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Finally a New Grow Area

C

changeofpace2014

New member
We moved over a year ago and I had to demo the old tent.): - .The old tent was 4 x 5 x 6.5 ft and it was totally light and air tight with fresh air and exhaust...I never had any issue with the design, heat, smell etc..

New grow has some Serious Height issues 38" inches but I now have two 3 x 4 bays in a tent that is 8 ft long but only 38" high. This will really be a challenge and learning curve for me...In the past Nebulas manifold technique really cut the height down ( well I grew thai and it only reached about 4.5 ft).

A second light was added since there are now two bays, but this B... runs hot...The led diode fixtures run much hotter then led cobb fixtures or at least in my case. I had to add two 18" piece of angled aluminum with thermal pad all the way across both ends of the fixture (mars hydro ts2000) and it is tucked up to the floor joist.. The heat issue is with the exhaust. I only have a 200 cfm inline fan and carbon filter..I suspect the actual cfm are 130 or so because the fan is rated at 200 cfm by it self...The grow area cubic feet is around 94 so I assumed my intake box and fan, producing 44 cfm would suffice for required air exchange, in fact I added a second 44 cfm fan in a push and pull to bring more air in but the temps still run around 88 f. I cut a hole in the side as high as I could and mounted a 2x4 then mounted a Honeywell floor fan (small) now I know there is enough cool air being forced in but the temps remain... Had to crack the door to bring temp down to 85 f. Maybe this will change as the weather cools off by Dec we should be at or below freezing for the day time...

In hind sight I would tell any one planning a grow build to buy larger fan and run it at half speed...Maybe by the time the girls go into flowering I can cut this 4" inline out and put in a 6" with 400 cfm.. Seeds are still on paper towel and seed mat...The grow will be blueberry and gorilla glue lemon fire and hopefully we can pollinate or that is the plan...
 
i want to solve a similar problem before next summer. I'm looking at some sort of "greenhouse film" to put between the lights and plants. Then evacuate the heat from the top area with one fan and filter the plants with a second fan on the lower side. Just an idea at this point. Also maybe just cardboard with cutouts for the lights at the light level to separate the two areas. The heat from the driver and presumably half the heat from the LEDs might be in the upper half, again, evacuate that with a separate fan. Anyway, try to separate the heat from the plants.
 
we have a green house outside, and had to replace a panel after bad storm. I could not find any of the old green house panels, that are actually greenish but rather clear ones.. there is some kind of treatment on them, however they are still clear...

there is not much of a temp difference between 36 " and 24" maybe a degree. initially I thought the issue was with the voulme of cool air being pushed in, but after cutting a hole and adding a floor fan to force cool air in, the high temps remain..Conclusion is there needs to be much higher exhaust..there is more then enough fresh air to replace 94 cubin feet in tow minutes at most, but to bring the temps down I think it needs to be replaced every minute..

Hind sight I should of purchased a 6" in line fan and not this small 4" 200 cfm. There was never a heat issue with the old tent, maybe it has to do with the fact, the filter is tucked between the joist and over the mars hydro. I have no other option to relocate the exhaust fan..Bigger is better!!

These days we have the option to run lights and fans at half power...

Your idea is a good example of "out of the box thinking....."
 
beans have been on plate and towel for 3 days now and so far nothing....Mind you the seeds have been around for over a year...Dam the fresh beans sprout right away...Already considering ordering again..I wonder if rocket will issue a credit if they do not germinate...Doubt it as the purchase was over a year ago...
 
A few pics...
 

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What's that big duct over top of your light? It's keeping you from getting your light all the way up inside the joists. Imagine you can take over that duct. Cut it so that your light fits between. Board over between the joists on both sides of your light and put as duct can on one end of the duct to blow the top heat out of the other side. 60% of your watts are heat not light, this would keep half of that outside your tent (and give you said more inches of grow hight.
 
I have been using some pretty old beans seem good if stored in a cool area. I got them in a tupperwear box on the floor of a closet.
 
The duct over the right light is the carbon filter; the inline fan is also mounted up there..The light will not tuck in the joist area "to small". I should of purchased a 6" inline fan with 400 cfm..I will probably have to cut the old one out and replace it, before flowering..

4 days and still no germination. The seeds are over a year old but were sealed from cropking and kept in cool dry area with lots of rice and decan pack. The seeds from previous pollination are more viable.
 
