We have 3 heat pumps now and I’ve had heat pumps my entire life. They may be more efficient now, but they are significantly less reliable. Rarely do 6 months go by without us having a problem with...
We have 3 heat pumps now and I’ve had heat pumps my entire life. They may be more efficient now, but they are significantly less reliable. Rarely do 6 months go by without us having a problem with one of them. Two of the units are Mitsubishi mini-splits (one ducted and the other with wall-mounted heads). The other is a more traditional unit. The more traditional one is a Bosch unit.
At the moment, the Bosch (less than 3 years old) is broken. The wall-heads mini split exploded 2 days ago, when a circuit in it blew, causing all the coolant to leak out.
We never had problems like this in the 80s and 90s. Quality has plummeted.
Based on purely anecdotal evidence, I've heard that for modern heat pumps that Daikin are the most reliable. I know >1 people who have either Mitsubishi or Panasonic heat pumps and they hate them....
Based on purely anecdotal evidence, I've heard that for modern heat pumps that Daikin are the most reliable.
I know >1 people who have either Mitsubishi or Panasonic heat pumps and they hate them. At least one of those samples got a Daikin and said it was much better in quality.
Where I live here Daikin is the brand we all go for, and our winters go down to -30 degrees C. My opinion is they are incredibly good, like I'm shocked by the magic heat and cold these things produce out of nearly nothing. Some owners here have had them for 10+ years.
All that said, I've heard from owners in the UK saying that Mitsubuishi, Panasonic and even Daikin units are garbage for heating, I don't know if its the climate, the installation or the models, but the difference in opinion is pretty stark.
It definitely isn't the climate. The UK has pretty mild winters comparatively and doesn't regularly reach temperatures where heat pumps start struggling.
It definitely isn't the climate. The UK has pretty mild winters comparatively and doesn't regularly reach temperatures where heat pumps start struggling.
Yeah I mean on paper I totally agree with you, but I hear nothing but bad reports from the UK. I'm not sure if it's actually legitimate or if its placebo or something. I don't know if climate as...
Yeah I mean on paper I totally agree with you, but I hear nothing but bad reports from the UK. I'm not sure if it's actually legitimate or if its placebo or something.
I don't know if climate as in maybe humitidy or something else. Who knows its very hard to judge especially on purely anecdotal evidence.
Just to balance out the anecdotes you've heard, I'm in the UK and my heat pump is doing just fine. As are the heat pumps of the various family and friends who have them. My sister lives in...
Just to balance out the anecdotes you've heard, I'm in the UK and my heat pump is doing just fine. As are the heat pumps of the various family and friends who have them. My sister lives in northern Scotland and is overjoyed with how warm her house is now - previously her only heating was a couple of coal fires!
Houses here are generally not designed for forced air heating, but there's no reason you can't connect a heat pump to a circulating water heating system (although you do lose the capacity for cooling in the summer if you do that)
That's good to hear some good reports! I've heard from friends, family, coworkers and just asking about for my sources. Who knows. A gas engineer once told me that he felt like there was a smear...
That's good to hear some good reports! I've heard from friends, family, coworkers and just asking about for my sources.
Who knows. A gas engineer once told me that he felt like there was a smear campaign in the UK against heat pumps but its hard to believe without some facts.
Heat pumps need fairly well-insulated homes to be effective, don't they? Every house I've encountered in the UK has had some issue with either draughts or damp, so there's always some gap to the...
Heat pumps need fairly well-insulated homes to be effective, don't they? Every house I've encountered in the UK has had some issue with either draughts or damp, so there's always some gap to the outside undermining any heating efforts. I wouldn't be surprised if that were a contributing factor.
I’m not an expert, but I don’t see how insulation would affect reliability or performance. Obviously if you loose less heat, you don’t need as much heating capability, but that just means you can...
I’m not an expert, but I don’t see how insulation would affect reliability or performance. Obviously if you loose less heat, you don’t need as much heating capability, but that just means you can get away with a smaller heat pump. Cars are not very well insulated, and they all have heat pumps (used for cooling only, but it’s the exact same technology).
Cars are significantly smaller than houses, and are usually way more effective at keeping the driver and front passenger comfortable than anyone else, so I'm not sure how well that comparison...
Cars are significantly smaller than houses, and are usually way more effective at keeping the driver and front passenger comfortable than anyone else, so I'm not sure how well that comparison scales.
