[HN Gopher] Heat Pumps - The Well-Tempered Future of A/Cs
___________________________________________________________________
Heat Pumps - The Well-Tempered Future of A/Cs
Author : mfiguiere
Score : 69 points
Date : 2023-07-05 15:47 UTC (7 hours ago)
(HTM) web link (spectrum.ieee.org)
(TXT) w3m dump (spectrum.ieee.org)
| [deleted]
| davidmurdoch wrote:
| 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 failure mode that causes
| your house to be heated in the summer to 95F while you sleep.
|
| Anyway, my heat pump just stopped working this weekend, and its
| getting very hot in here.
| chrsig wrote:
| My electric furnace needed to be urgently replaced in the
| beginning of the winter, I'm quite happy that my new heat pump
| would default to heat...Half of the year :)
| MrRadar wrote:
| 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
| sold to the US market haven't really tried all that hard (they
| probably don't/didn't expect a large enough market to offset
| the development costs). It's newer market entrants from Asia
| that are really pushing the envelope of heat pump efficiency
| and making it feasible.
| Maxion wrote:
| 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.
| __MatrixMan__ wrote:
| 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.
| elil17 wrote:
| There's no reason you couldn't just switch a couple valves out
| in your AC and perhaps change the refrigerant to make it into a
| serviceable heat pump. However, you'd need to retrofit
| controls/electronics, which I don't think most HVAC technicians
| would know how to do. It's also not advisable to attempt to DIY
| something like this because it is very easy to accidentally
| vent the refrigerant, which is a very potent greenhouse gas.
| __MatrixMan__ wrote:
| Right. It's a problem best confronted by the AC manufacturer.
| Except they have no incentive to do so (because if they
| don't, they get to sell an entirely separate heat pump down
| the line). Which means it's perhaps a problem for the
| regulator.
|
| There are tax breaks involved with installing "energy star"
| rated equipment. Perhaps we ought to start witholding the
| star from AC units that are not easy to convert to heat pumps
| (and from thermostats, etc, which are not ready to handle the
| conversion).
| elil17 wrote:
| I think that would be an excellent regulatory solution. You
| should write to your representatives. Since heat pumps are
| getting a lot of regulatory attention, it might actually
| get considered.
| amluto wrote:
| Converting an A/C to a heat pump is a bit like upgrading an old
| Lenovo laptop to a modern CPU. It's surely doable, and the
| parts are unlikely to be terribly expensive, but as a practical
| matter it's pretty specialized and no one does it.
|
| What you do is wait for the A/C to hit end of life (or end of
| efficient life if new systems are enough more efficient) and
| replace it outright.
|
| (I once got a quote, in an expensive market, to add an A/C to
| an existing furnace and, separately, to remove the furnace and
| add a three-head multi-split heat pump. The two quotes were
| almost the same price. The equipment is not especially
| expensive.)
| [deleted]
| GlickWick wrote:
| I switched in New England when my freon system hit end of life.
| I wouldn't recommend doing it beforehand, but as a replacement
| it's been incredible. All the ductwork and infrastructure
| largely remained the same. Pulled out the furnace, evaporator
| coils, and compressor of course.
|
| It cools better than the old system, and the fact that it runs
| longer instead of in short bursts means it regulates humidity
| way better too.
|
| For heat we did go dual fuel, which means the backup heating
| element uses gas, since we already had the line. This works
| really well in a cold snap where temps drop well below
| freezing.
| ilamont wrote:
| Fellow New Englander here. We had a 4 unit heat pump system
| installed a few years ago, replacing a bunch of window air
| conditioners. Not only is it a vast improvement over the
| window ACs in terms of ease of use, sound levels, comfort,
| and electricity use, it has become our default heat source in
| the winter as well, greatly reducing our natural gas bills.
| nightski wrote:
| The thing is (especially where I live) I'd still need a gas
| furnace. We regularly see -20F to -40F in the winter. While the
| 95% scenario sounds great, in practice still needing gas means
| we still need all the gas infrastructure. From my understanding
| natural gas burns pretty clean. The problem is leaks in
| infrastructure and drilling, which isn't going away because I
| buy a heat pump.
| elil17 wrote:
| Although natural gas is "clean" compared to, say, coal, the
| advantage of a heat pump is that it uses less total energy
| than natural gas. That means it would be more efficient to
| run a heat pump off a natural gas power plant than to burn
| natural gas to heat your home directly.
| Alupis wrote:
| People's AC summertime electric bills regularly get into
| triple-digits - it's not uncommon to hear someone with a
| moderately sized home having a $200-400 electric bill in
| the summertime.
|
| However, even in the midst of winter, gas heating bills
| rarely climb above $100 monthly.
|
| What am I missing here? It seems a heatpump, while more
| efficient, will cost significantly more to operate. Natural
| Gas is _cheap_... and clean enough.
| bluSCALE4 wrote:
| I'm with you here. I replaced a gas water heater with a
| hybrid water pump and I'm paying more for my troubles.
| The thing is, I do plan on installing PV panels in a few
| years--I can't generate my own gas so once I make that
| happen, I'll be a happy camper.
| kibwen wrote:
| 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 research. However, it remains
| true that, in terms of greenhouse gas emissions, it is
| usually preferable to heat a home with a heat pump than
| by burning gas directly (there exists a temperature below
| which any given unit will become less efficient than
| burning gas, but unless you live in a place where this
| temperature is common then heat pumps will still come out
| on top (and the fact that residential gas lines are
| notoriously leaky and basically just venting nonstop into
| the atmosphere makes the calculation even more
| favorable)).
| Alupis wrote:
| 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 problems it's attempting to replace. Additionally,
| Natural Gas is vastly more clean in terms of emissions
| than some other alternatives still used around the
| country.
