[superultramega]

Originally Posted by Dankblueberries

There are a lot of factors to consider when you are sizing your ac for your grow. Outside temperature is a major factor to consider. The difference between summer and winter is huge. In the summer, my setup uses 3000 btu per 1000 watt, in the winter half of that. Humidity is a factor also. If it is dry, the ac runs less efficient. To give you an example of how I came up with 3000 btu per 1000 watt light, here is how mine is set up.

I find a large garage that I can build a smaller room inside the garage. Inside this room is where I grow. The Ac unit(s) blow cold air inside the grow room, while the back of the AC blows the hot air into the rest of the garage. This space that is in your garage, yet outside of your grow room, has a charcoal filter strapped to the ceiling, blowing the hot air either inside your living space (free heat in the winter) or outside the house/garage.(in the summer) If this garage area that the ac units are dumping their heat is small, or your exhaust filter is not getting rid of the heat fast enough, than the ac units will not work as efficiently.

I have seen a set up where someone custom built a box straight off the back of the AC, and inside this box, was a charcoal filter sucking the hot air to the outside. So no hot air from the AC ever escaped the custom box. He said the ac unit worked even better this way as it never tried to cool itself with the hot air it just blew out the back. I liked the idea.

The best of course is to have a split ac, where the condenser sits outside. If you want to run it in the winter you have to get a model that is made to run when it is freezing outside. I guess people would wonder why you have an AC running in the winter, but if you are running a legal(state law) grow, who cares. I have not used a split ac, but I will in the near future. It is the way to go if you are not worried about people wondering.

Hope this clarifies some questions.

Basically what I have done is convert a window unit to a split system. A window unit is a split system all housed in one box. I opened up the box and fabricated an air handler for the evap coil and use a separate fan wired into The fan control that runs the compressor and condenser coil fan. Most (maybe all) window units use the same motor to run both the blower fan and the condenser coil fan so doing this requires an additional fan. I found this to be a much cheaper alternative to using a small split system. Also, for my 2kw room even the smallest split system wouldn't run enough to pull the water out of the air and an additional dehum unit would be necessary. Perhaps if I remember I'll take a couple photos to show how I did this. It's a $99 window a/c unit, $20 worth of ducting and sheet metal and a $80 dayton blower. The trickiest part is dealing with the condensate (which I have plumbed to a drain) and avoiding kinking the refrigerant lines while fitting your air handler box around the evap coil.
As far as the moisture content of the air affecting efficiency, I think you wrote that backwards. It takes energy to pull the heat energy out of the water in the air to condense. They use more energy the more water in the air. The opposite effect can be seen in swamp coolers where the heat energy of the air is used to evaporate the the water which cools the air.

[Dankblueberries]

Originally Posted by superultramega

As far as the moisture content of the air affecting efficiency, I think you wrote that backwards. It takes energy to pull the heat energy out of the water in the air to condense. They use more energy the more water in the air. The opposite effect can be seen in swamp coolers where the heat energy of the air is used to evaporate the the water which cools the air.

Not so sure you are right about that. Seems logical what you are saying. All I know is that when the humidity is low, my ac units have a real hard time getting the temps to where I like them. As soon as the plants get big enough to transpire moisture in the air, the AC units work beautifully. Also, the water that is splashing around in the pan of the AC is there to help cool the condenser. If it is dry, there is no water to do this. I never use the condensate drain. I let the water stay in there, it is supposed to be there. My air conditioners run more efficient when it is humid. I can not explain the science behind it, but it is definitely true.

[PoopyTeaBags]

Originally Posted by Dankblueberries

Thanks everyone for the debate on air cooled lights. I have tried it myself only once, and found it to be a pain in the ass. I understand the concept that you can get the light closer, so more lumens on the buds, but like a previous poster said, you are making your light footprint smaller. So you are illuminating less square footage.

Has anyone tried an experiment, back to back? I would really like to know for sure what works better. Either way, I believe, getting an an air conditioner is crucial if you are running more than 4 - 1000 watts.

I have watched my friends struggle with heat problems, trying to integrate air cooled lights, plus an exhaust in the room that is always running to get rid of the heat. How do you keep your CO2 levels up if you are constantly exhausting? To me it seems like basic physics. Filter out 5% - 10% of the light, you get close to 5%-10% less results. I know you are using more electricity with an air conditioner, but I believe it pays for itself.

Maybe its hard to admit that, the sick air cooled venting system that you spent so much time putting together and spent so much money on, could have been easily replaced by an air conditioner, at half the cost and it doesn't look as cool?

If the debate is about which setup uses more electricity, AC of course. If the debate is about which one looks cooler, vented hoods! For me the debate is about yield per 1000 watt light. Keep in mind, the systems I am talking about are 6 - 1000 watts, or more. If you are just running 1-3 lights, the difference is irrelevant.

All i know is I haven't heard of anyone getting the yields i get, with vented hoods.(actually, vented or not) Maybe someone on ICMAG can beat my record? Is there a thread on maximum yields? I'll start one if not, I need some healthy competition. I am sure I'll find it here.

Keep the debate going!