I'm no expert either, just looked into getting a heat pump a year or two ago and all the "is it right for me?"-type articles I've read highlight a need for eliminating draughts, improving insulation, and getting "heat loss survey" done to even decide whether a heat pump is viable. Though what ultimately stopped me was needing something like 2m of unobstructed outside wall space.
It’s less about “is a heat pump viable?” and more about whether or not you have more cost effective options to improve your home’s ability to stay cool/warm before you invest in a heat pump.
It’s less about “is a heat pump viable?” and more about whether or not you have more cost effective options to improve your home’s ability to stay cool/warm before you invest in a heat pump.
One potential issue is operating temperature: at least in North America, we’ve historically used under floor heating with heat pumps, which works because they work at a (relatively) low operating...
One potential issue is operating temperature: at least in North America, we’ve historically used under floor heating with heat pumps, which works because they work at a (relatively) low operating temperature over a wide surface area. Radiators (as are more common in the UK, I think?) need to operate at much higher temperatures in order to heat effectively due to their small size. And in that case, insulation and air sealing could mean that radiators don’t need to run as hot.
All that said, modern heat pumps work just fine at producing higher temperature water, it’s just a little less efficient.
I can confirm my Daikins have yet to cause any issues after two years. I know someone with Mitsubishis and while they are considered very good too they do cause trouble once in a while.
I can confirm my Daikins have yet to cause any issues after two years.
I know someone with Mitsubishis and while they are considered very good too they do cause trouble once in a while.
I'm not sure what qualifies as a heat pump versus a central air unit, despite them being basically the same thing. (Maybe when they're used primarily for heating, people call them heat pumps?),...
I'm not sure what qualifies as a heat pump versus a central air unit, despite them being basically the same thing. (Maybe when they're used primarily for heating, people call them heat pumps?), but I've lived in Florida most of my life, and literally every single building has heat pumps. It would be impossible to live a comfortable life here without them.
As such, every place ive ever lived has one, and I rarely have had problems with them. A capacitor died on my compressor about four years ago, but other than that the same unit has been running strong for 10 years.
It's interesting hearing about heat pumps as if they're a new or not widely deployed technology, because basically any place built within the last 50 years down here was built with them in mind, and the ones that weren't have long since been retrofitted to accommodate them.
Heat pumps come with incredibly efficient air conditioning basically baked in, but it's only relatively recently that we've been able to implement efficient heating using the same technology....
Heat pumps come with incredibly efficient air conditioning basically baked in, but it's only relatively recently that we've been able to implement efficient heating using the same technology. That's the innovative part.
Talking with my HVAC Nerd buddy, Heat Pumps are essential the same as an AC just with a reversing valve at the compressor. Yeah, the compressor tech is significantly better over the years as well,...
Talking with my HVAC Nerd buddy, Heat Pumps are essential the same as an AC just with a reversing valve at the compressor. Yeah, the compressor tech is significantly better over the years as well, but the two things are fundamentally different.
I'm far from an expert in HVAC, so my understanding of the technology is very much from other people explaining it to me! So I trust your HVAC friend's explanation lol
I'm far from an expert in HVAC, so my understanding of the technology is very much from other people explaining it to me! So I trust your HVAC friend's explanation lol
The recent innovation with heat pumps is how cold the cold side can be, therefore if they can operate well in cold climates. They have always, since invention, been able to provide heat just fine.
The recent innovation with heat pumps is how cold the cold side can be, therefore if they can operate well in cold climates. They have always, since invention, been able to provide heat just fine.
Of course they have been able to provide heat, but the heat that comes off the back of the refrigerator isn't going to be used to heat a home. Being able to utilize them for efficient home heating...
Of course they have been able to provide heat, but the heat that comes off the back of the refrigerator isn't going to be used to heat a home. Being able to utilize them for efficient home heating took additional engineering is all I meant.
Only because a refrigerator is a very low power heat pump. Install a window AC unit from the 1950’s backwards and it will heat a house just fine. An air conditioning outputs exactly as much heat...
Only because a refrigerator is a very low power heat pump. Install a window AC unit from the 1950’s backwards and it will heat a house just fine. An air conditioning outputs exactly as much heat as it removes (technically slightly more because of friction losses in the system). The only difference between a “heat pump” and an AC is a cheap valve that allows it to run backwards. And the only innovations that happened recently allow the cold side to be colder.
To be fair, I also suspect there's some design difference regarding condensation or icing. An air conditioner operating in a hot climate shouldn't be seeing ice buildup.
