Heat Pumps Twice As Efficient As Fossil Fuel Systems In Cold Weather (theguardian.com) 196
Long-time Slashdot reader AmiMoJo shared this report from the Guardian:
Heat pumps are more than twice as efficient as fossil fuel heating systems in cold temperatures, research shows. Even at temperatures approaching -30C, heat pumps outperform oil and gas heating systems, according to the research from Oxford University and the Regulatory Assistance Project thinktank...
Reports have spread that they do not work well in low temperatures despite their increasing use in Scandinavia and other cold climates. The research, published in the specialist energy research journal Joule, used data from seven field studies in North America, Asia and Europe. It found that at temperatures below zero, heat pumps were between two and three times more efficient than oil and gas heating systems.
The authors said the findings showed that heat pumps were suitable for almost all homes in Europe, including the UK, and should provide policymakers with the impetus to bring in new measures to roll them out as rapidly as possible.
"The Guardian and the investigative journalism organisation DeSmog recently revealed that lobbyists associated with the gas boiler sector had attempted to delay a key government measure to increase the uptake of heat pumps."
Reports have spread that they do not work well in low temperatures despite their increasing use in Scandinavia and other cold climates. The research, published in the specialist energy research journal Joule, used data from seven field studies in North America, Asia and Europe. It found that at temperatures below zero, heat pumps were between two and three times more efficient than oil and gas heating systems.
The authors said the findings showed that heat pumps were suitable for almost all homes in Europe, including the UK, and should provide policymakers with the impetus to bring in new measures to roll them out as rapidly as possible.
"The Guardian and the investigative journalism organisation DeSmog recently revealed that lobbyists associated with the gas boiler sector had attempted to delay a key government measure to increase the uptake of heat pumps."
-30C = -22F (Score:2)
The low temp. mentioned here conflicts with the article below from Consumer reports. I think I will trust them more that the guardian. Also, how many days can it "heat" at -30C/22C ?
https://www.consumerreports.or... [consumerreports.org]
Many models in the database can heat as effectively at a frigid 5F (-15C) as they can at a mild 47F (8C)
Where I am, we can be well below 5F (-15C) for weeks at a time. Anyone can say it can heat at -30C, but for how long and how warm will the inside of your home be ?
And they mention the UK and Scandinavia ? Every hear of the Gulf Stream ? That keeps the Ave Temps warmer in the Winter than i
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Many models in the database can heat as effectively at a frigid 5F (-15C) as they can at a mild 47F (8C)
Unless they have a Nobel Prize for overturning the laws of physics, that is implausible.
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Many models in the database can heat as effectively at a frigid 5F (-15C) as they can at a mild 47F (8C)
Unless they have a Nobel Prize for overturning the laws of physics, that is implausible.
This is a common deceptive marketing trick that confuses many. What they are talking about is the temperature range at which the heat pump is able to deliver 100% of rated capacity. When they say "as effectively" it is referring to the ability to provide heat not the ability to do it efficiently. They conveniently leave out the cost of delivering that 100% goes up as temperature differences increase.
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I'd argue that resistive heating elements are also extremely efficient, but the bonkers thing about this study is it glosses over cost in the name of efficiency coefficients which is missing just a huge massive point both in practicality and just simple economics.
That, and, if this study has an agenda, surely they could cherry pick what they'd like. That may be a foolish thing to just throw out there, but they do mention ground-source heat pumps, which, as far as I know, simply aren't installed anywhere I'v
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This is total BS unrelated to reality. Here is a recent analysis [iea.org] from the International Energy Agency. It begins,
Global sales of heat pumps grew by 11% in 2022, according to the latest IEA analysis, marking a second year of double-digit growth for the central technology in the world's transition to secure and sustainable heating.
Got that? The industry is not in a catastrophic recession. It's growing by double digits. Given your rant about the "Cult of Gaia" and their "stupid, anti-engineering and anti-scientific drivel," it's clear you aren't even trying to be objective. But at least don't make up wild lies like this. Try to stick to things that have at least some connection to truth.
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Lots of nonsense - also in the comments (Score:2)
Best pumps are more efficient with smaller temperature differences. Obviously.
