[HN Gopher] You and the planet need a heat pump
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You and the planet need a heat pump
Author : g8oz
Score : 48 points
Date : 2022-03-20 20:01 UTC (2 hours ago)
(HTM) web link (www.wired.com)
(TXT) w3m dump (www.wired.com)
| sokoloff wrote:
| I'll be replacing an aging (1950's) boiler this summer. I would
| love to get an air-source hydronic heat pump (air-to-water heat
| pump).
|
| Even with a $10K rebate, it's far more cost-effective to go with
| a modern gas boiler (which has its own $2750 rebate) and I have
| no worries of ~72 hours/year of being unable to maintain
| temperature. (That's not that big of a worry for me and wouldn't
| be a blocker, but it's a small inconvenience.)
|
| Basically, the heating contractors know the rebate amounts and,
| unsurprisingly, bake that into their bids. I can't really blame
| them for following the incentives, but it means that the energy-
| savings incentives don't have the intended effect.
| bertil wrote:
| The incentives are encouraging people in trades to learn about
| how to set-up such pumps and encourage their clients to get
| one. That sounds like it's working as intended.
| sokoloff wrote:
| That's a fair point! By the time it gets to the end user's
| financials though, a modern gas boiler ends up being far more
| attractive, which undermines the pace of the transition.
| KyeRussell wrote:
| Can anyone explain the recent fascination with heat pumps? I
| first noticed it with Technology Connections. Here in sunny
| Western Australia heat pumps have been the norm for a long time.
| Our climate has historically been dry enough for evaporative air
| conditioning to work as well, but for some reason (/s) the
| climate is changing such that this is increasingly not the case.
| That said IIRC these units have been common in my life for
| decades, so I assumed that the rest of the world had cottoned on.
| frxx wrote:
| Funny thing about heat pumps is, that they often operate with
| over 100% efficiency. Took some time for me to wrap my head
| around it.
| pengaru wrote:
| Every "air conditioner" is a heat pump, the only newish
| development for the US is for reversible ones to become more
| common that can pump the heat in both directions.
|
| I don't understand why there's been so much brouhaha over heat
| pumps as of late, it's nothing new.
| gwbas1c wrote:
| They used to work poorly in colder climates like the
| northeastern US. Newer models are better able to handle sub-
| freezing temperatures.
| brightball wrote:
| The integrated systems with a computer controlled thermostat
| and multi speed fans have tremendously helped.
| toomuchtodo wrote:
| Because air source heat pumps are the only efficient way to
| electrify HVAC besides heat pump boilers. Climate change
| mitigations (in this case, gas->electric) and all that jazz.
| orzig wrote:
| Having just bought one, I think they have recently gotten a lot
| more efficient, and/or cheaper. Several installers couldn't
| name any options, but the more savvy ones were talking about
| all the new manufacturers in the game
| veemjeem wrote:
| Sadly most popular window a/c units don't have true heat pump
| abilities. Usually the heating portion of window units use
| resistive heating.
| powera wrote:
| Yes, but ...
|
| At a high level the article is correct. At a tactical level there
| are a few issues:
|
| * If you don't have a "geothermal" system, heat pumps aren't
| economical in regions where it gets below 0F/-20C.
|
| * There is a 20 year depreciation cycle for furnaces, and it
| doesn't make sense to install them at a significantly faster
| rate.
|
| * You lose a lot of the efficiency benefits when the electricity
| is generated from burning fossil fuels elsewhere. And we are
| nowhere near having enough electricity from solar and wind to
| heat houses in the wintertime.
| danhor wrote:
| Regarding the last point: Together with the 20 year deprecation
| cycle, an expansion* of heat pumps makes sense now in
| anticipation of higher buildup of renewables as well as
| creating additional electricity demand, making construction of
| new renewable power sources more attractive.
|
| * I only know the numbers for germany, where even in new
| buildings there are a lot of fossil furnaces getting installed
| still. Replacements in older houses also usually don't switch
| to a heat pumps, pushing both numbers >80% would already be a
| major achievement in my book.
| sparker72678 wrote:
| Heat Pumps are great, and the latest generation of variable speed
| units are really cool and our most efficient ones yet.
|
| Still, for heating, especially in really cold climates, a Heat
| Pump is going to have a hard time competing against other
| approaches, in efficiency, efficacy, and cost.