The only difference between a “heat pump” and an AC is a cheap valve that allows it to run backwards.
To be fair, I also suspect there's some design difference regarding condensation or icing. An air conditioner operating in a hot climate shouldn't be seeing ice buildup.
They've been common in warmer climates like where you are, but further north with colder winters they've been almost non existent in the market. This due partly to them struggling at the colder...
They've been common in warmer climates like where you are, but further north with colder winters they've been almost non existent in the market. This due partly to them struggling at the colder temperatures they'd need to reach and because of how cheap natural gas is in most parts of the region so it's the cheap option for heat. Cold climate heat pumps are the solution to that in order to electrify heating in colder regions, so that's why they're getting so much press.
Comment box Scope: summary, information Tone: optimistic Opinion: not really Sarcasm/humor: none Residential reliance on natural gas is no longer necessary for the overwhelming majority of the...
Comment box
Scope: summary, information
Tone: optimistic
Opinion: not really
Sarcasm/humor: none
Residential reliance on natural gas is no longer necessary for the overwhelming majority of the population. Modern cold-climate heat pumps are increasingly available and extremely efficient, even at negative temperatures.
3-4x efficiency improvement not only means much fewer emissions, but a lower energy bill!
In October, the Energy Department announced that eight manufacturers participating in its challenge to produce efficient residential cold climate heat pumps had created appliances that would enter commercial production as early as this fall. These heat pumps were shown in tests to be capable of operating at 5°F (-15°C) or lower “with energy performance well beyond current best-in-class products,” according to the Energy Department.
Carrier, one of the companies that participated in the Energy Department’s heat pump challenge, said its technology could operate at full capacity at 0°F (-18°C). Trial units of these heat pumps were field tested in homes in Syracuse, New York, and the company said they operated reliably, though not at full capacity, down to -13°F (-25°C).
In lab testing, the units were able to operate down to -23°F (-31°C).
Emphasis/tweaks mine. These are real-world tests of heat pumps in very cold climates. They are extremely economical in sub-freezing temperatures and still perfectly suitable for freak cold periods. The lab data indicates that further progress on this front is all but inevitable.
In addition to climate benefits, there are personal ones:
“Cold climate heat pumps can lower bills while maintaining comfort in very low temperatures, especially for people who use inefficient systems that rely on propane, oil or electric resistance,” she said.
She added that some people in places with higher electricity rates could see savings because cold climate heat pumps will switch to backup electric resistance heating less often.
“They’re very reliable,” she said. “They can control the comfort significantly better than a furnace.”
The challenge here that I see folks missing is two fold: When it's very cold, the COP of low-temperature heat-pumps drops significantly, as does the experienced performance (more defrost cycles...
The challenge here that I see folks missing is two fold:
When it's very cold, the COP of low-temperature heat-pumps drops significantly, as does the experienced performance (more defrost cycles leading to cold air intervals inside)
Electricity is much more expensive than Natural Gas / Propane / Oil in many areas, especially the Northeast US.
Combined, the experienced reality of heatpumps is massive electrical bills in the deep winter, and lack of indoor comfort caused by defrost cycles. For us, our equivalent propane was $200/mo, the electrical cost was $1000+.
So while everything in the article is true - and it's a huge leap that we've moved from "don't work when it's very cold" to "you can depend on only a heat pump year-round" - the experienced reality isn't QUITE what's being sold. Especially not lower energy BILLS, despite there being lower energy USE (theoretically).
EDIT: I'll also clarify that this isn't just my lived experience. There are a number of folks in a group I am in who all switched to heat pumps as their primary heat source around the same time. Nearly all (but not all) experienced the same themes and sticker shock at their electrical bills.
Comment box Scope: comment response, information Tone: neutral Opinion: lightly Sarcasm/humor: none The heat pumps described in this article have higher COPs than models that have been on the...
Comment box
Scope: comment response, information
Tone: neutral
Opinion: lightly
Sarcasm/humor: none
The heat pumps described in this article have higher COPs than models that have been on the market in the past. It is specifically talking about new heat pumps that are only just barely entering commercial production. So that anecdote is not applicable.
If you read the CCHP Technology Challenge Specifications discussed here, the detailed specifications (p.6) require that heat pumps in the challenge have COP values of 2.1–2.4 at 5°F (-15°C). That means the heat pump can operate at 210–240% efficiency in these particularly cold conditions—minimum. Many can do even better.
