Using Water to Heat Enclosures

bryverine

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Apr 18, 2012
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Hello,

I'm looking to heat a small, enclosed, insulated closet. As far as energy requirements, it will need to be as low as possible as it may need to be run on battery (car size) from time to time.

I'm thinking about using a 24"x4"x18" (LxWxH) or so glass enclosed area filled with DI water. By enclosed, I mean put a 'lid' on and leave a small hole with a cork to top it off or take the heater(s) out for maintenance.

Do you think this can provide a mellow, consistent heat for the tarantulas?

-The DI water should be able to maintain heat the best
-Glass is better than acrylic if I want heat to be transfered to the surrounding area (higher thermal conductivity)
-two low wattage aquarium heaters should be able to heat the water more consistently

I've looked into a couple options like heat tape, small ceramic heaters, heat mat with thermostat controllers, etc. The water/heater combo seems to be a good bet if I can seal it properly because those heaters can be pretty reliable in order to keep fish alive.

Anything I might not have thought of? Other advice relating to my heating problem?
How feasible is it to seal a glass aquarium that's only 3" deep?
 

The Snark

Dumpster Fire of the Gods
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Only thought that comes to mind is think thermal battery as a heat regulator. A dense material that absorbs and releases heat slowly like rock or concrete. Thermal batteries work great if your heat source heats the dense material which in turns releases the heat slowly into the enclosure. The peaks and low temps get evened out.
 

bryverine

Arachnoangel
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Apr 18, 2012
Messages
894
Only thought that comes to mind is think thermal battery as a heat regulator. A dense material that absorbs and releases heat slowly like rock or concrete. Thermal batteries work great if your heat source heats the dense material which in turns releases the heat slowly into the enclosure. The peaks and low temps get evened out.
That was precisely my intention! :D Turns out pure H2O is quite hard to bring up to a specific heat, but that means it also takes longer to dissipate that heat.

The heat capacity (in J/(g·C)) times density of a couple materials:
  • Concrete 0.88*2400 kg/m3=2112e3(J/m3·C)
  • Granite 0.79*2700 kg/m3=2133e3(J/m3·C)
  • Aluminum 0.90*2800 kg/m3=2520e3(J/m3·C)
  • Brass 0.38*8500 kg/m3=3230e3(J/m3·C)
  • Water 4.18*1000kg/m3=4180e3(J/m3·C)
  • Brown Rice 4.38*801kg/m3=3508e3(J/m3·C)

So next time you want a heat pad, get yourself a sock, throw in some rice, toss that puppy in the microwave, and voila!
 
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The Snark

Dumpster Fire of the Gods
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Probably the most radical thermal battery I've encountered. In the center of a 2 story heavily insulated house. A concrete column 6' x 6' standing on bedrock just below the floor level and extending up 6 feet above the roof. It had a lot of copper rods in it reaching down to the bedrock. Above the roof it was painted black, the top sliced off at a 45 degree angle facing south with solar reflectors aimed at it on the north, east and west sides. Temperature on the surface of the concrete varied from 58F at ground floor level to 88F second floor ceiling January and February with the interior of the house varying accordingly. Outside temperature during those months went from 30F to 75F. The house had R60 insulation in the walls, R90 in the ceiling. It needed no supplemental heating.
During the summer there were vents in the ceiling around the column that could be opened and vents at floor level of the first floor. The heat of the column provided enough convection to keep the house cool.
 

bryverine

Arachnoangel
Joined
Apr 18, 2012
Messages
894
Probably the most radical thermal battery I've encountered. In the center of a 2 story heavily insulated house. A concrete column 6' x 6' standing on bedrock just below the floor level and extending up 6 feet above the roof. It had a lot of copper rods in it reaching down to the bedrock. Above the roof it was painted black, the top sliced off at a 45 degree angle facing south with solar reflectors aimed at it on the north, east and west sides. Temperature on the surface of the concrete varied from 58F at ground floor level to 88F second floor ceiling January and February with the interior of the house varying accordingly. Outside temperature during those months went from 30F to 75F. The house had R60 insulation in the walls, R90 in the ceiling. It needed no supplemental heating.
During the summer there were vents in the ceiling around the column that could be opened and vents at floor level of the first floor. The heat of the column provided enough convection to keep the house cool.
R60??! :eek:

Thats at least 6" of insulation with the "good stuff". I'm looking at putting in some R5 1" thick foam (the solid, foam core type pink stuff) like so:
Side.png Front.png
 

The Snark

Dumpster Fire of the Gods
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Thats at least 6" of insulation with the "good stuff". I'm looking at putting in some R5 1" thick foam (the solid, foam core type pink stuff) like so:
6 inches. 90 is about 9. Fiberglass.
That isocyanate-polyo foam, catalytic closed cell, is extremely good. Unsure of the R but the K is very low. Less than half that of fiberglass. Often used in cryogenics.
 

viper69

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Why might you need DC current instead of AC current?
 

bryverine

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894
Why might you need DC current instead of AC current?
I plan on moving into a smaller place - specifically an RV. I'll be building my enclosures as large & small as possible into something like the images shown above. That being said, the heating element needs to be able to maintain temperature efficiently enough while not taking up tons of space or heating too hot in a single area.

While I normally should have power, as we will be stationary the majority of the time, I might be running off a generator or possibly straight from the battery occasionally. Those DC/AC converters can only provide so much power.
 
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