Portable AC question

[SamWE19]

ive got an attic grow and I'm planning on converting it to co2 with no exhaust to help with temp swings.

It's a huge attic and I need 36000 btu I've found the only supplier of dual hose ACs here and it's only a 12000 btu.

It comes with a 1.5m hose at 150mm diameter which is nowhere near long enough for me to get to the chimney stack.

So I'll need to extend it to about 2.5-3m I also need 3 units to make it 36000 btu to cover the total 25000 btu that I put out including all lights and pumps co2 etc

I was thinking I could get a double swept tee and connect all 3 outlet hoses into one and then out the chimney stack.

I have some 500m3 inline fans that I can connect directly at the outlet to the AC units to suck the air out and force it through the junction and out the chimney.

I was hoping someone on here might have experience with these AC units and can tell me if this will blow up in my face or wether it just means they are slightly less efficient and I'll have enough headroom to make it ok

I can't make the outlet in the chimney stack any bigger unfortunately and I don't want to vent out eves due to choppers

Cheers

 

[rkymtnman]

i'm no AC expert but i'd go with a mini split instead for that many btus.

 

[SamWE19]

i'm no AC expert but i'd go with a mini split instead for that many btus.

No way to get a mini split I've already considered it there's no way for me to install it myself and there's no way for me to get the gas line to the outside from the loft without drilling through several floors of my house, plus the outside unit would be 10m below the indoor unit and would need a 20m gas line

 

[SchmoeJoe]

ive got an attic grow and I'm planning on converting it to co2 with no exhaust to help with temp swings.

It's a huge attic and I need 36000 btu I've found the only supplier of dual hose ACs here and it's only a 12000 btu.

It comes with a 1.5m hose at 150mm diameter which is nowhere near long enough for me to get to the chimney stack.

So I'll need to extend it to about 2.5-3m I also need 3 units to make it 36000 btu to cover the total 25000 btu that I put out including all lights and pumps co2 etc

I was thinking I could get a double swept tee and connect all 3 outlet hoses into one and then out the chimney stack.

I have some 500m3 inline fans that I can connect directly at the outlet to the AC units to suck the air out and force it through the junction and out the chimney.

I was hoping someone on here might have experience with these AC units and can tell me if this will blow up in my face or wether it just means they are slightly less efficient and I'll have enough headroom to make it ok

I can't make the outlet in the chimney stack any bigger unfortunately and I don't want to vent out eves due to choppers

Cheers

Depending on the square area of the garden space more smaller units can actually be better. It can give better coverage and help stop weird isolated pockets of inconsistencies. Probably the easiest way to duct them together would be to have them call on the side of the room with their ducting going straight up into a t spliced into a single straight run of ducting. If you need a to bend the ducting uoeard to a flange use a smooth sided 90° elbow. It's the most efficient. Anything else actually causes a lot if drag on the air that seriously cuts down on the air flow.

You should also put a small booster fan inline in the ducting between to AC's and the exhaust end if the ducting run. You'll need to keep the opposite end of the ducting wide open so that the fan doesn't pull on the ac's. If you want to keep the space completely completely sealed you'll need the intake end if the ducting connected to a flange that supplies air from outside of your garden. The highest yielding garden designs out there use everything you'd use with a fully sealed system except that they run a small continual exhaust. The theory is that this helps control the build up of gases from the plants like ethylene. Some gardens are even hitting 5 a light (1k) this way. A typical small duct boost fan would be about perfect for it.

 

[JDMase]

Hey mate I was given some advice about air con, can you optimise your exhaust and intake fans to avoid AC?

I was looking at a 12000 btu and it drew 2.6kw and if you're running three of them, I hope ur house wiring is up to the job.

I also have seen reviews of people extending the outlet from their AC and saying it gets the units hot as they're less able to get rid of the heat so then I'd think an inline fan if ur gonna extend would be a good idea but again another power draw.

Once you've figured out your total power draw you need to work out the cost of that energy against ur yield and price then you need to figure out ur profit margins..

 

[SchmoeJoe]

Hey mate I was given some advice about air con, can you optimise your exhaust and intake fans to avoid AC?

I was looking at a 12000 btu and it drew 2.6kw and if you're running three of them, I hope ur house wiring is up to the job.

I also have seen reviews of people extending the outlet from their AC and saying it gets the units hot as they're less able to get rid of the heat so then I'd think an inline fan if ur gonna extend would be a good idea but again another power draw.

Once you've figured out your total power draw you need to work out the cost of that energy against ur yield and price then you need to figure out ur profit margins..

I've seen a few systems that use relatively cheap geothermal. One guy buried a piece of ducting 9 feet down that runs 90 feet from a filtered intake in a shed all the way to his indoor garden. He as 65°f intake year round. Obviously not practical for most people but something to think about.

 

[JDMase]

I've seen a few systems that use relatively cheap geothermal. One guy buried a piece of ducting 9 feet down that runs 90 feet from a filtered intake in a shed all the way to his indoor garden. He as 65°f intake year round. Obviously not practical for most people but something to think about.

That's a really good point. Would that be considered a lung room? I know everestF on YouTube and Instagram has a room dedicated to pulling in air that's cool (I think his basement?)

 

[SchmoeJoe]

That's a really good point. Would that be considered a lung room? I know everestF on YouTube and Instagram has a room dedicated to pulling in air that's cool (I think his basement?)