|
| The latest gen of "ductless" or "mini split" units are awesome
| *AC* units (efficient, quiet), and I'd definitely recommend
| checking them out for _cooling_. If you 're somewhere that it
| doesn't get too cold in the winter (lows in the mid-20s at the
| lowest), you _might_ be able to tolerate using one for heating,
| but any colder and you 're going to need another solution.
| ericd wrote:
| From what I've heard, heat pumps with ground loop heat
| exchangers maintain a 450-500% efficiency rating all year
| round, regardless of how cold or hot it is outside. Here's a
| variable speed one that claims COP of ~5:
| https://www.waterfurnace.com/residential/products/geothermal...
| (I think that's only when it's running at 30%, though, drops to
| 4.5 when at high speed).
| pbhjpbhj wrote:
| Surely mid 20-s, 25degC ,is really hot? Where is that a winter
| low.
| hanklazard wrote:
| Fahrenheit not Celsius.
| reverend_gonzo wrote:
| Fahrenheit.
| mckirk wrote:
| In places that use a silly system called 'Fahrenheit'.
| hinkley wrote:
| The laws of heat engines are governed by the relative
| temperature on the hot and cold side. It's easy to push a
| little water uphill, but beyond a little it becomes a
| progressively more farcical exercise.
|
| Cold and humid seem to be the worst combination from reviews
| I've seen for minisplits, because the second biggest problem is
| heat transfer, and transferring heat through ice is very
| inefficient. Every time the ice begins to insulate the coils,
| you have to run the system backward to heat the pipes above
| freezing and melt off the buildup. Not only does that lower the
| efficiency of the system but eventually it limits the duty
| cycle, because you can't be thawing and pumping at the same
| time. And so you are attacked from all sides by both physics
| and logistics.
| BolexNOLA wrote:
| New Orleans here. Mini-splits are fantastic.
| lifty wrote:
| Air heat pumps yes, but ground heat pumps can work in very cold
| climates.
| scythe wrote:
| Conveniently, the USDA publishes a map specifically suited to
| this question:
|
| https://en.wikipedia.org/wiki/Hardiness_zone#/media/File:201...
|
| Anywhere in yellow (8a) or warmer can use a heat pump, no
| problem -- the best heat pumps go down to about 0 F (-20 C)
| intake temperature. That's about half the country. With good
| construction it should work down to 7a (light green), and this
| transition zone includes DC/Philly/NYC. The darker green and
| blue regions need more advancements in the tech to rely on
| them.
|
| But it's mostly the US that has this problem. By contrast,
| practically everyone in Latin America / Africa / Southern Asia
| should have no trouble switching to heat pumps (if they need
| heating at all, i.e. Zone <10):
|
| https://upload.wikimedia.org/wikipedia/commons/a/a7/World_Ha...
|
| Since many of these countries are industrializing during the
| efforts to mitigate global warming, hopefully they will get
| heating right sooner rather than later.
| Arubis wrote:
| You can do two things, if so inclined: I'm in the midst of
| having a heat pump system installed in line with my existing
| gas furnace, the so-called "dual fuel" approach. The heat pump
| should suffice for most cool days, with the furnace available
| for when it's truly cold. (Colorado front range; we don't get
| the same winters that we used to.)
| archi42 wrote:
| Heat pumps are just half the story; properly insulating buildings
| is essential as well. And for older houses, the effect can be
| tremendously huge. E.g. we're planning to cut the energy
| requirements of our house to about 20% (no typo). And that will
| then be supplied by a heat pump.
|
| Sadly, all this is immensely expensive AND takes a few decades to
| financially amortize. Which means for people with lower incomes,
| who would benefit the most from this, still have to burn money to
| stay warm. :/
| _spduchamp wrote:
| Absolutely this! You have to seal and insulate when switching
| to heat pump. We just switched our house HVAC to heat pump, and
| there is no way the heat pump would be able to keep up with the
| heat loss had we not added an extra layer of insulation to the
| exterior of our house. Insulation is passive energy savings, so
| it just makes the most sense to focus there first.
| ars wrote:
| I've never understand why
| https://en.wikipedia.org/wiki/Absorption_heat_pump are not more
| popular.
|
| They are even more efficient than electric ones.
