# Heating with water-cooled lights



## andyh (Jan 30, 2009)

I have a separate thread over in the Lighting forum about setting up 60 LED's on my 135g planted tank http://www.aquaticplantcentral.com/forumapc/lighting/59475-one-more-diy-led-thread.html, but I want to take a chunk of it and discuss a different topic here: using the heat generated by the 60 LED's (which will be substantial) to directly or indirectly heat the aquarium supplementing 600W of heaters.

I'm thinking that attaching the LED's to a square titanium, stainless steel or aluminum tube in my full canopy would improve the heatsink capabilities by water-cooling. The 135g tank is kept at 83 degrees for Discus and Angelfish, and the water is filtered through a central trickle system in the basement along with several 20g breeding tanks (the basement is generally 60 degrees, which causes a lot of heat loss in a trickle system). 10% of the water is replaced daily with RO water at 55 degrees also (dripped in with a water-changing system).

Has anyone ever experimented with using the heat produced by lighting to heat the tank? If so, what were your results?

I'm thinking of a closed-system (for safety of water near electrical). I could either directly use the water that passes through the pipe at the sump (direct use), or run it through a coil to transfer the heat (indirect use).

I'll post progress on this as it moves along (pictures, etc) if anyone expresses interest, but right now I'm looking for anyone's experience or experiments - especially if it involves the control/monitoring of such a system.

Please be aware that I'm not envisioning any moves of the filtration system, changes to the filtration type, changing the temperature, etc., so any posts suggesting those are wasted efforts.


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## TAB (Feb 7, 2009)

How many BTUs of heat are we talking here? 

A btu is the ammount of heat to raise 1 lb of water 1 degree. water is ~ 8 lbs per gallon. So to raise the temp of 100 gal tank 5 degrees. you would need 4000 btus. I really doubt you could get that from any LED set up.


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## andyh (Jan 30, 2009)

Obviously nobody rates the LED's in BTU's, because LED's are made for light generation and not heat generation. The LED's that I am using will be running at 3.7W each and each can heat 6-8 sq inch of aluminum heatsink to 185 degrees F if not actively cooled with fans. That's each one, and I will be using 60 of them (even more in a later phase). These are NOT the LED's that are found in Christmas lights or junk products on EBay. The heat is not minor nuisance heat. I might as well use it rather than use fans to blow it into living space only to pay again to remove it with A/C in the summer. I don't expect that I will be able to replace all of my 600W of heaters, but if I get a free reduction in electricity costs by supplementing the existing heaters, that's great!

I'll be posting my results in this thread as soon as the project goes on...


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## TAB (Feb 7, 2009)

Calculating BTUs is pretty easy. you just need to know the the specific heat of the AL heat sink is, its mass and temp change.


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## Patchworks (Dec 20, 2008)

I'm going to pay attention to this thread. It is amazing how much heat my lights produce and this all needs to be cooled in the summer. Unfortunatly, I use the heat to pretty much eliminate using the heater in the winter. 

One thing I wonder is are you going to be using the same amount in running a pump to circulate the water?

One idea I was thinking of but I'm not sure if it would work, but you might be able to have tubing that goes up to the top of the canopy and over the lights and back in to the tank. If you can heat the middle of the tube, would it cause a flow of the heated water to rise to the top which in return would form a flow pulling in new water? Does this make sense?

As I got to thinking about this topic, I came back and added to my post. For example, I have 8 ballasts mounted under my tank. I'm wondering if I setup a simple tube to go down to the ballasts and somehow transfer heat into the water, shouldn't it cause the hot water to rise and therefore produce a circulation. I think it would be be best to have you return go straight to the top of the tank before it cools. Anyway, worth some thoughts!!

It appears it is called Thermo siphoning, check out http://en.wikipedia.org/wiki/Thermosiphon

g


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## andyh (Jan 30, 2009)

As I'm prototyping with this stuff, I'm experimenting with redirecting a small amount of water from the main pump return, and also with a small, self-priming 3W pump that pumps 3.5gph and costs about $9. The decision will be made on what the temperature of the water is when it exits the aluminum heatsink if its 3.5GPH moving through it.


