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Water Cooling LED's Discussion Thread

Douglas.Curtis

Autistic Diplomat in Training
I see water cooling as a direction to go with LEDs. (Edit: At least on a small scale so far) There are a number of advantages I can see right away.


  • Removal of light generated heat from the grow space
  • Minimal head space requirements
  • Central pump instead of multiple fans
  • Tiny space required vs. very large heat sinks
  • Relatively inexpensive to keep a reservoir below 158F/70C
  • Water cooling blocks are less expensive than heat sinks/fans

I can also see a number of disadvantages right away.


  • Water + Electricity = Bad! Extra work required to ensure safety
  • Leaks
  • Pump failure (though the Ming & Ben ships have thermal shutdown circuits, a lot do not)
  • Did I mention leaks? lol The pressures won't be massive, but they'll be enough
  • Hose added to Cord issue when raising/lowering lights

My first project is to build at least a 100w cabinet with 2 50w, water cooled, LEDs. Eventually I want 2-3 of these cabs running off the same reservoir, pump and radiator. :)


QUESTION: Any idea if an aluminum cooling block needs to be larger than the chip size? I have an 80mmx40mm LED base and can get an 80mmx41mm water cooled CPU block. Will this be enough for most applications, or will it really depend on the temp of the water being circulated? :)

Edit: What Useful Things Can Be Done With The Heated Water?
Depending on the temperature, this heated water can be used to heat something else. My first thought was an active heating system for soil pots. I flower at 68F and low humidity, which does not work so well for microbes in soil.
 

Lost in a SOG

GrassSnakeGenetics
Naww cute little coolers..

It will hugely depend on base water temp and whether you're using a water cooler and the flow..

My instinct with cooling is to go bigger if possible and sane.. but then i might try both as well :dunno:
 

Lost in a SOG

GrassSnakeGenetics
One option for anyone growing somewhere super warm might be 60 x 60 x 25mm ones running on this aquarium cooler..

https://www.amazon.co.uk/gp/aw/d/B07HYS7Q1X/ref=psdcmw_949408031_t2_B07HYTV2WR

https://www.amazon.co.uk/Akozon-Thermostat-Temperature-Refrigeration-Compressor/dp/B07FKQZVGH

Anyone doing this id advise testing the sinks first and so long as there is no leaking besides the junctions then getting some silicone sealant and puttng it all around the join before heatshrinking over the whole thing for a super OTT water tight seal.. how do they donthis with computers?

You will also have to glue the chip down as it cant be mounted with screws lol.. a thermal pad underneath or thermal grease and a few blobs of glue.. you can get metallic thermal glue as well.. but it shouldnt need to be a special super tolerance glue as you might be able to get the chips into the 70s with a cooler..

Admittedely the cooler is 70w at full wack which is a cob and a half of energy but it might mean someone can get more power and lifetime out of them at the same time :dunno:

Its an interesting concept ill give you that.. ive thought about water cooling a few times but had not thought about those little water sinks..
 
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Douglas.Curtis

Autistic Diplomat in Training
Been wanting to try this myself.
I suddenly realized it had become inexpensive enough to qualify as a low budget project. :woohoo:



Naww cute little coolers..

It will hugely depend on base water temp and whether you're using a water cooler and the flow..

My instinct with cooling is to go bigger if possible and sane.. but then i might try both as well :dunno:
Yeah, this was my thought as well. The higher the temp, the higher quality, or larger the cpu cooler would have to be. Right?

That's definitely a thicker cooler. I was thinking a bit bigger than the aquarium cooler, but I can see where this would work for some applications.


Anyone doing this id advise testing the sinks first and so long as there is no leaking besides the junctions then getting some silicone sealant and puttng it all around the join before heatshrinking over the whole thing for a super OTT water tight seal.. how do they donthis with computers?
Computers use very tight connections. I haven't priced them yet, but I was thinking of trying zip ties and tubing first. Standard fuel tubing (if I can find a size which fits) runs up to 140C, so should be fine for long term use. It also cinches rather well, I'm just not sure about the strength of the nipple.


You will also have to glue the chip down as it cant be mounted with screws lol.. a thermal pad underneath or thermal grease and a few blobs of glue.. you can get metallic thermal glue as well.. but it shouldnt need to be a special super tolerance glue as you might be able to get the chips into the 70s with a cooler..
Completely correct! Unless I find some other way to keep it mashed tight to the cooler, it's really the only option. The CPU blocks *do* have small areas you could put some screws, but the adhesive options are good enough.