Modern heat pumps can handle differentials of 40C or more. After a certain point, they have to supplement with resistance heating. In really cold climates, you may be better off with bore holes rather than using ambient air.
TFA (or at least TFS) is nonsense. Read the specs of *your* heat pump. They vary widely...
I experimented.. (Score:2)
recently and can only see a 50 percent improvement over resistive heating.
Does this sound right?
Twice the efficiency, but the energy maybe 4x cost (Score:5, Informative)
Where I live, electricity is about four times as expensive as gas - so replacing gas heating with electrical heat pumps that use half as much electrical energy as the gas boiler uses gas energy will result in paying twice as much for energy overall.
Not everyone can afford to spend that and few want to.
Fortunately it is not usually cold enough that the heat pump works at only 2x efficiency - 3x-4x is more typical - but we need more than 4x to avoid spending more on energy than we do already.
That's probably only because of externalized costs (Score:2)
Also, you're kind of in the minority. Gas prices are low, but not that low. Go watch YouTuber Technology Connections video on the subject, they're a huge cost savings for most consumers. The only problem is they're so new and in such high demand they're can be tough to get.
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Gas heating would have been more expensive, if the UK government hadn't capped the unit cost last winter.
Even before the crisis, a heat pump typically cost as much to run as a gas boiler, i.e there was no benefit, but no additional cost either.
In the future we may well need heat pumps for cooling anyway. UK housing is not designed for hot summers.
What we really need is cheaper electricity. Renewables are the cheapest, but we aren't building them fast enough.
How is this news? (Score:2)
Wouldn't, at minimum, anyone who designs and manufactures these things know this? You're saying they invested in and built them without knowing or measuring their efficiency in various situations in comparison to the competing systems?
This is misleading. (Score:5, Informative)
This is a trivial statement. Heat pumps are by nature always more efficient "at the appliance level" if they move any heat whatsoever. You burn a fossil fuel, you extract maybe 75% of the heat (some is lost in exhaust). A heat pump retains almost all the heat produced by the electricity it uses, plus any additional heat it moves from outside the building. The report goes on...
Correct, except air-source heat pumps drop below 3 if it's cold enough. Then they mention that in very cold climates ground-source heat pumps are better than air-source to avoid this problem, and they show a chart indicating that previously-installed heat pumps usually have a COP above 2 "in mild cold climates".
But again, the report is talking "at an appliance level" which neither the Guardian nor Slashdot mentioned. To claim "heat pumps are more efficient overall" you must be looking at the primary energy supply, which this report ignores. For example, is it more efficient to burn natural gas in a power plant to generate electricity at 44% efficiency and then transmit that to your home (with minor line losses) and use that electricity to power a heat pump, or is it more efficient to send the natural gas to a home and burn it there? The actual answer is "it depends on the heat pump and the temperature of the outdoor heat source".
A heat pump will probably be more efficient overall if you get a high-efficiency model, or if it's not too cold, or if you have a ground-source heat pump.... but it probably won't be "twice as efficient". And even if it is more efficient, that doesn't mean you won't pay more for the energy. I once computed that electricity in my location cost four times more than natural gas for the same amount of energy. Electricity actually should cost more than twice as much to account for generation losses and line losses, but on top of that you have to help pay for the power plants themselves, and their profits.
People should switch to heat pumps in the long run because burning fuel causes global warming, and higher energy demand stimulates building more clean power plants (wind and nuclear - solar in winter is a weak energy source, and yes I am aware solar panels are more efficient in cold weather, but that boost doesn't come anywhere close to making up for the lack of sunlight).
You may or may not save money in the long run with a heat pump. Generally, the colder your climate is, the less likely you are to save money, although if your location lacks natural gas lines then heat pumps probably make sense. Here's a nice video [youtube.com] about the nuts and bolts of home air-source heat pump technology.
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Yes, just jaw dropping this qualifies for "research". Electricity cost is often 3-4x more expensive, which makes sense for the reasons you covered. In the UK at least houses are not well insulated, some insulation is being subsidised such as cavity and loft insulation, but it's very difficult, expensive and often simply impossible to retrofit good insulation - a requirement for heatpumps to operate well. Your costs to install a ground source heatpump can be as much as £45,000 (vs £1,500 for a ne
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So I live in a locale where the temperature swings about 70C over the course of the year; we have temps around -25C in the winter and easily topping 35C in the summer. For me, it's obvious that a heat pump is going to be better, because the climate here has always been like that, and you're always going to need to cool in the summer and warm in the winter. There's about 8 weeks a year where it's off all together because the temperature is just right.