| politelemon wrote:
| I don't know how true this is since I'm no expert, there's a
| YouTube video explaining why heat pumps may not be so simple a
| solution at least in the UK
|
| https://m.youtube.com/watch?v=GhAKMAcmJFg
|
| Interestingly the prediction he made, regarding gas prices, did
| come true.
| RobinL wrote:
| I live in the UK. Last September, I bought an air-to-air source
| heat pump for environmental reasons, to reduce our use of gas
| for central heating. I did the calculations and knew when we
| bought it it wouldn't save much money (you get a 3-4x
| efficiency improvement, but electricity is 3-4x the cost of
| gas, at least at September's prices).
|
| Our main family room/kitchen is the largest room downstairs,
| and the only one we heat during the day in the winter. So
| rather than figure out the complexity and additional cost of an
| air-to-water, it seemed logical to dip our toes in with
| something simple.
|
| It's been great. Our gas usage is less than half what it was
| the previous year. The room heats up faster in the mornings, so
| there's no need to have the heat on before we come downstairs.
| On cold days this winter, we were heating the whole downstairs
| for about 15kwh/day, meaning we're getting roughly a 3-4x COP
| real-world (closer to 4 i think, but have no way of precisely
| measuring). If I'm feeling chilly, I can sit directly under it
| in a nice warm breeze.
|
| It cost PS2,275 installed. The model was the Daikin-FTXP60M.
|
| (Recognise that this does not necessarily undermine the
| argument in the video. But I do find it odd air-to-air source
| heat pumps are not considered more often in the UK)
|
| Also interesting to compare this relatively modest investment
| with an electric car. Very roughly, the carbon savings we're
| seeing are comparable to the savings from replacing 10k miles
| per annum in an ICE with an electric (I think, rough back-of-
| the envelope calculation!).
| AitchEmArsey wrote:
| > I do find it odd air-to-air source heat pumps are not
| considered more often in the UK
|
| Could be due to housing density and the reputation for noise,
| though I'm not sure how well-deserved that really is.
|
| Mostly I just think it is a mismatch between the age of
| housing stock (and the pre-existing heating solutions) with
| incentives.
|
| If I were building a new house I wouldn't bother with a gas
| supply and would use a ground-source heat pump combined with
| underfloor heating - but retrofitting that to my 150 year old
| house is never going to be cost effective versus a boiler.
|
| For residential developments, the government should just
| mandate no new domestic gas supplies and be done with it.
| dageshi wrote:
| I believe it has mandated that from 2025.
| sokoloff wrote:
| IMO, it's worth watching HeatGeek's two videos covering that
| video: https://www.youtube.com/watch?v=P22W-4mXrbw
| https://www.youtube.com/watch?v=0cYvJPPmVGs
| ars wrote:
| Something I would like is a tool where I could enter my costs for
| electricity, natural gas, and efficiency of my boiler and a new
| heat pump I'm considering.
|
| I'd like to see if I'm really saving energy (and money) doing
| this. And how long the payback period is for buying new
| equipment.
| linuxlizard wrote:
| I _just_ ripped out our ~10yo heat pump at home, installed a
| fully gas furnace. The accursed thing was so loud and it sat
| right outside my office. When working from home over the winter,
| it would fire up and drown out any conversation in my office. I
| gladly ripped it out and danced on its grave.
| mdoms wrote:
| The American reluctance towards both heat pumps and induction
| hobs is very puzzling to me. Both systems are commonplace enough
| that they would be the default option for any new build or
| replacement system in my country, unless you have special
| requirements.
|
| I understand the issues with very cold temperatures, and I'm
| curious what proportion of American households would expect to
| see outside temperatures below -17C/0F - I doubt it would be
| enough to explain the reluctance but I could be way wrong.
| NonEUCitizen wrote:
| What country are you in and what are the major brands of heat
| pumps used there?
| mdoms wrote:
| New Zealand. The major brands are the same as everywhere -
| Mitsubishi, Panasonic, Fujitsu, LG, Daikin etc.
| tpmx wrote:
| Heat pumps are and have been extremely common in Sweden for the
| past 20 years or so, ever since our silly government (looking at
| you S/MP/C/V) started a) exporting electricity to Europe and b)
| shutting down perfectly fine nuclear plants, and thus started
| raising the price of our once very cheap electricity.
