When I needed a new air conditioner a couple years ago I was quoted $17,000 for a heat pump. I can only guess at that point whatever energy cost savings it would bring would never be realized within the service life of the system. I went with a $6000 standard replacement AC unit.
Unless the installer was ripping you off those were not comparable units. I've seen the manufacturer MSRP sheets and the cost difference between heat pump and non-heat pump for the same unit is small. Nowhere near enough to account for $11k.
It sounds like they quoted you a bottom of the range 11 SEER A/C vs a top of the line multi-stage compressor variable speed blower 19 SEER heat pump system. Those are not the same thing.
Might have been what I call a "fuck off" quote. That is, the people who gave you the quote didn't really want to do the job (too small, inconvenient location, or who knows what) and so quoted you an outrageous price figuring you'd either decide not to do it or if you did, you'd end up paying enough to make it worth their while. Happened to me a few years ago when I needed to re-tar my roof. The first guy quoted a figure that was like 4x what the next guy quoted.
Not a handy man, but we build power electronics and a lot of customized stuff. I also often give quotes that are really high for stuff that we don't actually want to do. It's kind of better than saying we cannot do it (because then they will never ask again) and if they agree to it we make a lot of money. For larger investments it makes sense to get a second quote.
What size? The last split system I bought cost about AU$1600 installed ( ~$1060) for 3.5kW... Looking at prices now, even going up to a ducted 14kW Mitsubishi Electric heat pump/AC is only AU$5000 (before installation, and you would need to add ducts and vents etc. - that's just the controller, outdoor unit and in-ceiling unit, but still)...
Is this in the US? Maybe the market is distorted just because not enough people are buying them yet, so nobody has much stock and there's little competition... We have that problem I think for air to water - super common in the UK and Europe, but since everybody uses air to air, split and ducted systems are super cheap but air to water are quite expensive. I really would quite like some heated floors in my bathrooms if I end up doing a big renovation, and don't want to go electric in-floor because hydronic with a heat pump should be more efficient.
For whatever reason both solar and heat pumps are insanely cheap in Australia vs America. It’s mostly in the labor part for some reason. This comes up all the time in the solar subreddit where Americans are routinely quoted at $4.00+ per watt for solar and $20,000+ for heat pump installs.
What kind of a system were you installing? We had a heat pump installed three years ago for less than $5k Canadian. Can't remember if we got a rebate on top of that or not.
I can only speculate, but in my last replacement scenario, higher-SEER units (17+) had dramatically higher quotes, to the point where it was difficult to justify financially. On top of that, there were dramatic (~100%) variations in prices on similar equipment (but different brands) between installers. I can only imagine that regional differences are yet another source of variation...
All that is to say, my first guess is that the GP was quoted a high-SEER unit for name-ish brand equipment.
I had the exact same experience last month. I was really excited to go heat pump. It ended up being $8k vs $12k (dual stage) vs ....... > $20k for the heat pump
The guy made no attempt to upsell me and if anything was pushing the cheapest option
Suffice to say I don't plan on staying at that house long enough to ever get my moneys or enjoyment out of it. Bummer.
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I think it's true that the cost only goes up "a little" between models, but the issue is, they make you go up across the board of equipment and it all adds up dramatically. The high end option requires buying their custom thermostat which was $1200 alone
The differences are usually overall efficiency (that Trane is one of the most efficient models, SEER rating of 29.5), noise and overall capacity. This was for a >4000 sq ft house with extensive west facing glazing, not an ideal scenario.
The difference of heat pump an AC is pretty much just a reversing valve, so as others have noted this is probably not an equivalent unit.
One caveat to that is if you have a furnace, they may have wanted to install a full new air handler and run electric emergency heat vs just swapping the coil and condenser.
You can configure a heat pump coil with a furnace as the emergency heat but it might take some more thinking than an off the shelf AHU condenser pairing that maybe the contractor wasn't comfortable with doing that.
Not too far off. I got 5 quotes recently. Most are from $17,500 for $19,000 for a 3.5 ton Mitsubishi heat pump, with an outdoor condenser unit and an indoor fan+coil unit. Permit and inspection from the city add another $1,000.