I think there's something to be said for the versatility o
Needs some context... (Score:2)
So generally speaking, all things being equal, if you are already having to do a new/replaced system in this day and age, heat pump is a credible winner.
However, rip and replace of a perfectly functional gas furnace may not be the wisest use of our resources at this juncture. While the heat pump is crazy efficient, the grid may be generating from natural gas, which is relatively inefficient and significantly counters the heat pump efficiency. So if we were going to spend a lot of money on something, it'd
I wish (Score:2)
I wish a heat pump under everybody's window who thinks it is a good idea.
These things work great (Score:2)
Air source heat pumps work great. For the places where it gets too cold for the heat pump a small amount of time each year, you could use either an electric heating element or a gas burner to heat the air. Or for places where its too cold in general for an air source heat pump, install a ground source heat pump (which can work even at the lowest of temperatures.
The excellent YouTube channel "Technology Connections" has a bunch of videos talking about heat pumps (both air source and ground source) and why th
Cogeneration issues (Score:2)
Heat pumps are widely used here in Finland, and there's an increasing interest in geothermal systems for residential buildings. But as others have already pointed out, these consume a nontrivial amount of electricity. There's a particular problem with combined heat and power, as the power plants will always generate these in a given ratio. If there's less demand for district heating, these plants will have to wind down both kinds of output. It's pretty bad for the market if the supply goes down at the same
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How fast do the current crop of heat pumps hit payback? It needs to be fast enough that I have some time to build up savings before the warranty period expires.
That's like saying your hot water heater/refrigerator/blender needs to payback before their warranty expires. You do not get appliances as an investment opportunity.
Re:How fast to payback? (Score:5, Informative)
I think you're missing the point.
If heat pumps cost a lot more than furnaces, this will discourage people from buying them. Most of us live on a budget, and can't necessarily afford to buy a heat pump just because it's a more virtuous choice. Price matters, if we want people to make more environmentally-friendly choices.
Re:How fast to payback? (Score:5, Informative)
I think you're missing the point.
No, I think you're missing the point: People don't throw away their appliances when the warranty expires.
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If you go back and read the original post, the concern is that after the warranty expires, repair costs can be prohibitively expensive. There was no suggestion that you have to replace the unit after the warranty expires, but that if something goes wrong, you might have to because of the high cost of repairs.
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If you go back and read the original post, the concern is that after the warranty expires, repair costs can be prohibitively expensive. There was no suggestion that you have to replace the unit after the warranty expires, but that if something goes wrong, you might have to because of the high cost of repairs.
Furnace repair costs are not free. Like any appliance, there will be repair costs. For those that are concerned about repair costs, there is the option of a home warranty.
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Furnaces tend to last a lot longer than heat pumps, in part because there are fewer moving parts, and because they're simpler. Home warranties don't eliminate the cost, they just spread it out over time. And my experience with home warranties is that they are mostly a scam, because they always find a ton of "non-covered expenses" regardless of what the repair is.
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Furnaces tend to last a lot longer than heat pumps, in part because there are fewer moving parts, and because they're simpler.
Bases on who? My furnace would have cost $6K to repair if I did not have a home warranty.
Home warranties don't eliminate the cost, they just spread it out over time. And my experience with home warranties is that they are mostly a scam, because they always find a ton of "non-covered expenses" regardless of what the repair is.
Home warranties are also not payback investment scenarios. They are insurance for catastrophic loss like fixing my furnace.
Dubious (Score:3, Insightful)
Bases on who? My furnace would have cost $6K to repair if I did not have a home warranty.
Just because your warranty paid $6k to repair your furnace, does not mean it would have cost $6k to repair the furnace....
Try half that figure. Or less. Look up YouTube videos on furnace repairs and tell me what part you think really costs $6k to replace.
Or did you really not know how these warranty repair games are played?
Re:How fast to payback? (Score:4, Insightful)
If your furnace repair cost $6,000, you got screwed. My regular A/C guy quoted me a brand new 3 ton Amana furnace for $1,700, including labor.
