I switched from T5 to LED and now my greenhouse is seeing temps as high as 110

[Glaucus]

That's crazy.
LEDS are supposed to be cooler than florescent bulbs. That's one of the whole points of switching in the first place.

They are more efficient. However, they still are not 100% efficient, of course. So they still produce heat directly.
But more importantly, even the electricity that is very efficiently converted into light rather than heat, that light still has energy.
And in your grow tent, that light isn't radiating away into the vacuum of space. It hits the wall of the grow tent, gets reflected, then hits somewhere else, then gets absorbed.
That produces the heat. So even indirectly, you are going to create heat eventually. Unless of course the plant captures that energy of that light and converts it into chemical energy.

 

[cmeg1]

One strong exhaust fan with a temperature regulated on/off will get the job done.

Thats actually a very nice idea………I am so used to running co2.I cool the room and vent air in.That way the co2 tank will last so much longer.
I cool and dehumidify the room……..and vent into the tent when humidity is higher than 60-65 RH.
It keeps my temperature around 80-86f……mostly 82-84.
If it goes over 86 or so it will also vent in for temperature and shut down co2 fill while doing so.

 

[MrFancyPlants]

I would be tempted to mount the light at the top and cut out the tent so that the back of the lights are out of the tent. Heat out light in. Then use a fan to circulate within the tent. Yours lights are 200w and I have 150w on top of a 40 Gallon aquarium, and never had a heat problem. I have a supplemental heater in the water. Way more light than T5, but those watts are your heat output.

 

[Paradox]

They are more efficient. However, they still are not 100% efficient, of course. So they still produce heat directly.
But more importantly, even the electricity that is very efficiently converted into light rather than heat, that light still has energy.
And in your grow tent, that light isn't radiating away into the vacuum of space. It hits the wall of the grow tent, gets reflected, then hits somewhere else, then gets absorbed.
That produces the heat. So even indirectly, you are going to create heat eventually. Unless of course the plant captures that energy of that light and converts it into chemical energy.

I understand they do still throw off heat but always thought they were supposed to be cooler than fluorescent tubes.

I suppose it depends on the brand and what it is intended for.

I switched to LEDs from fluorescent for my fish tanks specifically because they run cooler besides the lower electricity consumption. One of them was a reef tank which requires high intensity lighting so they better run cooler. Controlling heat in a fish tank is an important factor.

 

[penumbra]

I understand they do still throw off heat but always thought they were supposed to be cooler than fluorescent tubes.

I suppose it depends on the brand and what it is intended for.

This is why I am installing a Spider Farmer Light in my tent today. The off brand cheaper lights are all less efficient. I do have an exhaust fan so it was never a huge issue but I am done buying bargain lights.

I would be tempted to mount the light at the top and cut out the tent so that the back of the lights are out of the tent.

You could do this but you lose all control over light height adjustment. This might not be an issue for some plants but it is for others.

 

[Glaucus]

The light unit itself will be cooler. But if you have a 100 watt light, then you will eventually get 100 watts of heat. Even if you get 80 watts of photons as part of this process.
And unless this energy is able to escape the room/grow tent, it will increase the temperate by that much.

A fluorescent tube produces light when it is heated up. So you produce heat to get light. An LED is much more efficient and will turn electricity into light. But the energy is conserved.
But the energy of the light will eventually heat up the room. When you turn off a light, a room turns dark pretty quickly. So that is the rate in which light is converted into heat.

That said, an LED will produce more light at an equivalent wattage. So it should be cooler because it is lower wattage for an equivilant amount of light when compared to a traditional bulb. But if the wattage is equal, the amount they heat a room is basically the same.

 

[MrFancyPlants]

This is why I am installing a Spider Farmer Light in my tent today. The off brand cheaper lights are all less efficient. I do have an exhaust fan so it was never a huge issue but I am done buying bargain lights.

You could do this but you lose all control over light height adjustment. This might not be an issue for some plants but it is for others.

