this post was submitted on 09 Jul 2024
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Non-native English speaker, but I looked it up the other day and it seems that pedantically an A/C only cools things down and heat pumps can both heat and cool.
ACs are just heat pumps where they forgot to install the reversing valve.
Heat pumps running in heating mode are basically ACs that are trying to cool down the outside. The fundamental technology just moves heat from one place to another, leaving one place warmer and one place colder.
This is also how fridges and freezers work - they have heat pumps that pump out the heat from inside their box and as such make the room they are in warmer.
It's why it's so annoying that dual function AC/Water CH don't seem to exist (or at least, they don't qualify for government subsidies).
In the summer, I'd like 3KWH of cooling. And in the winter, maybe 15KWH of heating. But to do that, I have to buy two boxes.
Most ACs nowadays can do both. And are actually more efficient at heating.
Yes, an air conditioner is a heat pump with a fixed orientation, what basically equates to a handful of valves to switch the direction of the refrigerant. The actual expensive parts that generate the temperature difference are identical between the two machines.
In my country, air conditioners can condition air that's too cold. Sounds like American air conditioners can only condition in one direction. Our air conditioners do all of the air conditioning.
No we have both, and they're still heat pumps. The direction the heat pumped is irrelevant; the fundamentals are the same.
Yes, air conditioners and heat pumps are indeed the same thing. Americans just don't call the two-directional heat pumps air conditioners for some reason. I guess they don't believe you can condition air by making it hotter. In my country, we consider heating part of conditioning.
We call it HVAC (Heating, Ventilation, Air Conditioning), and so do other countries that speak English for a reason. It’s different from heating in that air conditioning can also involve controlling air humidity/quality.
Heating gets its own because until reversible heat pumps, it was a separate system that only heated the building (sometimes not even the air directly in the case of heated floors).
Nope AC at least where I have been can do both. Heat pumps are for water.
Probably a local nomenclature thing. Heat Pump is the most common name for phase change cooling/heating system. (No matter the medium(s) being heated/cooled)
Yet I have never seen a food refrigerator called a heat pump. Air-to-air always seems to be called AC to differentiate it from the air-to-water the UK government wants to push.
I never see refrigerators being called AC either, and they're air-to-air heat pumps too. People just call things what they want regardless of the technical details.
The actual technology is called refrigeration. We should really be calling them all refrigerators, including AC, heat pumps, whatever. AC is a specific application of the refrigeration cycle, and so is a heat pump.
Pointless discussion, but they're all heat pumps. Refrigeration cycle is the name of the physical process. Most heat pumps make use of that thermodynamic principle, but there are some niche ones that don't. But people don't care about that, and so find it more useful to call them by what their purpose is, and that varies locally.
Actually that's wrong. When we build food refrigerators using peltier modules, it's still a refrigerator. The reverse carnot cycle is just one type of refrigeration cycle, reverse rankine and reverse brayton cycles still count.
Sure you could call them all heat pumps, and you might be technically right. Nobody actually calls them that though. Most people probably haven't figured out that an AC unit, a heat pump, and a food refrigerator are all actually the same concept in different dressing and sizes.
It's only an irrelevant topic if you can actually communicate clearly, which is actually very hard as almost no one understands this stuff. Especially in the UK where this is all viewed as newfangled, expensive, and unreliable technology. To be fair they aren't wrong in this country: the way we handle, specify, and install ASHPs makes them feel and act inferior to a good old condensing gas boiler. It's a sad state of affairs.
I was referring to electrocaloric, and Stirling engine heat pumps.
There are currently no production heat pumps using the electrocaloric effect to my knowledge. Stirling engine I doubt as well. Either way still classes as refrigeration. In fact a Stirling engine heat pump/refrigerator would still need refrigerant as it needs a working fluid.
Edit: also pretty sure a Stirling engine is an implementation of a carnot engine
Because at some point society decided to call them refrigerators or AC. The thing *inside the refrigerator or air conditioner" that makes it work is called a "heat pump" -- that's the unambiguous name of the device. Just like the bit inside a car that provides motive force is called the "engine" or the "motor".
The device that uses a heat pump to both heat and cool a building is actually called an Air source heat pump, but since that's a mouthful most people simply call it a "heat pump" to distinguish it from traditional AC that only works to cool an area. Sure, maybe you get that odd area the calls it something different (my region calls soft drinks "pop") but that's not the norm.
Round here we call that bit the compressor, as in "Need a new fridge/AC unit.. compressor's broke." The term generally encompasses the compressor and the condenser, even though they are separate bits witch, together make a "heat pump." I've never heard it called a heat pump in that context though (USA).
Nope you can have AHSPs that only heat. The Wikipedia article even says so.
There are also heat pumps that only heat. It takes a second valve or so to enable it to switch directions.
I could just mount it backwards in my window!
Colloquially, "air conditioner" often refers to a centralized system with ducting, while a "heat pump" usually refers to a ductless mini split.
At least in North America, the term "Air conditioner" means a device designed to cool a room, where a "heat pump" can cool or heat that room. They work by the same exact principle (all the compressing, condensing, evaporating stuff) but a "heat pump" has a method of running in both directions. You could probably contrive one that could run the pump in either direction but I think most use a valve to switch which is the high pressure/hot side and which is the low pressure/cold side.
I grew up in a house with a heat pump, I currently live in one with an air conditioner and a furnace. When it's time to replace my air conditioner (or do other heavy maintenance to the system) I'm going to look into a heat pump, with the furnace as a backup heater in lieu of strips.
Nope AC does both. What the word heat pumps means seems to vary on where you live. Here it's mostly things that only heat water for radiators or hot water tank.
Arguably they should all just be called refrigerators as they all use the refrigeration cycle.