Heat Output - COB vs LED

[Randomblame]

Yeah, for C. use of course only the corresponding temp range. It shows you what humidity to use at diffenrent temps and is calculated with 2° less leaf than ambient temp in mind, like we found it with white LED's.

That table by no means that you need to go that high, so it's more a joke, isn't it?

A too high VPD would cause issues like below

 

[1212ham]

I'm having a little trouble understanding that chart. Is it telling me that if I ran 45C in the tent with 80% RH it would be okay? Seems , no?

80% RH will give a good VPD, but it would be much better to get temps. down to 30°C or so. As RB pointed out....

Nope! At night, <50% is good to aviod boitritis/bud rod but over the day there is no problem.

Also "The problem with running a high relative humidity when growing indoors it that fungal diseases can become an issue and carbon filters become less effective. It is commonly stated that above 60% RH the absorption efficiency drops and above 85% most carbon filters will stop working altogether."

Worth reading!
http://www.just4growers.com/stream/temperature-humidity-and-c02/vapor-pressure-deficit-the-hidden-force-on-your-plants.aspx

 

[cogitech]

Fans don't cool, they can at best move some hot air around.

Exhaust and intake fans, when configured even half-assed decent, do a fine job of cooling due to the fact that they are exchanging the air in the tent. Hot air out, cooler (room ambient temp) air in.

 

[OneHitDone]

its HPS's (or the suns) IR's effect on leaf temp
ideal with hps is upper 70s to low 80s air temp
ideal with LEDs is low to mid 80s air temp

leaf temp same in both cases

all light heats up leaves.
IR more so than other spectrums
LED has little to none

Can you add some clarification as to what specific nm is being referred to as "IR" in led speak?

 

[ANC]

It is at best recirculating the heat into the room. if left for an indefinite amount of time, it will reach equilibrium, after which inside and outside the tent would be the same temp. As opposed to an actual split mini AC or evaporative cooler if the air is dry enough.

 

[Randomblame]

@OneHitDone IR or infrared is the range from 700nm(looks like deepred) to 1mm wavelength(pure heatwaves). Above that you got microwaves/radar/....
Up-to 750nm plants can use for PS but it is also used for signaling. For example, it tells her if she is in the shade or if she has big neighbors. Higher IR wavelengths only increase the elongation or, for example, can also prevent the germination of seeds.
LED's are available in 740nm, 840nm and 940nm and the higher wavelength are used in cameras or night vision goggles. HPS produce a lot IR ~840nm which you can feel when you hold your hand under it.(30%)
CMH has much in the range 700-750nm and then slowly drops to ~ 800nm. This means a higher portion is useful for plant growth and for this(and other) reasons they yield better.

 

[OneHitDone]

IR or infrared is the range from 700nm(looks like deepred) to 1mm wavelength(pure heatwaves). Above that you got microwaves/radar/....
Up-to 750nm plants can use for PS but it is also used for signaling. For example, it tells her if she is in the shade or if she has big neighbors. Higher IR wavelengths only increase the elongation or, for example, can also prevent the germination of seeds.
LED's are available in 740nm, 840nm and 940nm and the higher wavelength are used in cameras or night vision goggles. HPS produce a lot IR ~840nm which you can feel when you hold your hand under it.(30%)
CMH has much in the range 700-750nm and then slowly drops to ~ 800nm. This means a higher portion is useful for plant growth and for this(and other) reasons they yield better.

Have you seen 840 being used in any led fixtures or builds?

 

[Randomblame]

Have you seen 840 being used in any led fixtures or builds?

Nope! Till today no..

 

[ANC]

It is at best recirculating the heat into the room. if left for an indefinite amount of time, it will reach equilibrium, after which inside and outside the tent would be the same temp. As opposed to an actual split mini AC or evaporative cooler if the air is dry enough. Once you add a big enough light there is no amount of fanning that would cool it.