When my AC finally needs replacing I'm going heat pump, and then also ditching my gas water heater. The constant fees of a gas line are ridiculous at this point and any more electricity usage will be offset by the 9 months of the year I'd never turn on the heat.
Now you can even get water heaters with heat pumps and combo units that dump your waste heat from your hvac heat pump into the water heater. It’s wild.
When we put the solar on the roof we bundled in heat pump hot water system as well.
It's timed to only use power right in the middle of the day when the sun is shining, and in the middle of the night when power is cheap. (needs both because the tank is fairly small and my kids like long showers)
Heat pumps are great, but it’s the dc inverter and advances in compressor efficiency that is really the biggy on energy usage here.
Every one of these “heat pumps are the future” articles is so soft on data, and they often fail to explain the basics or a simple “why.” Once we get past the clickbait heat pump articles, we can actually make an impact.
I think the consensus on why heat pumps _should_ be the future is that you can power them with low carbon electricity, as opposed to literally world destroying natural gas.
A quick Google search says that natural gas -> electricity has an efficiency of about 44%, with an additional 5% loss during transmission. Lets call this about 40% efficiency for getting energy from natural gas to your electric heat pump.
A heat pump operating at 250% efficiency will use just as much natural gas as a furnace operating at 100% efficiency.
Modern heat pumps can often exceed 250% efficiency, making them use less natural gas, even if they are ultimately powered by a natural gas burning power plant.
I think many people suddenly realized that moving heat translates to efficiencies far north of 100%, also for heating. Moving in opposition to creating heat, which tops out at 100% in the best case.
Plus, they can run on any power source, including green and/or decarbonized.
They're quite popular in the Netherlands due to high natural gas prices (since the Ukraine war) and two types of government subsidies. One is a direct subsidy on buying a heat pump device, the other is based on our energy pricing.
Basically you can offset all energy-taxes across the year with solar production. Everything you over-produce in summer carries over to the winter. So if I assume for example that my solar system is written off in 10 years to zero (reality is probably better than that) my total energy cost per kWh is only 7 cents all year round.
A pretty low capacity heat pump is able to provide 90% of the heating and cooling of a normal house. They're combined here with gas based systems to cover for the few days a year that it's exceptionally cold or when you need more hot water than the heat pump could deliver. That means you can buy a much smaller capacity (cheaper) heat pump.
If you compare the running cost of heating at only 7 cents per kWh with a heat pump to natural gas prices "pre Ukraine" it'a already roughly about 4 to 5x cheaper. Now with gas prices nearly doubled you're looking at a 8x cost saving with a heath pump vs using natural gas. The only hurdle is that you need to buy and install a heat pump device, so it takes some time to make that back.
The government is planning to slowly reduce the energy-tax offset from 2025 to 2031. But even without that it's expected that the move from gas to heat pumps will continue.
I have new heat pumps in a very old, under insulated, and leaky house. I didn't use my oil furnace last winter (the first since two additional pumps). My costs were about half of the previous year, and I'm sure my carbon footprint was much better as well.
Can you say more about what your comment is supposed to mean?
Our house (in Europe) is relatively old and not well insulated by modern standards, and all of the advice we read and receive from experts is that heat pumps are not a good fit without additional insulation.
The gist is that we’d need to spec larger units and/or run them harder than usual, removing savings vs. gas.
Without fixing leaks and insulation, you've done the tech equivalent of throwing large amounts of resources at the problem rather than fixing the root cause :) Your CO footprint will be far better if you decided to fix the leaks & insulation.
There are options to do a full passive house retrofit, or just add exterior insulation if you have the funds and inclination. Plus you can get better air quality with filtered air, lower mold/pollen issues, lower noise if you care about that and overall home comfort.
Not only that, but since a heat pump is at least 3x as energy efficient as the most efficient gas furnace, using one results in about 1/2 the E2E CO2 emissions as the gas furnace when the grid electricity being consumed is natural gas based. If you live in an area with abundant zero emissions electricity, then you are heating without any C02 emissions at all.
That said, we should do both heat pumps and insulate better.
And it's irrelevant. Everyone is like "but if you have better insulation..." well golly gee, guess I'll get right on that. Tearing out all my drywall? Re-sarking my roof? Cost-free! Definitely not hugely disruptive, invasive and expensive activities which stand a good chance of forcing me to move out of my house while the work is complete...
