DIY leds Discussion Thread for all your how tos and doubts and anything related

[greyfader]

How much was the yield?
I've grown 90 plants on 54 ft² under 4×600 W many times. Standard yield was 2400 g.
I switched to full LED now and have more photons available but dropping yields. This is why I feel I have to learn to grow grass all over.

they were pulling 8-10 lbs regularly with a 3 week veg in place. they used one set of ballast flip-flopping between 2 rooms with light on 12-12 both in veg and flower. they prevented flowering with a single 150 watt incandescent in the vegging room.

these were bare mogul socket bulbs hanging vertically. 3600 watts.

 

[Neferhotep]

1000 + 4×600 = 3400 ?
Anyway, 1 kg per plant is quite something. Another fine vertical grow practice.

Now redo that with LED

 

[Rgd]

leds doing well..hps doing well..

have two solacure uv/b fluros in [for science]

I should put another 300 w in

so far 900w 4ft x 10ft

 

[Neferhotep]

This is my first experiment with LED. 4 × 600 W and the last five weeks I added 6 × 100 W strips. The result was very good.
The strips are 100 W nominal so I drove them that way or slightly less. I then ordered more strips and immediately noticed that the new strips had higher light output than the ones I used once and I've been underdriving leds ever since.

The plants one week earlier:

 

[Ttystikk]

True. For my situation using super efficient LEDs that don't emit enough heat doesn't make sense. I can either use only inefficient LEDs to get temps up high enough or use super efficient LEDs plus some heating mats. Only LEDs is simpler and cheaper as I dont need to buy heat mats plus the inefficient LEDs are cheaper.

Or maybe use insulation and slow down air transfer to keep the heat where you want it.

 

[Ttystikk]

I'd like to add ambient temperature.
So PAR, infrared and ambient temp. (and infrared needs to be specified because the range is huge)
And I'd like to have 300 tents to do experiments with

I'm talking about the energy added to the facility.

Ambient temperature isn't necessarily from the lighting or other energy use.

That said, you are correct that ambient temperatures need to be taken into account.

I'm often suggesting adding insulation to help maintain optimal ambient temperatures.

 

[Neferhotep]

I'm often suggesting adding insulation

Yeah but the air throughput is immense so energy will be blown out by large fans. So while insulation is never wrong, you'll blow every inch of heat out of the room quickly, replacing warm air with cold air.
Therefore an air to air heat exchanger is the answer. But they are quite bulky and need filters that with a large throughput also are bulky.
I don't have the space for that. I would have to remove part of the wall which I can't do in this rented house.

Another idea is to not have a large extraction fan and work with CO2. But then you'll need an air drier and need power for that.

 

[Drop That Sound]

In a 1st, scientists turn light into a supersolid that flows like liquid

Scientists have turned light into a supersolid for the first time, merging properties of solids and fluids in a quantum breakthrough.

interestingengineering.com

 

[Drop That Sound]

 

[greyfader]

1000 + 4×600 = 3400 ?
Anyway, 1 kg per plant is quite something. Another fine vertical grow practice.

Now redo that with LED

duh, i get by with a little help from my friends! i can't count to 21 with my pants off!

 

[greyfader]

Yeah but the air throughput is immense so energy will be blown out by large fans. So while insulation is never wrong, you'll blow every inch of heat out of the room quickly, replacing warm air with cold air.
Therefore an air to air heat exchanger is the answer. But they are quite bulky and need filters that with a large throughput also are bulky.
I don't have the space for that. I would have to remove part of the wall which I can't do in this rented house.

Another idea is to not have a large extraction fan and work with CO2. But then you'll need an air drier and need power for that.

i'm into sealed rooms. if you have proper insulation the equipment doesn't run much.

 

[Drop That Sound]

i'm into sealed rooms. if you have proper insulation the equipment doesn't run much.

 

[Ca++]

i meant tracks on the ceiling. i should have been more specific.

This sort?

Smaller image might of been helpful. It's not for lifting an engine out.

 

[Ca++]

Yeah but the air throughput is immense so energy will be blown out by large fans. So while insulation is never wrong, you'll blow every inch of heat out of the room quickly, replacing warm air with cold air.
Therefore an air to air heat exchanger is the answer. But they are quite bulky and need filters that with a large throughput also are bulky.
I don't have the space for that. I would have to remove part of the wall which I can't do in this rented house.

Another idea is to not have a large extraction fan and work with CO2. But then you'll need an air drier and need power for that.

Heat exchanger can be a duct in a duct. Something like that insulated duct pictured, but with the stuffing pulled out, and replaced by an air jacket in inlet air.
Obviously you wouldn't actually strip duct or use such a short length. You would snake it round for a bit. A proper A2A core is like 250mm square, and maybe 25 plates. So bedroom length homemade liebig condenser should give comparable contact time. It would need the exhaust to get condense removed though. So can't be exceedingly rubbish.