|
| There's no way the average home is going to stomach 2-4x
| more heating expenses on average without some real
| tangible benefit (hand-wavy emissions numbers don't
| factor into the average homeowner's decision making).
|
| I must be missing something here...
| Maxion wrote:
| > 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.
| Alupis wrote:
| > Yes you are, your natural gas subsidized, i.e.
| government handout, i.e. you're not paying the real
| market cost.
|
| > Your energy grid is shit, which is why your electricity
| price is so high.
|
| Adding a heatpump solves this issue, or makes it worse?
| __MatrixMan__ wrote:
| Where I live, you can bank solar credits. If you cash them
| out you get the "wholesale" energy price for them (much
| lower), but if you spend them on electricity then you've
| avoided paying full price for that electricity. So if your
| system produces more than you consume, you've got this free
| energy budget to spend--a budget that applies to heat pumps
| and not to gas furnaces.
| bklyn11201 wrote:
| You need a backup heat source, but it doesn't necessarily
| mean you need full infrastructure of gas lines, ducting, and
| gas furnace. You could have an electric backup connected to
| ducted heat pump (e.g., non-efficient, pure electric) or
| could use electric strip heating, electric portable heaters,
| wood stoves, etc.
| nightski wrote:
| We have electric baseboard. It would cost hundreds more per
| month to utilize something like that instead of gas when it
| is -30F. In fact if we just leave it on over night a single
| time we notice it on our bill.
| thehoff wrote:
| Replaced our entire system (furnace, a/c) mid last year. Heat
| pump with backup oil for colder days.
|
| We cut the amount of gallons we used by over 50% compared to
| last year. Sure the oil infrastructure is needed to get it
| delivered (I wish we didn't need it) but I'm very happy that
| our heating (oil+electricity) bills are so much lower, even
| with the increased oil prices.
|
| We went with a mid-range system but now I kind of wish we
| sprung for the "Cadillac" version.
| nightski wrote:
| I suppose this would be true if gas is expensive where you
| live. It's really cheap here, our heating bill is like
| $80/mo in the coldest of months for a 3k sq ft house. A
| heat pump even with the efficiency gains would be on par
| with that (unless we jumped into solar, which I have
| considered).
| GlickWick wrote:
| They make heat pumps with backup gas systems now.
| epistasis wrote:
| It's a $300 part that allows swapping the direction of heat
| flow. This tiny upfront cost is enough to block tons of good
| practice.
|
| Nate the House Whisperer is a guy who has been trying to build
| a new generation of HVAC practice, and though he says he's
| usually a libertarian, he advocates for adding a tax to AC-only
| units that would eliminate this price difference (or some
| similar practice, I forget the exact details...)
| [deleted]
| earlyriser wrote:
| I live some 5 hours north of Montreal, we have few days at -40C
| and wall radiators (not sure about the name) are needed, but
| for most of the winter days we use the heat pump to heat the
| house (-21C and up). Some members in my family work in
| AC/Refrigeration industry and all of them have thermo pumps,
| which make economic and ecologic sense. On the other side I
| don't know about AC/heat pump replacements as it's not common
| to have AC for the just a handful of days that could be very
| hot.
| jillesvangurp wrote:
| 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 wherever. Works
| great, ground temperatures tend to be very stable and it
| actually goes up the deeper you dig.
|
| - Air source heat pumps. The expensive ones still work okish at
| extreme temperatures like -25-ish degrees C. Which is a reason
| these are actually more popular than ground sources even in
| places (e.g. most of Scandinavia) that reliably get such
| temperatures each winter.
| simonblack wrote:
| 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 also have a heat-pump condensing clothes dryer. The
| overall heat thrown out into the room is extremely low. The
| hot-air comes out the hot-side of the heat-pump to dry the
| clothes. The warm-moist air then passes over the cold coils,
| condensing out the water from the clothes and returning the
| heat to the cold-side of the heat pump which then pushes that
| heat-energy out the hot-side, producing more hot air to
| complete the cycle. I've had this Miele heat-pump condensing
| dryer going strong since 2009 - 14 years.
| lsaferite wrote:
| 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?
| verve_rat wrote:
| 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.
| Maxion wrote:
| 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.
| pkaye wrote:
| I was trying to find heat pump adoption rates for Europe
| and US.
|
| Seems like its still pretty low in Europe outside some
| northern countries. Germany is less than 2000/100000
| people.
|
| https://www.theecoexperts.co.uk/heat-pumps/top-countries
|
| Meanwhile this link says US has a 15% adoption rate
| across all income groups. That seems higher than I
| expected.
|
| https://energypost.eu/u-s-heat-pump-adoption-is-evenly-
| sprea...
|
| Is there a better source on heat pump adoption rate in
| Europe and US?
| rayiner wrote:
| 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
| HVAC company) operate at just 40% of rated capacity at 0F.[1]
| Meanwhile, Chinese and Japanese-made inverter driven heat
| pumps will happily go down to -5F at 100% of rated capacity,
| and -22F (-30C) at 80% of rated capacity.
|
| [1] You can of course get a much larger heat pump to
| compensate, but that leaves the unit way over-sized for
| cooling loads.
| ZeroGravitas wrote:
| 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
| amluto wrote:
| In my local market, if you ask an installer for a heat
| pump, you get something from Japan or Korea. I've never
| encountered an American unit.
|
| (I'm referring to normal air-to-refrigerant-to-air heat
| pumps. I know of a really weird system that is thoroughly
| American and an utter pain in the arse to replace because
| it's specialized and undocumented. It's quite loud, too,
| because it's single-speed, and that single speed is
| _waaaaay_ too high.)
| nielsbot wrote:
| Can't you get backup heating in addition to a heat pump for
| the coldest days?
| lsaferite wrote:
| 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.
| simonblack wrote:
| 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 it is coming out the hot-side at high temperatures.