In contrast, a resistance heater operates at 100% efficiency. A gas furnace operates at 80–95% efficiency. So unless the electricity to heat a given space is more than 2.4x more expensive than the gas to do so, the heat pump is still a cost saving. In New England, it only sometimes gets below 5°F (-15°C) anyway, and rarely below 0°F (-18°C). From a cost perspective, New Englanders are not going to see major cost increases because their heat pumps will mostly be working super efficiently. The occasional cold spell may reduce the efficiency of the units somewhat, but only briefly.
I hear your propane example, but that seems anomalous even for the northeast. The cost of generating electricity will continue to drop in the near future as the cost of solar and wind continue to decline. If you're purchasing a heating system for the future, it's best to think about future energy costs and not just anecdotal past costs or even exclusively current ones.
I don't see any problem with having a woodstove or gas furnace as a backup to a heat pump, if indeed the area is cold enough and electricity prices are unusually high, but I don't think it is necessary anymore for the climate most people live in.
The raw efficiency doesn't tell the whole tale though. @ACEmat could probably explain it better. One therm of gas is roughly equivalent to 100,000 BTU. So if you have a house that needs...
The raw efficiency doesn't tell the whole tale though. @ACEmat could probably explain it better.
One therm of gas is roughly equivalent to 100,000 BTU. So if you have a house that needs 50,000BTU/hr, that means you're using about 1/2 therm per hour. 1 kW is roughly equivalent to 3,500BTU. So to heat the same house for an hour with resistive heat it'll take about 14kWh. A COP of 2.4 will translate to an electric use of about 5.8 kWh for a heat pump.
So then you take your prices and can figure out your hourly costs. If we take electricity at $0.13/kwh and gas at $1.63 per therm:
Gas heat: ~$0.81
Electric heat: $1.82
2.1 COP heat pump: ~$0.86
2.4 COP heat pump: ~$0.75
So while the heat pumps do have the potential to be better (and generally are when temps are over 30F), it still will result in sticker shock for somebody coming from gas during the coldest parts of winter. And that shock will be better/worse depending on costs of electricity and gas. If gas is heavily subsidized, the math looks even worse for heat pumps.
Am in Colorado, gas is $1.01/therm, lowest electricity rate (off peak hours) is $0.12/kWh... Gas heat at 80% for 100M BTU: $1,262.50 Heat pump at 250% for 100M BTU: $1,406.80 ...and that's with...
Am in Colorado, gas is $1.01/therm, lowest electricity rate (off peak hours) is $0.12/kWh...
Gas heat at 80% for 100M BTU: $1,262.50
Heat pump at 250% for 100M BTU: $1,406.80
...and that's with only using the lowest possible electricity rate.
I'm also waiting for this "solar/wind will make electricity cheaper" to happen. Electric providers aren't stupid, they know not to build more than they can sell for a profit and none of them are eager to make electricity prices go down. Looking at the 10 year price history for electricity in Colorado the base rate in January of 2014 was $0.04604/kWh in January of 2024 it was $0.07136/kWh; adjusting for inflation the 2014 rate was $0.06. In the same amount of time Colorado went from producing 7,975GWh to 21,318.5GWh of renewables annually.
Great data points. I wonder what's pushing electricity costs up so high, if renewables are getting so much cheaper and so many grids are incorporating renewables? Something in my mental model must...
Great data points. I wonder what's pushing electricity costs up so high, if renewables are getting so much cheaper and so many grids are incorporating renewables? Something in my mental model must be wrong, because it just doesn't add up. Unless it's just corporate greed.
I do worry that solar is somewhat pointless in much of the USA during the cold half of the year. In the Northeast, we get so little daylight and so much cloud coverage I doubt we coud meaningfully rely on solar October-April. Unless we massively overbuild it, I suppose?
Am in South Jersey. Gas is $1.61/therm, cheapest electricity (winter rate) is about $0.23/kWh. The good news is milder climate means that the heat pump is usually operating closer to 4-6 COP. More...
Am in South Jersey. Gas is $1.61/therm, cheapest electricity (winter rate) is about $0.23/kWh.
The good news is milder climate means that the heat pump is usually operating closer to 4-6 COP. More good news is that I have a 15kw solar array on the roof that came with the home that drastically tips the scales.
You're right that at utility scale, green energy will never mean cheaper rates. The good news is that solar (and wind) are fairly cheap to install at home, which helps counteract that. Check Project Sunroof, I've found it fairly accurate for a quick guesstimate. Unless you have assets, the subsidized loans are the way to go...NEVER USE A SOLAR LEASE.
