method. If I do not correct the ac exhaust, I will just be dumping large amounts of CO2 out of the room. I wanted to keep my "seal" as best as possible. Do you think running an extra fan through the intake hose would help? The only issue with that would be that it will remain blowing even when the ac unit shuts down and therefore possibly causing a positive pressure scenario, or even creating positive pressure inside the ac unit (if it's truly sealed). My last option I'm thinking would be to tape up and seal that back intake panel (the one on the back of the unit that takes air from inside) and create a new vent so it intakes from the outside as well. Or cut a hole in the original intake to merge them both to suck air from the same hose?

What do you all think? I really need some help and ideas. On another note.. what are you guys filtering the intake with without reducing suction? So far I only put in bug screens. Thanks

what van you do ? cut a small hole put in a filter in its place like cotton filter . this room has to be sealed tight as hell ! I just sealed a room with insulation took me 10 hours to do a 20/20 holds the cool air for hours and cant hear a stereo out side when its turned full blast .I have a 18500 btu window unit in but no negative vacuum . both of those hoses are exhaust ? of is one an intake ? also if the intake is on the unit in the front you can put the intake into a hose as well and put it out side draws the out side air in and just blows cool . ???? this work for you ? or if your already sucking the out side air then reverse it let it suck the air from the room into the ac unit just put the hose up high hot air goes up so it can suck out the hot air at the same time . hard to say with out being there hope I gave you a few ideas

bryan oconner said:

what van you do ? cut a small hole put in a filter in its place like cotton filter . this room has to be sealed tight as hell ! I just sealed a room with insulation took me 10 hours to do a 20/20 holds the cool air for hours and cant hear a stereo out side when its turned full blast .I have a 18500 btu window unit in but no negative vacuum . both of those hoses are exhaust ? of is one an intake ? also if the intake is on the unit in the front you can put the intake into a hose as well and put it out side draws the out side air in and just blows cool . ???? this work for you ? or if your already sucking the out side air then reverse it let it suck the air from the room into the ac unit just put the hose up high hot air goes up so it can suck out the hot air at the same time . hard to say with out being there hope I gave you a few ideas

Click to expand...

So that window ac unit is working efficiently for you? I am almost considering buying one if I can't get this portable one to work. Yes the left hose is an intake, and the right is exhaust. They claimed there would be no negative pressure since it is in taking air from outside. The only problem is the exhaust is literally blowing out twice as much air as the intake hose is suckling in. I'm not sure if I have a bad fan in the unit, or what.. I contacted Whynter support and they are ignoring my replies. They're trying to say the portable ac unit is too large for my 12x20x8 ft room. Which I do not believe to be true. No matter the room size.. the exhaust should never blow twice as fast. I hear it should only be 20% greater airflow than the intake MAX. Please tell me what you think. Window ac's create no negative pressure at all? And if I were to get a window ac, what size should I get? What BTU's

if you already have this portable . take the intake hose put it in the room your cooling on the top of the room far away as possible from where its putting in cold air don't want to suck up the cold air your pumping .this will resolve your issue . it should eliminate the negative pressure . also so you know I do not know what unit you have . my experience a window ac unit even a cheap one will cool 2 times as much as a portable . I only have experience with lg ac portables . I am not saying ones that cost 600 bucks don't work good but ones that cost 300 are trash . I have a 5k btu in a 10/10 cools twice as much as a 10k portable . ill help you out choosing a window ac unit . how many lights are you using ? how are you producing co2 ? a burner ?

air cooled ? open hood ? types .

Thanks for the reply. I have a Whynter ARC-14SH dual-hose portable AC running right now. It is 14,000 BTUs. It was rated for a 500 square ft room. If I can get this to work, that would be great. It cost me like $570. I feel like this should be sufficient for my room.. And it's too late to get a refund for it now

I have 6 600W LEDs from HydroponicsHut, and a Gotham Hydroponics 8-burner for CO2. This is a completely sealed grow room. No outside air is flowing in. Maybe my AC unit has an air leak and that's why it's blowing out more than it's sucking in? When I go outside.. the intake feels very weak. The exhaust is very powerful.

yeah put the intake in the room . if that does work then place it on craigs list . honestly if you have the cash I would if possible get a window unit or best mini split if your serious grower . a window unit cools just as good as a mini split per 1 large room . here is the problem I had with a portable ac unit I had 2 10000 btu in a room cooling 6000 watts and a 10 burner co2 unit . the room got toasty I kept it about 83 for the co2 but once the room temp spiked the ac units fell behind on a hot day . and the operating temps on the portable units are 110 ?depending on the unit . they both shut off !!!!!!! the room was 120 f need I say this is hot as hell . they don't operate in those temps go into protect mode . so I had to put the ac unit on the out side of the room cut a hole in the room . so the cold air blew into the room and I put the thermostat into the room I was trying to cool I had to take the unit apart it was a bit of work to get it to work until I could save up get a real ac unit . point is portable ac units not the best choice for cooling plants your rolling the dice . use it for now . mabe you will need it for your veg or clone room to keep it cool in the future . can you turn the fan down on the unit that blows air in ? mabe that will help put it on low speed .