| Reduce the heat in, and you will reduce the heat out.
| rayiner wrote:
| 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...
| __MatrixMan__ wrote:
| I've been on zoom calls with two separate co-workers who are
| all bundled up because their heat pump can't handle the
| weather. It doesn't mean that the technology is inadequate in
| principle--probably their systems have some problem that
| competent HVAC installers know how to avoid.
|
| But its an unfortunate fact that there are places in the US
| where installers that recommend heat pumps can't be found for
| 100 miles. It doesn't really matter if I'm technically
| correct about the merits of the tech in principle--if I can't
| find somebody to fix my system and my pipes start exploding,
| I've still made the wrong decision.
|
| Also, heavy snows cause power outages in places where tree
| limbs fall on overhead lines. If gas outages happen... well
| I've never experienced one. Sure, if I lived in Norway I'd
| have a government that cares about updated infrastructure and
| I wouldn't have these problems, but since I don't, I do.
|
| Given my local constraints, a dual-fuel system sounds pretty
| great.
| jillesvangurp wrote:
| Gas outages happened at a large scale in Texas when they
| were struggling with a bit of cold weather. When they
| needed it the most, it failed them. Coal plants also
| struggled. Both had challenges with supply of fuel and
| cooling water being disrupted. That kind of systemic
| infrastructure failures is on the rise in the US. There are
| all sorts of reasons why governance just isn't great in the
| US. But the reality indeed is that things are unlikely to
| improve on that front.
|
| Which are all good reasons why the market for domestic
| solar, batteries, and heat pumps is so hot right now. The
| US is no exception to this.
| nawitus wrote:
| Properly designed heat pump system includes backup for the
| coldest days - usually direct electric heating.
|
| Most houses in Finland have a (decent) fireplace for
| heating in case of an electric outage.
| gambiting wrote:
| Air source heat pumps are super popular in Poland too, this
| winter it was about -20C for couple weeks straight and not
| had any problems, toasty house without any issues. The key is
| that the heat pump exchanger really needs to be huge(ours is
| taller than a person) to get the heat out of the air.
| aurizon wrote:
| These gradient comfort guys want $5000 for an 8000 btu unit with
| a total weight of $150 pounds. Compressor and heat exhaust hand
| outside. Evaporator and fan/control hang inside, It has a SEER
| rating of 10. There are dozens of minisplits for $1000 that have
| a SEER from 19-24. I can see no reason why a close coupled mini
| split with a 1" armored electrical/freon joint could not be made.
| This is what a gradient comfort is WTF $5000
| https://www.gradientcomfort.com/products/gradient-window-hea...
| web3-is-a-scam wrote:
| 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.
| bfuller wrote:
| Heat pumps require more specialized techs to work on them too.
| lsaferite wrote:
| HVAC techs can work on Heat Pumps just as well as on
| dedicated ACs. They are not significantly different.
| xenadu02 wrote:
| 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.
| amluto wrote:
| As a (small) reason, the controls involved in operating a
| heat pump plus furnace/fan are more complex than the controls
| involved in operating a plain air conditioner plus
| furnace/fan. (Possibly more than a little more complex if the
| heat pump is only operable under certain conditions and the
| heat pump and/or furnace is multi-stage or actually variable
| speed.). HVAC controls are very solidly stuck in the 1980s
| (or 1950s or whatever), with the main exception of highly
| integrated and proprietary variable speed heat pump controls.
|
| I say this as someone who recently helped undo the damage
| after an inept HVAC technician replaced someone's thermostat
| (for $500, thanks California prices) and did it wrong. The
| quality of the instruction manuals is low, and the quality of
| online resources about how conventional HVAC controls work is
| lower.
|
| As far as I can tell, the theory is that HVAC systems used to
| consist of a bunch of discrete components, strung together,
| with control power coming from one or two transformers or
| thermocouples [0], and essentially no logic in the equipment.
| A relatively modern heat pump may well rely on a mechanism
| _in the thermostat_ to protect the compressor. The actual
| equipment contains nothing resembling a microcontroller.
|
| [0] Yes, the actual power available from the equipment to the
| thermostat may be negligible, and old thermostats were
| mercury switches on bimetallic strips that were powered
| solely by temperature changes in the room.
| Casteil wrote:
| Similar climate here, although days it gets below -10f / -23c
| are uncommon. Most winter days in a climate like this you could
| heat with a modern/high tech heat pump, but:
|
| - It's probably going to be more expensive than heating with
| natural gas if you're in the northern US - at least as things
| are today.
|
| - A modern/high tech heat pump capable of heating when the
| outdoor temp is < 10f / -12c is likely going to be quite a bit
| more expensive than a standard AC unit - making it even more
| difficult to justify financially
|
| - A natural gas furnace can keep you warm (and keep your pipes
| from freezing/bursting) even if there's a power outage. It
| doesn't take much of a generator to run a furnace/blower fan..
| but good luck staying warm with ONLY a heat pump in those
| circumstances.
|
| The one thing that can really help improve the financials of
| getting a heat pump is if you intend to install solar power at
| some point in the future. Depending on your power company, you
| may be able to generate enough credit in summer with excess
| generation to pay for heat the entire winter. I'd still go with
| a heat pump AND gas furnace for backup though.
| martythemaniak wrote:
| Same situation, but I'm looking to replace the AC with a HP.
| For a little extra money, you get the flexibility to choose
| your heat source. Newer thermostats can be programmed to switch
| between the power sources and you can hedge against one price
| fluctuations in one of the power sources.
| mason55 wrote:
| Is that the typical range in a normal year? Or is that the all-
| time extreme record?
