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.
It’s the same principle, but in the US I expect a “heat pump” to run well in both directions where an “air conditioner” might not have a reversing valve at all, or won’t really defrost the outside coils in cold weather.
So ... yes, the heat pump can be run in either direction, and is "reversible" in the sense that the heat flow can be reversed through the pump.
The process is not thermodynamically reversible in the sense that there's a net energy expenditure either way. No free lunches.
What a heat pump can do is to move a greater amount of energy than it uses to move it. Measurements of this include COP (coefficient of performance), EER (energy efficiency ratio), and SEER or ESEER ((European) seasonal energy ratio).
The COP is a direct measure of energy moved divided by energy input, and ranges from about 2--4, with typical ground-loop heat pumps achieving scores around 3--3.5. That is they move three times the heat energy that they run under. It's as if a furnace output three times more heat energy than fuel input.
In your example, we'd first want to correct power (watts) to energy (watt-hours or joules). But 10 watt-hours of electricity would move about 30 watt-hours worth of heat, for a typical heat pump. If you're heating, you'd dump the additional 10 watt-hours into the heated space, if you were cooling, you'd want the heat pump's own heat to be directed to the external environment.
Discussion of heat gained/wasted with heat pumps is ... complicated. Note that effectiveness in moving heat decreases as the differential being moved against increases. That is, if you're trying to cool a space in an environment that's already warm, you're pumping heat "uphill". Similarly, if you're trying to warm a space from a cold environment, there's not much external heat to extract.
Ground-loop heat pumps benefit by the fact that ground temperatures tend to be more moderate than outdoor ambient air temperatures, so the temperature gradients are more favourable and predictable.
This. Heat pumps are just AC run backwards, and it doesn't take much to make an AC able to run in both directions. The only thing is if you need a lot more heating than you need cooling you may need a larger system. But because they're new a different, as well as in demand, you get price gouging on installation compared to an AC in a lot of places.
As the name implies, a heat pump moves heat around. When you heat your house with a heat pump, you're not (just) converting electricity into heat. The electricity is being used to move heat from outside your house into the house. You make the interior of the house warmer while making the exterior (very slightly) colder. It's exactly the same as an air conditioner or refrigerator, just pointed the other way.
Of course, energy has to be expended to move heat around, and there are inefficiencies. But with real-world equipment and common cold-but-not-too-cold temperatures, a single unit of electricity can be used to move several times as much heat as it would produce if you just converted it to heat directly.
A computer is as efficient as anything when it comes to converting electricity to heat. Heat pumps win because they're ultimately playing a different game.
Strange article. It seems to imply that air-conditioners and heat-pumps are two different animals. But all air-conditioners are just heat-pumps. They just work one-way only. For a few extra bucks, the so-called 'heat-pump' merely has the capability to direct the hot and cold air-flows in the opposite direction.
(In other words, if you took that window-installed air-conditioner and reinstalled it to face the other way in autumn, it would blow the cold air outside in Winter and the hot-air inside.)
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.
It moves existing heat from the outside to the inside of the house. It works exactly like an air conditioner, but in the other direction. (And some heat pumps are reversible so they can be used as both)
However there are air heat pumps which differ from the AC ran in reverse only in how the heat is distributed around the house. For example with warm water in the pipes not just blowing warm air around.
In some countries (Australia), heat pumps are often called Reverse-Cycle Air Conditioners. Some newish (last 25 years or so) houses have no other form of heating.
In other words, reverse the cycle, and instead of the air-conditioner pushing cold air into the room and warm air outside, it will push warm air into the room and cold air outside.
The quickest way for people who know about air-conditioners and don't know about heat pumps is to consider what would happen if you put your air-conditioner the wrong way around in the wall. Instead of lovely cold air coming in and waste hot air going outside, the waste hot air would be heating the house and the cold air would be going outside.
There is no such division of things into air-conditioners and heat-pumps. Air conditioners ARE heat pumps.
In some parts of the world dual-direction heat-pumps are (or rather were) called 'Reverse-Cycle Air Conditioners' meaning they they could be switched from cool-inside/warm-outside to warm-inside/cool-outside.
Another thing to learn is the difference between temperature and heat. It's very similar to the difference between voltage and kilowatt-hours.
And 'cold' or 'freezing' are just labels. A litre of water at 70 degrees C will give the same amount of heat going to 40 degrees C as a litre of water going from 40 degrees C to 10 degrees C.
Similarly 100 cubic metres of 'freezing' air at zero degrees C going to -10 degrees C can give as much heat as 100 cubic metres of air going from 30 degrees C to 20 degrees C.
That 'freezing' air at 0 degrees C is actually at 273 degrees Kelvin. It has A LOT of heat in it.
In the UK domestic heat pumps are typically only capable of heating water, in order to be a drop-in replacement for gas boilers for central heating. These heat pumps are not reversible, and there's no cooling option at all, since houses don't have air ducts for AC, and retrofit is usually infeasible.
An heatpump is either an Air Conditioner (which is really jusf a refrigerator) running in reverse, or an A/C with a reversing valve so it can move (pump) heat in either direction, depending on the application. Heat pump driers and water heaters never cool the clothes or the water, but home heat pumps are almost always setup for heating or cooling.
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