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)

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)

I don't think that's right... Homes rarely are a few steps lower than outside (half a flight for a basement apartment, but not 2 or 3 steps), and steps are rarely if ever just inside the door. However, it is extremely common for indoors to be 2 or 3 steps up (as a wheelchair user, let me assure you of this fact, LOL!), and steps are often right up to the door like this. :) NiceGuy1 (talk) 05:50, 24 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)

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 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)

(I'm not to editing wikis) User:Marta (talk) 05:25, 17 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 originally indented you a bit more, as well as it now having that timestamp to make precedence clear, but as soneone disliked the indentatiom I'm rearranging in 'threaded'-order).

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)

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? NiceGuy1 (talk) 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)

Let's NOT say it's winter, because it's summer. :) It seems horribly unlikely he'd publish a winter-themed comic in the summer (the BEGINNING of summer, when everyone in our region - mine and Randall's - has been patiently waiting for the summer weather). Anyways, it really DOESN'T make sense, being a cold area means there's a lack of heat, none to transfer. I would think a temperature pump/device that absorbs temperature can't pick and choose WHAT to absorb, if there's cold it would absorb cold. Like in a 10° environment it'll absorb 10° temperature, in 30° it'll get 30°, and it's combining it with the target area which will determine the effect it'll have. It being summer suggests this was meant the other way. Perhaps the person who was convinced this was related to the Germany thing swapped it, but the person who removed the Germany connection didn't notice to swap it back? NiceGuy1 (talk) 05:41, 24 June 2023 (UTC)

"... being a cold area means there's a lack of heat, none to transfer." - Only true if you're talking about O°K(/0°Ra). Otherwise what you have is less heat, but can still technically remove some of that heat to make it even lower. (By manipulating a substance though P₁V₁/T₁=P₂V₂/T₂ to make something with the same general heat have a reduced T₂ so that T_external will warm it/be cooled by it, before you bring it into a new environment and then make it revert to the new T₁ that is warmer than T_internal... for example.)

Assuming you're using Fahrenheit for 10° and 30°, how about I reframe your other bit in °C? "Like in a -12° environment it'll absorb -12° temperature, in -1° it'll get -1°" ... Temperature doesn't know where you're (semi-arbitrarily) setting your zero-mark. A device that can extract 10F° of 'temperature' from a 10°F atmosphere in the US would find itself forced only to add (approx) 12C° of 'temperature' from an otherwise identical atmosphere if operating in the UK/EU/most other places? No, it'll have the same warming/cooling power in both scenarios. It'll vary by what the temperature differential is (and where on the scale, as a change of 10 degrees (whatever scale) is not the same difference of energy as a subsequent onward change of 10 degrees (same scale), and a 4:9ish ratio of how you'd enumerate it in F or C (or Rankine or Kelvin), but it'll make unpleasant temperatures pleasant (or vice-versa) or store/cook your food at the right practical temperature in exactly the same way whether the thermostat displays in Celsius, Fahrenheit, Kelvin, Rankine, Réaumur, Rømer, Delisle or whatever unit...

As to whether he posted a winter-appropriate comic at (nearly) the peak of summer..? Confusing, but not necessarily a deal-breaker.141.101.98.44 13:40, 24 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)

I've always understood that fridges - refrigerators - applied refrigeration, as in applied cold to make it cold. Like keeping a powered ice cube in there. And the heat exuded out the back is a byproduct of all the power powering that cold takes. :) NiceGuy1 (talk) 05:55, 24 June 2023 (UTC)

"Cold" is not a thing. It's a lack (or, rather, reduction) of heat. It was often considered a thing (because cold hard stuff like ice is more 'obviously a thing' than slippery water or frankly intangible stuff like steam) or looked at how things expanded/contracted against other things in a contrary direction to how they really related to each other. Early attempts to measure temperature used that assumption (prior to 1743, water boiled at 0°C, froze at 100°C, before they switched the defined limits; the archaic Delisle unit [i]still[/i] 'measures backwards') but then understanding dawned and hascsince been improved upon. Something at Absolute Zero is (rare/more a theoretical state than a lractical one! ...but, apart from that) not a source of cold but a sink to any nearby heat that happens to be currently radiating/conducting towards it.

