all heat pumps work in one direction. You can't move cold around with any mechanism. Only heat can be moved. The difference is residential "heat pumps" just have a set of reversing valves so you can move heat from outdoors to indoors.
Have to imagine that the niche market for making 40F/4C "cold" water from luke-warm tap water (if you live in an area that is so hot the tap water is warm) is fairly small.
It's not a niche market. Every office in the world has a water cooler.
The market for evaporative water coolers is niche, or probably only big in the developing world. Other than that water coolers use refrigeration aka a heat pump.
In the trades in the US we would exclusively use the term heat pump to describe a system where the “indoor” or “outdoor” coil can change from condenser or evaporator depending setting. Us HVAC guys would generally call a conventional system a conventional DX system (for direct exchange rather than chiller) or a split system (like a mini-split, minus the mini).
I work in the HVAC industry and "heat pump" in the context of A/C units exclusively refers to models that cool and heat by reversing the refrigerant flow.
It feels like very much a could country / could region distinction. In warmer regions of the world, heat pumps have been using for efficiently heating in winter since the 1980s (that's as far as my memory goes). Of course, when the temperature rarely went below 0℃. If you look at the single-room AC units that now dominate these markets, you'll rarely find anything that cannot do both heating and cooling.
Interesting, I’ve never heard of that interpretation. Heat pumps have always been a technology to me. The same tech that is in everyone’s refrigerator.
Technically, from the point of view of physics, yes. That said straight cool systems (alternate name for air conditioners) are only one way heat pumps (in a physical sense) as they lack the reversing valve needed to reverse the heat flow. Heat pumps (in the common sense) can move heat in either direction.
Compared to a traditional air conditioning unit, the reversing valve is the major difference. Your standard AC can only move heat from indoors to outdoors. A heat pump can do the reverse to warm your space. My basement heat pump is rated to provide heat even when it’s -20F outside.
I think any and all AC units sold in europe (split systems with inside and outside module) can do heating and cooling just fine with great efficiency. Many models rated to work at -20C, sometimes -30C
I think the media has once again assigned a term their specific definition and created a meme out of it. I guess it makes sense if you have no preconceived notions of what a "heat pump" is. But yes, to anybody that knows an air conditioner is a type of heat pump, these articles read akin to "Personal cars create too many emissions. Companies have come up with an innovative way to reduce this problem: vehicles". (with the reader in the memestream of taking the generic term "vehicles" to mean only electric vehicles)
Trying to parse the mumbo jumbo, I think these articles are trying to point out and encourage the trend of designing new installations of cooling systems around cooling and heating, with a reversing valve and whatnot. Because it no longer makes sense to lean on a separate heating system that burns fossil fuels. But gosh I wish they would just come out and say this directly instead of beating around the bush as if "heat pumps" are some magical new invention.
It’s not the media doing this; “heat pump” has been industry lingo (in the US at least) for an A/C with a reversing value since at least the early 1980s.
My parent’s house had a heat pump then and does so today (albeit much improved over the decades).
I'm aware of HVAC lingo, but that's not the entirety of it. The media is explaining them as if they're some completely different advancement, rather than focusing on the commonalities. Look at this nonsense:
> Heat pumps are also compatible with natural refrigerants with lower climate impacts. They can consume less electricity than conventional central air conditioners
Like no, any efficiency gains for cooling have nothing to do with a unit being a "heat pump". And same thing with refrigerants - adding a heating mode can only constraint the choice of refrigerants. So they're touting benefits that have nothing to do with "heat pump" and everything to do with newer technology - but instead of describing this accurately, it's just being ignorantly lumped under this "heat pump" banner.
It’s not just a heat pump thing, it’s the entire industry. The state of science and tech journalism is pretty sad right now.
That’s what happens when few people are willing to pay for quality research and writing.
All that said, it is relatively recently that Americans have had access to heat pumps this efficient and they work reasonably well in sun-freezing temps.
I grew up with heat pumps. It was pretty normal for it to kick into emergency (electric heat element) when the weather got nasty (for DC, so the mid-teens F).
I agree, but I'm specifically calling out the treatment of heat pumps here because that is the topic under discussion. A meta point about journalism as a whole wouldn't really be on topic, nor easily applicable.
I don't have heat pump experience, or even much central AC experience, but I do know that there has been many advancements that make them practical for a wider audience rather than the previous niche. I wish articles would describe these advancements rather than effectively saying "a heat pump is this new awesome invention, go buy one".