One other idea: there are multiple ports at the top of your enclosure. Separate the airflow from above and below the lights, like with a fitted piece of plexiglass. And vent the top section well. Then you can keep the humidity up in the growing section with a cpu fan circulating the air.

 

[Toshi]

Mine looks hodge-podge, but it works.

Grow Tent for Tropicals - setup guide

Setting up a grow tent can be daunting to get started. I've been pretty successful with mine for the past several years, so I thought I'd put together a quick guide on what works for me. I grow orchids, tropicals, and several 'houseplants'/kusamono successfully. I assemble it typically in...

www.bonsainut.com

One strong exhaust fan with a temperature regulated on/off will get the job done.

For temp control:

https://www.amazon.com/Inkbird-Max-...house+light+controller&qid=1632831444&sr=8-12

Outlet fan:

https://www.amazon.com/VIVOSUN-Inline-Booster-Noise-Grounded/dp/B01C82SZRM/ref=sr_1_21?dchild=1&keywords=greenhouse+fan+6"&qid=1632831500&sr=8-21

I like it! Laying the tent on its side is really clever and and the angled lights are a great idea.

 

[Toshi]

That's crazy.
LEDS are supposed to be cooler than florescent bulbs. That's one of the whole points of switching in the first place.

My train of though exactly. Prior to purchasing I did read that LEDs are not totally effective in mitigating heat given off but certainly didn't expect this.

 

[Toshi]

I would be tempted to mount the light at the top and cut out the tent so that the back of the lights are out of the tent. Heat out light in. Then use a fan to circulate within the tent. Yours lights are 200w and I have 150w on top of a 40 Gallon aquarium, and never had a heat problem. I have a supplemental heater in the water. Way more light than T5, but those watts are your heat output.

Your post in another thread was actually the inspiration for me going down this road haha

One other idea: there are multiple ports at the top of your enclosure. Separate the airflow from above and below the lights, like with a fitted piece of plexiglass. And vent the top section well. Then you can keep the humidity up in the growing section with a cpu fan circulating the air.

I do like this idea as well, have to think on it

 

[penumbra]

I don't really have a heat issue with my set up. The small fan runs 24/7, I just change the angle frequently, mostly to simulate nature. I may add another.

This exhaust set up does the job. It has a carbon filter that is not really needed for tropicals, but only for plants that are odoriferous.

My new Spider Farmer Light. I love the fact that it has a built in dimmer. It is also link-able, up to 20 lights. And the unit itself is smaller, lighter and brighter than my last two lights. Installed in 5 minutes 10 minutes ago.

All the black cords are coming out today seen in exhaust photo. They were for hanging LED corner lights that I no longer need with the new light.

 

[Toshi]

I don't really have a heat issue with my set up. The small fan runs 24/7, I just change the angle frequently, mostly to simulate nature. I may add another.
View attachment 454964
This exhaust set up does the job. It has a carbon filter that is not really needed for tropicals, but only for plants that are odoriferous.
View attachment 454965
My new Spider Farmer Light. I love the fact that it has a built in dimmer. It is also link-able, up to 20 lights. And the unit itself is smaller, lighter and brighter than my last two lights. Installed in 5 minutes 10 minutes ago.
View attachment 454966
All the black cords are coming out today seen in exhaust photo. They were for hanging LED corner lights that I no longer need with the new light.

Before going all out on a ventilation kit I'm going to try my luck with an oscillating fan the same way you have yours set up. I'm hoping that'll be enough.

 

[penumbra]

Before going all out on a ventilation kit I'm going to try my luck with an oscillating fan the same way you have yours set up. I'm hoping that'll be enough.

The little fan is a clip on for posts. I have had it quite a while but I am sure it was off Amazon.

 

[Wattsy]

Before going all out on a ventilation kit I'm going to try my luck with an oscillating fan the same way you have yours set up. I'm hoping that'll be enough.

