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Heat Pumps – The Well-Tempered Future of A/Cs

spectrum.ieee.org

11–20 of 406 posts

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#11
post #3

Isnt any a/c a heat pump though?

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.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#12

Well this was an oddly terrifying introductory paragraph for an IEEE article: "... half of Phoenix residents are at risk of an emergency room visit or worse if their electricity fails during a future heat wave, according to a recent study. Air conditioning is what keeps people there comfortable—and alive—a growing fraction of the year. The extreme heat already kills hundreds of Phoenix-area residents every year, a nu…

I've read a few times that the population of the entire US south only really started to grow in earnest once AC was invented.

Ah, here's an article: https://www.nytimes.com/2017/08/04/upshot/the-all-conquering...

It's pretty crazy because growing up in central/northern Alberta, I never even really encountered air conditioning until I was into my early 20s and moved to southern Ontario (where living without it would be complete hell in the summer, hot humid disgusting "I feel like I'm being smothered in someone's armpit" summers). Our cars never had it and our houses certainly didn't need it; just an open window. Summers were mild and the heat when it came was a dry heat.

But now when I go home to visit there, A/C is everywhere there, and it's frankly needed; the last summer I spent time out at my parents west of Edmonton there were multiple days in a row over 30C and it was frankly quite hellish and them having a ground source heat pump that cooled the house was a godsend. Just the 2-3C difference in peak temperatures from the 80s til now is enough to push it over the edge into new territory.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#13
post #3

Isnt any a/c a heat pump though?

Yes, but typically “heat pump” is used to mean it can provide heating too, whereas standard “A/C” is a “one-way” heat pump that only provides cooling.

I always went with this description too, though oddly a "heat pump water heater" only works one direction, yet "heat pump" is still in its name.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#14
post #5
post #3

Isnt any a/c a heat pump though?

I have never really understood the difference between a heat pump and an A/C myself. Any expert care to explain it in layman's terms?

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.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#15
I live in a colder climate where heat pumps are not popular. After talking with a number of HVAC people about this I was surprised to learn that despite being very similar to an AC system in principle, in practice converting an AC system into a heat pump system doesn't make economic sense--you end up just ripping one out and installing the other.

I don't fully understand why this is the case, but I hope that there's something that can be done to improve it. I'd love it if I could drive my AC unit as a heater for 95% of the winter, resorting to natural gas only during in the extreme cases.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#16

Well this was an oddly terrifying introductory paragraph for an IEEE article: "... half of Phoenix residents are at risk of an emergency room visit or worse if their electricity fails during a future heat wave, according to a recent study. Air conditioning is what keeps people there comfortable—and alive—a growing fraction of the year. The extreme heat already kills hundreds of Phoenix-area residents every year, a nu…

Sure, but it can happen anywhere. I was just reading yesterday about a person who died in Portland of heat during the dome. Same with cold weather, if the gas/electric goes out during the winter. There's really only a few places one can live with moderate enough weather to avoid those scenarios.

Half of Phoenix vs A person in Portland.

It seems like there’s an important scale issue there. So the risk isn’t really the same everywhere.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#17

I live in a colder climate where heat pumps are not popular. After talking with a number of HVAC people about this I was surprised to learn that despite being very similar to an AC system in principle, in practice converting an AC system into a heat pump system doesn't make economic sense--you end up just ripping one out and installing the other. I don't fully understand why this is the case, but I hope that there's…

[deleted]

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#18
post #5
post #3

Isnt any a/c a heat pump though?

I have never really understood the difference between a heat pump and an A/C myself. Any expert care to explain it in layman's terms?

* 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.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#19
post #5
post #3

Isnt any a/c a heat pump though?

I have never really understood the difference between a heat pump and an A/C myself. Any expert care to explain it in layman's terms?

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.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#20
I have both HVAC and a ducted heatpump for one part of the home. The biggest issue with the heatpump is that in the climate I live in there are times of year where you may have the heat on in the morning and the AC in the afternoon. Or you may leave and when you return you want to change the temperature. A furnace and an AC can do this rapidly. A heatpump takes time. It's more of a trickle of climatized air than a blast of it.

Also, I'd never want a ductless system as they look awful in a room.

They are the future though. Especially as new regulations go into effect by 2035. Sadly, many American manufactures haven't taken it seriously and are far behind the Asian companies like Daikin.

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