Fridges move heat energy, as do all heat-pumps. In the fridge's case, you're interested in moving heat to cool one place (not too fussed about where the heat moves to, just outside the refrigerator/its freezer compartment). In an air/water/ground-source heat-pump used to warm an internal space you're bothered about where the heat goes far more than where it comes from (except for if you start to get ice on the cold end of the device, which reduces the efficiency in leaching the regular air/water/whatever) but very similar processes are used to do the basic movement (and the actual work needed to power the change adds a net energy output, in extra heat/noise/airflow/etc). 141.101.98.44 13:40, 24 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)

The link is to a hand-crank fridge. The rubber bands are on a wheel, and get stretched/released depending on whether they are inside or outside of the fridge. The construction is quite similar to the comic. 172.71.255.21 13:39, 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)

Given his obvious lack of grasp of the impracticality of the solution, maybe he's actually trying to cool down the outside.172.70.162.229 13:34, 19 June 2023 (UTC)

Outward doors exist, though inward is most common. Basically, an outward door is more common than an indoors that is 2 steps down, and more common than an indoors that has steps right at the door. NiceGuy1 (talk) 06:03, 24 June 2023 (UTC)

Maybe not the intent of the comic, but it's interesting how the red/blue for temperature are also the political colors of the united states. After recent schisms, I imagine many people feel like they are walking between huge crowds of red->blue or blue->red slowly trying to build communication like an ant building an anthill grain by grain. 172.71.255.21 13:39, 19 June 2023 (UTC)

Interesting to note that Blue and Red are UK political colours (as they are elsewhere), but that here it is Labour (left-leaning, occasionally very left leaning) as red, Conservatives (right-leaning, occasionally very right leaning) as blue. Which always amuses me when I see Democrats (right of centre) and Republicans (so right of right of centre that it's not really funny any more) coloured how they are. Also, Libertarians aren't Liberals (UK: yellow, centre-ground fence-sitters), despite the similarity of name. About the only close match are the Greens (green!), but I think your lot might tend to being more militant than ours, at least the politically-inclined ones.

Anyway, the colours are the usual colours. At least it's less confusing than taps labelled C(old) and H(ot) in the UK, but F(roid) et C(haud) in France, at least when you see only the "C" first. 141.101.99.85 14:55, 19 June 2023 (UTC)

Heh, that reminds me of my confusion as a kid when sometimes bathrooms would be labelled D and H (Damer/Herrer = ladies/gentlemen), and sometimes P and D (Piger/Drenge = girls/boys). Villemoes (talk) 12:12, 21 June 2023 (UTC)

Your parlance vary but to me a heat pump is a device that can heat or cool. (strangely, this would be easier to explain if I spoke of 'caloric' and coolth.' A heatpump is not an air conditioner except that it actually is when it wants to be: it can both move energy into a space and out of the space. Refrigerators only move energy out. Air conditioners only move energy out, (for the standard way to install them) the argue about summer and winter? Stop being silly. Here the outdoor temp has varied a lil in the past ten days. I think from a low of 45F (light jacket weather) to a high of 92 (uncomfortably warm). Here, to keep it comfortable inside at this time and (similar weather in the fall) I need to cool from about 3-7 pm and heat from about 3-9 am. If you live in a country that has rationing, my sympathies. "But apartment manager!! the toilet is frozen over!" "Yeah, doesn't matter. I can't turn the heat on until December 15." Sort of thing.172.70.130.86 00:17, 23 June 2023 (UTC)

¿Que? You sound confused. And pumps (heat- or otherwise) needn't be bidirectional. Perhaps it's easier, even, with something slightly different like a peltier-effect system (with switchable power-flow) than to make a fully reversible source/sink set of radiators and compression/expansion chambers, on top of whatever you do to thaw frosting over of the cool-side, etc. 172.70.86.25 01:04, 23 June 2023 (UTC)