People love throwing in about how effective insulation is, completely ignoring the vast difference in difficulty and cost it actually represents.
Putting more insulation in the attic does not mean redoing the roof. Depending on what you have it might just be blowing in some insulation or adding matting. Of course there are options like spray foaming but it's not the only one.
You are of course right that if your walls are completely uninsulated you will probably want to rip out that dry wall and that will cost you. Maybe blown insulation is an option too depending on your specifics.
Do some math and see if it makes sense to do it if you don't want to do it purely for the sake of the planet. Drywalling isn't that big of a deal actually. The worst would be the ceiling and you don't have to touch that. Regular drywall on a wall is easily done solo by a home owner. Been there, done that.
It's funny what money makes you do. I had a choice to pay tens of thousands to have professionals do it or pay hundreds for materials and do it myself. I did lots of TIL and I have beautiful white walls again.
There are other advantages to fixing leaks & insulation such as controlling humidity/moisture, lowering mold/pollen/dust, lower noise, adding better air filtration, maybe even better fire protection. By "lower" I mean you can eliminate some of these issues. Not to mention a far lower energy bill. I would not describe these as irrelevant to most people.
Depending on the house, location and condition, adding exterior or interior insulation and/or aero barrier, or spray foam could be more cost effective and not so invasive as you think.
It's actually exactly the reverse: for a house that's well-insulated, it barely matters how efficient your heating and cooling appliances are, especially if you're considering replacement of working systems.
The worst is when you rent. I live in an area that doesn't really expect much cold or heat. All the windows are single paned. The sun beating on the roof raises the top floor to the outside temperature plus 5 degrees. I can't fix any of it because I'm only here for a few years.
Some jurisdictions will actually basically pay the landlord to improve those things, worth checking community block grants and other similar search terms for your location.
It's kind of nice in cool climates. I've rented places where I never had to turn on the heat once all winter thanks to all the heat coming up from lower floors. Temps were almost always above 60F and usually above 65 which is perfectly fine for cozy sweaters and blankets.
Aero barrier and/or spray foam for an existing home should work well. But they are not long lasting and are often not environmentally friendly. You can also look into exterior insulation.
I would start by blowing insulation into the exterior walls (assuming they don’t have any), and insulating the attic. Also, upgrade the windows to double paned or better.
Fixing unintended holes in exterior walls is probably also reasonably safe.
However, randomly plugging intended leaks without understanding how the house is supposed to breathe can lead to condensation issues (mold and rot), carbon monoxide poisoning (if you have natural gas) and radon poisoning (if that is a thing where you live).
If you want to do more than I mentioned above, consider hiring an architect, or reading up on house ventilation designs.
Some home energy companies will do a free audit, in my case it's Mass Save. My in-laws on a limited income even got new windows and insulation for free.
It feels like very much a could country / could region distinction. In warmer regions of the world, heat pumps have been using for efficiently heating in winter since the 1980s (that's as far as my memory goes). Of course, when the temperature rarely went below 0℃. If you look at the single-room AC units that now dominate these markets, you'll rarely find anything that cannot do both heating and cooling.
Interesting, I’ve never heard of that interpretation. Heat pumps have always been a technology to me. The same tech that is in everyone’s refrigerator.
Technically, from the point of view of physics, yes. That said straight cool systems (alternate name for air conditioners) are only one way heat pumps (in a physical sense) as they lack the reversing valve needed to reverse the heat flow. Heat pumps (in the common sense) can move heat in either direction.
Compared to a traditional air conditioning unit, the reversing valve is the major difference. Your standard AC can only move heat from indoors to outdoors. A heat pump can do the reverse to warm your space. My basement heat pump is rated to provide heat even when it’s -20F outside.