Yeah, that's the part of all the "heat pump" coverage that I find amusing and odd. I've lived with a heat pump for at least 40 years at this point. Every house I've lived in for the last 40 years has been fully electric actually.
In physics we call a device that uses the compression and expansion of a fluid to move heat between parts of a system a heat pump.
An air conditioner uses a compressor to convert a refrigerant and sends the compressed fluid through a condenser. The condenser rejects heat from the system into the environment. This is the component of an air conditioner that is found outside. The compressed fluid is then passed through an expansion valve and into an evaporator where it is allowed to expand. Expansion is a process that requires heat. The heat flows into the expanding fluid from the environment inside the home. Air is blown across the evaporator coils to transfer heat energy from the home into the fluid which is then returned outside.
A heat pump is capable of reversing the flow of heat energy. The flow of fluid is reversed from an air-conditioner using something called a reversing valve. The compressor sends compressed fluid into the home where heat is rejected through the evaporator coil. The fluid then flows into the condenser coil and is allowed to expand outside, drawing in heat from the outside environment. The heated fluid is then returned to the compressor and the cycle continues.
In HVAC terminology an Air Conditioner is a one way physical heat pump and a heat pump is a bidirectional physical heat pump. Hopefully that helps clear it up a bit.
An A/C works almost identical to your refrigerator. Using a closed loop of refrigerant with specific thermal properties, it will remove heat from one side and emit heat from the other.
If you are able to run this system backwards, you could in theory swap which side is a heat sink (the cold side) and heat source (the hot side). While a traditional A/C cannot do this, heat pumps can electronically switch which side of the system is collecting the heat and which side is releasing it.
This is an improvement over resistive heating (think space heater) because we’re not pumping electricity into some filament that resists current flow and emits off heat due to the resistance. Instead, we are taking heat from inside and moving it out or taking heat from outside and moving it in.
Fun fact, a resistive heating device is a rare case of something being 100% electrically efficient in that all the energy it uses will be turned into heat, whereas heat normally is a byproduct of imperfect conductors, which everything is, and is therefore considered wasted energy in almost all other applications.
> Fun fact, a resistive heating device is a rare case of something being 100% electrically efficient in that all the energy it uses will be turned into heat
My understanding is that you get considerably more heating per watt-hour with a heat pump than with resistive heating, though. I get that it's not creating that heat but moving it, but still that seems like even more efficiency from the perspective of energy consumption per useful heat made available.
Well the word “efficient” always needs context. You have to define the goal first before you can define efficiency.
OP said electrical efficient so the goal is conversion of electricity to heat and it’s 100% efficient.
Even an electric heater compared to a propane heater is more electrically and energy efficient, but it’s not as storage-efficient (because fossil fuel gases have much higher energy density per volume AND weight than lithium batteries).
> OP said electrical efficient so the goal is conversion of electricity to heat and it’s 100% efficient.
I am not an engineer and I am only nitpicking to have fun, so don't engage me if it's not fun, but doesn't some of the energy go into degradation of the materials used to build the device?
Yes, but energy is not consumed by that process, it is only converted into heat. The degradation usually is a result of the heat produced. If we’re talking about mater to energy transitions, we need to start talking about special relativity.
I said 100% electrical efficiency because from the prongs of the plug, through the conductors in the appliance cord, the rheostat, all electrical connection and contact points, and of course the hearing element itself all will product heat as a consequence of electricity flowing through, and being resisted by, it’s various components.
It was pointed out that this does not mean “energy bill efficient” which is totally correct: this whole thing is a somewhat silly thought experiment to consider what it really means for something to be efficient.
The coefficient of performance of a heat pump isn't a measure of thermodynamic efficiency, because as you pointed out, a heat pump moves heat rather than creating it. That's why you get more heat per Watt-hour, because you aren't expending energy trying to make heat.
The closest analogy that I know of is in electrochemical processes where some of the energy input is allowed to take different forms. If you put in 85 units of electrical energy, 15 units of waste heat from a different process, and get 90 units worth of product, your process is 90% thermodynamically efficient, but has better than 100% electrical efficiency. In the case of a heat pump, measuring units of heat per Watt-hour is a bit like this in that some of the input energy (for the heat generation) has already been provided by a different process.
A heat pump is an A/C with a reversing valve; in A/C operation, the A/C cools the inside and heats the outside; in heating operation, the reversing valve is toggled and the system heats the inside and cools the outside.
It's kind of confusing terminology. I'll stick with how these terms are used by industry/laymen - heat pump also has a scientific definition that's more broad than how it's normally used.