When did you guys switch? Even three years ago this tech was in its infancy. I have a not-cold-climate system that was installed in 2021, and I can say with a degree of certainty that it's still...
When did you guys switch? Even three years ago this tech was in its infancy. I have a not-cold-climate system that was installed in 2021, and I can say with a degree of certainty that it's still infinitely better than electric baseboard.
I will agree that during cold spikes, you'll definitely pay more than gas. I retain a backup heating system for a prolonged cold snap for just such occasions. But for those of us where average temps rarely drop below 30, it's still a pretty solid win if you're looking to keep gas out of your home (like its seriously bad for you).
I think the correct answer in the future is going to be some sort of combo unit where you could have a small auxilary combustion heat source attached to the outdoor coils to aid in those sub-zero conditions.
Somewhat relatedly, it’d be nice if there were a way to simultaneously push for improved house air sealing + insulation (or the envelope overall), and retrofits for existing buildings. For folks...
Somewhat relatedly, it’d be nice if there were a way to simultaneously push for improved house air sealing + insulation (or the envelope overall), and retrofits for existing buildings. For folks that don’t feel that they can switch to electric heating, it would at least let them cut costs on fuel, which helps everyone long term.
I don’t think it’s possible to make “inspect homes using a variety of equipment, model energy over the day/year, and meticulously retrofit walls & windows” as interesting as a cool new technology straight outta science fiction, though, so I’m probably chasing a pipe dream.
The only programs they have are the tax incentives to do it yourself. The US government doesn't really socialize programs, they individualize them and capitalize on them, so I don't suspect you...
The only programs they have are the tax incentives to do it yourself. The US government doesn't really socialize programs, they individualize them and capitalize on them, so I don't suspect you will see this happen in our lifetime.
Tax incentives are better than nothing, I suppose. I'm pretty young and not in the US though, so I'm more optimistic about seeing some better programs to improve energy efficiency in homes before...
Tax incentives are better than nothing, I suppose. I'm pretty young and not in the US though, so I'm more optimistic about seeing some better programs to improve energy efficiency in homes before I die.
Mini splits are great for small apartments, and warmer climates. Geothermal heat pumps on the other hand are where you find incredible gains. I have had one for three years now, and my propane...
Mini splits are great for small apartments, and warmer climates. Geothermal heat pumps on the other hand are where you find incredible gains. I have had one for three years now, and my propane bill is now $0 down from $800/mo in the winter. My electricity bill is only $175/mo during that same billing period, and that includes the electricity I am using for everything else, which is pretty incredible considering I work and live in this house 24/7.
I’d imagine that you already know this, but for anyone else reading, split units can also be big and not “mini”! The main differentiator is whether they try to push/pull heat out of the ground...
I’d imagine that you already know this, but for anyone else reading, split units can also be big and not “mini”! The main differentiator is whether they try to push/pull heat out of the ground (ground source, like thread OP) or out of the air (air sourced, like in the article). Both are very efficient and perfectly capable of hearing or cooling a house, and air source heat pumps have the bonus of working in very rocky terrain!
We have 3 heat pumps now and I’ve had heat pumps my entire life. They may be more efficient now, but they are significantly less reliable. Rarely do 6 months go by without us having a problem with one of them. Two of the units are Mitsubishi mini-splits (one ducted and the other with wall-mounted heads). The other is a more traditional unit. The more traditional one is a Bosch unit.
At the moment, the Bosch (less than 3 years old) is broken. The wall-heads mini split exploded 2 days ago, when a circuit in it blew, causing all the coolant to leak out.
We never had problems like this in the 80s and 90s. Quality has plummeted.
Based on purely anecdotal evidence, I've heard that for modern heat pumps that Daikin are the most reliable.
I know >1 people who have either Mitsubishi or Panasonic heat pumps and they hate them. At least one of those samples got a Daikin and said it was much better in quality.
Where I live here Daikin is the brand we all go for, and our winters go down to -30 degrees C. My opinion is they are incredibly good, like I'm shocked by the magic heat and cold these things produce out of nearly nothing. Some owners here have had them for 10+ years.
All that said, I've heard from owners in the UK saying that Mitsubuishi, Panasonic and even Daikin units are garbage for heating, I don't know if its the climate, the installation or the models, but the difference in opinion is pretty stark.
