doubt about heat and air

[calibragem]

Hi
I have a room.
First question:

1- Is there any problem of the window be always closed and so the door and the only entering air is from the air conditioned? The air conditioned will be off when the lights turns off, so is there any problem about the plants receive only new air from the air conditioned and be without new air for about 6 hours or 12 hours?

2- Six High pression sodium 400w in this room, the air conditioned deals with the right temperature?

thanks

 

[dreadedhead]

You shouldnt have any real problems...i know plenty growers that their only source of fresh air is the air condioner....good luck and happy growin..

 

[dankdeezz]

With a sealed room, I believe, you will need to inject Co2 into the room. Otherwise, your plants will exhaust the supply quickly, when they are larger. Sealed rooms are perfect for co2 enrichment. Goodluck...

 

[dreadedhead]

With a sealed room, I believe, you will need to inject Co2 into the room. Otherwise, your plants will exhaust the supply quickly, when they are larger. Sealed rooms are perfect for co2 enrichment. Goodluck...

I would say the size of the room is the difference if you need co2 or not

 

[dankdeezz]

I'm unsure of the context of your last post, how is the size of the room going to make any difference? Either way, Co2 will be exhausted if the room is sealed, with no fresh air and no Co2 enrichment. Please correct me if I have the wrong end of the stick.

 

[Tony Aroma]

Doesn't the air conditioner (window unit?) suck in air from outside? If not, can't you set it so it DOESN'T recirculate?

As far as turning the AC off, it's not optimal but is not a big deal. I only have my exhaust fan running when the lights are on for most of the grow. When the lights are off, there's only a small fan on circulating air within the cabinet. However, toward the end of flowering I leave the exhaust on 24/7 to control the odor (the exhaust has the carbon filter attached).

 

[dankdeezz]

Even on vent mode, only a small amount of external air is added, is it not? I use a sealed room with air con (recirculate mode) and co2 and it's the bomb. Just trying to resolve the matter for the original post. I also have exhaust fans and inlet fan both with carbon filters, one to stop insects entering and the extractor for smell, but I don't use them as such, extractor comes on briefly after co2 is used up, then the process begins again... ( I also use ladies tights for double insect security!) Anyway, I'm digressing!

 

[Hempstress]

What do you plan to do for exhaust. You cannot just push air into a sealed room without some kind of exhaust. You need to exhaust CO2 depleted air and bring in fresh air. Ventilation works better when you have a fan pulling air from the room creating negative pressure. Plants need a continual supply of fresh air all the time the lights are on for proper photosynthesis.

 

[NiteTiger]

If you are running a true sealed room, you'll need CO2 injection.

But, if you're using a window a/c in an actual window, you're not running a true sealed room, so we'll analyze from a non-sealed perspective.

Size matters on these questions, because it effects the air exchange rate. This determines how effective your cooling and ventilation is going to be.

If your in a tiny space, like a cab/pod, exhausting by drawing room air through a cool tube, you'll have massive air exhange rates. This will require large passive intakes, or an active intake. Using passive intakes at least twice the size of the exhaust is the generally preferred method, as it's easier to manage your cooling needs versus air exchange.

These massive air exchange rates are often preferred by new growers, as it can provide effective temperature control and ventilation in one simple solution. This is also the reason it is often advised by many older growers. This has led to a mentality of "you can never have too much ventilation", which is not quite accurate.

When you add a second process to your cooling equation, like air conditioning, things change quite a bit. You've added an addional intake to your room as well as another heat source to your environment. You've also, obviously, added a cooling source, but effectively using that source changes your air exchange equation. Oh, and don't forget, you've added a dehumidifying aspect to the mix too. Those issues all have to be addressed.

First, you've added an intake, which is not necessariy a bad thing, but that also means you've added a potential security issue. Power outage? Hope you didn't stick that window a/c in a window that faces your nosy neighhbor's driveway This also shows why a window a/c in a window makes for an unsealed room - neg pressure in your room will actively draw in outside air through the a/c. (Side note: Another reason you don't see a/c's used in true sealed rooms is because you actually want higher temps in a sealed room. Higher temps causes the plant to respirate faster, allowing the higher CO2 concentration to be more effective in promoting more growth. Sealed room+CO2 injection+Higher temps = win! Also = expensive)

The heat source issue comes into play when your intake air is drawn from the same area your window a/c is dumping into. An example would be a pod/closet/storage room inside a garage. If your window a/c is dumping to the garage, and your intakes are drawing from the garage, you end up heating your intake source, seriously diminishing any cooling efforts from that point on. This is also a problem with exhaust from room/light ventilation. Watch the new cab and especially new closet growers to see this in action. They've got their air exchange cranked up to ten times a minute, and still struggle with temp issues. Why? Because all the heat they're pulling out is dumping into the bedroom from one side of the closet, then being sucked right back in by the intake on the other end of the closet. It's an issue with any doubly enclosed room.

Remember, with max airflow method, your grow will never be cooler than the intake air.

As to cooling effect changing air flow, it is often over-looked. People take their max airflow rooms, add an a/c, and don't understand why they only see a few degree, if any, difference. Why? Because by changing the air multiple times a minute, you're sucking out the cooled air faster than it can do any real good. The cooling power is there, it's just working at pitiful effeciency. The simple solution? Speed control your exhaust fan. Simple and effective. Cheap too.

You can also do what I did once, and design and build a custom ventilation system, with dampers on all intakes. It worked great, but what a pain in the ass to build and adjust! Adjust one intake, gotta re-tweak them all. :-/ Next build, I used a speed control on the fan, and kicked myself in the ass everyday after. Tryin' to save you the ass-kicking step

To the dehydrating factor, it will really only be an issue in the winter when the RH (relative humidity) drops overall (cold air can't hold as much water). Then, in an a/c'ed room, veg especially, you can see steep RH problems, like an RH of 20%. Humidifiers are cheap and widely available in almost all supermarkets and drug stores, so an easy fix. Well, as long as you're not swapping your humidified air out 10 times a minute

Room size changes all this, because it effects your air exchange rates.

Also, now you know why max-air is often used by and recommend to new growers- simplicty. A dis-service in the long run, perhaps, but on a first grow, simplify everything you can. You'll have plenty of other more important things to be worried about

Lots of info to dump on you, but lacking specific info, I gotta give the most general response.

Quick end note on max-airflow, it can reduce the effeciency of your carbon scrubber, resulting in an infrquent, but real, security issue. Thats a topic for another post, though. Suffice it to say you can overload your carbon scrubber with airflow.

Hope this helped!