And the last time I used a home warranty, they replaced a condenser unit, charging me $900 in "non-covered expenses." The unit they installed was terrible quality. Later, I found out that the warranty company was owned by the same guy that owned the repair company.
A couple of years later I replaced it with a new one, for $1,400. That's not much of an insurance policy, if they only cover 1/3 of the cost.
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"Part" of a high efficiency furnace may also be a condensate pump which is another "moving part". But, yes, it's generally cheap and easy to replace.
In some cases one may argue it's not "part" of the furnace. But it's typically initially installed with the furnace, when it fails many people will call their "furnace guy", and it's typically only used for the furnace.
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The home warranty doesn't make the repair costs go away, it just has you pay into it monthly plus some extra (since they need to make a profit).
Reducing actual repair costs will be even better.
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No, but these days, once the warranty expires, they're about to die and need replacement (thanks to 'value engineering', that is, engineering it to give me as little value as possible). A more efficient but more expensive unit makes financial sense only if by the time it dies, it has saved at least as much as it's own extra cost.
In practical terms but numbers pulled from my butt, if a furnace costs $2000 or a heat pump costs $4000, then the heat pump only makes sense if it saves me $2000 before it has to be
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I mean, that's disgusting. It's dirty.
*Seriously though fast fashion is a problem.
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How does a heat pump cost more than a furnace?
A heat pump costs about $1400 more than an A/C unit of the same capacity.
A 95% AFUE natural gas furnace costs more than that.
Unless you're living without A/C (and how's that wor
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The article was focused on the UK, where only 5% of home have air conditioning. https://time.com/6199029/air-c... [time.com]
Further, it states that heat pumps cost 2-3 times more than traditional heating systems. https://www.theguardian.com/en... [theguardian.com]
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https://www.statista.com/stati... [statista.com]
Re:How fast to payback? (Score:5, Informative)
Funny, because more and more UK homes need A/C [mansionglobal.com], the article says that the research "used data from seven field studies in North America, Asia and Europe" and that "France, for instance, installs 10 times as many heat pumps as the UK" with "the findings show[ing] that heat pumps were suitable for almost all homes in Europe, including the UK."
Also very many people living in the U.S. are commenting, including yourself?
Yes, heat pumps are more expensive than a furnace. A/C is more more expensive than a furnace. But the difference between A/C and a heat pump is not more expensive than a furnace, capeesh?
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If heat pumps cost a lot more than furnaces, this will discourage people from buying them. Most of us live on a budget, and can't necessarily afford to buy a heat pump just because it's a more virtuous choice. Price matters, if we want people to make more environmentally-friendly choices.
A heat pump replaces both the AC and the furnace which means overall less cost. Installation costs are lower or the same with a heat pump than a furnace. There are benefits to having a heat pump including a smaller footprint. Unlike a gas furnace, there is no combustion and therefore no risk of fire. There are downsides like the fact that heat pumps are electric meaning they will not work in a power outage but a gas furnace will. Looking at "payback" is looking at the wrong factor.
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You are correct, when air conditioning is taken into account, the cost is easier to justify. But the article was focused on the UK, where only 5% of residents have A/C https://time.com/6199029/air-c... [time.com], while the cost of a heat pump is 2-3 times that of a traditional heating system (according to the original article).
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Yet a lot more UK residents are finding themselves in need of A/C [mansionglobal.com]. Perhaps the modest additional cost to make the system reversible (i.e., buy a heat pump) is deed worthwhile, eh?
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Re:How fast to payback? (Score:5, Informative)
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But again, a lot more UK residents are finding themselves in need of A/C [mansionglobal.com]. Perhaps the modest additional cost to make the system reversible (i.e., buy a heat pump) is deed worthwhile, eh?
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Most of us live on a budget, and can't necessarily afford to buy a heat pump just because it's a more virtuous choice.
That's why the average person has to finance the upfront cost, and then the extra money they'll be paying back over time goes to the banking industry rather than the fossil fuel industry. Probably so some rich bankers can drive around in their massive gas guzzling SUVs.