|
| One thing people tend to do when they look at heat pumps is
| look at the typical extreme low for the year and size the heat
| pump based on that. But even if you touch -20 a few times a
| year, your heat pump doesn't need to be sized to heat in a
| constant -20. If you hit -20 once or twice per year then it's
| usually only for a few hours and the lowest that you really
| need to heat through is usually much closer to -10 or higher.
|
| But, yes, if you're in a climate that sees frequent and
| sustained temps of -40 then a heat pump probably isn't for you
| or the rest of the Canadian Prairies.
| nielsbot wrote:
| -40C? That's an extreme situation. Heat pumps can be installed
| with backup heating as I understand it.
| ZeroGravitas wrote:
| You also get "hybrid" heatpumps that work alongside other
| sources of heat.
| Alupis wrote:
| > Heat pumps can be installed with backup heating as I
| understand it.
|
| Then, what's the point? If you still have to have gas lines
| and infra, just use the gas. It's vastly cheaper.
| mason55 wrote:
| > _Then, what 's the point? If you still have to have gas
| lines and infra, just use the gas. It's vastly cheaper._
|
| A) Not everywhere
|
| B) Heat pumps can be powered with solar, reducing costs
| even if your gas would normally be cheaper
|
| C) Some people are willing to spend a little more if it
| helps push electrification forward, for environmental
| reasons
| frumper wrote:
| I tend to need heat when the sun isn't warming everything
| up.
| Alupis wrote:
| > Some people are willing to spend a little more if it
| helps push electrification forward, for environmental
| reasons
|
| It's not a little more though, that was the point. In my
| area, California, it's about 4x more. Gas here is so
| cheap, it's almost free.
|
| Anecdotally, I don't know anyone who's opted into the
| "green energy" plans offered by the area's utility
| providers - because they all cost a lot more than
| regular.
|
| People talk a lot - but their bank account dictates their
| actual decision making. Running a heatpump seems very
| expensive for a lot of the country, with negligible
| gains.
|
| Natural Gas isn't exactly what we would call "dirty"...
| seems like a min-max issue, with people forgetting
| there's still areas burning coil and oil for electricity
| production.
|
| > Heat pumps can be powered with solar
|
| Not in the dead of winter you can't... not everyone lives
| in big cities folks, and where it snows, it gets quite
| cold.
| zamalek wrote:
| D) Carries the risk of killing you with CO.
| baseballdork wrote:
| > Then, what's the point?
|
| Minimizing your gas use?
| dtgriscom wrote:
| That depends on the temperature difference. For smaller
| differences, heat pumps are much more efficient, but at
| some level they lose efficiency and gas is cheaper.
| usrnm wrote:
| > That's an extreme situation
|
| Depends on where you live
| galangalalgol wrote:
| Its 48C down to -10C here. Some years get down to -18, but
| not enough to build for it. That extra 8C has a qualitative
| difference to the steps that need to be taken for people
| and structures. The problem this year has been high
| humidity at that high end, much more than normal. When you
| have over 40% relative humidity and its over 45C it makes
| air conditioners work extra hard due the specific heat of
| the water vapor they are cooling. There were some
| dessication technologies being talked about last year that
| would really help as they operated prior to cooling the air
| but I haven't seen them rolled out yet. I've heard
| anecdotes about EVs refusing to operate due to battery
| safety, and public transit shutting down due to
| insufficient cooling capacity.
| loeg wrote:
| It's an extreme climate that ever reaches -40.
| xeonmc wrote:
| Fahrenheit or Celsius?
| abulman wrote:
| Yes.
| scq wrote:
| -40 is the one value where Fahrenheit and Celsius line up
| exactly.
| kuchenbecker wrote:
| [flagged]
| NovemberWhiskey wrote:
| It doesn't matter.
| thsksbd wrote:
| [dead]
| Darrengineer wrote:
| I'm curious which areas this occurs on earth and what percent
| of population live there. I would guess a negligible portion.
| In the US, I would think it's almost nonexistent. I'm from
| Minnesota and went to university in North Dakota - places with
| some of the coldest and most severe winters in the US. +40C in
| the summer and somewhat regularly down to -40C windchill
| temperature in the winter. If it were me, a place with actual
| air temperature of -40C with any kind of wind occurring would
| require multiple forms of heating for me to consider it safe
| for my family relying on only one or even two sources of heat
| doesn't seem reasonable.
| loeg wrote:
| Most people live somewhere with vastly milder winters.
| Generalizing from your -40C winters is not useful.
| nemo44x wrote:
| 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.
| davidmurdoch wrote:
| Mine take maybe 2 minutes to switch from heating to cooling, or
| cooling to heating.
| nemo44x wrote:
| I'm saying the time it takes to change the temperature in the
| home, not the time to switch function.
| davidmurdoch wrote:
| I use a thermostat that can switch modes automatically to
| keep temps within a certain defined range. So I think
| that's why it's not a problem for me.
| [deleted]
| itzworm wrote:
| There are ceiling cassettes for mini-split systems that aren't
| nearly as much of an eyesore as the wall mount ones are.
| Schweigi wrote:
| Mini split systems can be used with ducts. All big venders
| sell heads which are specifically made to be connected to
| ducts. That way you get the best of both worlds and its also
| easy to retrofit to an existing (ducted) house.
| samtho wrote:
| This is a little known fact outside of the HVAC trades as
| everyone associates mini-split systems with the infamous
| wall-mounted indoor unit. I bought this LG unit[0] which I
| used some duct-foam board to build an adapter for and
| fanned out ductwork for that zone. People are amazed when I
| tell them this is a ducted mini split.
|
| [0]: https://www.supplyhouse.com/LG-LDN127HV4-12000-BTU-
| Multi-F-C...
| adgjlsfhk1 wrote:
| If you have the heat on in the morning and AC in the afternoon,
| your home is horribly under-insulated (or you are trying to
| keep in way too small a temperature range).
