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Laptops contain very efficient heat pipes, which can transfer heat over long distances with extremely low thermal resistance, hundreds of times more efficiently than pure copper.

Laptop heat pipe

It seems to me that these would be very useful in the home for transfering heat from E.G. the radiator of a freezer to the outside of the house. This would be especially useful in summer time when the freezer is heating the house while the AC is trying to cool it.

But I can't find any examples of this technology being used in homes.

Question: Are there any examples of heat pipes being used in homes, either to pipe unwanted heat outside, or to distribute heat around the home? If not, why?

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    This technology is used, and one example is that it is used in a type of solar water heating system. Also it uses evaporation / condensation of a fluid which is used in some AC and refrigeration systems.
    – Solar Mike
    Jul 24, 2020 at 11:42
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    I think ALL AC and refrigeration systems use evaporation/condensation of a fluid - the working medium - to move the heat from one location to another. It's the phase change of the fluid that allows this to happen. And the same principal is at work is heat pipes. The main difference is that heat pipes are entirely passive - no moving parts.
    – SteveSh
    Jul 24, 2020 at 21:52
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    steam heating is basically heat pipes.
    – Jasen
    Jul 25, 2020 at 4:41

2 Answers 2

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Expense, complexity and serviceability are your main reasons.

In point of fact, the time you list as being "most useful" would be very unlikely to work well, as hot exterior temps requiring the use of A/C are often hotter than the coils on a freezer, so heat would not move then...the time you'd be able to really save on energy with heat pipes on a fridge is that part of the year when the heat pipe alone could cool the refrigerator or freezer from cold outside temps, rather than heating the house and then cooling the fridge/freezer inside the house. But this requires a bunch of complicated plumbing with unfamiliar constraints and simple "packaged units" that require only a power outlet, and perhaps a waterline for an icemaker tend to win in the marketplace.

If you want to get fridge/freezer heat outside and you have adequate budget, commercial units requiring a refrigeration tech to run lines between an outside compressor unit and the inside cooling unit are available. They are very rarely seen in houses due to the cost relative to a packaged unit.

The same factors affect other schemes such as using refrigeration waste heat to pre-heat water.

So, you could certainly try to apply heat pipes in your house, but that's going to require that you become comfortable designing and constructing them, or that you have so much money to hire people to do that, that the energy savings make no financial difference to you. If constructing them, you will almost certainly need a vacuum pump, and you'll need plumbing skills at the "no vacuum leaks" level.

I recommend The Tubular Thermosiphon: Variations on a Theme by GSH Lock as a good introduction to the subject if you pursue the build-your-own path. It's not too expensive as a used book.

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  • Choosing the correct fluid to match the temperatures is part of the design and enables the system to be efficient.
    – Solar Mike
    Jul 24, 2020 at 18:27
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I don't think they do what you think they do.

Heat pipes are conductors of heat. They can help move heat from a hotter place to a cooler one more efficiently, which is why they're used in laptops to help cool chips.

But they're strictly passive -- they provide no heating or cooling themselves, they're just a way to move a heat sink away from the place the heat is being generated.

That really isn't especially useful for heating or cooling houses. You still need to have a heat generator or extractor; all this would do is reduce losses between that and the room. But cost and maintenance hassle would be huge, and simply improving insulation is far more cost-efficient. (Or changing the basic heating/cooling system to something more efficient, like a heat pump. Or both.)

Speaking of heat pumps: a phase-change fluid is exactly how they carry heat between the compressor and the rooms being heated or cooled. But it's one designed to be driven rather than passive, since the purpose is to move heat "uphill" against an existing temperature gradient. (An air conditioner is essentially a self-contained heat pump that only runs in one direction and isn't as efficient.)

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  • They scale really well, actually. onlinepubs.trb.org/Onlinepubs/trr/1984/962/962-008.pdf
    – Ecnerwal
    Oct 12, 2023 at 2:56
  • Correction accepted.
    – keshlam
    Oct 12, 2023 at 2:59
  • My apologies. I thought I had made it clear in the question that I understood how heat pipes work, using words like "transfer" and "thermal resistance", but perhaps my inclusion of the word "pump" confused things. I should have said "pipe". Oct 12, 2023 at 14:39
  • So you are just asking about why they aren't used for residential heat distribution? Cost, complexity, maintainability.
    – keshlam
    Oct 12, 2023 at 14:45
  • Please elaborate. I would have thought that cost, complexity and maintainability would all be very good / better for heat pipes, since they are fairly simple, sealed devices. Indeed, they need no maintenance, and are clearly cost effective and simple enough to be used in their millions in laptops in preference to pumped water. Oct 12, 2023 at 14:57

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