Talk:2790: Heat Pump

woah! an xkcd with color what was the last one with color? (im kinda new to xkcd) 172.71.122.48 21:17, 16 June 2023 (UTC)Erfaniom

I guess the last one with a lot of color was 2750. More at Category:Comics with color. 162.158.167.11 17:29, 17 June 2023 (UTC)

I suppose color was needed to show the air temperature. Odd, though, that in summer (in the northern hemisphere), the character is trying to increase the indoor temperature. Davidhbrown (talk) 21:27, 16 June 2023 (UTC)

He's not. He's moving the hot air from inside to the cooler outside. Barmar (talk) 22:18, 16 June 2023 (UTC)

he's actually heating it, the comic is set in winter. It's a reference to the discussion about regulating heating systems in Germany. I added something about that in the explanation, but I don't think I made the citation right (I'm not to editing wikis) User:Marta (talk) 05:25, 17 June 2023 (UTC)

The citation does not appear to strongly relate to the comic to me. I might be curious if Randall had a lot of comics queued and actually published a winter one in the summer, for example. 172.69.59.112 00:19, 18 June 2023 (UTC)

I agree, I think the Germany thing might probably be coincidental. Randall lives in North-Eastern America. It's unlikely, though quite possible, he was inspired enough by such foreign matters to base a comic on it. Still, you never know from whence inspiration may strike, in which case he published when he thought of it instead of when it'd be relevant... NiceGuy1 (talk) 04:40, 18 June 2023 (UTC)

News of this had not otherwise reached me over the German Ocean (i.e. North Sea), never mind where Randall is, way over the Pond (i.e. Atlantic). Not saying it wasn't a prominant bit of news, in his media feeds, but usually the problem is that something 'popularly heard about' state-side confuzzles anyone in (say) Europe/ex-Europe when used as inspiration for a comic without enough setup to it. Now, if say Penn./Mass. state legislature were being similarly proactive on such matters, I'd say it might be the cue for this. Otherwise, it might be better as an afterthough/Trivia instead of the lead-on paragraph. But I also don't know enough to know that it isn't worthy of such prominance, so this is just my thoughts, leaving others to alter it if they so wish... Anybody can do it, after all... 162.158.74.96 09:55, 18 June 2023 (UTC)

Nearly right. Simple "insert URL" as a 'number' is single []s, or [<url><space>some text] to have it given linking text (preferable).

Plus you seem to have not used the four tildes, i.e. ~~~~ to sign the above comment (made it correct, for you), plus confusingly replied before another reply (so I indented you a bit more, as well as it now having that timestamp to make precedence clear).

But these are all things you'll pick up, I'm sure, if you're going to be getting [used] to wikis... Welcome! 172.71.178.139 05:35, 17 June 2023 (UTC)

I actully think he's warming the inside, already warmer than outside, by effectively (and literally!) squeezing the heat out of the cooler outdoors air.

By compressing the cool outdoor air, he increases its temperature (p1v1/t1=p2v2/t2) to warmer than the warm indoor air, creating a squeezebox->room flow of heat energy, then returns to the outside before decompressing and lowering the temperature in his squeezebox below the cool-air temperature in order to create an outdoors->squeezebox flow of energy and repeat. (The comic has the cycle start at roughly half-way through that, and wraps round, but the heat-to-room seemed the most obvious starting place here.)

Right now, I'd not wish to heat my indoors up (even at 11:30pm, like now), so I agree that it's a funny time of year show heat-adding (rather than heat removing), but it definitely is that. 172.70.86.154 22:31, 16 June 2023 (UTC)

Assumption(?): Indoors is on the LHS and higher, outdoors on the RHS and lower, door opens outwards and steps down to "outside". He COULD instead be cooling a basement apartment with a door that opens inwards (like mine)... however he seems to make a noticeable difference to the red, not the blue, so... probably not.  :-/ 172.70.34.160 02:36, 17 June 2023 (UTC)

Since panel 3 shows it at its widest and bluest with "Release", I understand that to mean he's releasing the heat outside from inside - like an A/C does. The weird thing is then showing the reddest/smallest with "Radiate", that word means "make and release heat" to me. The thing is, past experience tells me Randall lives in roughly the same part of the world as me, same climate. That he's in the northern states (like, within a day's drive of the Canadian border), and the Eastern time zone, and it's summer for us. Only heat pumping people should want is pumping heat OUT of the house... NiceGuy1 (talk) 04:16, 18 June 2023 (UTC)

Releasing the spring. At that point, there's the same amount of heat within the device, but it's spread out more so that the temperature is lower (than it was, but also than the surrounding air, which is also negligibly compressed outwards of course). NB, it does not draw air into it.