|
| Lots of houses here used to be heated using resistive, electric
| radiators. Now most of those houses are primarily heated using
| heat heat pumps.
|
| Mitsubishi is the by local heat pump aficionados most recommended
| manufacturer.
| jqpabc123 wrote:
| * ... not by pumping cool air in, but by pumping warm air out.*
|
| Technically not correct. A heat pump does not pump air in/out of
| a building. It pumps a refrigerant around in a closed loop. Part
| of this loop is inside and part is outside.
|
| When used for heating, the efficiency of a heat pump system
| declines as the outside temperature drops. At a temperature of
| around 32F, a heat pump essentially becomes useless. As a result,
| most have an auxiliary fallback heat source.
| lasson wrote:
| How do freezers work if heat pumps stop working at 32F?
| throwaway0a5e wrote:
| Freezers use a different refrigerant that gives them a
| different working temperature range.
|
| Additionally, for proper efficiency the key components of the
| system need to be sized for your target temperature and the
| temperature range of your ambient air.
| wernerb wrote:
| 33F is 0 degrees celcius for those lucky enough to have enjoyed
| the metric system
| michaelcampbell wrote:
| Well, 32F is 0C if we're going to go that route.
| yardshop wrote:
| Well, also, 33F converts to 0.55555(etc)C, so if one's
| device didn't show fractional degrees and didn't round
| normally, 33F would look like 0C. But yes, 32F is 0.0C.
| DiabloD3 wrote:
| Older ones stop working at around 32F. Modern ones meant for
| colder climates start losing efficiency at 0F. I live in Maine,
| we rarely get nights that are subzero, my heat pump works fine
| except for those 3 or 4 nights out of the year.
|
| The heat pump dramatically decreased my power bill vs baseboard
| electric.
| sokoloff wrote:
| Heat pumps in heating mode lose efficiency on a continuous
| (with lowering temperature) basis; the colder it is outside
| and/or the hotter output (air or water) you want to get from
| the unit, the lower efficiency they have.
|
| https://www.researchgate.net/figure/e-efficiency-of-an-
| Air-S...
| teruakohatu wrote:
| That is true, but the curves have improved dramatically
| since 2006 (when that graph you linked to was posted). At
| 0C they are still much more efficient than electric.
| derkoe wrote:
| Can confirm that. Our heat pump (cheap all-in-one, 8 years
| old) works down to -10degC (14degF) without issues. Modern
| ones work down to -20degC (-4degF). Water based heat pumps
| work with any outside temperature. In any case a heat pump is
| the cheapest way to heat a building.
| arpinum wrote:
| Modern heat pumps, for example by Mitsubishi and sold in the
| UK, maintain a COP > 2.5 at -7C.
| AussieWog93 wrote:
| Every single time I see these articles about efficient
| heating/cooling technology, it reminds me of just how plainly
| _dumb_ a lot of the systems we have are.
|
| Loungerooms with no doors, so the split system on the wall has to
| work 3x as hard to cool half the bloody house.
|
| Ducted heating/cooling without any valves, so your choices are
| either "heat up every room in the house", "get up on a step
| ladder to close off each vent manually" or "be cold".
|
| Cheaping out on insulation to knock a grand or two off of your
| million dollar new build.
|
| Just like in the software world, I suspect we'd be able to make
| massive efficiency gains just by actually engaging our brains. No
| special technology required, nor specialist knowledge. Just think
| about things for two seconds before putting in the semi-permanent
| installations.
| BooneJS wrote:
| We're building a house in Wisconsin soon. We think that ground-
| source geothermal is required for efficient electrical HVAC
| without gas, but if we can save a ton of $$$ and go with air-
| source heat pump, that would be awesome.
| faitswulff wrote:
| Fellow midwesterner here. The last time I looked into it, heat
| pumps were significantly less efficient in cold temperatures.
| Is that still the case?
| veemjeem wrote:
| Still better than electrical resistive heating (space
| heaters) which has a COP of 1. Even when it's super cold
| outside, heat pumps with a HPSF around 10 would still have a
| COP around 2. See the graph:
| https://www.researchgate.net/figure/e-efficiency-of-an-
| Air-S...
|
| Of course space heaters are far easier to move around the
| house compared to a mini-split system and would use less
| power if you only plan to heat a small room.
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