It definitely isn't the climate. The UK has pretty mild winters comparatively and doesn't regularly reach temperatures where heat pumps start struggling.
Yeah I mean on paper I totally agree with you, but I hear nothing but bad reports from the UK. I'm not sure if it's actually legitimate or if its placebo or something.
I don't know if climate as in maybe humitidy or something else. Who knows its very hard to judge especially on purely anecdotal evidence.
Just to balance out the anecdotes you've heard, I'm in the UK and my heat pump is doing just fine. As are the heat pumps of the various family and friends who have them. My sister lives in northern Scotland and is overjoyed with how warm her house is now - previously her only heating was a couple of coal fires!
Houses here are generally not designed for forced air heating, but there's no reason you can't connect a heat pump to a circulating water heating system (although you do lose the capacity for cooling in the summer if you do that)
That's good to hear some good reports! I've heard from friends, family, coworkers and just asking about for my sources.
Who knows. A gas engineer once told me that he felt like there was a smear campaign in the UK against heat pumps but its hard to believe without some facts.
Heat pumps need fairly well-insulated homes to be effective, don't they? Every house I've encountered in the UK has had some issue with either draughts or damp, so there's always some gap to the outside undermining any heating efforts. I wouldn't be surprised if that were a contributing factor.
I’m not an expert, but I don’t see how insulation would affect reliability or performance. Obviously if you loose less heat, you don’t need as much heating capability, but that just means you can get away with a smaller heat pump. Cars are not very well insulated, and they all have heat pumps (used for cooling only, but it’s the exact same technology).
Cars are significantly smaller than houses, and are usually way more effective at keeping the driver and front passenger comfortable than anyone else, so I'm not sure how well that comparison scales.
I'm no expert either, just looked into getting a heat pump a year or two ago and all the "is it right for me?"-type articles I've read highlight a need for eliminating draughts, improving insulation, and getting "heat loss survey" done to even decide whether a heat pump is viable. Though what ultimately stopped me was needing something like 2m of unobstructed outside wall space.
It’s less about “is a heat pump viable?” and more about whether or not you have more cost effective options to improve your home’s ability to stay cool/warm before you invest in a heat pump.
One potential issue is operating temperature: at least in North America, we’ve historically used under floor heating with heat pumps, which works because they work at a (relatively) low operating temperature over a wide surface area. Radiators (as are more common in the UK, I think?) need to operate at much higher temperatures in order to heat effectively due to their small size. And in that case, insulation and air sealing could mean that radiators don’t need to run as hot.
All that said, modern heat pumps work just fine at producing higher temperature water, it’s just a little less efficient.
UK wise I'd imagine it's likely a combination of installations and the comparative cost of electricity Vs gas heating.
I can confirm my Daikins have yet to cause any issues after two years.
I know someone with Mitsubishis and while they are considered very good too they do cause trouble once in a while.
Going on year three here without any problems on a Daikin 3 zone heat pump, in an area with temps well below zero (C, and even F) in the winter.
I'm not sure what qualifies as a heat pump versus a central air unit, despite them being basically the same thing. (Maybe when they're used primarily for heating, people call them heat pumps?), but I've lived in Florida most of my life, and literally every single building has heat pumps. It would be impossible to live a comfortable life here without them.
As such, every place ive ever lived has one, and I rarely have had problems with them. A capacitor died on my compressor about four years ago, but other than that the same unit has been running strong for 10 years.
It's interesting hearing about heat pumps as if they're a new or not widely deployed technology, because basically any place built within the last 50 years down here was built with them in mind, and the ones that weren't have long since been retrofitted to accommodate them.
Heat pumps come with incredibly efficient air conditioning basically baked in, but it's only relatively recently that we've been able to implement efficient heating using the same technology. That's the innovative part.
Talking with my HVAC Nerd buddy, Heat Pumps are essential the same as an AC just with a reversing valve at the compressor. Yeah, the compressor tech is significantly better over the years as well, but the two things are fundamentally different.
I'm far from an expert in HVAC, so my understanding of the technology is very much from other people explaining it to me! So I trust your HVAC friend's explanation lol
Your buddy isn't called Troy by any chance, right?
Haha, nope. Joel.
The recent innovation with heat pumps is how cold the cold side can be, therefore if they can operate well in cold climates. They have always, since invention, been able to provide heat just fine.
Of course they have been able to provide heat, but the heat that comes off the back of the refrigerator isn't going to be used to heat a home. Being able to utilize them for efficient home heating took additional engineering is all I meant.