I think any and all AC units sold in europe (split systems with inside and outside module) can do heating and cooling just fine with great efficiency. Many models rated to work at -20C, sometimes -30C
I think the media has once again assigned a term their specific definition and created a meme out of it. I guess it makes sense if you have no preconceived notions of what a "heat pump" is. But yes, to anybody that knows an air conditioner is a type of heat pump, these articles read akin to "Personal cars create too many emissions. Companies have come up with an innovative way to reduce this problem: vehicles". (with the reader in the memestream of taking the generic term "vehicles" to mean only electric vehicles)
Trying to parse the mumbo jumbo, I think these articles are trying to point out and encourage the trend of designing new installations of cooling systems around cooling and heating, with a reversing valve and whatnot. Because it no longer makes sense to lean on a separate heating system that burns fossil fuels. But gosh I wish they would just come out and say this directly instead of beating around the bush as if "heat pumps" are some magical new invention.
It’s not the media doing this; “heat pump” has been industry lingo (in the US at least) for an A/C with a reversing value since at least the early 1980s.
My parent’s house had a heat pump then and does so today (albeit much improved over the decades).
In physics we call a device that uses the compression and expansion of a fluid to move heat between parts of a system a heat pump.
An air conditioner uses a compressor to convert a refrigerant and sends the compressed fluid through a condenser. The condenser rejects heat from the system into the environment. This is the component of an air conditioner that is found outside. The compressed fluid is then passed through an expansion valve and into an evaporator where it is allowed to expand. Expansion is a process that requires heat. The heat flows into the expanding fluid from the environment inside the home. Air is blown across the evaporator coils to transfer heat energy from the home into the fluid which is then returned outside.
A heat pump is capable of reversing the flow of heat energy. The flow of fluid is reversed from an air-conditioner using something called a reversing valve. The compressor sends compressed fluid into the home where heat is rejected through the evaporator coil. The fluid then flows into the condenser coil and is allowed to expand outside, drawing in heat from the outside environment. The heated fluid is then returned to the compressor and the cycle continues.
In HVAC terminology an Air Conditioner is a one way physical heat pump and a heat pump is a bidirectional physical heat pump. Hopefully that helps clear it up a bit.
An A/C works almost identical to your refrigerator. Using a closed loop of refrigerant with specific thermal properties, it will remove heat from one side and emit heat from the other.
If you are able to run this system backwards, you could in theory swap which side is a heat sink (the cold side) and heat source (the hot side). While a traditional A/C cannot do this, heat pumps can electronically switch which side of the system is collecting the heat and which side is releasing it.
This is an improvement over resistive heating (think space heater) because we’re not pumping electricity into some filament that resists current flow and emits off heat due to the resistance. Instead, we are taking heat from inside and moving it out or taking heat from outside and moving it in.
Fun fact, a resistive heating device is a rare case of something being 100% electrically efficient in that all the energy it uses will be turned into heat, whereas heat normally is a byproduct of imperfect conductors, which everything is, and is therefore considered wasted energy in almost all other applications.
A heat pump is an A/C with a reversing valve; in A/C operation, the A/C cools the inside and heats the outside; in heating operation, the reversing valve is toggled and the system heats the inside and cools the outside.
It's kind of confusing terminology. I'll stick with how these terms are used by industry/laymen - heat pump also has a scientific definition that's more broad than how it's normally used.
There's a process called a "vapor compression cycle" which essentially works by moving energy from a cold area to a hot area (which makes the cold area colder and the hot area hotter).
Air conditioning is when you put the cold side of a vapor compression cycle in a building to keep it cool.
The term "heat pump" most typically refers to a device where the hot side of the vapor compression cycle is put in a building to keep it warm.
However, many heat pumps have an air conditioning mode, where the hot and cold sides of the vapor compression cycle switch places depending on the season. So air conditioner refers only to cooling, while heat pump may refer to heating along or a device which can both heat and cool.
* A/Cs are heat-pumps (when using the scientific definition of "heat-pump")
* Heat pumps, when referring to HVAC technology specifically, refer to systems that are essentially the same as A/C units, except they're designed to work in reverse.
* The term "heat pump" when used in Europe, more-often refers to geothermal heat-pumps ( https://en.wikipedia.org/wiki/Ground_source_heat_pump ) which is very different to an A/C-style heat-pump, though achieves similar end-result (livable indoor room air temperature).
As someone who spends a lot of time in the year in both North America and Europe I frequently come across people confusing the two.
Yes modern day a/c is usually a heatpump. I’ve noticed a lot of people misunderstanding heat pumps, and thinking it’s some sort of replacement for A/C. Or that heat pumps are some new tech.