Always buy bigger ( bigger fan, bigger light) etc. Today fans and lights have dimmer on them, so they can run at 1/2 power. Live and learn, but is sucks when you put a lot of work in and find out there is a issue with the design. Big difference trying to control heat in such a small area. The math to calculate air flow for optimal plant growth is out the window, because controlling heat requires way more cfms. The exhaust really needs to be expelled through the carbon filter to scrub future smells..
 
Some one mentioned the led drivers could be located out of the tent on there fixture..I will have to look at the cable length...Every degree you can take back is a plus...I was disappointing when the honey well was cut in, as I thought that would surely bring in enough cool air. It was after that attempt when I realized the issue is with exhaust being restricted in the joist.
 
Day 4 hell it might be day 5 and nothing...These beans were ordered in july 2021 but they have been stored in cool, dry environment, along with a lot of other seed stock. Sent Cropking an e-mail...O have them in chat now "we will see" honestly if I have to buy them again so be it...Dam we need some kind of seed club to trade beans...lol
 
Over the 2 year mark...but they issued a 10% off code..along with 20$ shipping..i think that is bit excessive for a dam envelope and no T-Shirt....MSNL shipped cool t-shirt...
 
It is my hope the colder winter temps in the crawl space will allow a 80 - 85 range. Plan B is to buy a 6 "in in line fan with 400+ cfm and carbon filter. I think it would tuck right in the corner with out to much obstruction. There would be to much work to cut the old one out with plants in there. In the mean time the Mars can be used in lower power to veg... Today would of been the 5th or 6th day in germination ...Flushed them this morning and watched that bill go down the toilet....Order blueberry seeds again but held off on the Gorilla Glue Lemon Fire because there are 3 beans left. Really this grow needs to bee from seed to set them up for training with Nebula 4 way method. Screen is out because we need pollen...
 
I'm still thinking about it. There's math for the CFM needed but it needs a lot of info that's not likely to be had. So maybe brute force is the answer. Wall off a much bigger area and use a big fan to spread out the heat into the bigger space... Sort of like leaving a grow tent door open to lower the temp inside. Then run the smell filter from inside the larger space... This separates the problems of heat exchange from the need for air exhaust.

I wonder how far you can take Neb's method. There's seems a point where they're allowed to grow upwards but maybe you don't have to?
 
Most of the heat is radiant and that is hardest to control with just air movement. Make sure the humidity is where it should be as a higher humidity helps considerably with controlling higher temps.
 
It's it? I've read that LEDs are maybe 30 to 40 percent efficient and I don't know if that includes driver efficiency. So I've been SWAG-ing assuming about 2/3 of the heat can be removed by conduction and convection. That was where thought of a film between the lights and plants comes from trying to separate radiant from other heat. I have not tested this idea but it's basically what I see when I look at picture of vented HPS lights.
 
Your idea might require fire retardant material...I was going to seal the top of / floor joist area with plastic, but then I quickly considered, how hot the light gets and how close it would be to the plastic...
 
90Gizmo said:
I'm still thinking about it. There's math for the CFM needed but it needs a lot of info that's not likely to be had. So maybe brute force is the answer. Wall off a much bigger area and use a big fan to spread out the heat into the bigger space... Sort of like leaving a grow tent door open to lower the temp inside. Then run the smell filter from inside the larger space... This separates the problems of heat exchange from the need for air exhaust.

I wonder how far you can take Neb's method. There's seems a point where they're allowed to grow upwards but maybe you don't have to?
Click to expand...

A larger area to absorb the heat is a good idea and it would help...but that is an after thought at this point....That is a good idea for some one with available sq ft and no means to exhaust.

I hope the winter temps bring the tent temperature down...I can regulate the temps around 80 - 85 f with door open, but I really want the tent sealed up...crawl space does have spiders, and if there are spiders there must be some measure of bugs..

Nebulas flat top technique with a 4 way is the plan...plants have to be from seed to do that...One of her post Nebula suggested you keep training and tying them down for 2 weeks into the stretch.
 
problems just help you narrow the search. I was looking at theatrical lighting film used to protect color gel cells from the heat (good for 1000 watt tungsten lamps) at first until I saw greenhouse film was much cheaper. There's always glass... so why not just run an air conditioner?
 
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