15000 btu window unit will be more then enough to cool this room it will turn off and on . and your 14k portable may . run 100 % of the time lights on . very hard to say . I would have to say the led are as hot as t5 . I have a 18500 window unit cooling 4800watts open hoods with 10 burner co2 / 20/20 hps . spooky thing about portable units and co2 . you keep your room about 85f range to take advantage of your co2 and the ac unit shut off slightly over 90 slim line . if you have the portable unit under lighting or bt the co2 gen it may arm the unit up and fail to work . plae it in the shad

When I ran my.sealed, co2, dual hose portable (ac inside the room), it would also create a neg pressure. I had an active air 14k dual hose that was UTTER garbage. I had the unit in the room, intake hose outside the sealed room, and exhausting out the window. You can caulk the internals to minimize the neg pressure, but it's still gonna hapoen.

it's your typical bad engineering. tough you might be able to fix the problem...

intake hose goes up(within the room)

and exhaust goes out
what the difficult thing is, is making sure you seperate your unit condenser from the rest of the unit..
What is happening is the condenser fan that is sucking air trough the condesner and out the room, is winning from the intake fan.
so if you could build some kind of box around the unit (except the output), tape it well, and hook it up to a hose that is also taking air from OUTSIDE the room, you won't have anymore negative pressure.
BUT BUT BUT : this could inhibit the unit of functioning properly. depening on how good you take care of the air flow

sorry for my bad english

No hose should be sucking air from inside the sealed room.

if he sucks air form the room also sucks the injected co2 in wich will turn on the burner its a LOT of heat his unit will be like a 10k btu heater ! and this will make the ac turn on , so this ac unit may run 100 % of the time close to it . damn ac burner kick on then the ac and finally the ac catches up to the burner then the lights heat up the room in 5 minutes ? ac kick back on then the burner . so on and so on . I have been here and done it . kills the gas bill and the electricity bill . its better then nothing . but not intended to cool a room this size with co2 its great for tents the unit goes out side crank it up .

What do you guys think if I installed a 400 CFM fan connected to the intake hose? Think this would equalize the pressure? My only concern is that it would be hard getting that fan to run at the same time as the actual ac unit. And it might also create a positive pressure inside the unit causing it to fail. But I bet there's a lot of air leaks inside the unit so maybe it would work afterall? Basically, when I'm standing outside, the intake only feels like a suction compared to a 100 CFM fan and the exhaust feels like 400 CFM if not more. The exhaust burns to the touch so I feel like this unit is just overworking itself.

Why would you want to force more air in the intake side? Chances are you'll impact the work of the unit.i use a 6" 440 cfm fan on the exhaust, as I run about 20' of exhaust ducting. I just put the ac and fan on a timer.

I would put a fan in the intake to keep up with the exhaust fan. I am not having positive pressure in the room, it's negative pressure. Every little crack in the floor and walls are sucking air through them trying to replinish and equalize pressure. I have a pull door on the front of the shed, and overnight the pressure builds up to where it's hard to even open the door next morning. So it's not just that the negative pressure is inconvenient, it's dangerous. If I didn't go in the room daily, I feel like the vacuum pressure would build so strong that if I left for a few days and came back I would be unable to open the door. When I spend more than a half hour in there, I get very sick and lightheaded. I believe it's because all the breathable oxygen is being dumped outside, that's how fast this ac unit is pushing air out and not sucking enough in.

I put a 240 CFM fan in the intake as a test and it relieved the pressure by a little. The vinyl flooring did not parachute up as bad. But the exhaust is still like twice as strong as this 240 CFM fan lol.

sounds like your going to spend some cash to get it fixed

I know you dont want to hear it....but mini split ac is damn near the only way to run a sealed room if you want the least amount of headaches in the long run. And if you want about 1200 ppm of co2 to be in the grow room blowing around at all times during lights on for plants to explode in growth. Ive been down that road on the cheap out window shaker and portable bullshit ac units...modifying and whatnot. God i dont miss any of that. I just got off the coin (saved up) and got the proper appliance (mini split air-conditioner) for the heat load of the lamps. Dude....trust me.

Thing is...portable ac's...whether dual or single....are so inefficient and expensive to run on a yearly basis that the money you pay in a year running those pieces of shit....you could of bought one or 2 mini splits depending on the size. You just have to bite the bullet on the initial sticker price shock. Minis are a completely different animal in efficiency and long term cost savings.

All them bad ass grow room pics you see of clean ass rooms with a nice aisle down the middle with multiple lights shining over tables on either side packed full of buds busting through a net....look at the upper wall if you can...a minisplit handling whatever heat those hot ass lamps try and dish out. Again...trust me.

I've been running portable ac for 4+ yrs now. Mine sucks A LOT of power, 12.5 amps, more than a 1k light. I do not have the luxury of putting in a mini split, cash is not the problem, placement and well the Crack heads would steal it 30 mins after install.