| nemo44x wrote:
| Old homes tend to not have any insulation. Parts of my house
| have modern insulation due to renovations/additions but other
| parts not so much. I wouldn't swap out the original windows
| and glass on the facade, for instance. And insulating it
| would probably be a destructive action as you need proper
| vapor barriers for insulation to not rot your home.
| Kye wrote:
| It's interesting how a sufficiently large local norm can affect
| perspective. I thought everyone had heat pumps for the longest
| time. I've rarely seen a building without them. I also live in
| the southeast where they're at their best.
|
| Then this recent rise in popularity elsewhere dispelled that
| notion.
| digdugdirk wrote:
| 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 number that went up by 25 percent from
| 2021 to 2022."
| genmud wrote:
| Luckily, the local grid here in AZ is fairly robust, probably
| one of the best in the US. During the 3 years I lived in DC
| area, I probably had 3 or 4 power outages due to weather
| (ranging from a couple hours to multiple days).
|
| In the 30+ years I have lived in Arizona, I have experienced
| probably 2 outages, lasting a total of a few hours (one was
| when a car hit a transformer, the other was when a microburst
| knocked a bunch of aging poles down).
|
| The last outage I had was like 6-8 years ago.
| silisili wrote:
| 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.
| colechristensen wrote:
| Eh, it is much much easier to keep warm when it's -40
| outdoors than it is to keep cool when its 120+ outside.
|
| Unless you have a terribly insulated shelter, blankets,
| coats, and friends will keep you warm enough to the extent
| that unless you are not really capable of taking basic care
| of yourself, you're not dying of the cold when your heat goes
| out. You can always do more insulation, and you only need so
| much for your body to keep you warm.
|
| With heat though you run out of things to do.
|
| There is a difference between an impaired person or a person
| doing something unwise dies of the heat or cold... and there
| being an environment where there's nothing a healthy adult
| can do to survive without powered heating/cooling.
| ericd wrote:
| And that's why you see fireplaces/stoves in a lot of houses
| in the northeast, even if they have gas/electric heat.
| phpisthebest wrote:
| >>Same with cold weather,
|
| I 100% disagree with this...
|
| Heat is made by everything, waste heat is a byproduct of all
| modern things, and there are TONS of easy low cost ways to
| make heat even it is just as simple as burning something.
|
| Also the body makes head naturally so adding layers to trap
| this heat does not require continual inputs from an outside
| resource
|
| Cooling on the other hand is MUCH harder, and electricity is
| really the only avenue to make cooling. Even if you say use
| ICE, well that Ice was made at some point by a freezer
| running on Electricity
|
| IMO hot climate is MUCH MUCH more dangerous than cold, which
| is why I choose to live in an area where there are only 1 or
| 2 months of even remotely hot climate.
|
| As I told my last HVAC... Heat I can make 100 ways... Cooling
| I need central air for...
| silisili wrote:
| For a young/healthy person, sure. But these aren't
| generally the at risk people in the first place.
|
| I grew up around the 38N parallel, gross enough to get too
| hot in the summer and too cold in the winter. Every winter
| people froze to death, just the same.
|
| It's not as bad as Phoenix percentage wise, but it's still
| a risk in the vast majority of places that people in the US
| live.
| phpisthebest wrote:
| Of course people can and do die from cold, that was never
| my claim
|
| My Claim is providing people with emergency heat is FAR
| FAR FAR FAR easier and cheaper than providing people with
| emergency cooling.
|
| Do "at risk" people die in the north from the cold,
| absolutely but I am not sure how that means the cold is
| worse
|
| As it stands right now, just from my daily activities my
| waste heat in my home makes my home about 10-15 degrees
| above ambient. Meaning in the winter if my target temp is
| 65deg, it would have to be 50 degrees or colder outside
| before I would even think about running my heat.
|
| In the winter time that means my AC is working hard to
| not only combat the outside temp but the internal waste
| heat from computers, cooking, TV's, humans, etc.
| tiahura wrote:
| 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.
| RationPhantoms wrote:
| Good point on the scale. However, Phoenix is also a
| retirement destination so you're looking at a larger
| portion of the population being susceptible to heat waves.
| AlbertCory wrote:
| > Phoenix is also a retirement destination
|
| People who retire there most likely go up to Flagstaff in
| the summer, or further north.
|
| Or they just have good A/C.
| zht wrote:
| what?
|
| do you really not see a difference between a place where the
| event is much more likely to happen for a much longer % of
| the time than another place where the same event is much less
| likely to occur?
| cmrdporcupine wrote:
| 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.
| retrac wrote:
| I've likewise read arguments that AC is linked to the
| substantial economic growth in the second half of the 20th
| century, in regions like southern France, southern Japan, and
| the southern United States. All regions that historically
| lagged economically behind their culturally and economically
| similar more northern counterpart regions. Hard to say how
| much of a factor, but there has to be some truth to it: just
| imagine productivity in a Texas factory at 40 degC and 90%
| humidity vs. 25 degC and 50% humidity.
| kalleboo wrote:
| The man credited with making Singapore the powerhouse it is
| today has also been adamant that without Air Conditioning,
| tropical countries couldn't develop
| https://www.vox.com/2015/3/23/8278085/singapore-lee-kuan-
| yew...
| londons_explore wrote:
| It raises the question of if we should deploy 'emergency
| coolers' - perhaps single-use barrels of some chemical that
| gets cold when a pull-tab is pulled. To be a workable solution,
| it needs to be more reliable/cheaper/more effective than just a
| regular gasoline generator powering a regular aircon unit.
|
| After a flood/hurricane/nuclear strike, they would provide
| enough coolness to keep people alive for a few days.
| sigilis wrote:
| Water can be used for this purpose, and swamp coolers are
| something that can be pretty trivially implemented by people
| in relatively dry areas. For very humid places you generally
| need energy input for cooling.