There's a process called a "vapor compression cycle" which essentially works by moving energy from a cold area to a hot area (which makes the cold area colder and the hot area hotter).
Air conditioning is when you put the cold side of a vapor compression cycle in a building to keep it cool.
The term "heat pump" most typically refers to a device where the hot side of the vapor compression cycle is put in a building to keep it warm.
However, many heat pumps have an air conditioning mode, where the hot and cold sides of the vapor compression cycle switch places depending on the season. So air conditioner refers only to cooling, while heat pump may refer to heating along or a device which can both heat and cool.
* A/Cs are heat-pumps (when using the scientific definition of "heat-pump")
* Heat pumps, when referring to HVAC technology specifically, refer to systems that are essentially the same as A/C units, except they're designed to work in reverse.
* The term "heat pump" when used in Europe, more-often refers to geothermal heat-pumps ( https://en.wikipedia.org/wiki/Ground_source_heat_pump ) which is very different to an A/C-style heat-pump, though achieves similar end-result (livable indoor room air temperature).
As someone who spends a lot of time in the year in both North America and Europe I frequently come across people confusing the two.
Only if they used GPT 3.5, if they used GPT 4.0 is more like someone using their paid access to a subscription to a scientific journal to look up research papers for someone.
Not really - a scientific journal contains information of a high quality. The fact that money is involved here makes no difference. A better analogy would be using your paid subscription to a horoscope.
Yes modern day a/c is usually a heatpump. I’ve noticed a lot of people misunderstanding heat pumps, and thinking it’s some sort of replacement for A/C. Or that heat pumps are some new tech.
And isn't the refrigerant the same with a heat pump?
The article says that heat pumps are "compatible with natural refrigerants with lower climate impacts". Why couldn't A/C units use the same natural refrigerants?
It's an industry term for mechanical equipment that can heat AND cool. One piece of equipment replaces your AC AND heat source.
Heat pumps in particular are getting a push from "green" initiatives because they only use electricity for fuel which can potentially be supplied by "renewable" sources.
It's not just buzz. It's more efficient than resistive heating and modern units have better performance in cold temps. Hence the push to promote them. The downside is that you have added complexity driving up installation costs and reliability down.
Walk around in the American Heating and Refrigeration conference for a while to get a feel of these trends, this was specifically called out by many manufacturers as driven by the green movement.
It's being driven by government pressure to reduce energy consumption and dependence on fuel imports. That isn't a bad thing. It's the sort of thing a responsible government should be planning for.
Heat pumps are expensive to operate, and a nightmare to fix. There is a big movement to build whole subdivisions without using natural gas at all, electric ranges and heat pumps. I don't know why it upsets me so much but it does.
Heat pumps for homes aren't expensive to operate. They are cheaper to "operate" than resistance heaters. I doubt they're a nightmare to fix - I have actually had to get mine "fixed" once. It was still fairly new, and it turned out there was a leak in the tube so the coolant gradually (over the last year) got out. The company came and fixed that easily enough. Since then (January 2011) the heat pump has been running 24/7 with no issues whatsoever. In fact you're not supposed to turn them off at all, the moving parts are supposed to keep moving. So, if I'm away for some weeks I simply set the temperature to the recommended "idle" temperature of 17C, which in practice means it's not really doing any work, but it's not off either.
But they are used in commercial kitchens. I joined a cooking course arranged by a well-known restaurant where I live, and to my surprise the kitchen we used used induction. Very easy to operate, and you could easily set the heating exactly. It worked basically as a gas restaurant kitchen, just without the gas.
> because they only use electricity for fuel which can potentially be supplied by "renewable" sources.
They also can operate at >100% efficiency. Under the right conditions (I'll let someone who knows more about it fill that in) they can provide more heat than the same amount of power going into a resistive heater (which is I think per-se 100% efficient right?). Kinda wild.
This should happen under a fairly wide range of temperatures for modern heat pumps. Quoted figures are usually in the 3-4x more efficient than resistive heating when adjusted for seasonality for air source heat pumps. Ground source are more like 5+ I think.
That's lab figures though so I guess similar to car efficiency figures.
OR another (incorrect) way of thinking is that resistive heating is 100% efficient as every bit of heat generated is inside the home. VS mechanical heat has some "loss" with some of the heat being left outside the home.
But yes, mechanical might be up to 600% efficient depending on how you think about it as moving heat around based on energy usage per therm delivered inside the home is really what people are looking for.
Same principal. But an aircon pumps the air over a radiator cooling/heating it, with a fan. Heat pumps rely on radiators in the room to cool/heat the ambient air generally.