I'm using a thermal adhesive paste, this stuff here. Super thin layer, let it set up overnight and you're golden. I also have some silver based epoxy, for creating a thermal/conductive connection on a more *ahem* permanent basis. lol


Admittedely the cooler is 70w at full wack which is a cob and a half of energy but it might mean someone can get more power and lifetime out of them at the same time
dunno.gif


Its an interesting concept ill give you that.. ive thought about water cooling a few times but had not thought about those little water sinks..
I was thinking a little larger, actually. Somewhere around a 5-7 gallon bucket as a reservoir to start with. It might be better to use two pumps. One to circulate through the CPU coolers, and another one to circulate through a radiator and back to the res.

My idea for a radiator was more motorcycle or transmission oil cooler type. $25 at parts stores, then maybe a large blade, slow air movement fan? Using a second pump also allows me to choose one specifically for the radiator. Yes, a second pump also means more heat. heh :)

Added a Question to the original post.
What useful thing would you like to do with the heated water before cooling it?

:tiphat:
 

Lost in a SOG

GrassSnakeGenetics
I wasnt sure what scale you were doing this on.. i thought it was a micro grow lol

Ahh zip ties is there anything they cant make better haha.. good thinking.. ive seen people use them to hold leds to things as well..

You could strengthen the nipple somehow lol..those little cooler sinks have some bad reviews around but a certain amount are bound to be duff they are chinese made.. just scanning amazons anyway but hey worth a play. Shame we cant use propane to cool the water as well in some way because i just feel gas is left out :biglaugh:

I have some great heatsinks for my cobs so maybe ill leave the water cooling concept just for now but i wish you he best of luck with this doug..
 

Ibechillin

Masochist Educator
Water cooling is more expensive and barely more efficient than air cooling when building high performance overclocked computers, I dont think the minimal increased cooling would offer any real benefit over air. I saw you mentioned water cooling could be cheaper than running heatsinks and fans, Curious to see how your build turns out DC.
 
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Drop That Sound

Well-known member
Hey my man, I'd love to pass my idea off to you and your thread. Or anyone that wants to try it before I get around to it. I think I have before somewhere on icmag land, a few years ago...

I've been wanting to to water cool some LED strips/COBs too. It doesn't have to be all that expensive, especially on a large scale, with a little bit of work.


So here's the idea:

Buy 6' sections on aluminum 2x1" square tubing for like $25 plus shipping (or smaller pre cuts that are cheap too but 6 gets you more for less) from a place like this https://www.onlinemetals.com/merchant.cfm?pid=18003&step=4&id=1268#.


Then cap the ends with another small 2x1" rectangle, by gluing, brazing?, or the best would be welding it.

Add a fitting on each end and pump water through, simple enough right?

Use a cheap heater core from the junkyard or something for the radiator, and whatever fan you can get that fits.. Or a core from a blown out AC unit or something.

PC water cooling radiators would work if ya wanna blow cash I suppose. Might be better for a smaller 1-2 COB unit. I bought one for my PC, suppose it could cool 100 watts if it can cool my processor OC'ed at 4.3 ghz :)

Any other "water cooling" parts i've seen can cost fortunes, especially pre made stuff for larger systems. I guess its not that bad,but why buy multiple water blocks when you can cut or buy the tubing any size on the cheap? Copper is what will eat you up i'm sure.

I would say 2 COBs could fit nicely on a 12-18" piece, and cool them off well! A micro system would be fun to make.

3-4 ft long blocks would be awesome, could use the tubing as the actual fixture itself, as the frame with multiple tubes next to each other in rows.

I've seen guys spend as much on fancy extrusions, just to build the frames to hang there heat-sinked air cooled COBs lol. Why not build the whole fixture out of hollow tubing with water being pumped through? Beats me!

Here's a video that shows how to make a cheap block, but I thought it would be easier to use the same glue (E-6000) he does and just cap the tubing: https://www.youtube.com/watch?v=h0nL3NIJxUU
 

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Douglas.Curtis

Autistic Diplomat in Training
Water cooling is barely efficient in computers, because they're usually cooling less than 300w. They're also doing it with very expensive equipment, so it fits in a confined PC case. :)

I flower at 68F, so any heat I'm paying to create inside the cab/tent/room, I'll be paying to cool back down. Water cooling can also allow for remote radiators, much like a mini-split A/C.

I'm still bouncing around the subject of using the waste heat for something. Heated soil for cold frames in the winter comes to mind. Colder climates, I would think about using something like in-floor heat tubing as a radiator. Keep your floor warm and your lights cool. :)

The aluminum channeling looks cool. Thanks :D Not sure about the E-6000 adhesive, I'd rather use an industrial epoxy without flex. lol Still, it represents a possibly cheaper way to approach this.

So, nobody has experience with the small aluminum CPU blocks? Looks like I'm gonna have to order one or two. lol The LEDs are less than $2.50 each, so I can afford to mess a couple up. Wondering how long it will take 2 of these 50w cobs to heat up 4 gallons of water to over 120F? hehehe
 

f-e

Well-known member
Mentor
Veteran
I have a PC cooler kit here, picked up for the job, but not used. I could be tempted to post it, if your going to use it.