Of course, that's assuming we're talking about a central HVAC system in places where you really do need a serious amount of BTUs to keep from freezing to death. Here in Florida, air-source heat pumps are incredibly common because they only
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I live in Houston, where the weather is pretty similar to Florida. But the article was focused on the UK, where only 5% of the population have air conditioning. https://time.com/6199029/air-c... [time.com] Agreed, for us US southerners, a heat pump makes a lot more sense.
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Only 5% may currently have A/C, but more and more UK homes need A/C [mansionglobal.com]. Perhaps the modest additional cost to make the system reversible (i.e., buy a heat pump) is indeed worthwhile, eh?
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We have a 70-year old furnace in one side of the basement that is still working. It's now a backup to the 4 heat pumps we installed. The heat pumps cost us $22K, and we expect them to last 20 years. I can see why people are leery of them, the long term price/performance ratio is sorta meh at this point.
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Two years ago I went through the process of quoting out a ground-source heat pump. Total out of pocket cost for Installation was around $40k. Payback took about 16 years, using whole year savings estimated (both heating and A/C). The warranty on the unit was only 10 years, and as mentioned above my neighbors got hit with a $16k repair bill when their unit failed right around the pa
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No appliance lasts forever. Everything wears out eventually (usually before you die). Gas furnaces wear out.
I've had to replace all of the gas furnaces in my house and office building. Replaced them with heat pumps starting 12 years ago. No service required on the heat pumps so far.
Also, I have energy cost savings when running the heat pump every day.
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I think you aren't engaging the main point. Appliances are not an investment, but the increased cost of a more efficient appliance as compared to other choices has to be evaluated by looking at lifetime operating costs.
The framing here isn't the appliance as an investment -- it's in how to compare and chose between different appliances that perf
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In a lot of North America it's a no brainer since many homes already have AC systems so when those are due for replacement installing a unit with heat pump is obvious, everything is already in place and the ROI isn't really relevant, you are buying an AC no matter what, the heat pump is an instant win over gas/oil for heating most of the year in that case.
I believe in Europe there is less AC systems so it's a bit of a taller ask but I imagine increasing temperatures is going to increase the amount of homes
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I love
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Ground source is an entirely different ballgame to air source though. Air source is literally a drop in to your existing AC, no extra work required. Colloquially when we say "heat pump" we mean "air source heat pump", i would classify a ground source as "geothermal".
That said if your environment supports it and you are going to be in your house a long time a ground source may make a lot of sense, even with the high cost but it's a much more involved job than just replacing your old AC with a new model with
Re: How fast to payback? (Score:2)
The vast majority of the cost for the ground source system is the ground loop. That's just hot water and maybe antifreeze flowing through it in the ground. And if that's properly done, it should last 50+years.
If the ground loop lasts even a year without issue, it's most likely going to last at least 50 years.
If your building a new house with AC, and your not in areas that go below like -5 degrees Fahrenheit, it makes no sense not to get a heat pump. It'll almost definitely save money, even up front becaus
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Fore sure, but let's consider how much of the US population is in the other 4 zones where a heat pump makes a ton of sense, especially as a majority of those homes already have AC units. Wisconsin, Minnesota, etc, you folks have your own unique issues, not every solution has to solve every problem everywhere and everybody else in the country using less heat oil and gas will also make life better for those of you who really really need it.
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In a lot of North America it's a no brainer since many homes already have AC systems so when those are due for replacement installing a unit with heat pump is obvious, everything is already in place and the ROI isn't really relevant, you are buying an AC no matter what, the heat pump is an instant win over gas/oil for heating most of the year in that case.
The cost isn't an "easy win". I bought my heat pump something like 15 years ago, when natural gas prices were high and going up. I found someone to install it, and took care of processing the government incentives for me. A few year later the cost of natural gas took a dive, and with that any potential to saving money.
As a bit of insult to injury I had the fancy control unit built for this heat pump die on me. The cost of just getting a replacement board was on the border of getting a new heat pump. Ra
Re: How fast to payback? (Score:2)
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Ten years if you ignore opportunity cost - thirty years if you don't and it doesn't fail.
No warranty is that good.
That said the whole system rarely needs replacement and if you have solar power or home atomic energy you can be independent of fuel suppliers.