And isn't the refrigerant the same with a heat pump?
The article says that heat pumps are "compatible with natural refrigerants with lower climate impacts". Why couldn't A/C units use the same natural refrigerants?
It's an industry term for mechanical equipment that can heat AND cool. One piece of equipment replaces your AC AND heat source.
Heat pumps in particular are getting a push from "green" initiatives because they only use electricity for fuel which can potentially be supplied by "renewable" sources.
It's not just buzz. It's more efficient than resistive heating and modern units have better performance in cold temps. Hence the push to promote them. The downside is that you have added complexity driving up installation costs and reliability down.
> because they only use electricity for fuel which can potentially be supplied by "renewable" sources.
They also can operate at >100% efficiency. Under the right conditions (I'll let someone who knows more about it fill that in) they can provide more heat than the same amount of power going into a resistive heater (which is I think per-se 100% efficient right?). Kinda wild.
Same principal. But an aircon pumps the air over a radiator cooling/heating it, with a fan. Heat pumps rely on radiators in the room to cool/heat the ambient air generally.
Wow, I never cease to be amazed at how few of the HN comments have anything to do with the original post.
I guess I'll jump on the bandwagon, while my comment is tangential, it does have to do with the article's focus on reducing greenhouse gases and fuel consumption.
Switching to a heat pump should be done in all cases where a traditional A/C is being replaced, but the biggest bang for the buck is in how the house is constructed in the first place. "Passive solar" orientation and insulation can prevent a HUGE amount of energy consumption. To point to another HN post article:
I've been saying for 20 years here in San Diego county, that if developers built track housing with passive solar orientation, and covered them with photovoltaic, the neighborhoods would be power plants. They could offer free HOAs and free electricity for the life of the house. Instead, we orient, organize and build for the maximum efficiency of a group of people who are only onsite for about 1 year (the developers) and then leave the people who live there for decades holding the bag.
In India, we have been using "Ductless Air-Source Heat Pumps" aka split AC units with 3,4,5 star energy ratings for decades. The more efficient ones come with dual inverter compressor which allows them to operate at lesser power (for lesser cooling) during long continuous operation periods (like sleeping at night).
Their application is however limited by climate: I've heated a room with a split AC last winter, but around here that is quite a bit of noise for quite a lot of time in the day/year. Having a heat pump warm up central heating water and use appropriate radiators or floor heating allows you to move the noisy bits outside the rooms you're in.
It's interesting how a sufficiently large local norm can affect perspective. I thought everyone had heat pumps for the longest time. I've rarely seen a building without them. I also live in the southeast where they're at their best.
Then this recent rise in popularity elsewhere dispelled that notion.
Readit News
It sounds like they quoted you a bottom of the range 11 SEER A/C vs a top of the line multi-stage compressor variable speed blower 19 SEER heat pump system. Those are not the same thing.
Otherwise, heat pumps are essentially the same as modern A/C units.
Is this in the US? Maybe the market is distorted just because not enough people are buying them yet, so nobody has much stock and there's little competition... We have that problem I think for air to water - super common in the UK and Europe, but since everybody uses air to air, split and ducted systems are super cheap but air to water are quite expensive. I really would quite like some heated floors in my bathrooms if I end up doing a big renovation, and don't want to go electric in-floor because hydronic with a heat pump should be more efficient.
All that is to say, my first guess is that the GP was quoted a high-SEER unit for name-ish brand equipment.
These things are quite expensive. I think the HVAC installers are making a large commission though. The actual equipment costs much less than that.
The guy made no attempt to upsell me and if anything was pushing the cheapest option
Suffice to say I don't plan on staying at that house long enough to ever get my moneys or enjoyment out of it. Bummer.
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I think it's true that the cost only goes up "a little" between models, but the issue is, they make you go up across the board of equipment and it all adds up dramatically. The high end option requires buying their custom thermostat which was $1200 alone
One caveat to that is if you have a furnace, they may have wanted to install a full new air handler and run electric emergency heat vs just swapping the coil and condenser.
You can configure a heat pump coil with a furnace as the emergency heat but it might take some more thinking than an off the shelf AHU condenser pairing that maybe the contractor wasn't comfortable with doing that.