Only because a refrigerator is a very low power heat pump. Install a window AC unit from the 1950’s backwards and it will heat a house just fine. An air conditioning outputs exactly as much heat as it removes (technically slightly more because of friction losses in the system). The only difference between a “heat pump” and an AC is a cheap valve that allows it to run backwards. And the only innovations that happened recently allow the cold side to be colder.
To be fair, I also suspect there's some design difference regarding condensation or icing. An air conditioner operating in a hot climate shouldn't be seeing ice buildup.
Heat pumps can heat and cool. They're basically the same thing but they can go in both directions, dumping heat inside or outside.
They've been common in warmer climates like where you are, but further north with colder winters they've been almost non existent in the market. This due partly to them struggling at the colder temperatures they'd need to reach and because of how cheap natural gas is in most parts of the region so it's the cheap option for heat. Cold climate heat pumps are the solution to that in order to electrify heating in colder regions, so that's why they're getting so much press.
Comment box
Residential reliance on natural gas is no longer necessary for the overwhelming majority of the population. Modern cold-climate heat pumps are increasingly available and extremely efficient, even at negative temperatures.
Context - what's the problem?
3-4x efficiency improvement not only means much fewer emissions, but a lower energy bill!
Emphasis/tweaks mine. These are real-world tests of heat pumps in very cold climates. They are extremely economical in sub-freezing temperatures and still perfectly suitable for freak cold periods. The lab data indicates that further progress on this front is all but inevitable.
In addition to climate benefits, there are personal ones:
The challenge here that I see folks missing is two fold:
Combined, the experienced reality of heatpumps is massive electrical bills in the deep winter, and lack of indoor comfort caused by defrost cycles. For us, our equivalent propane was $200/mo, the electrical cost was $1000+.
So while everything in the article is true - and it's a huge leap that we've moved from "don't work when it's very cold" to "you can depend on only a heat pump year-round" - the experienced reality isn't QUITE what's being sold. Especially not lower energy BILLS, despite there being lower energy USE (theoretically).
EDIT: I'll also clarify that this isn't just my lived experience. There are a number of folks in a group I am in who all switched to heat pumps as their primary heat source around the same time. Nearly all (but not all) experienced the same themes and sticker shock at their electrical bills.
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The heat pumps described in this article have higher COPs than models that have been on the market in the past. It is specifically talking about new heat pumps that are only just barely entering commercial production. So that anecdote is not applicable.
If you read the CCHP Technology Challenge Specifications discussed here, the detailed specifications (p.6) require that heat pumps in the challenge have COP values of 2.1–2.4 at 5°F (-15°C). That means the heat pump can operate at 210–240% efficiency in these particularly cold conditions—minimum. Many can do even better.
In contrast, a resistance heater operates at 100% efficiency. A gas furnace operates at 80–95% efficiency. So unless the electricity to heat a given space is more than 2.4x more expensive than the gas to do so, the heat pump is still a cost saving. In New England, it only sometimes gets below 5°F (-15°C) anyway, and rarely below 0°F (-18°C). From a cost perspective, New Englanders are not going to see major cost increases because their heat pumps will mostly be working super efficiently. The occasional cold spell may reduce the efficiency of the units somewhat, but only briefly.
I hear your propane example, but that seems anomalous even for the northeast. The cost of generating electricity will continue to drop in the near future as the cost of solar and wind continue to decline. If you're purchasing a heating system for the future, it's best to think about future energy costs and not just anecdotal past costs or even exclusively current ones.
I don't see any problem with having a woodstove or gas furnace as a backup to a heat pump, if indeed the area is cold enough and electricity prices are unusually high, but I don't think it is necessary anymore for the climate most people live in.
The raw efficiency doesn't tell the whole tale though. @ACEmat could probably explain it better.
One therm of gas is roughly equivalent to 100,000 BTU. So if you have a house that needs 50,000BTU/hr, that means you're using about 1/2 therm per hour. 1 kW is roughly equivalent to 3,500BTU. So to heat the same house for an hour with resistive heat it'll take about 14kWh. A COP of 2.4 will translate to an electric use of about 5.8 kWh for a heat pump.
