This LEGO Air Conditioner Is Cooler Than Yours

What’s the coolest thing a person can build with LEGO? Well it’s gotta be an air conditioner, right? Technically, [Manoj Nathwani] built a LEGO-fied swamp cooler, but it’s been too hot in London to argue the difference.

This thoroughly modular design uses an Arduino Uno and a relay module to drive four submersible pumps. The pumps are mounted on a LEGO base and sunk into a tub filled with water and ice packs. In the middle of the water lines are lengths of copper tubing that carry it past four 120mm PC case fans to spread the coolness. It works well, it’s quiet, and it was cheap to build. Doesn’t get much cooler than that.

[Manoj] had to do a bit of clever coupling to keep the tubing transitions from leaking. All it took was a bit of electrical tape to add girth to the copper tubes, and a zip tie used as a little hose clamp.

We think the LEGO part of this build looks great. [Manoj] says they did it by the seat of their pants, and lucked out because the copper and plastic tubing both route perfectly through the space of a 1x1x1 brick.

DIY cooling can take many forms. It really just depends what kind of building blocks you have at your disposal. We’ve even seen an A/C built from a water heater.

Building A DIY Heat Pipe

Once the secret design tool for aerospace designers, the heat pipe is a common fixture now thanks to the demands of PC CPU cooling. Heat pipes can transfer lots of energy from a hot side to a cold side and is useful when you need to cool something where having a fan near the hot part isn’t feasible for some reason. Unlike active cooling, a heat pipe doesn’t require any external power or pumps, either.

[James Biggar] builds his own heat pipes using copper tubing. You can see a video of one being made, below. There’s not much to it, just a copper pipe with some water in it. However, [James] gets the water boiling to reduce the pressure in the tube before sealing it, which is an interesting trick.

One limitation of his technique is that there is no internal wick. That means the tube can only be installed vertically. If you haven’t looked at heat pipes before, most of them do have a wick. The idea is that some working fluid is in the pipe. You select that fluid so that it boils at or below the temperature you want to handle. The hot vapor rushes to the cool side of the pipe (carrying heat) where you have a large heatsink that may have a fan or active cooling system. The vapor condenses and–in this case–drops back to the bottom of the tube. However, if there is a wick, capillary action will return the fluid to the hot end of the tube.

You might think that using water as the working fluid would limit you to 100°C, but remember, [James’] technique lowers the pressure in the tube. At a lower pressure, the water will boil at a lower temperature.

We’ve seen heat pipes and wine chillers used to cool a PC before. In fact, we’ve even seen them in builds of completely fanless PCs.

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