| mindslight wrote:
| I believe the straightforward answer is to dig a hole. But it
| would certainly be interesting to calculate exactly how much
| cooling capacity you could get out of one or two 55 gallon
| drums of some endothermic precursors. Bonus points for being
| easily reversible when the electricity comes back on (like
| those sodium acetate heating packs).
| afavour wrote:
| I've only ever visited Phoenix but when I did it was mid July
| and being outside genuinely did not feel hospitable to human
| life. That statement doesn't surprise me at all. Unless you're
| employed in, I dunno, the solar power industry I really feel
| like you shouldn't be living there. It should be like living on
| an oil rig.
| melling wrote:
| Can't deal with a little extremes on earth?
|
| Sort of makes one wonder how we're ever going to colonize
| Mars so we're not a single planet species.
| brabel wrote:
| Do you think people shouldn't be living in Chicago (or most
| of Canada and the US midwest for that matter) because without
| heating it's just completely inhospitable to human life
| during the winter?
|
| Or pretty much all Australian cities in summer?
| pkulak wrote:
| Relying on a coat for survival is very different from
| relying on an HVAC system. One has no moving parts,
| requires no external inputs, and is routinely handed out
| for free to those who can't afford them.
| afavour wrote:
| Heating is considerably more energy efficient than having
| to run ACs all over the place. And if you need to go
| outside when it's cold you can: you add layers of clothing.
|
| In Arizona, in the middle of summer, you could be buck
| naked and you'd still overheat (and get burnt, to boot).
| triceratops wrote:
| > Heating is considerably more energy efficient than
| having to run ACs all over the place.
|
| That's actually incorrect. Heating takes considerably
| more energy.
|
| When you're cooling you're looking at a temperature delta
| of at most 20 degrees C/45 degrees F between outside and
| inside. When you're heating, it can be easily be twice
| that. Or even more, in parts of Canada or the Great Lakes
| states.
|
| Air conditioning is a heat pump and can achieve up to
| 300% efficiency. Whereas most houses in cold climates use
| furnaces, which have at most 98% efficiency.
|
| Now that we have more efficient cold-climate heat pumps
| all of this may gradually change. But as of right now,
| what you're saying is wrong.
| mindslight wrote:
| > _Air conditioning is a heat pump and can achieve up to
| 300% efficiency. Whereas most houses in cold climates use
| furnaces, which have at most 98% efficiency._
|
| No. You can't directly compare "efficiency" numbers
| across different energy sources. My understanding is that
| the efficiency of gas powered electricity generation is
| around 33%, meaning that powering a heat pump with a COP
| of just under 3 will be of similar end-to-end efficiency
| as burning the gas directly in a condensing
| boiler/furnace.
| triceratops wrote:
| End-to-end efficiency calculations are tricky and depend
| on a lot of variables.
| elcano wrote:
| Heating under usual winter conditions would consume more
| energy than cooling under practical conditions. Yes.
|
| But that's very different than claiming than cooling is
| more efficient than heating. In A/Cs the ratio of energy
| (in the form of heat) removed to energy consumed is very
| low, around 10-15%.
|
| In furnaces the ratio of energy added to energy consumed
| is around 90%, which was pretty good until the emergence
| of heat pumps. There almost all the energy consumed is
| added to the output in addition to all the energy removed
| from the other side. That's why the efficiency in heat
| pumps is beyond 200%.
|
| In summary, no. Cooling is not more efficient than
| heating. But given the temperature differential when
| cooling the energy consumption is usually higher.
| triceratops wrote:
| > In A/Cs the ratio of energy (in the form of heat)
| removed to energy consumed is very low, around 10-15%.
|
| Why is that?
|
| Obviously I'm referring to efficiency in practice. In
| theory, heating and cooling should be equally efficient
| for a perfect heat pump, right?
| megaman821 wrote:
| Heating takes considerably more energy than cooling.
| Especially since most heating is done with natural gas,
| if homes were heated with a heat pump it would already
| 2-4x more efficient. Then if you look at the temperature
| delta between outside and room temp, the cold climates
| have a much larger difference. Taking 100 degree air down
| to 75 takes less energy than bring 20 degree air up to
| 65.
| rcme wrote:
| Until the widespread use of heat pumps, AC was much more
| energy efficient than heating.
| chickenpotpie wrote:
| I haven't formed an opinion on the matter yet, but I do
| think there's a large difference between it being too cold
| and too hot.
|
| If I'm too cold and my power goes out I have a lot of
| options to survive. I can put on more clothes, get under a
| blanket, light my furniture on fire, etc
|
| If I'm too hot and my power goes out, I die. Once the wet
| bulb temperature gets above a certain level in shade,
| there's nothing that can be done to stop me from dying
| except Air Conditioning.
| addisonl wrote:
| Wet bulb isn't an issue in notoriously dry Phoenix. If
| your power goes out in Phoenix you jump in a pool.
| chickenpotpie wrote:
| What? That doesn't make any sense at all. The whole point
| of wet bulb temperature is to adjust for humidity. Also
| only 33% of Phoenix homes have a pool. Using a pool as a
| solution to prevent people from dying is a "let them eat
| cake" idea
| addisonl wrote:
| Like the other commenter who already corrected you, it
| makes perfect sense if you actually understand how wet
| bulb works, here's a calculator for you:
| https://www.omnicalculator.com/physics/wet-bulb
|
| Hint: Phoenix is at 17% humidity today, even their all
| time high of 122 doesn't push the wet bulb temp out of
| the safe range.
| chickenpotpie wrote:
| I understand how wet bulb temperature works just fine.
| You didn't need to write a snarky response to engage in
| this discussion.