It's on my to-do list, as real one's keep slipping through my fingers. A crap effort to prove function was promising though. A couple of C transfer, probably could be done in that 75cm? pictured.

 

[greyfader]

This sort?

Smaller image might of been helpful. It's not for lifting an engine out.

actually, i was thinking of aluminum channel but screw eyes and hooks would work too. we wouldn't be moving them very often.

 

[Neferhotep]

i'm into sealed rooms. if you have proper insulation the equipment doesn't run much.

In a sealed room you'll have to remove from the air every liter of water the plants have evaporated. So first you need to provide the energy to evaporate, then you need to provide the energy to condense it all A nice split air conditioner can condense but they consume quite a bit of power.

Heat exchanger can be a duct in a duct.

I've had it in the past and it worked. It was about 3 m or 10 ft long. 250 mm outer duct and 150 mm aluminium inner duct, the latter shaped as a sinus. Counter flow of course. Efficiency was some 25 % or so.
It's better than nothing but I think there are better choices, heat exchangers off the shelf.
Condensed water could probably be collected more easily. In the winter you'll need controlled inflow however to avoid freezing of the exchanger. And needed are one or two good filters.
Something like this:

 

[Ca++]

25% is good. Good to know. The 80% efficiencies possible with commercial units, might never happen anyway. The transfer rate being directly linked to the temperature differential across the surfaces. I'm not sure if there is a standard to meet, measuring them. It seems reasonable to expect the two airflows to match in volume. However these units never give a fixed performance value to compare them. From a design prospective, that makes them hard to specify.
I guess from your freezing comment, you were bringing some proper cold air in, past the warm air going out. I had actually hoped for better efficiency. I was passing 22C air over a 30C duct, and effecting both a couple of C. Best take that with a pinch of salt though. It wasn't ducted, it was just blowing the inlet air along the side of the exhaust. Warming the inlet about 2C, cooling the faster exhaust a little less.

 

[Drop That Sound]

There's a lot of variables to consider when going with energy recovery ventilation units. Whatever zone you reside in will determine whether or not you need a regular HRV, or an ERV, which is a lot more sophisticated with motorized dampers and fan controllers, etc, and also has special membranes built into the core plates to help recycle some of the humidity back into the incoming air, and also is able run thaw cycles so the core doesn't freeze up in the winter time.

Going with a proper dual crossflow core setup, you can expect more than 90% efficiency. 2 cores instead of one, in a compact package.

Lets be real though.. Most DIY or not LED growers are cultivating in grow tents or small rooms, and a simple air to air cross flow exchanger using the current intake/exhaust fans (you'll want to go active cooling instead of passive, with a fan for each air stream) that isn't even that efficient would help keep the temps inside the tent (even without extra insulation) a few degrees warmer than the rest of the room its in, without sucking all the heat generated from the light away too quickly.

 

[Drop That Sound]

I always imagined the best insulation would be none at all. Just fill all the exterior walls and roofs cavities with big flat stacked cross flow heat exchanger panels, in between every stud. All connected, with some way to mitigate all the condensation that will inevitably build up, and keep from molding up. Basically, the entire structure would be one giant breathing heat ex-changer on the outer shell, that retains almost 99% of the heat or cooling inside, while also being ventilated so good it's as if you were outside in the fresh air...

 

[Ca++]

There's a lot of variables to consider when going with energy recovery ventilation units. Whatever zone you reside in will determine whether or not you need a regular HRV, or an ERV, which is a lot more sophisticated with motorized dampers and fan controllers, etc, and also has special membranes built into the core plates to help recycle some of the humidity back into the incoming air, and also is able run thaw cycles so the core doesn't freeze up in the winter time.

Going with a proper dual crossflow core setup, you can expect more than 90% efficiency. 2 cores instead of one, in a compact package.

Lets be real though.. Most DIY or not LED growers are cultivating in grow tents or small rooms, and a simple air to air cross flow exchanger using the current intake/exhaust fans (you'll want to go active cooling instead of passive, with a fan for each air stream) that isn't even that efficient would help keep the temps inside the tent (even without extra insulation) a few degrees warmer than the rest of the room its in, without sucking all the heat generated from the light away too quickly.

Yes, a gain is a gain, and using heaters less, is full of win. Especially if it just means moving some ducting about.
My mock-up was a fan to pick up cold air coming in the door, and using a fan, duct it to the exhaust run. Some people might find this as difficult as placing a desk fan by the door, to get the cold air chucked up where it's warmer.
My tents room is about 20c at the floor, and 24c at ceiling. It's quite a gradient if not mixed up. My tents inlet socks are ducted straight up the side of the tent. Where the roof seam and a bulldog clip hold them in place.
Heat recovery can take a few forms.