Fuel line is perhaps a bit much. Silicone might be more tolerant. Cable ties are likely fine, but do lead to leaks as they don't really work at the fastening area. A lot of effort goes into hose clamping in many areas, but for us, the spring clips used in motor vehicles would offer a good 360 degree clamping force, that's both adequate and hard to get wrong. So you won't cave in a round pipe with uneven force.

I like the long rectangular tube idea. Fittings can be put in with chemical metal. It's done on fuel rails that hold 120psi (the miata duel feed mod). Using long sealed units, limits the number of hose joins, and it's on a scale like hosepipe and pond pumps. Using cooling blocks is a bit restrictive to flow. Lots of blocks, would start making pump choice a little 'louder' and pressure a little higher.


Here are a few more thoughts on the subject


I think the first one will be the most leak resistant, and offers a solution that could be marketable. Copper pipe has a common diameter of 15mm in the UK. I could drill a 15mm hole in a block of metal, then saw it in half.

The square tube idea has me thinking I could take a round tube, and flatten it where I wanted the lights. Solder on the squares of copper for the leds, and have such a thermal mass that in the event of a pump fail, it might radiate quite a bit of heat still anyway. Speaking of which, pipe lagging is common in this size, and hosepipe will go over 15mm copper, if it's a cheap hose, not well reinforced.

The hardcore solution is really all about the gasket. Its not hard to put two plates together, using thick gasket to create a channel.

As always, I prefer copper over alloy. It's nearly twice as good at conducting heat away. 400 not 200. Water though is about 0.6 and air a lot lower still.

Water being reluctant to take heat on, then reluctant to loose it, will mean radiators in the system. Refrigeration systems are likely a good source for radiators of a decent size, containing pipes of suitable dimensions.

I imagine anyone taking this on, knows all about pump placement and reservoir height.


The smart cob I pictured is 100w. You can get 300w versions as big as your hand now. Such a cob could go the the bottom of a metal box. In the box, directly over it, a ~100w heatsink. Then the box filled with water. That's the general idea anyway. The box would be copper plate, as steel is only about 45 on that conductivity scale. just 25% of the alloy plate used in the LED, which is the area a lot of work goes into. We can't be crap about this. Though I have put cobs on copper plates, to spread the heat over a bigger area, then fixed the copper plate to the steel sheet I passed the heat though. The idea being if steel was 4 times worse, I needed a contact area 4 times bigger. It works fine. But back to our box. Making it from copper and soldering it up, means it can be a perfect fit, and sealed with a lid, and have hose barbs soldered on. Making a single 300w watercooled light. Not multiples of 50w

I will sit back and await peer review. Bat in hand :biggrin:
 

Douglas.Curtis

Autistic Diplomat in Training
Excellent points f-e, thank you :D

I'll be looking up the Miata mod, it sounds like just the type of tech needed to keep things flowing. Using lengths of channeling is looking very interesting. lol The reduction in hose numbers, the lower pressure on the pump, very good points. I'll have to start with extruded aluminum, budget constraints, but I will definitely work with copper for the 'finished' piece.

Spring Clips? Oh yeah! They hold high pressures for years, at high heat. Perfect!

Refrigeration cooling coils! Much better solution than an automotive radiator designed for high airflow. Smaller diameter tubing makes higher head pressure easier as well. ;) Reservoir location becomes less important, since the liquid is easier to move around under pressure.

I love the idea of adding heat sinks in the fluid flow. Building the cooling boxes yourself allows for some interesting options. Instead of passive cooling, I would prefer thermal sensors and cut-off switches. The Ming & Ben chips have a built in thermal cut-off. Too much heat and they shut down to protect themselves. I believe the passive cooling, in case of pump failure, would mean too much resources in creating a larger water volume at the cobs. :)

Stronger cobs are for larger spaces, and those look like excellent lights. In the micro box I'm thinking, staying with 50w cobs means multiple points of light. I'm thinking Scrog to maximize efficiency in my situation. I would go SOG if you have no restrictions on plant numbers.

Completely changed my direction on a few things. Again, thank you so much, f-e. :tiphat:
 

Douglas.Curtis

Autistic Diplomat in Training
So.... no on the tiny CPU cooling blocks for me, 6 blocks is too much pressure/tubing. lol

My plan has changed to extruded rectangular tubing. Capped and fitted at each end, long enough to reach the full depth of the cab. 3 cooling bars, 6 cobs, 300w. Automotive fittings, silicone tubing, automotive spring clips to secure the lines. Will need a manifold to split the pump line to the three cooling bars.