|
| Now include climate change raising the temperature and
| changing the length and severity of monsoon season,
| continued development raising the heat island effect.
|
| It doesn't matter what the average wet bulb temperature
| over the entire coty over a long period of time. It
| matters what the peak wet bulb temperature is for
| significant number of vulnerable people. The wet bulb
| temperature only has to get very high once to kill a
| large swath of people.
|
| I understand just fine the wet bulb temperature has been
| within safe levels for the vast majority of people so
| far. My concern is about the future.
| addisonl wrote:
| The entire south is at a much higher risk from wet bulb:
| https://www.iflscience.com/southern-us-reaches-dangerous-
| wet... so my point still stands, wet bulb isn't an issue
| in Phoenix.
| chickenpotpie wrote:
| You didn't respond to any of my points at all. One area
| being at risk of something doesn't lower the risk in a
| different area.
| CarVac wrote:
| It's not an issue because Phoenix is always dry, so the
| wet bulb temperature is always low.
| chickenpotpie wrote:
| The wet bulb temperature of Phoenix still gets very high.
| Last July, there was an average wet bulb temperature of
| 73 degrees Fahrenheit. 95 degrees will kill a healthy
| human, it takes much less to kill a vulnerable person or
| someone performing manual labor. Climate change is only
| going to raise that number.
| mathgeek wrote:
| As a thought experiment, the same logic can be applied to any
| region where lack of shelter or heating would make human life
| unsustainable.
| afavour wrote:
| If you completely ignore the concept of energy efficiency,
| sure.
| mathgeek wrote:
| That's why I mentioned it as a thought experiment. We
| have been burning energy for centuries to keep folks
| alive in both extremes of climate.
| interestica wrote:
| Time to start calling it Life Support Systems
| ashconnor wrote:
| I would imagine solar panels would be a good investment in a
| climate like this.
| genmud wrote:
| There is actually efficiency issues with the high heat... but
| they do help offset the AC requirements, so overall even if
| the efficiency is down 20-40% because of heat, you require
| potentially 20-50% less A/C because it shades the roof.
| willis936 wrote:
| Or a solar boiler connected a refrigerant compressor. The
| hotter it gets the more cooling power you have. Steam punk
| for the 21st century.
| post_break wrote:
| When my AC finally needs replacing I'm going heat pump, and then
| also ditching my gas water heater. The constant fees of a gas
| line are ridiculous at this point and any more electricity usage
| will be offset by the 9 months of the year I'd never turn on the
| heat.
| pdx_flyer wrote:
| I was looking for a whole home heat pump and got some quotes that
| started at $27,000 for a home that is 1800 square feet. That
| price is a bit hard to swallow. I really don't want to just cool
| one or two rooms in the house.
| zamalek wrote:
| Are you sure you aren't getting quotes for a ground-sourced
| (AKA geo) heat pump? We just installed a 4.5 ton (overkill for
| your sqft) 20 seer unit for $18000.
| cwkoss wrote:
| I got a very similar quote ($27k for ~2000sqft home) in
| seattle a few months ago.
|
| Salesperson said there is excess demand for both labor and
| machinery for heat pump installations in the past few months.
| I wondered at the time to what extent this is a regional
| phenomenon (seattlites are nerds who like energy efficiency)
| vs. supply chain issues vs. a sales technique.
|
| Interestingly, I learned that it will be too cold for heat
| pumps <10 days out of the year, so most people either keep
| their gas furnace as backup, or install an electric furnace
| for these rare days.
| hedgehog wrote:
| Getting anything at all done in the Seattle area is super
| expensive. Not sure why. The rep is wrong about the too
| cold bit though, even just what's in stock at Lowe's is
| rated to well below record lows for the region.
| loeg wrote:
| We have heatpumps in Seattle. They have integrated
| resistance heating (like baseboard heaters) for cold
| weather situations where the heatpump doesn't work well --
| no need for a separate unit.
| mynameisash wrote:
| I had an AC unit installed just after the heat dome.
| Interestingly, while there was a lot of _interest_ in
| people getting AC installed, few people were willing to put
| down 60% of the cost of the unit, which meant I was at the
| front of the line.
|
| I was interested in doing an air-source heat pump (because
| hey, my furnace was 19 years old and would have to be
| replaced soon anyway), but due to the excessive cost, the
| payback time was figured to be something like 50 years. I
| would have loved to do that, but it just doesn't make
| sense. Instead, it was new AC unit + new natural gas
| furnace.
|
| Nevermind ground-source, which would have been much more
| expensive.
| nottorp wrote:
| Isnt any a/c a heat pump though?
| cyfex wrote:
| 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?
| metiscus wrote:
| 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.
| samtho wrote:
| 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.
| chrischen wrote:
| I think a lot of American houses have central air with A/C
| systems that cool, and a furnace that heats rather than the
| AC, if I understand correctly.
| toast0 wrote:
| 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.
| DaiPlusPlus wrote:
| * 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.
| elil17 wrote:
| 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.
| lhoff wrote:
| [flagged]
| ptmcc wrote:
| Please stop with these sorts of posts, it's the 2023
| equivalent of "let me google that for you"
| davidmurdoch wrote:
| 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.
| t8sr wrote:
| 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.
| adgjlsfhk1 wrote:
| The difference is whether you add a $20 of valves to let it
| run in reverse (and possibly some extra smarts to keep it
| from frosting up)
| [deleted]
| llm_nerd wrote:
| I believe heat pump is limited to reversible systems, while an
| AC is one way. It's just a more limited variant.
| sdflhasjd wrote:
| Strictly speaking any compressor AC is a heatpump, but more
| colloquially, "heatpump" usually refers to reversible or
| heating-only units.
| brianpan wrote:
| 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?
| Moto7451 wrote:
| 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.
| nottorp wrote:
| Pretty sure all acs sold here can reverse and heat a bit.
