Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

spectrum.ieee.org

Post reply on HN
Print view View original

181–190 of 406 posts

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

#181

Post by rayiner »

simonblack wrote: post #156
rayiner wrote: post #129

Earlier quoted context omitted.

The myth exists because the US is probably 10-20 years behind Europe and China in terms of HVAC and insulation technology. I recently had some reasonably high efficiency heat pumps installed at my house, and I’ve been very unhappy with the low temperature performance. It doesn’t even get very cold here—rarely below 5F (-15C) and a record low of -8F (-22C). The heat pumps I got (recommended by the well-regarded local…

Sounds like the units you are describing don't have an efficient (read 'big enough') heat-exchanger which is why they aren't being effective in not-so-low temperatures. The temperature of the cold-side should not be below outside ambient temperatures if the heat exchanger coils are sufficient. In other words heat-energy should be going into cold side of the heat-pump (even at a low temperatures) at the same rate as i…

It’s a typical size for a heat pump in a US home: https://www.amana-hac.com/products/heat-pumps/18-seer-aszc18...

My understanding is that improved low temperature performance has something to do with varying the amount of refrigerant in the loop: https://www.mitsubishicomfort.com/articles/keep-warm-this-wi...

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

#182

Post by chpatrick »

metiscus wrote: post #11
nottorp wrote: 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.

Here in Europe all modern ACs have that feature. The difference with heat pumps is that they're bigger and usually use underfloor pipes.

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

#183

Post by Alupis »

bfuller wrote: post #166
Alupis wrote: post #140

Earlier quoted context omitted.

Natural gas is available in abundance, is nearly free in terms of cost, and is vastly more "green" than many alternatives available today. It may not be as green as pure electric can be in theory, but in large portions of this country electric isn't all that green either. Heat pumps appear expensive to operate. Imagine running your AC year-round... that very thought makes many-a-homeowner shudder.

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.

Well, the no-gas thing upsets me because cooking on modern electric cooktops/stoves is still staggeringly awful.

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

#184

Post by lsaferite »

simonblack wrote: post #142
jillesvangurp wrote: post #97

Earlier quoted context omitted.

This persistent myth just needs to go away. People use heat pumps all over Scandinavia, including in the arctic circle. They are extremely popular there. They were early adopters of this technology there decades ago. There are two popular varieties: - Ground source heat pumps. Those work pretty much anywhere; just dig below the perma frost and you are good to go on the northern tip of Canada, Alaska, Norway, or where…

Ditto Australia. We've been using 'reverse-cycle air-conditioners' for heating in Australia for decades. I'm puzzled as to why there is any debate at all on their use for heating. A heat-pump is far more efficient for obtaining heat than direct resistive heating using electricity. Many houses here use no other form of heating at all. And then at the press of a button, we get cooling in summer too. What's not to like?…

I've seen heat-pump base water heaters, but never a clothes drier. That sounds interesting. Now I have something new to research, thanks! Personally, I'm always curious why there isn't a more unified heat-exchanger system built into the structure of a house. HVAC, Water, Refrigerator, they all need to move heat from one place to another, why not work together?

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

#185

Post by Maxion »

verve_rat wrote: post #172
simonblack wrote: post #142

Earlier quoted context omitted.

Ditto Australia. We've been using 'reverse-cycle air-conditioners' for heating in Australia for decades. I'm puzzled as to why there is any debate at all on their use for heating. A heat-pump is far more efficient for obtaining heat than direct resistive heating using electricity. Many houses here use no other form of heating at all. And then at the press of a button, we get cooling in summer too. What's not to like?…

Yeah, as a Kiwi, watching all the debate happening here is just super weird. Meanwhile, I'm annoyed that heat pumps that dump the waste heat into the hot water cylinder aren't standard.

It's just the Yanks that have subsidised natural gas in many states, and a messed up energy infrastructure that gives electricity prices in the same range as what we have in Europe while being at war.

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

#186

Post by lsaferite »

nielsbot wrote: post #133
rayiner wrote: post #129

Earlier quoted context omitted.

The myth exists because the US is probably 10-20 years behind Europe and China in terms of HVAC and insulation technology. I recently had some reasonably high efficiency heat pumps installed at my house, and I’ve been very unhappy with the low temperature performance. It doesn’t even get very cold here—rarely below 5F (-15C) and a record low of -8F (-22C). The heat pumps I got (recommended by the well-regarded local…

Can't you get backup heating in addition to a heat pump for the coldest days?

I live in FL and we have a backup resistive heating element that kicks in as needed. Mostly only comes on a few days in the year or for short bursts when there's a cold snap that the heat pump can't keep up with.

