We're running a 400w HPS hortilux bulb and four 40w (comperable to 150w reg. light) CFL's... Size of grow room is about 7l x 4w x 8h... Grow area is separated from rest of room by blackout-plastic curtain, which is lined with mylar (as are the 3 other walls)... We are using that slinky-esque, metallic looking, dryer duct for intake and exhaust. Unfortunately, we are using desk fans to propel the air, because we can't afford four $200 fans in addition to what we've invested already. However, we've taken some steps to maximize their potential and make them fit well with the ducts. IMPORTANT---> the system i'm describing (and seen in the attatched drawing) is NOT the complete system. We intend on buying a carbon scrubber (with one of the good $200 fans built for exactly that) and incorporating that into the exhaust system we already have. I'm sure this will add extra power... but as it stands now, temperatures in the room have reached the high 80's, and sometimes low 90's. We havent planted yet, so we have time to make plenty of adjustments. Also, we are in the Northeast US, so i'm sure things will improve once the average temp. goes way down. Still, i'm hoping some of you have some original suggestions or anything that might help us in getting the temp down to managable range. Some Questions: --Does the length of the intake/exhaust tubes have any effect upon how well the air is propelled through them (if there are fans at both start and end of tube)? --If it comes down to a last resort and we have to purchase a portable AC unit, can these units have any negative effect upon the plants? -- Is our problem mostly the result of the ambient intake air being too warm, or a flaw in the system itself? If you have something helpful to say, THANK YOU!!! **PS, THE DRAWING BELOW IS AN OVERHEAD VIEW OF THE ROOM**
im running a similar scenario and at the beginning was facing some of the challenge's you are. First I tryed the whole desk fan's with cardboard duct taped to the tubing and it worked so so. Then I went with a cardboard enclosure duct taped to a A/C unit placed in the window(only covered one vent, the other vent cooled the room itself)with tubing and the power of the A/C fan was phenomenal and kept the temp in a 4lx4hx2deep at about 78 degrees' F. and that was with the light about 8 inches from the canopy. And I simply just plugged the A/C into a strip outlet that was run off a timer that additionally had the light plugged in. Another thing that is a plus for you guy's if you aren't looking to do anything mentioned above is that you mentioned a carbon scrubber with a good 200$ fan, and I'm almost positive I read that if you have a really good exhaust it will increase suction of the intake and that alone with the desk fan may cool you guy's those few degree's into the low 80's, that is of course if the room is sealed off. Just my opinion...
ohh yea I forgot, yeah the length's of the tubing kinda made a difference in how much blowing power was coming out of the end, but the air was so cold off the A/C that it didn't make a noticeable difference. Even so I just had it laying at the bottom of the room so all in all unless you plan on having your intake be a source of blowing on your plant's for stem stability the length of tubing won't really be your biggest problem to worry about
You shouldn't need a/c if you're in a temperate climate You didn't say what the ambient temperature is nor the temp where you plants are. Typically you should be able to keep your temps within 10F ...meaning if your ambient is 70F your inside grow area would be 80F. These temp differences I'm talking about are for a 1000W HPS. 1000W light generates approx 3,000btu heat, yours a lot less. Efficiency of your ducting in/out, is determined by many factors. The size of your duct, the number of bends your duct hase, the inside surface of your duct, and also of course the size/power of your blower. Lets compare your duct to a road or highway. 1. Size of duct --- width of highway, you can get more traffic through a wide highway compared to a narrow one lane road. 2. Number of bends in Duct ---- Your car can travel at higher speeds on a straight road than on a winding road. 3. Inside surface of duct ---- Your car can travel faster on a newly paved road than on a road that looks like a washboard with gravel on it. 4. Power/size of blower ---- A newer Corvette can travel faster than most 20 yr old Toyota pickup trucks. In general, the type of 'ducting' you chose is the worst possible, all those little rings that make up a flexible duct make air terribly difficult to travel through smoothly, regular 'warm air pipe' would work far better. Don't recall what size you used, but remember the bigger the highway the better. Distance the air travels is also important, so keep it as short as possible.....and if you need to make a curve or go around a corner, make them as gentle as possible. If you turn left or right on an intersection, you will have to slow down your vehicle a lot more than if you were on a road with a slight left or right bend in it. You might also consider, if you're short of funds, using the twor smaller fans to EXHAUST your warm air, and have a passive intake. Also its not a good idea to have exhaust and intake using the same window, as if conditions are right you may just suck the warm air right back into your room that was just exhausted. keylime
Get the air moving! Get your money out and go get a blower to suck that air from the window into your room.. It'll drastically change the ventilation of those little cheesy fans.. If your gonna have a HID you have to have ventilation to cool it or your gonna cook your plants.. not grow them.. eheh.. I would just get a 265 or 465 if you wanna be sure to get it real cooled off.. get an intake flange and output flange for it( or you could spend more on an inline- I don't) and hook up your ducts to it(preferebly 6"- larger the better) ..... Don't skimp on the blower.. you didn't skimp on the light.. You could probly wait on the carbon scrubber... with just a 400 canopy you'll probly be able to contain the smell mostly....
weve been reading your responses and are finding a lot of it helpful... just wanted to say thanks for helpin out and bein thorough in your explanations
Just a noob guess but if your intake and exhaust are going out the same window and mounted closed together wont the intake start sucking in your exhausted heat? Also this is a stretch and im not sure in what type of climate you live in. but if its semi humid in your area adding a substance called damprid to your intake will essentially suck the moisture out of the air cooling it. now weather this cooling effect is worth the loss in airflow that is something your thermometer is going to have to tell you but take a straw and some damprid pellets put a few in the straw and blow on your hand. You will notice the cooling effect, also this is something that you would have to change rather often depending on the humidity of the outdoor air. BTW if you live in an arrid climate this whole post is totally useless.
ahh we used to use that stuff in my old (first) grow, b/c it was in a basement.... hadn't thought of that.