| metiscus wrote:
| 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.
| chpatrick wrote:
| Here in Europe all modern ACs have that feature. The
| difference with heat pumps is that they're bigger and usually
| use underfloor pipes.
| shusson wrote:
| 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.
| Maxburn wrote:
| 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.
|
| ie; it's a buzz word.
| 1-more wrote:
| > 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.
| Maxburn wrote:
| 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.
| IanCal wrote:
| 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.
| kevin_thibedeau wrote:
| 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.
| Maxburn wrote:
| 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.
| kevin_thibedeau wrote:
| 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.
| Alupis wrote:
| 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.
| bfuller wrote:
| 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.
| Alupis wrote:
| Well, the no-gas thing upsets me because cooking on
| modern electric cooktops/stoves is still staggeringly
| awful.
| cycrutchfield wrote:
| Induction cooktops heat faster and more evenly than gas
| jonny_eh wrote:
| Being responsible is so trendy.
| triceratops wrote:
| That doesn't make them a buzz word.
| jondwillis wrote:
| Why put renewable in quotes? Because it isn't 100%?
| Maxburn wrote:
| Basically yes. Renewable is more of a supplement to current
| grids for most of us. There might be a couple rare few
| areas that currently claim 100%.
| triceratops wrote:
| Vs the alternative, natural gas, which is famously 100%
| renewable?
| Maxburn wrote:
| Master-Blaster rules Bartertown!
| mindslight wrote:
| 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.
| alistairSH wrote:
| 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).
| lsaferite wrote:
| 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.
| morepork wrote:
| In a technical sense yes, outside of niche systems such as
| evaporative coolers.
|
| Also all refrigerators contain a heat pump.
| theonlybutlet wrote:
| 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.
| cornstalks wrote:
| 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.
| LUmBULtERA wrote:
| 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.
| triceratops wrote:
| A "heat pump water cooler" also exists and is better known
| simply as a water cooler. You know, the one that people
| gossip around.
| wcfields wrote:
| 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.
| triceratops wrote:
| 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.
| thsksbd wrote:
| [dead]
| Phrodo_00 wrote:
| Every fridge with a cold water tap is literally this (in
| addition of being a fridge and a freezer, obviously)
| throw0101a wrote:
| Perhaps think of "heat pump" as something that can (also)
| bring heat _into_ a building, whereas A /C generally (only)
| _removes_ heat from it.
| Maxion wrote:
| An A/C is a heat pump. Stop trying to change existing
| terminology
| unholythree wrote:
| 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).
| nsxwolf wrote:
| I've only ever known the term "heat pump", in the context
| of HVAC, to mean "an air conditioner that can also be
| used to heat".
| sidewndr46 wrote:
| 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.
| nsxwolf wrote:
| When I needed a new air conditioner a couple years ago I was
| quoted $17,000 for a heat pump. I can only guess at that point
| whatever energy cost savings it would bring would never be
| realized within the service life of the system. I went with a
| $6000 standard replacement AC unit.
| SECProto wrote:
| What kind of a system were you installing? We had a heat pump
| installed three years ago for less than $5k Canadian. Can't
| remember if we got a rebate on top of that or not.
| BaculumMeumEst wrote:
| wow that's insane. i replaced an oil furnace with an oil
| furnace + heat pump hybrid for 7k in a high COL area.
| ramesh31 wrote:
| Swamp coolers are massively underutilized as well. The vast
| majority of residential cooling in all but the most humid
| climates can be done with nothing but a fan and some cold water;
| no compressed gases necessary.
| metiscus wrote:
| The issue with swamp coolers (evaporative cooling) is that you
| need relatively low humidity for them to work and they increase
| the humidity of the interior cooled environment. If you use
| them in combination with an air conditioner, they will very
| likely reduce the efficiency of the air conditioner by
| increasing the dehumidification load of the air conditioner.
| rimunroe wrote:
| > The vast majority of residential cooling in all but the most
| humid climates can be done with nothing but a fan and some cold
| water
|
| Aren't swamp coolers only really useful when the humidity is
| under something like 50%? I guess I'm assuming you're talking
| about the US, but I don't think "vast majority" of people live
| in such areas. A quick search for average humidity of US states
| in July and August shows many of them have an average daily
| humidity of over 50%.
|
| It certainly rules out every place I've lived on the east coast
| (Richmond, Virginia, Long Island, and the Boston area), as the
| humidity in those places is usually at least 60% at the height
| of summer when most people actually use their AC.
|
| As a side note, I suspect most people overuse their air
| conditioning and don't let their bodies adapt to the warmer
| summer weather. It's weird how many people keep their houses
| under 75 degF when the heat index is only in the mid 80s.
| ramesh31 wrote:
| >Aren't swamp coolers only really useful when the humidity is
| under something like 50%?
|
| They are less effective, but still work. As long as the dew
| point is ~72 degrees, or lower, they can still cool enough to
| do the job (although of course not to the extent of an AC).
| But yes, ultimately it comes down to people being ok with not
| setting the AC to 68 degrees when it's 80 degrees out, and
| using the minimal amount of cooling necessary to be
| comfortable.
| elil17 wrote:
| This sort of true? There are many hours per year in many
| climates where direct evaporative cooling alone could suffice
| to keep people comfortable. However, most climates also have a
| good number of hours where air conditioning is required for
| comfort.
|
| You can use this tool to visualize this:
| https://drajmarsh.bitbucket.io/psychro-chart2d.html
|
| (Use the Givoni Bioclimatic Chart overlay and select a weather
| station using the globe icon.)
|
| That said, there are a number of more complex devices which
| could further reduce how often AC systems need to be used: dew-
| point (Maisotsenko Cycle) coolers, indirect evaporation
| cooling, and thermal energy storage to name a few.
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