How to make a wharehouse grow work

[James Howlett]

If you use proper sized fans to cool your hoods... And a quality ac setup, I'd say more like 2500-3000btu per cooled 1000w light.
I've been running a 24k btu daikin cooling 8- 1000w lights in 1500cf sealed rooms for years without an issue.
Recently setup 2- 24k btu daikins with 15k watt lights sealed in a 6000cf room and can bring my temps down as low as 64 if I wanted on a 100 degree day. That's no bs. No exhaust, fully sealed.


Don't get me wrong, over kill isn't a bad thing and is ideal but no need to spend twice as much as you need if you do it right.

Use quality exhaust fans. I use a 700cfm 8" max fan cooling each row of 5. Which by most standards would be considered under powered. But I can put my face on the hood glass no problem and bring my plants within 10-12 inches without any heat issues and hold a efficient canopy temp. Lung room with steady 70 degree is the key. And air moving fans keeping even air temps throughout the canopy.

My post was referring to NON air cooled lights, ballasts in the room.

With air cooled you can absolutely run less AC, but I'd rather just oversize AC and not worry about fans and ducting.

Im just assuming anyone setting up a warehouse these days is going with DE non air cooled lights.

 

[megayields]

More like 50 g plus. That's just to start...

 

[Floridian]

I agree with the above,at least 3-4000BTU for non-cooled lights.I run 3 1K vertizontals with a 12,500 BTU with little problems but it gets close during the 2 months of the hottest past of the year.I like keeping a canopy temp of 80F as opposed to the suggested 85 F,I just feel better at 80 and like I said,it could sneak close to 85 in Aug through September.I could easily get by flowering during dark hours but that's not going to happen.One thing I learned after using a few different units is the vast majority bottom out at 65 degrees,a few will go down to 60 though and those 5 degrees can really make a difference at times.Make sure it bottoms out at 60F!

 

[queequeg152]

I dont know where youre getting that calculation from but thats just not enough.

From real world experience running sealed rooms, you want at least 5k btu per non air cooled 1000w light. I run 12 lights max off a 5ton AC. Theres no way id try to run 16+.

You always want to oversize a bit with AC, especially in a commercial space.

20tons minimum for 50kw. 25 would be better.

i got that calculation from elementary physics and ASHRAE.

it is the definition of "enough", trust me.

if you run 50kw in a perfect insulated isothermal enclosure ignoring all heat gain, and then remove a perfect 14.65k btuh temperature will remain nearly constant.

in the real world external heat gain/heat loss is always added to the internal loads though, and this is where you need to do the manual J calculation.

external heat gain changes from structure to structure, and location to location, so there is just no rule of thumb what so ever.

you should do a manual J every single time you spec hvac equipment period.

 

[Spaventa]

i got that calculation from elementary physics and ASHRAE.

it is the definition of "enough", trust me.

if you run 50kw in a perfect insulated isothermal enclosure ignoring all heat gain, and then remove a perfect 14.65k btuh temperature will remain nearly constant.

in the real world external heat gain/heat loss is always added to the internal loads though, and this is where you need to do the manual J calculation.

external heat gain changes from structure to structure, and location to location, so there is just no rule of thumb what so ever.

you should do a manual J every single time you spec hvac equipment period.

Why bother? its all still an approximation. Just HIRE aircon, - as much as it takes to run the warehouse at full tilt , then you KNOW how much you should buy. No guessing, miscalculating or buying the wrong spec. Same goes for ventilation etc.

 

[queequeg152]

hire aircon?

what do you mean, i dont understand. you mean like rent hvac equipment?

 

[Spaventa]

hire aircon?

what do you mean, i dont understand. you mean like rent hvac equipment?

I mean rent large mobile AC units to see how much you need

 

[James Howlett]

You can do all the calculations you want my friend.

I'd like to see you try to cool a 50k with 15 tons. Maybe at night in the middle of winter.

There is a rule of thumb. People have been building grow rooms for a long time and 5k btu per 1000w open light is standard. This includes all other heat loads in the room as well. No physics needed.

 

[Loc Dog]

I would like to know if he ever identified the bugs on his plants. Looks nothing like the broadmite damage I had, and have seen pictures of. They make leaves turn shiny, and the problem does not go away. I was barely able to see them with a microscope. Here is picture of crop ruined by them.

 

[Floridian]

Wow they look almost like fake wax leaves.I'd like to know what happened too.I guess broadmites are a lot smaller than southern red spidermites if you actually need a microscope to see them.The brick red bastards I used to have to deal with were crystal clear under 10x,the first time I saw them I about shit myself.My gut started burning lol that fear you get when something sudden happens.I wasn't expecting a brick red crablike creature that's for sure.Using a cool mist humidifier in veg really has kept them at bay for some time now.

 

[queequeg152]

You can do all the calculations you want my friend.

I'd like to see you try to cool a 50k with 15 tons. Maybe at night in the middle of winter.

There is a rule of thumb. People have been building grow rooms for a long time and 5k btu per 1000w open light is standard. This includes all other heat loads in the room as well. No physics needed.

lol because i claimed you could cool it with 15 tons total right?

are you being purposefully ignorant as to what i am saying or what? i dont get it.

