Heat Pumps: the Future of Home Heating

It's so cold that it's hot.
Hey! So there have been a LOT of developments in the air-source heat pump space. A replacement for Part 2 is now live:

I referenced a lot of old videos in this one. Here they are, in clickity linkity form!
Chest Freezers; What they tell us about designing for X
Old-fashioned rice cookers are extremely clever
Reusable handwarmers that get hot by freezing
I also made passing references to
Forced-air Furnaces: The What, Why, and How
and
Portable Air Conditioners - Why you shouldn't like them

Technology Connextras (the second channel that stuff goes on sometimes):
Technology Connections on Twitter:
The TC Subreddit

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[TechnologyConnections]

Hello! Here's a comment with some extra info on efficiency and the metering devices used in heat pumps.
First: my wording on the efficiency drop in the cold was sloppy, and it sounds like I'm suggesting the need for defrosting is the only reason it loses efficiency. It is _a_ reason, but not the biggest one - that's simply that as the outdoor temperature gets colder, it's harder for the refrigerant to absorb heat because the temperature difference between it and the air gets smaller. In fact, in the clip when it was -10°, it wasn't building much frost at all because it was very dry. But that was so cold that the refrigerant could barely capture any energy, which is why its output was tepid. And to be clear, its rating down to 5° doesn't mean it operates at full efficiency at that temperature. That's just the lowest temperature that it can sustain its rated heating output.
Re: metering devices. I still somewhat suspect that the mini-split has a capillary tube and largely because of its cost. It was surprisingly inexpensive (this unit was about $1000, but the smallest units from this same manufacture only cost $750 and are fully capable heat pumps). If you use a thermal expansion valve or similar, you need one for each direction which adds to the system's complexity somewhat. I'd still argue that it hardly does - it is, after all, one or two small components of a large system. But simply reversing the refrigerant flow doesn't work on its own in systems that use these more complex metering devices. They'd need some additional piping and valve work (some such valves were visible in the demo rig) to accommodate two metering devices for each direction of flow.

[mrflamewars]

If it's not absolute zero there's some energy. Let's steal it!

[Altoclarinets]

my mother: shut the door, we ain't paying to air condition the entire neighborhood
alec: ... what if you were

[MegaBrokenstar]

This channel is basically the modern version of old school public access programming. I could totally imagine watching this on PBS at 11pm. Really cool that people still watch this type of content nowadays. Getting smarter via entertainment is an amazing use of free time.

[Frost_smitten]

HVAC tech from the EU here, I'm probably late to the party on this but just wanted to add, most mini splits with variable frequency compressors don't use capillary tubes or TXVs but electronic expansion valves for even more adjustability and efficiency and they're usually in the outdoor unit and not the indoor one which is why insulation of the copper piping from outside to inside is so important as well. Anyway, love your content, keep doing what you're doing!

[Gamecrazy]

This video is the linchpin of the Technology Connections Cinematic Universe

[LevelNoneMusic]

I remember subscribing when you were at around 150k subs, and I prayed that WHEN you hit 1 million, the videos would stay the same, and they have. This is honestly one of the best channels ever. You've taught me a lot more than anyone else could, and about things that are actually interesting. Thank you for staying true to edutainment. I honestly think you would make an amazing teacher.

[thomasphillips]

When your entire upload history is a prequel series for a single video.

[AshtonRob]

This video ended up inspiring me to go into an HVAC career, I just got hired as an apprentice :) thanks for the great content!

[keri-lynnmiller]

One of the perks of being hearing impaired is that I always have subtitles turned on and therefore catch things like “Coefficient of smooth jazz” and it makes me feel happy. :)

[jdatlas]

Yay, Technology Connections finally made that heat pump video we’ve all been waiting for!

[jusjaisinghani]

I was happy to hear at the end of a 35 min video that this was just part 1, tells me how much I love your content.

[WarrenGarabrandt]

We installed mini-split heat pumps on our house this year, and so far, we've noticed a significantly lower energy bill both during summer and now in winter. Your videos on heat pumps are a big reason why we did this. Thanks for making these videos. It's a small thing, but these videos are making the world a better place.

[fifzeppelin]

2:09 I have an MS in chemical engineering. I know very well how the refrigeration cycle works. Yet I refuse to skip any explanation this channel does about it. It's just that good.

[jamesgates]

Entropy: "No!, you can't just concentrate latent heat wherever you want"
Humans: "Ha, Ha, compressor go burrrr"

[xyzyxz]

for 20 years I've been asking sales reps to explain heat pumps, how they work, and how my cost would go down as brochures and signs say. No one could tell me. Next door got a huge carrier unit installed I asked installers, they couldn't be bothered or didn't know. Now I know. THANK YOU SOOO MUCH!

[per-olamjomark]

Fun to watch. I live in Sweden and close to 60 percent of all Swedish detached houses have a heat pump. The number of houses with heat pumps has also increased by almost 50 percent since 2009.

[maximum]

The day after this video comes out, my thermodynamics class starts going over second law and heat pumps. This got me ahead of the game.
Amazing

[midimusicforever]

Meanwhile in Sweden, I'm annoyed that my heat pump doesn't cool. It would have been sweet to have air conditioning in the summers!

[EtherImperial]

As someone who lives in the south, you have taught me something new about my A/C unit. I always thought that the heating mode was just turning on a space heater style system as it's commonly referred to here as the "heating coil". This also explains why it takes a minute to swap between heating and cooling.