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## Patchworks (Dec 20, 2008)

andyh said:


> As I'm prototyping with this stuff, I'm experimenting with redirecting a small amount of water from the main pump return, and also with a small, self-priming 3W pump that pumps 3.5gph and costs about $9. The decision will be made on what the temperature of the water is when it exits the aluminum heatsink if its 3.5GPH moving through it.


What are you using for the heat eachange?

g


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## andyh (Jan 30, 2009)

See the top post, or the link to the original post. The LED stars will be directly attached to an aluminum, titanium or stainless steel square tube. Water will flow through the tube, cooling it and the LED stars. LED's work most efficiently at lower temperatures.


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## Patchworks (Dec 20, 2008)

andyh said:


> See the top post, or the link to the original post. The LED stars will be directly attached to an aluminum, titanium or stainless steel square tube. Water will flow through the tube, cooling it and the LED stars. LED's work most efficiently at lower temperatures.


Ok, you did say that... I'm stuck right now thinking of a way to get my ballasts to transfer heat. I was thinking of a few ideas, but none are any good yet.

g


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## Patchworks (Dec 20, 2008)

Ok guys, i spent some time this weekend and made my inline heater that heats from my ballasts. It also has a normal heater which would be sit lower than the ballast temp so it only works when the lights and ballasts are off at night.

g


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## andyh (Jan 30, 2009)

Any results? Did it heat noticably?


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## JERP (Feb 4, 2003)

Please connect the ballast to a GFCI outlet. That way no one gets hurt if something goes wrong.


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## Patchworks (Dec 20, 2008)

andyh said:


> Any results? Did it heat noticably?


Haven't gotten it connected to the Ballasts yet, but I don't see how it can't heat noticeably with 8 ballasts.

I'm still working on the heat transfer from the Ballasts. I'm thinking about using 1/2" Copper tubing and flatten it with a vice!

g


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## criminalhate (Mar 19, 2009)

andyh said:


> I'm thinking that attaching the LED's to a square titanium, stainless steel or aluminum tube in my full canopy would improve the heatsink capabilities by water-cooling.


Aluminum tubing would be your best beat. Aluminum has one of the better thermal conductivity then your other 2 options. Ti and Stainless are actually pretty poor conductors of heat. I believe you would definitely get a good amount of heat added to your tank this way.Plus all the heat you generate is a byproduct of what you are already doing so every little bit helps. Make sure to use thermal compound of some sort between your leds and the tubing to help conduct the heat.

Thermal conductivity
W/(m·K) 
Stainless steel 12.11 ~ 45.0 
Aluminium 200
Titanium Alloy 5.8
Titanium, pure 15.6 ~ 21.9
Silver, pure 406 ~ 429

Source: the complete table can be found at 
http://en.wikipedia.org/wiki/List_of_thermal_conductivities


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## criminalhate (Mar 19, 2009)

Patchworks said:


> Ok guys, i spent some time this weekend and made my inline heater that heats from my ballasts. It also has a normal heater which would be sit lower than the ballast temp so it only works when the lights and ballasts are off at night.
> 
> g


Have you thought about relocating the ballast below the tank so the rising heat will help heat the tank? You could still route the water to them to be heated also.


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## Patchworks (Dec 20, 2008)

criminalhate said:


> Have you thought about relocating the ballast below the tank so the rising heat will help heat the tank? You could still route the water to them to be heated also.


Yes, my stand had an open bottom to the tank and I thought about attaching the ballasts to the bottom of the tank, but I don't have a way to control the temp that way.

I'm still trying to come up with a clever way to transfer heat from the ballasts. My current idea is to flatten some cooper tubing with a vice.

g


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## criminalhate (Mar 19, 2009)

Patchworks said:


> I'm still trying to come up with a clever way to transfer heat from the ballasts. My current idea is to flatten some cooper tubing with a vice.
> 
> g


Stay away from copper because inverts tend to hate it and wind up dieing. 
I was thinking about it some after reading your idea. I would clamp on a piece of square tubing (using large hose clamps) to each ballast and run the water through them. Also you may want to add a thermal compound between the ballast and tubing. You should be able to get the tubing from a home improvement store or hobby shop, and you can get the thermal compound at an electronics shop or a real computer store (one you can buy parts to build them).

Problem with square tubing is making a water tight fit. So you may want to look into getting standard round tubing and maybe clamping a couple smaller diameter pieces to the top and / or bottom of the ballast.