+ external heat gain. its simple.

rules of thumb are shorthand for hack installs. period.

 

[Lazyman]

Just to be clear I am currently in a space that i am going to abandon because of broad mites. I have been told by experienced friends that they can be a nightmare and it might be easiest to just restart in a new space. Only problem with the new space vs the old one is that it is 26600 total cubic feet where as the first wharehouse was 5400 cubic feet so the air exchange is now a problem...

That's crazy. I've had mites many times, and would never give up a spot because of my own failure to spray the right thing.

Look, rotate pesticides (miticides) from different companies, that have different modes of action. Very quickly the mites will all be gone, bit you must keep up a rotation of sprays to keep them at Bay.

Use good systemics, but avoid the ones everyone uses, so no avid, or floramite.

Use forbid 4h, bifenthrin, tetrasan wdg, kontos, phantom, all are around 1ml per gallon, spray with lights and fans off, give them 6 hours to slowly dry before anything gets turned back on. Repeat every 3 weeks, until you're in week 5 of flower. Rotate sprays! It's called integrated pest management, or IPM. Look it up. Hell, pm me your email address and I'll send you my IPM spreadsheet we use

 

[Lazyman]

I would like to know if he ever identified the bugs on his plants. Looks nothing like the broadmite damage I had, and have seen pictures of. They make leaves turn shiny, and the problem does not go away. I was barely able to see them with a microscope. Here is picture of crop ruined by them.

[URL=https://www.icmag.com/ic/picture.php?albumid=51120&pictureid=1680755&thumb=1]View Image[/url]

Aside from your bug problems, you're overfeeding. See the clawing leaves and burnt tips? It's been going on for a while but you missed it. Cut your feed rate by 20% after you flush them with plain water (or at most a 10% solution of feed) for about a week.

 

[Lazyman]

i got that calculation from elementary physics and ASHRAE.

it is the definition of "enough", trust me.

if you run 50kw in a perfect insulated isothermal enclosure ignoring all heat gain, and then remove a perfect 14.65k btuh temperature will remain nearly constant.

in the real world external heat gain/heat loss is always added to the internal loads though, and this is where you need to do the manual J calculation.

external heat gain changes from structure to structure, and location to location, so there is just no rule of thumb what so ever.

you should do a manual J every single time you spec hvac equipment period.

This is correct.

Most commercial buildings have little to no insulation, so you have to account for enough cooling on the hottest weeks of the year, to the coldest.

The ceiling height will also stratify heat, leaving it much cooler at ground level than at the ceiling. It would be wise to at least plan for some powered and carbon filtered exhaust at the ceiling to reduce the work load for the ACs at ground level.

There is no formula for calculating exactly how much you'll need because there are too many huge variables. I've seen guys cool 30KW with 5 tons of cooling, and 40 miles away the same size grow needed 10.

My advice is, start small and see what it takes to cool it at 15kw, buying 5 ton ACs. It's better to have multiple smaller units than one big one anyway. The amount of cooling needed won't be linear, either. If you can easily cool 15kw with 5 tons, it may only take 8 tons to cool 30kw.

Good luck, you're on your own for trial and error.

 

[queequeg152]

This is correct.

Most commercial buildings have little to no insulation, so you have to account for enough cooling on the hottest weeks of the year, to the coldest.

The ceiling height will also stratify heat, leaving it much cooler at ground level than at the ceiling. It would be wise to at least plan for some powered and carbon filtered exhaust at the ceiling to reduce the work load for the ACs at ground level.

There is no formula for calculating exactly how much you'll need because there are too many huge variables. I've seen guys cool 30KW with 5 tons of cooling, and 40 miles away the same size grow needed 10.

My advice is, start small and see what it takes to cool it at 15kw, buying 5 ton ACs. It's better to have multiple smaller units than one big one anyway. The amount of cooling needed won't be linear, either. If you can easily cool 15kw with 5 tons, it may only take 8 tons to cool 30kw.

Good luck, you're on your own for trial and error.

this is not true. the manual J is based on like 6 decades of hvac related studies and research.

you can get very very very close to the true heat gain of any enclosure if you want to.

the problem is people dont want to... for what ever reason i cannot say.

a professional manual J is like 500 bucks. the cost of an oversized unit can be thousands and thousands of dollars over that of a properly sized unit.

commercial buildings have an insane diversity of heat gain loads and yet we can STILL calculate them by referencing all of the components individually.

a grow room is insanely simpler to calculate though. you basically have an enormous internal heat gain from the lights, fans and pumps, and a smaller heat gain from the enclosure. the enclosure heat gain is calculated by simply determining the r value of the walls and ceiling and by verifying uniformity of insulation.

window size, window elevation, window treatments like blinds solar screens bug screens etc, soffit width, exposure direction, lattitude ( solar heat gain), shingle type, shingle color, envelope leakage... and shade characteristics are all factored into any rudimentary manual J... environmental factors are also factored in based on recorded data at your local airport weather stations.

you can get to within a few percent if you do everything. 10% if you do most of it.

there is no reason what so ever to blindly "rule of thumb", or "trial and error" your hvac equipment.