Building a water cooled LED light

[Paul B]

I just soldered the wire management system on the water cooled fixture. It's those small copper rings that will support the wires around the frame. I installed about 20 of them. Next I want to clean it up, make it nice and shiny, then shoot it with some clear coat to keep it from tarnishing. The next step after that is to glue on the 72 LEDs and solder them together. I doubt I will finish this for a while because of some hand surgery this week, but I will try,

 

[Paul B]

I finished soldering the 72 LEDs on the copper and tried the thing out. I can't believe it works. I had my doubts because the terminals on the LEDs are meant for a robot to install them on a circuit board so the terminals are the size of a pin head or smaller.
Now to make the enclosure for the drivers and get a heater core.

 

[Paul B]

I decided to build my heat exchanger so I just ordered a bunch of 5/16" rigid copper tubing. I realize I could use a heater core but after seeing these things work, I don't think I will need that much cooling. I would also rather build the thing myself.

 

[Paul B]

I just got home from the hospital for some knee and hand surgery and was surprised to see my circulating pump for my water cooled fixture arrived. It is smaller than I thought. I figured I would post it before the anesthesia wears off and I start screaming. This little pump is very cool but I hope it will run continousely.
I am tryng to type with two fingers from my left hand and not having much luck

 

[Paul B]

I finished the schematic and will start wiring it.

 

[Paul B]

The control box is built and tested. The copper tubes also arrived today so I can start building the heat exchanger.

 

[reefiness]

This is so awesome looking! By any chance have you thought about diverting the heat into the tank during the winter months?

 

[Paul B]

No need to divert the heat but the heat exchanger will be under the tank so it will be diverted there anyway.

 

[Paul B]

The system is finished except for the acrylic splash guard and some bleeder valves to get the air out of the system. It is being tested on my bench to see first of all how it runs and second, how efficient the cooling system is.

Here is the heat exchanger. I still need to put it in a housing and I may build another one to connect to it depending on how much cooling I need. It has been running for 15 minutes and the pipes and heat exchanger are only slightly warmer than room temperature.

 

[Paul B]

I re-designed and re built the water pressure switch and although it works better, I am still not happy with it so I can't install this fixture over my tank yet. That and I need to get a bunch of stitches out of my hand. The pump I have works good enough to circulate the water through the fixture, but it is hardly powerful enough to push the plunger all the way up in the switch so that it maintains a magnetic connection with the magnet switch to keep the LEDs energized. I need a stronger pump or a lighter plunger in the switch. There is a magnet in the plunger which weighs quite a lot and pushes back on the tiny pump a little too much. Tomorrow I will go to a LFS to get some of that cheap, thin walled plastic tubing they sell and build a much lighter plunger. If that works better, I will get the acrylic shield and find some help to aid me in getting this thing over the tank without dropping it in the water.

 

[Paul B]

Completed heat exchanger

 

[rookie07]

Paul,

This is brilliant!!
This actually blows my mind!

 

[Paul B]

Thank you. I am actually fairly proud of this, especially he heat exchanger. I am so glad I decided to build it rather than use a car heater core which would have been much heavier and over kill because I don't need that much cooling. I had the thing running for a few hours and the temp is just slightly warmer than room temperature. It was a fun build and as soon as I get the stitches out of my hand (tomorrow) and get the time to drive to the Bronx I will buy the acrylic splash guard and if I can get a little help, put this thing over my tank for the final test. I think it is cool, if not really needed.

 

[LongIslandAndy]

Nice job Paul, my only concern is that someone will break into your house to steal the copper to sell for scrap metal lol

 

[Paul B]

That is a concern, this thing is worth more in scrap than an actual light. I realize that virtually no one needs or wants a water cooled LED fixture, but I think it is extremely cool. Thank you Andy for giving me that non functional light so I could steal the parts to build this thing.

 

[crox99]

Paul,


why didn't you use PEX instead of copper?

 

[Paul B]

What is PEX?

 

[crox99]

Cross-linked polyethylene, commonly abbreviated PEX or XLPE, is a form of polyethylene with cross-links. It is formed into tubing, and is used predominantly in building services pipework systems, hydronic radiant heating and cooling systems, domestic water piping, and insulation for high tension (high voltage) electrical cables. It is also used for natural gas and offshore oil applications, chemical transportation, and transportation of sewage and slurries.
In the 21st century, PEX has become a viable alternative to polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC) or copper tubing for use as residential water pipes. PEX tubing ranges in size from imperial sizes of 1/4-inch to 4-inch, but 1/2-inch, 3/4-inch, and 1-inch are by far the most widely used.[1] Metric PEX is normally available in 16 mm, 20 mm, 25 mm, 32 mm, 40 mm, 50 mm and 63 mm sizes.

 

[Paul B]

OK, I know what it is. The problem with it is that it is useless for conducting heat and the whole design of this thing is to have a more efficient way to conduct heat away from the LEDs. Copper is about twice as efficient at conducting hear and about 3 times as expensive which is why it is not used more. The water is the means to take the heat to a place away from the fixture so it doesn't need a heavy heat sink with associated fans. This system is actually far simpler than an air cooled fixture would be and can be built much more compact which I may do if I get time.
I could put many more LEDs on this copper pipe than you could do with an aluminum heat sink, but I chose to only use 72 LEDs for this project. If instead of pipe I used a copper box with water in it, I could completely fill all the spaces with LEDs which is about twice the amount you could do with an air cooled aluminum heat sink.

 

[Paul B]

I just installed the new water cooled lights and they work perfectly. They seem brighter than my old lights and they should be because there are almost twice as many LEDs. I am running them a few inches higher than the old fixture for a day so the corals have time to put on sunscreen. So far I am very happy with it. The only complaint I have is that now the back of my tank is lit up and I don't like that. These LEDs have no lenses so the light goes all over the place. I will think of something to alleviate that.