So then you take your prices and can figure out your hourly costs. If we take electricity at $0.13/kwh and gas at $1.63 per therm:
Gas heat: ~$0.81
Electric heat: $1.82
2.1 COP heat pump: ~$0.86
2.4 COP heat pump: ~$0.75
So while the heat pumps do have the potential to be better (and generally are when temps are over 30F), it still will result in sticker shock for somebody coming from gas during the coldest parts of winter. And that shock will be better/worse depending on costs of electricity and gas. If gas is heavily subsidized, the math looks even worse for heat pumps.
Am in Colorado, gas is $1.01/therm, lowest electricity rate (off peak hours) is $0.12/kWh...
Gas heat at 80% for 100M BTU: $1,262.50
Heat pump at 250% for 100M BTU: $1,406.80
...and that's with only using the lowest possible electricity rate.
I'm also waiting for this "solar/wind will make electricity cheaper" to happen. Electric providers aren't stupid, they know not to build more than they can sell for a profit and none of them are eager to make electricity prices go down. Looking at the 10 year price history for electricity in Colorado the base rate in January of 2014 was $0.04604/kWh in January of 2024 it was $0.07136/kWh; adjusting for inflation the 2014 rate was $0.06. In the same amount of time Colorado went from producing 7,975GWh to 21,318.5GWh of renewables annually.
Great data points. I wonder what's pushing electricity costs up so high, if renewables are getting so much cheaper and so many grids are incorporating renewables? Something in my mental model must be wrong, because it just doesn't add up. Unless it's just corporate greed.
I do worry that solar is somewhat pointless in much of the USA during the cold half of the year. In the Northeast, we get so little daylight and so much cloud coverage I doubt we coud meaningfully rely on solar October-April. Unless we massively overbuild it, I suppose?
The northeast should be exploring wind like their lives depend on it.
Am in South Jersey. Gas is $1.61/therm, cheapest electricity (winter rate) is about $0.23/kWh.
The good news is milder climate means that the heat pump is usually operating closer to 4-6 COP. More good news is that I have a 15kw solar array on the roof that came with the home that drastically tips the scales.
You're right that at utility scale, green energy will never mean cheaper rates. The good news is that solar (and wind) are fairly cheap to install at home, which helps counteract that. Check Project Sunroof, I've found it fairly accurate for a quick guesstimate. Unless you have assets, the subsidized loans are the way to go...NEVER USE A SOLAR LEASE.
When did you guys switch? Even three years ago this tech was in its infancy. I have a not-cold-climate system that was installed in 2021, and I can say with a degree of certainty that it's still infinitely better than electric baseboard.
I will agree that during cold spikes, you'll definitely pay more than gas. I retain a backup heating system for a prolonged cold snap for just such occasions. But for those of us where average temps rarely drop below 30, it's still a pretty solid win if you're looking to keep gas out of your home (like its seriously bad for you).
I think the correct answer in the future is going to be some sort of combo unit where you could have a small auxilary combustion heat source attached to the outdoor coils to aid in those sub-zero conditions.
Somewhat relatedly, it’d be nice if there were a way to simultaneously push for improved house air sealing + insulation (or the envelope overall), and retrofits for existing buildings. For folks that don’t feel that they can switch to electric heating, it would at least let them cut costs on fuel, which helps everyone long term.
I don’t think it’s possible to make “inspect homes using a variety of equipment, model energy over the day/year, and meticulously retrofit walls & windows” as interesting as a cool new technology straight outta science fiction, though, so I’m probably chasing a pipe dream.
It may not be as flashy, but it's absolutely something that would be beneficial if there were a government program to help encourage/pay for it.
The only programs they have are the tax incentives to do it yourself. The US government doesn't really socialize programs, they individualize them and capitalize on them, so I don't suspect you will see this happen in our lifetime.
Tax incentives are better than nothing, I suppose. I'm pretty young and not in the US though, so I'm more optimistic about seeing some better programs to improve energy efficiency in homes before I die.
Mini splits are great for small apartments, and warmer climates. Geothermal heat pumps on the other hand are where you find incredible gains. I have had one for three years now, and my propane bill is now $0 down from $800/mo in the winter. My electricity bill is only $175/mo during that same billing period, and that includes the electricity I am using for everything else, which is pretty incredible considering I work and live in this house 24/7.
I’d imagine that you already know this, but for anyone else reading, split units can also be big and not “mini”! The main differentiator is whether they try to push/pull heat out of the ground (ground source, like thread OP) or out of the air (air sourced, like in the article). Both are very efficient and perfectly capable of hearing or cooling a house, and air source heat pumps have the bonus of working in very rocky terrain!
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