Now he has a cool device, heat naturally flows into it until (sufficiently) equalised after a small wait. Take the outside-cool (and expanded) device inside and compress it (it does not expel air!) to have that amount of heat be in a smaller space and thus a higher temperature. High enough to (quite naturally) flow into the room. Thus low-temperature heat taken from outside and used to increase the higher-temperature heat inside, which is different to what happens if you trap and move cold air into a warm room. Though perhaps it looks like that on first appearance, except for the colour-cues going all screwy. 162.158.74.96 09:55, 18 June 2023 (UTC)

This all rather assumes that Randall came up with the comic in response to his immediate situation, rather than just musing generally and abstractly on heat pumps and the way they work.172.71.178.51 10:20, 19 June 2023 (UTC)

Wasnt there a "My hobby is to open my refrigerator and when people tell me that doesnt help, I sneak into their house and use their AC?" Comic? I cant find it, but we should link it in the "how leaving a fridge open doesnt help" section 172.71.142.158 23:36, 16 June 2023 (UTC)

Sounds like Steven Wright, he has lots of those "my hobby is" jokes. Barmar (talk) 13:29, 17 June 2023 (UTC)

I think it's talking about leaving the door open in general i.e. forgetting to close it when getting groceries, not specifically when he's moving the heat pump Firestar233 (talk) 23:40, 16 June 2023 (UTC)

I can't think of a good reason to say this, but my new fridge doesn't warm up on the back. It warms on the sides. A bad (and quite a PITA reason) is I had to get a new fridge. Protip: don't panic, and do put the sacks of ice into something that won't leak. First time I've met a fridge that doesn't warm on the back. Btw, red hot blue cold. Pink? Light blue? A light blue a pink? Shrug. 172.70.43.31 23:57, 16 June 2023 (UTC)

How many trips would this take? I'll leave the exact parameters of the calculation up to you. (Nerd sniping attempt.) ~ Megan ^she/_her ^talk/_contribs 00:20, 17 June 2023 (UTC)

42. But stick figures are just lines and have no surface area for heat transfer.

172.70.134.236 01:02, 17 June 2023 (UTC)

Currently, the explanation says you use a heat pump to "transfer heat from a relatively cold area to a relatively hot area". I don't know anything about the named "ideal gas law" in order to be sure enough to change this, but isn't that the wrong way around? If an area is ALREADY cold, why would anybody transfer heat FROM it? 04:49, 18 June 2023 (UTC)

Let's say it's winter, and it's cold outside. It's warmer inside, but not as warm as you'd like it to be, so you need to warm it up. Where are you going to get the heat from? Traditionally you'd use a boiler to heat up water or electric coils, but these use lots of energy. A heat pump is more efficient, it moves some of the heat from the cold air outside to the inside. You need a pump because it won't move spontaneously -- heat always goes from warmer to colder areas. Barmar (talk) 09:49, 18 June 2023 (UTC)

[edit conflict with the above reply, thus repetition, but as I was adding other stuff too...] It's fridge-logic! i.e., that's what fridges do... and if you're living in a cool climate, you can potentially heat your house above "too cold for indoors" temperatures by extracting heat from the "far too cold for indoors" air that is outside. 162.158.74.96 09:55, 18 June 2023 (UTC)

Technically, it's not the ideal gas law in play, since air isn't an ideal gas, and the system would behave similarly for closer-to-reality gas behaviour models. But I can't think of a good way of modifying the article to reflect that. BunsenH (talk) 16:04, 18 June 2023 (UTC)

Noting you could make hand-crank manual heatpumps that are much easier to use than the one depicted. If it’s doable it’s of meaning because a heatpump can be a big electricity draw, and sometimes electricity is not available. You could also connect a horse, waterwheel, or windmill to it. Making homemade windmills out of bicycle parts is a thing. 172.69.59.147 20:03, 18 June 2023 (UTC)

You can make a rubber band heatpump which works the exact opposite: rubber bands heat when stretched and cool when the force is released. This seems counterintuitive, but stretching is adding entropy (as is compressing a gas) and releasing the tension is bringing the entropy back to normal levels again (as is relasing the gas pressure). IIVQ (talk) 05:04, 19 June 2023 (UTC)

Folks seem to be assuming that the red side is "indoors", and the blue side is "outdoors", but in my experience exterior doors tend to swing in, not out. The hinge pins on an outwards-swinging door can more easily be accessed, which makes an out-swinging door a poor choice as an exterior door. 172.70.100.224 20:26, 18 June 2023 (UTC)

But why would you have steps leading up to the door from the inside? Firestar233 (talk) 21:55, 18 June 2023 (UTC)

Many exterior doors open outwards as a matter of safety, especially emergency exits. It's not a big deal if only one or two people are expected to try to exit in event of an emergency, since whoever opens the door can probably take a step backwards to make way for the door. But if there's likely to be crowding at the door, there isn't room for it to swing inwards. BunsenH (talk) 22:28, 18 June 2023 (UTC)

For sure he is trying to heat up his house. And yes many places doors open in, but not always, and specifically not in public buildings for safety as just mentioned. --Kynde (talk) 08:34, 19 June 2023 (UTC)