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The Royal Institution 9 Jun 2026 40 here now

How do you heat a home with cold air? The physics of heat pumps

Heating a home with cold air sounds like it breaks the laws of physics. Actually, it uses them.

Air source heat pumps can be up to 5× more efficient than a gas boiler... and the secret is 200-year-ol

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These comments are hilarious - it's like being back on facebook! Is that still going?!?
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Basically an advert, but it's educational on the basics of heat pumps.

For people who struggle grasping the concept of a coefficient of performance that exceeds 100%, I've found it helpful to think of it in terms of using energy to move something else that has energy, for example, a petrol pump that runs on petrol. The pump moves a lot more petrol than it burns. A heat pump works the same way, except it uses a little energy in electricity to move a lot of heat energy out of the air.
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This is not a complete explanation of why heat pumps are able to move more energy than the amount of work put in with electricity

The reason is that the amount of work done in raising the fluid temperature is proportional to the absolute temperature of the system, not its relative temp.
So raising the fluid temp by 30C is equivalent to a 10% increase in absolute temp and so the amount of work done by that fluid is much less than the input work done by the electrical driven compressor and
thermodynamics is complied with

We live in a relative temp space so a relatively small increase in temp is all that we need
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@oldcowbb From YouTube ↗ 21 Jun 2026 4
a bunch of weirdos in the comment section
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As a plumber get one of these if you're wealthy
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In North Texas, the real question is, "How do you cool a home with hot air?"
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@skillbuilder Roger, this is a good short video
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How do you heat a home with cold air? The same way you chill a home with hot air, just in the opposite direction
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@jjspr From YouTube ↗ 21 Jun 2026 1
Yes, a HP transports „heat“ e outside into the house - as you said, Independent of who is living there, its, physics - likewise the heat goes straight through the chimney if the house is not well isolated. Your electricity provider will love you
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What do you guys think of the high temperature Heat pumps for retrofitting on older houses?
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@tlhIngan From YouTube ↗ 21 Jun 2026 1
Ground-source heat pumps are also known as "geothermal" systems. Very expensive to install retrofit. But the video does fail to mention the other benefit - it's an air conditioner, so you get heat in the winter, and cool in the summer. Something to think about since a normal air conditioner is 95% of a heatpump (it is technically a heat pump, just not a reversible one).
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Great content and undoubtedly the way forward. We should always call them 'electric' heat pumps, because the gas is compressed by electricity. Being old I walk around my area where I live quite often, it's amazing how often when a property is sold the heat pump disappears and a boiler flue appears. Load of used ones on E-bay too. Are they not being spec'ed and installed very well I do wonder?
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This is the same principle that AC units, dehumidifiers and fridge freezers work on
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Thank you.
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@fsphil From YouTube ↗ 21 Jun 2026 4
It's a fantastic technology and it's definitely how most of us will be heating our homes in the future,
but I expect the high price of electricity in the UK will hold it back for quite some time.
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@toni4729 From YouTube ↗ 21 Jun 2026 2
I can imagine eyebrows raising when someone first mentioned refridgeration.
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@Bugside From YouTube ↗ 21 Jun 2026 10
It's like an AC mounted backwards, you have the cold part outside and the hot part inside
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In physics, everything above absolute zero (−273.15 C contains thermal energy.
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🔫Technology Connections sends his regards.
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Would you switch your system to a heat pump?