JSheeze
Well-Known Member
Because its too late to add this data set to the existing post (and it seems they limit length, 10,000 characters) ill try to add like this...First off this really is extrapolating because I don't know all the variables and typically you'd try to control for one variable at a time.
One could say that the PPFD is the same between both lights and so it just requires 170 more watts to create that PPFD for the HPS compared to the LED and that this extra 170 watts is released as heat immediately, buuuut I won't cop out, ill go down the rabbit hole all the way with ya.
First off, I'm not sure if these were done side by side, at the same time, or at different times. If they were at the same time they will be interacting with each other throwing results off. We'd not know how much of the heat was flowing to the room by each tent respectively. This effects inside tent temps because a lower overall outside means inside heat flows out easier, or inside temps would be cooler. If outside air is heated by both sources we'd not know who to blame. I'd also like to know the temps outside the room as well as inside the room and inside the tent. These temps all matter as heat flows to colder environments.
Secondly, are the ballast and/or drivers mounted inside or out?
I assumed a few things.
1. They were conducted at different times. (Extrapolting back the clock vs temp on the vid it looks like the HPS started out in a colder room than the LED, this starting temp difference between the lights can be a possibility of a few things, being in different rooms, or conducted at different times, or convection currents and temp gradients in diff areas of the room but being conducted at the same time in the same room. I chose same room, same area of room, but at different times, too minimize variables, although I have no clue)
2. The outside temp of the room was the same in both runs.
Ok now my process...
The vid shows 2 temp gauges with running clocks but they aren't at the same speed. Also the video doesn't start the LED clock till 4ish min (so fast hard to tell) but you can't read the data till later anyways due to a black LCD screen. Because of this I started plotting my data points at 10min. I then took readings at 30min and 60min. This resulted in recording one 20min section (30min minus 10min), and one 30min section (60min minus 30min), and one 50min section (60min minus 10min).
Results:
LED inside tent temp rose 1.5° in the first 20min
HPS inside tent temp rose 6.9° in the first 20min
HPS increased inside tent temperatures 460% more than LED in the first 20min.
LED outside temp rose 0.1° in the first 20min.
HPS outside temp rose 0.8° in the first 20min.
HPS increased outside temps 800% more than LED in the first 20min.
LED inside tent temp rose 5.1° in 50min.
HPS inside tent temp rose 9.0° in 50min.
HPS increased inside tent temps 176% more than LED in 50min.
LED outside temp rose 0.2° in 50min.
HPS outside temp rose 1.2° in 50min.
HPS increased outside temp 600% more than LED in 50min.
Data & Analysis:
LED - HPS 10min...
View attachment 4232379 View attachment 4232380
LED - HPS 30min...
View attachment 4232381 View attachment 4232382
LED - HPS 60min...
View attachment 4232383 View attachment 4232384
Data points, delta's, plotted...
View attachment 4232385 View attachment 4232386
If you look at the graph you can see how the outside temps change rate at a more uniform rate. This is where I extrapolated the starting temps to be different. Each square of graph paper along the x-axis is 2.5min so 4squares left of the XY intersection is where you'd see the starting temps.
Lets assume the starting temps of 26.5° for the LED and lets say 26.0° for the HPS.
This results in a 6.0° delta T over 60min for the LED. And a 11.3° delta T over 60min for the HPS.
Not using trajectory to extrapolate starting temps and only using given data, then the LED is shown having a 5.1° delta T over 50min compared to a 9.0° delta T over 50min for the HPS.
Conclusion
We notice the different rates these lights heat up the inside tent and outside room.
We notice the HPS reaching an event horizon of internal temp as time progresses. We notice it builds up the internal temp quickly all the while increasing the outside temp more than the LED.
We notice the LED gradually and uniformly increasing inside tent temps and uniformly increasing outside temps but much less compared to the HPS. Also at much different rates. The final temps were less as well.
At the end of an hour both inside tent temps have increased but they have not reached the same temp. Both outside temps have increased but they have not reached the same temp. The HPS has reached its event horizon and increases outside temp faster (which will slow heat transfer over time from tent to room because the gradient will be less) while the LED has not reached an event horizon in temp inc and the resulting room temps rates are completely uniform and less.
Even when factoring the increase in wattage the HPS had over that of the LED, the rates and/or data still aren't satisfied by everyone's 1000w = 1000w when it comes to heat. ALL HPS DATA ARE INCREASED BY MORE THAN 148% or 1.48 (640w/430w).
60min delta I LED = 6.0°
60min delta I HPS = 11.3°
60min delta O LED = 0.2°
60min delta O HPS = 1.6°
50min delta I LED = 5.1°
50min delta I HPS = 9.0°
50min delta O LED = 0.2°
50min delta O HPS = 1.2°
If you convect your heat away, your going to have to start worrying about room temps much quicker with HPS than LED. These were enclosed tents. If convected the outside room is going to keep up with the heat production much easier with the LED than the HPS. Rates matter. Not closed systems. Even if they eventually level out their inside temps to be relatively close (we didn't convect heat away) the outside temp will be hotter with the HPS than LED, and it will get hotter quicker. And then it will need ducting. See how the rate at which something is heated matters? If they were closed systems itd be different but the fact that it's open means that the grow room walls and/or tent walls transmit heat at a certain rate inherently and thus the rate the you supply it with heat matters when looking at the temp inc over time.
The same reason we use big propane heaters to heat our houses instead of little heaters. If we used 100w little heaters for 10hrs the house would expel the heat as fast as it was being produced and you wouldn't really notice a temp change. If we used 1000w heater for an hr the same amount of work is done but at a different rate and thus the temp difference is noticed. You're right in saying that lights are pretty much crappy inefficient space heaters, the difference is, is that LEDs are crappier space heaters than HPS because they convert less of their initial energy into heat.
If the rooms were absolute barriers then yes I would say that over time 1000w LED will produce just as much heat as 1000w HPS, but as we clearly see these are not closed systems and HPS will heat up a room faster than LED.
A better expirement would have been equal wattage HPS vs equal wattage LED. Then plot internal tent temp and room temp increase over time. Also stating some initial conditions would have been nice. Ie how the experiment was set up.
Now there's a novel... Lol time to kill some brain cells haha
Liberty haze highly recommend...
View attachment 4232397
Oh and where do all the photons go? They get absorbed by anything that won't reflect them. Light reaches equilibrium fast, at the speed of light, it disperses its energy over a large area, it fills the room fast, and don't forget the inverse square law of light, the density decreases with distance. At the rate light is transformed into thermal over the vast area it absorbs into and at the density its finally realized at having when it gets to the wall or wherever its finally absorbed the possible temp increase is negligible compared to the operating temps of the lightbulbs and tech insid
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