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

#187

Post by xenadu02 »

web3-is-a-scam wrote: post #130

My 20 year old air conditioner recently died and I was looking into replacements. In my climate the temperature ranges from 40C in the summer, and -40C in the winter. After doing some research, it seemed pretty clear that having a furnace+AC was the way to go for my climate. Hardly a magic bullet technology.

There is zero reason not to get a dual heat system. A heat pump vs pure cooling A/C is mostly just a reversing valve. There is almost no difference between the two which makes sense: A/Cs are just heat pumps setup to move heat outside the home. A "heat pump" heating system simply runs the other direction to move heat inside the home. Either way it is standard vapor compression with a compressor, two coils, and two coil fans.

Modern heat pump systems have an outdoor temp sensor and will avoid even trying the heat pump if it is too cold outside. Your installer should be able to adjust that setpoint. How low it can go depends on the refrigerant and rating... in the US higher SEER ratings often also means it can extract useful heat at lower outdoor temps.

tl;dr: The heat pump function is a trivial bit of material addition to a standard A/C and saves you gas/electricity even if it is only used for part of the cold season. There is no reason not to use one.

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

#188

Post by Maxion »

Alupis wrote: post #135
kibwen wrote: post #131

Earlier quoted context omitted.

It's actually difficult to say what the cost would be if everyone switched over. The reason is that natural gas is subsidized, both on the production side (at least in the US, which wants energy security) and on the consumption side (because it's politically unpopular to let people freeze to death). Of course, electricity prices are also affected by subsidies. Figuring out the true operating prices would require some…

It seems to me, there is no future where a heatpump can be the only source of in-home heating then. 1) Natural Gas is vastly cheaper in most/all of the US. 2) Homes still require an alternative heating source when temperatures drop to low levels (coincidentally when people need heating the most). So, even if a heatpump is technically more efficient in terms of emissions, the technology does not solve all of the probl…

> It seems to me, there is no future where a heatpump can be the only source of in-home heating then. > > 1) Natural Gas is vastly cheaper in most/all of the US. > > 2) Homes still require an alternative heating source when temperatures drop to low levels (coincidentally when people need heating the most).

> ... > I must be missing something here...

Yes you are, your natural gas subsidized, i.e. government handout, i.e. you're not paying the real market cost.

Second, heat pumps do not have issues with cold temps, unless you're at like -40c. They're used all over the nordic countries - including above the arctic circle.

Your energy grid is shit, which is why your electricity price is so high.

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

#189

Post by ZeroGravitas »

rayiner wrote: post #129
jillesvangurp wrote: post #97

Earlier quoted context omitted.

This persistent myth just needs to go away. People use heat pumps all over Scandinavia, including in the arctic circle. They are extremely popular there. They were early adopters of this technology there decades ago. There are two popular varieties: - Ground source heat pumps. Those work pretty much anywhere; just dig below the perma frost and you are good to go on the northern tip of Canada, Alaska, Norway, or where…

The myth exists because the US is probably 10-20 years behind Europe and China in terms of HVAC and insulation technology. I recently had some reasonably high efficiency heat pumps installed at my house, and I’ve been very unhappy with the low temperature performance. It doesn’t even get very cold here—rarely below 5F (-15C) and a record low of -8F (-22C). The heat pumps I got (recommended by the well-regarded local…

I recently saw a transport nerd claim that US and Canadian (though interestingly not Mexican) busses were substantially and objectively worse in build and ride quality than European busses, even when they share the same engine components.

Which I guess similarly explains a lot of weird conversations and people talking past each other where busses are concerned.

https://youtu.be/U3qeYRI34C8

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

#190

Post by Maxion »

MrRadar wrote: post #116
davidmurdoch wrote: post #56

Being a Florida native, seeing an article titled "Heat Pumps [are] the Future of A/Cs" feels like it should have a ` [1973]` tacked on to the end of it. A heat pump is pretty much the only thing we use here, we just use them in reverse. Literally. Most residential units have a "reversing valve" that must be held open by a constant 24V in order to cool the air - the default mode is heating -- which is so smart to have…

A large part of it is that heat pumps only within the past decade became efficient enough to install in northern US climates, where temperatures are below freezing 4+ months of the year. It's relatively easy to design an air-source heat pump that will work efficiently down to freezing, it's much harder to design one that will work efficiently well below freezing, and frankly the A/C manufacturers who traditionally so…

Air source heat pumps have worked well at -20c for a few decades now over her ein Finland. Not sure what type of chinesium grade heatpumps you have over there in the US.
Post reply on HN