The models that work below -15F are even more expensive. Our local elementary school was closed for several days a couple years ago when they couldn't get the classrooms up to 55F like the day before.
A hybrid system is even better for resiliency and even
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Had to call a little bs on any article claiming that air source heat pumps are good all the way down to - 30C. Most conventional heat pumps are not going to handle such a large delta T well.
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Do you want to include the cost of risking catastrophic climate change? If you take taxes or other levies on fuels out of the equation, you will likely never get break-even on these things unless we see massive rises in fuel costs.
However, if you are of the opinion that we should stop our experiment on seeing what will happen if we dump as much CO2 into the atmosphere as we can, then it might be one of the more cost-effective ways of reducing CO2 emissions.
Obviously on an individual level such a device is g
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Just to be clear as well, I absolutely do not advocate for massive fuel cost increases. I think that there should be some kind of programme on doing these projects as a public service on a massive scale (not gonna happen in the US, but just my opinion), combined with an expanse of nuclear fuel. Timelines of that would be more like 20 years I guess. Getting regular people to sit in the cold because they can't afford to heat their homes sounds like a dystopian nightmare, but sadly is already something that in
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They had 10 years of energy savings which you don't seem to take into account.
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After 10 years you should change to the new version anyway.
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How fast do the current crop of gas furnaces pay back vs wood burning cast iron stoves is the real question. I've got a cast iron stove right now that never needs to be repaired and will last forever.
Re: ThinkTank (Score:2)
Heat pumps are better than resistive heating is an obvious statement. Heat produced by running the pump is obviously dumped into the system and heats the home. This is 100% efficient. Moving heat from the outside in will naturally add more heat into the home than a simple resistive heater. The problem is maintenance costs. heat pumps are also limited in the amount of current it can draw, so backup heat sources are required.
There is also loss converting fossil fuels to electricity. It's more efficient to bur
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There is also loss converting fossil fuels to electricity. It's more efficient to burn it directly in your home for heat.
This is sometimes true but often not. While direct burning furnaces in homes can be over 95% efficient modern gas turbines for power plants can be over 50% efficient so when a heat pump is in it's ideal operating zone it can reach a coefficient of 300-400% so more heating can be done with the electricity generated from the gas than just burning the gas. It's not true 100% of the time and not for all environments but it can be true much of the time even with a 100% gas power grid. Combine that with the fa
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Heat pumps are better than resistive heating is an obvious statement.
Yes, that is obvious.
It's only meaningful to compare the fuel consumed by a furnace to the fuel consumed by the power plant to generate the electricity that powers the heat pump.
I read TFA and the paper it references, and neither makes it clear what they are comparing.
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It is saying that heat pumps are more efficient than boilers/furnaces by a factor of two, per unit of energy, even in extremely cold weather.
Gas generation is more efficient with heat pumps at all times, with the gas cycle itself being typically about 55-60% efficient in UK plants. That's significant because most UK homes are heated by gas, so even without renewables a heat pump will reduce emissions even in the very coldest weather.
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It is saying that heat pumps are more efficient than boilers/furnaces by a factor of two, per unit of energy, even in extremely cold weather.
What it says is the following:
"In extreme cold climates, such as where the lowest temperatures approach â'30ÂC, performance data have shown that heat pumps can provide heat at efficiencies up to double that of resistive heating"
You are confusing factor of two for resistive heating with factor of two for furnaces. 2x is insufficient to break even with a gas furnace let alone be twice as efficient per unit of energy. It needs to be closer to 3x to have a compelling generally applicable story for "
Re: ThinkTank (Score:4, Informative)
A boiler is close to 100% efficient, but there are losses in the central heating system. Say 100% to keep it simple.
Let's say resistance heating is 100% efficient too. It's close to that. Discount distribution losses etc.
A gas electricity plant is 55-60% efficient.
So if you have a gas electricity powered resistive heater, you get 55-60% of the heat you would from just burning the gas.
But if you run a heat pump, you get at least 110% of the heat you would get from burning the gas.
And that's the worst case. Most of the time it will be more like 200-300%. And any renewable energy directly reduces the amount of gas you are using.
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A boiler is close to 100% efficient, but there are losses in the central heating system. Say 100% to keep it simple.