Question: If the COB cooling loop is all aluminum parts, and the radiator cooling loop has copper parts, can I still use distilled water as the coolant? Is it still a bi-metal system if they're only sharing a res, or does contact with the same solution make it an issue? lol I really don't want to use anything but clean water, and would prefer to design this so plants won't ever get wet with the cooling solution.

Running the fittings through the top of the cab would allow sealing it from leaks. Seal the cooling channel to the top of the cab, so leaks would spill over the top and sides, not in. :) lol Yes, I'll be planning leak collection paths. lol

Another consideration is air bubbles. I'd like to design the system so it can be filled with minimal air pockets, or to take minimal time to get air pockets out of the system. An air pocket in the wrong place can easily cause a problem. I'm thinking the long channels will help reduce the pockets near the surfaces the cobs are adhered to. I'll probably want hose diameters rather close to the cooling channel diameter.

With the right sized tubing, the cobs can be clamped to them with thermal paste, no adhesive. Talk about a "shiny" lol I'm rather excited about this. hehehehe
 

Drop That Sound

Well-known member
Sounds like a good plan! If you cut off a 2" section of the rectangular tubing, you could seperate into halves buy cutting down the middle of both the 1" sides, for 2 caps. The half inch sticking out, on the top and bottom of each end, could be drilled for mounts or hangers. Save having to buy a 2" flat section. Aluminum cuts easy ive used wood chop saw with backwards blades b4. A hacksaw go's quick too, but id use a chop for the ends to keep them square as possible for caps. Suppose you could even plug it, or fill with epoxy. heck you could probably use some thin flashing or cut a beer can.

I would try to source an aluminum radiator, I worried about mixing metals in a system too. A car heater core would be over kill but cheap at the junkyard. Im sure they are online for 25% of what a copper one would cost.

Reusing the heat is a great idea, you could do without a radiator with using plastic tubing in a big loop for radiant flooring, etc.


As far as coolant, I would use 50/50 RV antifreeze. If I remember right its a different formulation than regular auto AF. I cant remember why but other people recommended it on other threads.

Cant wait to see it in action, I would be on it if I wasn't messing with air cooling screw in LED bulbs. :)
 

Douglas.Curtis

Autistic Diplomat in Training
Great suggestions, thank you :D

I'm thinking of picking up 6' sections of extruded aluminum to start with. Plenty of extra inches for capping the way you suggested. :) I've started looking for different replacement parts (cooling coils) made from aluminum.

RV antifreeze eh? I was wanting to keep the coolant pure water, but antifreeze is an option. I'm possibly mounting the cooling channels above the box, with only the cobs exposed to the interior of the box. Properly sealed, it should not matter what coolant I use as far as plants are concerned. :)

I paid for 2 heat sink/fan combos for testing, then hit the water cooling idea. :) I can already see this project will take a long time. lol The anticipation is deliciously killing me. lol
 

Douglas.Curtis

Autistic Diplomat in Training
Veeery nice :D lol Yes, were it not for a budget I would be swimming in parts to play with right now. hehehehe Nice find, thank you!
 

f-e

Well-known member
Mentor
Veteran
Be careful using large bores, such as car radiators and 2" tubes. The fluid won't flow as fast where it needs to. It will straight line down the middle. Maybe you could use 1.5" box section, if you put both flow and return spigots on the same end. Extending the flow one internally, perhaps using hose, to reach the far end. So your delivery is at the other end to the return, and the waterway is reduced from 1.5", to the tune of a hosepipe width.

Antifreeze will reduce efficiency. While water is 0.6 glycol is around 0.2 so a 50/50 mix would reduce heat transfer by 33%. The stuff advertised as summer coolant, doesn't cool the engine, it stops the water taking on so much heat, so the coolant is cooler. This seems crazy, but stops it boiling around the combustion chambers, causing pockets of steam. Anyone looking for a corrosion inhibitor, could look towards domestic heating system additives.

I think RO is essentially deionised, but half the boric acid gets through. I doubt there is much boric to begin with though. Keeping it deoxygenated is going to be more important. Maybe warm it up a bit before using it. By 40c it's so flat that dwc plants are keeling over. A furry jacket on that main transfer surface, could be worse than a summer mix of antifreeze. Some alloy cylinder heads have rotted when additives were left out. So you may have to compromise and use something.

It's not going to leak anyway :)

The only real weakness comes from using square pipe, and round hose. The Miata fuel rail is a thin square alloy pipe. Too thin to start welding reliably. So they stick a barbed spigot in the end with epoxy, and may run upwards of 100psi.
You can get bungs in any size really. Chair and table legs use sturdy plastic ones, that could silicone in place reliably. I do something similar with tank floats I just dangle in. Opening up the idea of using a nut and rubber washer to 'through fix' a hose spigot in place. Through the bung or the side of the tube.
The pic a bit like this shown above, shows an extra little plate just to thicken the piece. Enabling it to take a thread.
 
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