I understand where your going with this but i beleive the lower light level makes up for the glass.... you take out the glass you raise the lights.... higher lights less lumens...i belive the glass works alot better as i aircooled and use a/c

[Juice_Box]

superultramega I'm interested to know what your relative humidity is?
You said an additional dehumidifier was necessary whereas DB is trying to get the humidity up, which is a constant battle in itself when RH levels are almost always below 50%

[Dankblueberries]

Originally Posted by PoopyTeaBags

I understand where your going with this but i beleive the lower light level makes up for the glass.... you take out the glass you raise the lights.... higher lights less lumens...i belive the glass works alot better as i aircooled and use a/c

One thing missing from your equation. Lower the lights, you are illuminating less square footage. You don't get more light from lowering your hoods. You get the same amount of light condensed in a smaller space. You do get less light by putting filters in front of the bulb.

[PoopyTeaBags]

i guess it would be grow room dependent... i run alot of lights and run my lights to get as close to 60-65 watts per square foot... doing thing my lights are close together and are not dependent on putting down a huge light footprint....

[superultramega]

Originally Posted by Dankblueberries

Not so sure you are right about that. Seems logical what you are saying. All I know is that when the humidity is low, my ac units have a real hard time getting the temps to where I like them. As soon as the plants get big enough to transpire moisture in the air, the AC units work beautifully. Also, the water that is splashing around in the pan of the AC is there to help cool the condenser. If it is dry, there is no water to do this. I never use the condensate drain. I let the water stay in there, it is supposed to be there. My air conditioners run more efficient when it is humid. I can not explain the science behind it, but it is definitely true.

You're seeing that effect due to the increased respiration of your plants. The plants themselves are effectively swamp coolers. If you look into increasing home efficiency one of the first steps is to properly size the cooling unit specifically due to the increased humidity that builds up with too large a system. When the system turns on it needs to expend more energy to take that water out of the air which wastes energy. A properly sized system runs often enough to keep the humidity low. It's all about keeping the peaks and troughs of the humidity cycle as low as possible.

A/C's do not need the condensate to cool. The cooling of the compressor is achieved through the condenser coil. Mine is plumbed nearly identical to a typical split system in your house. I took a length of 1 1/2" pvc pipe and attached a cap on one end and an el on the other with a FPT bushing to attach a hose directly to a sealed drain (with trap and check valve air inlet) I took the assembled pipe and ran it through a table saw to cut the top off and turn it into a trough where the evap coil sits. All the condensate is trapped in the trough and routed to a drain.

[superultramega]

Originally Posted by Juice_Box

superultramega I'm interested to know what your relative humidity is?
You said an additional dehumidifier was necessary whereas DB is trying to get the humidity up, which is a constant battle in itself when RH levels are almost always below 50%

It's right at about 50% I actually do have a dehum in the room hooked up to a humidistat, but it only tends to run late in flowering when the lights are off (and the a/c is obviously not running).
All that water you're losing from your res is coming through the plants into the air. That's a lot of water in the air! Any problems with low RH could be traced to an a/c that runs too often (too small) or ventilating with very low RH air (sucking out the moist air and replacing it with very dry air. Or both.

[Dankblueberries]

Originally Posted by superultramega

You're seeing that effect due to the increased respiration of your plants. The plants themselves are effectively swamp coolers. If you look into increasing home efficiency one of the first steps is to properly size the cooling unit specifically due to the increased humidity that builds up with too large a system. When the system turns on it needs to expend more energy to take that water out of the air which wastes energy. A properly sized system runs often enough to keep the humidity low. It's all about keeping the peaks and troughs of the humidity cycle as low as possible.

A/C's do not need the condensate to cool. The cooling of the compressor is achieved through the condenser coil. Mine is plumbed nearly identical to a typical split system in your house. I took a length of 1 1/2" pvc pipe and attached a cap on one end and an el on the other with a FPT bushing to attach a hose directly to a sealed drain (with trap and check valve air inlet) I took the assembled pipe and ran it through a table saw to cut the top off and turn it into a trough where the evap coil sits. All the condensate is trapped in the trough and routed to a drain.

That is something I never considered. The plants themselves, acting as swamp coolers. Thanks for bringing that up. I dig it.

As far as the ac's not needing the water in the pan, to cool itself, I am aware of that. It does help though. In the manual for the ac it says that is what it is there for. The pan is designed to fill with water to a certain level, so the fan splashes it up on the condenser fins. You probably already knew that though.

You bring up some interesting points about the humidity effecting efficiency. I'll have to think about that more.

[superultramega]

Originally Posted by Dankblueberries

That is something I never considered. The plants themselves, acting as swamp coolers. Thanks for bringing that up. I dig it.

As far as the ac's not needing the water in the pan, to cool itself, I am aware of that. It does help though. In the manual for the ac it says that is what it is there for. The pan is designed to fill with water to a certain level, so the fan splashes it up on the condenser fins. You probably already knew that though.

You bring up some interesting points about the humidity effecting efficiency. I'll have to think about that more.

Yeah that would certainly help as it would assist the condenser coil by adding some swamp cooling to the air cooling of the condenser coil. Mine seems to run efficiently enough as my elec usage is pennies on the dollar compared to yields. If you're in a situation where leaving that condensate is ok (not my situation) that would definitely help efficiency of your unit.