 

[cogitech]

It is at best recirculating the heat into the room. if left for an indefinite amount of time, it will reach equilibrium, after which inside and outside the tent would be the same temp. As opposed to an actual split mini AC or evaporative cooler if the air is dry enough.

Equilibrium will only be reached if the room is sealed. Maintaining appropriate ambient room temperatures outside the tent can be as easy as leaving a window and/or door open, or using house A/C as many people already do to keep themselves comfortable. In either case, the exhaust heat from the tent can be ducted to another area.

 

[Nutria]

Equilibrium will only be reached if the room is sealed. Maintaining appropriate ambient room temperatures outside the tent can be as easy as leaving a window and/or door open, or using house A/C as many people already do to keep themselves comfortable.

Attic with no windows here
lol

 

[ANC]

Lets say you put a 1000W HID in a tent. You may be able to run your plants at the toasty side of the spectrum.
But even doubling the fan pull wouldn't make a difference to the temp. You couldn't double the amount of power by just doubling the fans.

Growboss is a dumbarse but he has a very good video illustrating this with a number of setups running next to each other.

 

[a mongo frog]

Have you seen 840 being used in any led fixtures or builds?

Your not contemplating LED over HPS?

 

[Randomblame]

Have you seen 840 being used in any led fixtures or builds?

But I could imagine a 315w CMH surrounded on all 4 sides from 2ft. double row F-strips at 1,4A's. Would certainly be for sure a bad ass kickin '550w light. Strips would increase the brightness on sides and corners and plants can use the benefits from both spectrums. That's really something I would like to see. If only I had more room I would test it myself.

 

[cogitech]

Attic with no windows here
lol

Shit dude. Attics are the hottest part of the house.

But those tent temps aren't that bad anyway, and more air flow through the tent will bring it closer to room ambient. Is there a way to force more A/C air into your attic? A ceiling vent would improve things, even a passive one. This may seem counter-intuitive, but letting the hot air out of the top of your house will actually allow A/C air to flow to the attic better, and then all that heat from the tent wouldn't put as much heat load on the A/C system. I have seen this work many times. This is assuming a slight amount of positive pressure in the house.

 

[TimBar]

I have made some cree cobs that are good for veg - but I use the HPS for flower. Much less heat with my COB setup

 

[cogitech]

Nutria,

Does the attic have both a register (delivering A/C air) and a return?

If so, you could block the return which would create positive pressure in the attic (if the door is closed). Then install a ceiling vent and the heat will flow right out.

 

[kbone123]

I am mostly okay with venting the hot air out into the apartment as long as it isn't causing my AC to kick on all day causing a huge spike in my electrical bill. The issue I have with going from from the tent to the window/outside is that it while it WOULD vent out all that hot air, it would also vent out some cold air in the process.

So which is technically more efficient; venting out hot along with air conditioned air or venting hot into the apartment and letting AC fight it?

Currently at my locale, outside is cooler than inside which makes it okay to vent everything out and leave a window open, but that will change soon making the above question a dominant one.

 

[OneHitDone]

I am mostly okay with venting the hot air out into the apartment as long as it isn't causing my AC to kick on all day causing a huge spike in my electrical bill. The issue I have with going from from the tent to the window/outside is that it while it WOULD vent out all that hot air, it would also vent out some cold air in the process.

So which is technically more efficient; venting out hot along with air conditioned air or venting hot into the apartment and letting AC fight it?

Currently at my locale, outside is cooler than inside which makes it okay to vent everything out and leave a window open, but that will change soon making the above question a dominant one.

Why not set up a dedicated outside air intake to the tent and then vent that hot air outside.
A closed loop that is independent of the air inside the apartment

 

[InTheValley]

I run 4 luminus, 200-285watts--- 78F/48RH is where they pray. Try to get to VPD as much as possible, but seems my temp/RH meter is off. So i wait for them to pray, and take note, and thats where i came up with my numbers.

leafs almost point straight up,,,,,,,,,