A different sort of lung room but yeah. If you look up "growing citrus in North Dakota" you should be able find a YouTube video about a guy who uses a similar set up on his greenhouse. It might have been Nebraska.

 

[SamWE19]

Thanks for all the replies. Yeah I've factored in the total wattage and I can run 3 of these portable ac units fine along with AC but want to make sure it's efficient.

Im a bit confused with how describe it @SchmoeJoe ive drawn a little (crappy diagram) of how I imagine it do you reckon this will work?

Extra exhaust fans won't cut it tbh as today with no lights on at all and 6000m3 exhaust going and several circulation fans making it feel like a hurricane in there and I'm at 32C.

When lights go on I get a 10c raise due to radiant heat that exhaust can't pull out quick enough even at 6000m3/h.


Inline fans directly after the AC units pushing the air into the cross fitting and put the chimney?

Will the AC air be too hot and cause damage to the fans?

Cheers

 

[nevergoodenuf]

Have you factored in multiple/large dehumidifier? This is a must in a sealed room and will produce a lot more heat.

 

[SamWE19]

Have you factored in multiple/large dehumidifier? This is a must in a sealed room and will produce a lot more heat.

Total btu output of my room is currently 24000 not including dehumidifier as I'm not sure if I'll actually need one as at the moment I constantly have a humidity of 15-20% in my room I'm hoping I can get it to 60-70% by going sealed. But good point if I do need a humidifier I hope that 36000 btu of AC will have enough spare btu for it.

I am unsure what kind of dehumidifier to get tho, would a 20 litres be day dehumidifier be big enough?

 

[JDMase]

Don't air con units have dehumidifiers built in?

 

[SamWE19]

Don't air con units have dehumidifiers built in?

Yeah they remove humidity but can't remove a certain amount or work when there's no heat so on lights off they are no good

 

[SchmoeJoe]

Don't air con units have dehumidifiers built in?

Even without the built in dehumidifier they still dry the air. Maybe not enough to keep up with the plants transpiration and the moisture from the co2 generator though.

 

[SamWE19]

Even without the built in dehumidifier they still dry the air. Maybe not enough to keep up with the plants transpiration and the moisture from the co2 generator though.

Do you think my idea to put them all together and use booster fans will work? I'm concerned the air temps will be so hot that the fan will be damaged/ stop working?

 

[TintEastwood]

Fun project, I only wish I had a huge attic!

If I were in your shoes.....a couple ideas.
1. Bottled Co2 - 20lb tank
2. Build my grow box in the attic from 4x8 rigid foam sheets. (attic is lung room)
3. Miniumum dehumidifier 33litre/70pint. You will need it.

With the above, you could possibly mount a window shaker AC unit to the rigid box. Just have to direct the AC in/out airflow from attic.

Just food for thought, best wishes.

Example grow/dry box in a 2 car garage.

 

[SchmoeJoe]

Do you think my idea to put them all together and use booster fans will work? I'm concerned the air temps will be so hot that the fan will be damaged/ stop working?

This is the cleanest and most efficient way out. The straight lines with offset t's is the most efficient ductwork for it and spreading the AC's out will give better coverage. With this lay out you'll only need one booster fan.

Use ridgid ducting not flexible. Insulate it to make sure it's not radiating the heat that it's meant to be carrying out of the room back into it. Make sure your fan is rated for the heat that it will be handling and it'll be fine.
I've edited and deleted and reposted this a few times. This is the final draft, I swear.

 

[SamWE19]

Fun project, I only wish I had a huge attic!

If I were in your shoes.....a couple ideas.
1. Bottled Co2 - 20lb tank
2. Build my grow box in the attic from 4x8 rigid foam sheets. (attic is lung room)
3. Miniumum dehumidifier 33litre/70pint. You will need it.

With the above, you could possibly mount a window shaker AC unit to the rigid box. Just have to direct the AC in/out airflow from attic.

Just food for thought, best wishes.

Example grow/dry box in a 2 car garage.
View attachment 4156876

View attachment 4156877

No way I can use a co2 tank for the size of the room I'd have to get a refill daily and there's no local place

 

[SamWE19]

This is the cleanest and most efficient way out. The straight lines with offset t's is the most efficient ductwork for it and spreading the AC's out will give better coverage. With this lay out you'll only need one booster fan.

Use ridgid ducting not flexible. Insulate it to make sure it's not radiating the heat that it's meant to be carrying out of the room back into it. Make sure your fan is rated for the heat that it will be handling and it'll be fine.
I've edited and deleted and reposted this a few times. This is the final draft, I swear. View attachment 4156883

Nice idea my only issue is the shape of the room I can't do it like that

Due to the nature of the loft and the shape and size I only have one area to intake from and one to exhaust being the chimney stack.

Layout below:

I could have them all in a row but there would need to be two elblows in order for it to reach the chimney otherwise I'd need flexible house

 

[SchmoeJoe]

Nice idea my only issue is the shape of the room I can't do it like that

Due to the nature of the loft and the shape and size I only have one area to intake from and one to exhaust being the chimney stack.

Layout below:

I could have them all in a row but there would need to be two elblows in order for it to reach the chimney otherwise I'd need flexible house

Put a 90° on the intake flange with the AC's on that wall. A 90° at the corner and the chimney.