This won’t work trust me I live in the uk so not at all hot here I was running hps lamps but never the less I could not keep temps safe without an inlet fan and an exhaust fan I also had my lamp in a cooltube so I was running 3 fans but with led 2 should be ok

 

[penumbra]

You can't compare hps with led.

 

[luvinthemountains]

This won’t work trust me I live in the uk so not at all hot here I was running hps lamps but never the less I could not keep temps safe without an inlet fan and an exhaust fan I also had my lamp in a cooltube so I was running 3 fans but with led 2 should be ok

@Toshi I think @Wattsy is right. An oscillating fan is a great idea for air circulation, which is good for your plants. But the best it can do for cooling is to thoroughly mix the air, which will generally make the air around your plants hotter by mixing in the hottest air from the top of the tent. Plus, the fan motor itself generates waste heat, which makes the problem worse - not better. You have to move hot air out of the "closed" system and replace it with cool air.

 

[penumbra]

I am assuming your tent has vents. They probably all do. If you open a bttom vent and a top vent. preferably on the opposite side, it should make a difference with a fan or two moving the air around. You could evem position the fan or fans to help bring in and exit air. I know a few people who have done this in lieu of using a large exhaust set up. I only use my tent in fall, winter and early spring, but when we had a heat wave a few years back I left the door about half zipped. Temperature dropped quite a bit but humidity very little.

 

[cbroad]

I had the same issues with heat build-up in my tent; an exhaust fan (at the minimum) is a must for a closed tent system. Unless you're running low watt lights and your tent is big, passive air flow may be enough.

I had been running a 250W hps in there before, but switched to an led last year. With the new led running at 50% power, I still had as much heat build-up as the hps... Watts are watts, doesn't matter the way of delivering them, they're still going to produce heat as a byproduct.

Also, the tent won't be any cooler inside than the outside air. It is recommended to have a "lung room," or at least a place you can condition the air before entering the tent. This wasn't feasible for my situation, so I had to build a manifold to pipe in AC from a window unit (along with an inline intake fan) and this made it just "tolerable" enough to grow plants. My situation is a loft styled house, where all of the heat goes upstairs (where my lights are set-up). There are air cooled lights out there though, but that may be too much for hobbyists.

I figured out if I need to take care of the issues correctly, then I'll also need the correct tech. Normal DIY and tinkering just wasn't going to cut it for me.

 

[penumbra]

I fully understand the comments about heat being heat, watts and such. But let me share this.
My grow tent is 32" x 32" x 64". You have seen my setup. I seldom use the exhaust vent. I always use the fan. The light I used for the past few years was 65 watt LED (actual use). The temperature inside my tent with door zipped all the way, was about 8 - 12 degrees F warmer than outside the tent. It was quite manageable with zipper door open only at bottom.
Now, the only thing different is that I am now using a 100 Watt (actual use) SF1000 Spider Farmer LED. My light levels are significantly higher, but the temperature inside the tent with zipper only on bottom is 2 1/2 degrees F warmer. It may be a little warmer this afternoon, and I will check, the light came on at 4:00 am. The humidity is 78%. Full disclosure, my basement is only 72 F this morning so even if it was a bit warmer, it would hardly make a difference. I don't use the tent in the summer because most everything is outside, except the plants in my plant propagation room.
So again, I won't argue with watts and heat and such that many consider on paper to be paramount, but from first hand observation, I have more light and less heat with my Spider Farmer light than I had with prior lighting system. To boot, the fan that runs 24/7 is apparently having very little impact. I am going to install another fan and set them up on a timer so that it is a bit closer to what nature would provide.
So I appreciate all your serious analysis of watts and heat, but it is obviously not all that cut and dry.

The secret is in the sauce.

 

[penumbra]

vvv^^^ After 12 1/2 hours, temperature is 3 1/2 degrees over room temperature and humidity is 88%.^^^vvv

2 1/2 degrees F warmer. It may be a little warmer this afternoon, and I will check, the light came on at 4:00 am