Just a couple ideas to float around. Let us know how it ends up.

Also about mounting the ballasts underneath the tank. I wouldn't think they would be able to raise the temperature through the glass but a couple of degrees. I really don't think any of these idea's will replace a standard heater but act more as a supplemental heat source and use something your already making.

Edit: I would probably go with Aluminum tubing because it has the best thermal conductivity other then copper.


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## Patchworks (Dec 20, 2008)

criminalhate said:


> Stay away from copper because inverts tend to hate it and wind up dieing.


Yes, I've heard this about copper, but I don't know where to get Aluminum tubing and will it bend like cooper. I was thinking about trying to coat the copper that would be in contact with the water with that latex stuff people use to coat tool handles. That way copper would not be in contact with the water.



criminalhate said:


> I was thinking about it some after reading your idea. I would clamp on a piece of square tubing (using large hose clamps) to each ballast and run the water through them. Also you may want to add a thermal compound between the ballast and tubing. You should be able to get the tubing from a home improvement store or hobby shop, and you can get the thermal compound at an electronics shop or a real computer store (one you can buy parts to build them).
> 
> Problem with square tubing is making a water tight fit. So you may want to look into getting standard round tubing and maybe clamping a couple smaller diameter pieces to the top and / or bottom of the ballast.


Yes, I had thought about square tubing also, I could put a 2 ballasts on th tub, 1 on each side. Unfortunately, my problem is how to get a good fit on the square tubing.

g


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## criminalhate (Mar 19, 2009)

Patchworks said:


> Yes, I've heard this about copper, but I don't know where to get Aluminum tubing and will it bend like cooper. I was thinking about trying to coat the copper that would be in contact with the water with that latex stuff people use to coat tool handles. That way copper would not be in contact with the water.
> 
> Yes, I had thought about square tubing also, I could put a 2 ballasts on th tub, 1 on each side. Unfortunately, my problem is how to get a good fit on the square tubing.
> 
> g


I don't think you'll be able to get a good enough coverage inside of the copper tubing to prevent contamination. You should be able to get aluminum tubing at most big hardware stores, Hobby shops (that cater to the RC plane and model RR people) ,welding supply shops, and maybe at an auto parts store.

The only way to get a water tight fit on the square aluminum would be probably be through a welder that can TIG weld some sort of fittings to it for you.

Another thought alot of smaller tubes may actually heater better since ther would be more material touching more of the water.

A side note: I've never actually tried using copper tubing because of everyone saying it (copper) is bad for inverts but I'm kind of wondering now if it's only the copper found in meds that's bad. The reason I say this is most people in the USA have copper or galvanized (zinc coated steel) plumping and when I add water to my tanks I only treat for the chlorine in it not any thing else. I wonder if there is any good way to see if copper pipe/tubing actually leaches copper which would cause a buildup in a tank.


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## marine590622 (Dec 18, 2006)

criminalhate said:


> I don't think you'll be able to get a good enough coverage inside of the copper tubing to prevent contamination. You should be able to get aluminum tubing at most big hardware stores, Hobby shops (that cater to the RC plane and model RR people) ,welding supply shops, and maybe at an auto parts store.
> 
> The only way to get a water tight fit on the square aluminum would be probably be through a welder that can TIG weld some sort of fittings to it for you.
> 
> ...


On the copper pipes new copper will leach into the tank and cause problems. Older pipes have a layer of oxidation that prevents this. If you have copper in your plumbing and you need a repair done and they use new pipe this can cause problems for your tanks.

On connecting to the square tubing why bother. You can address this a couple of different ways.

purchase square tubing elbows and run square tubing from the intake all the way to the out let.
Probably the most expensive.

purchase square tubing end caps and barb fittings "Cap' the square tubing at both ends and install the barb fitting. This fitting would probably be ideal: 
http://www.usplastic.com/catalog/item.aspx?sku=64122&gclid=CIS_9avDw8wCFQkyaQodRNEMlw

It comes in 3/8ths 1/2inch and 3/4ths

Drill a hole that accepts the fitting on any flat surface. (place it where you can reach the inside and put the nut on the inside of the fitting) Add a gasket if testing proves it is needed and you are ready to attach hoses.


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## Yo-han (Oct 15, 2010)

I think it is safe to say that this project is either finishen or abandoned. This thread is 7 years old!


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