Let's say resistance heating is 100% efficient too. It's close to that. Discount distribution losses etc.
A gas electricity plant is 55-60% efficient.
You made two specific claims both of which are false. You asserted a 2x advantage for heat pumps per unit of energy in extremely cold weather. This is clearly false and you are not even contesting it in your restatements.
You then asserted efficiency numbers for gas plants that are substantially higher than reality. The average efficiency globally of gas plants is in the realm of 40%.. UK efficiency is below 50% not 55-60%
So if you have a gas electricity powered resistive heater, you get 55-60% of the heat you would from just burning the gas.
But if you run a heat pump, you get at least 110% of the heat you would get from burning the gas.
This is not true, it's actually well below 100%.
And that's the worst case. Most of the time it will be more like 200-300%. And any renewable energy directly reduces the amount of gas you are using.
While I agree in the UK air sourced
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The whole point of TFA is that they found that even in extreme cold, heat pumps are at least 200% efficient.
Gas plant depends on how old they are. The newer ones are better. The older ones are down at 40%, coal is about 37%.
Thing is, even at 37%, heat pumps are more efficient in almost all conditions. It has to get really cold for efficiency to drop enough for just burning the coal to provide more heat, colder than most of the UK ever experiences.
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It is saying that heat pumps are more efficient than boilers/furnaces by a factor of two, per unit of energy, even in extremely cold weather.
Citation needed.
Where in TFA or the referenced paper does it explicitly say that a gas-powered-generator+heat-pump provides twice as much heat as a gas furnace in extremely cold weather per unit of fuel consumed?
Please provide an exact quote, not just a description of what you think it's saying.
Maybe it does. But I couldn't find it. And I am very skeptical that it is true.
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Heat pumps are better than resistive heating is an obvious statement. Heat produced by running the pump is obviously dumped into the system and heats the home. This is 100% efficient.
Unfortunately this is not the take science provides us with. Resistive heating is nearly 100% efficient only emitting a couple milliwatts/watt or much less of escaped light, magnetic or electric field coupling, and sound.
Moving heat from the outside in will naturally add more heat into the home than a simple resistive heater.
Close, taking existing environmental thermal energy and concentrating it creates a higher temperature that will often greatly exceed 100% efficiency because you don’t pay for that free heat, hitting 500% or more efficiency peak in some cases.
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, it says that when the weather gets cold, a backup heat source is needed.
I believe the exact conditions are when it gets extremely cold, a secondary heat source is needed like a fireplace. I think that temperatures near freezing, a heat pump can adequately do its job. But for places that it routinely gets -15F, fireplaces are already common.
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Yeah they're not great if it gets super cold, but for most people it's way better to use an electric heatpump than electric or oil heating which are common in the US
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There's reports (I haven't seen them rise above anecdotal so far) of some modern heat pumps working down to -15F or lower. https://energynews.us/2022/07/... [energynews.us] .
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To quote the article you linked:
"Heat Pumps Are Not Covered In This Article
In fact, as we mentioned above, heat pumps are very efficient and will beat natural gas. Heat pumps are able to move more BTUs of heat energy for a given amount of electricity than an electrical heater can generate."
So I'm a bit befuddled what the point of the article even is. It seems to be debating resistance based heating versus gas furnace, but there's not a soul arguing for resistance based heating.
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No, it doesn't. In that site you linked it very specifically says they do not cover heat pumps. They are measuring traditional resistive heaters.
I have a heat pump and I can heat my whole house for what my gaming PC draws under load. The electric range and dryer are way more energy intensive.
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Uh, no, the refrigerant doesn't need to be checked every year. On the other hand, it's a good idea to have your furnace cleaned every year, so it balances out regardless.
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And I've had AC units that are the same, 20+ years no problem.
Unless something's wrong, the refrigerant doesn't need to be checked annually. If you're going to go that far with preventative maintenance, you should probably have your furnace cleaned and tuned annually as well.
I certainly had to do so with my oil fired boiler up in Alaska, but I'll readily admit that oil is far dirtier than gas.
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Oh, and I had a gas furnace that tried to kill me in North Dakota - the vent became blocked and started producing carbon monoxide.
So that's certainly something you should regularly check.
Also, to nitpick: If it's over 20 years old, it isn't modern.