It's timed to only use power right in the middle of the day when the sun is shining, and in the middle of the night when power is cheap. (needs both because the tank is fairly small and my kids like long showers)
Deleted Comment
Every one of these “heat pumps are the future” articles is so soft on data, and they often fail to explain the basics or a simple “why.” Once we get past the clickbait heat pump articles, we can actually make an impact.
A heat pump operating at 250% efficiency will use just as much natural gas as a furnace operating at 100% efficiency.
Modern heat pumps can often exceed 250% efficiency, making them use less natural gas, even if they are ultimately powered by a natural gas burning power plant.
Plus, they can run on any power source, including green and/or decarbonized.
They're quite popular in the Netherlands due to high natural gas prices (since the Ukraine war) and two types of government subsidies. One is a direct subsidy on buying a heat pump device, the other is based on our energy pricing.
Basically you can offset all energy-taxes across the year with solar production. Everything you over-produce in summer carries over to the winter. So if I assume for example that my solar system is written off in 10 years to zero (reality is probably better than that) my total energy cost per kWh is only 7 cents all year round.
A pretty low capacity heat pump is able to provide 90% of the heating and cooling of a normal house. They're combined here with gas based systems to cover for the few days a year that it's exceptionally cold or when you need more hot water than the heat pump could deliver. That means you can buy a much smaller capacity (cheaper) heat pump.
If you compare the running cost of heating at only 7 cents per kWh with a heat pump to natural gas prices "pre Ukraine" it'a already roughly about 4 to 5x cheaper. Now with gas prices nearly doubled you're looking at a 8x cost saving with a heath pump vs using natural gas. The only hurdle is that you need to buy and install a heat pump device, so it takes some time to make that back.
The government is planning to slowly reduce the energy-tax offset from 2025 to 2031. But even without that it's expected that the move from gas to heat pumps will continue.
No heat pump will help if your house is leaky or under insulated.
Can you say more about what your comment is supposed to mean?
I've lived in a home with a literal hole to the outside. During the winter we had to run the radiators non-stop and it was still freezing.
If you are trying to save energy, then sealing up and improving insulation will generally have the largest bang for the buck.
The gist is that we’d need to spec larger units and/or run them harder than usual, removing savings vs. gas.
This is a pretty broad topic, and you can watch videos from this channel to learn more: https://www.youtube.com/watch?v=dReyrSGokEQ
There are options to do a full passive house retrofit, or just add exterior insulation if you have the funds and inclination. Plus you can get better air quality with filtered air, lower mold/pollen issues, lower noise if you care about that and overall home comfort.
https://www.buildwithrise.com/stories/passive-house-retrofit...
That said, we should do both heat pumps and insulate better.
People love throwing in about how effective insulation is, completely ignoring the vast difference in difficulty and cost it actually represents.
Putting more insulation in the attic does not mean redoing the roof. Depending on what you have it might just be blowing in some insulation or adding matting. Of course there are options like spray foaming but it's not the only one.
You are of course right that if your walls are completely uninsulated you will probably want to rip out that dry wall and that will cost you. Maybe blown insulation is an option too depending on your specifics.
Do some math and see if it makes sense to do it if you don't want to do it purely for the sake of the planet. Drywalling isn't that big of a deal actually. The worst would be the ceiling and you don't have to touch that. Regular drywall on a wall is easily done solo by a home owner. Been there, done that.
It's funny what money makes you do. I had a choice to pay tens of thousands to have professionals do it or pay hundreds for materials and do it myself. I did lots of TIL and I have beautiful white walls again.
Depending on the house, location and condition, adding exterior or interior insulation and/or aero barrier, or spray foam could be more cost effective and not so invasive as you think.
https://www.youtube.com/watch?v=_nOI99ew5MMhttps://www.youtube.com/watch?v=eYjF1afRqvE
Do a blower door test and see where the air is coming in/out:
* https://www.energy.gov/energysaver/blower-door-tests
* https://www.youtube.com/watch?v=msZ_E-4GFs8
* https://www.youtube.com/watch?v=Q5vHxgq7GKo
Then plug the holes.
If possible and if you have the funds, try to do a retrofit: https://ekobuilt.com/2019/04/24/retrofitting-an-older-home-t...
https://www.buildwithrise.com/stories/passive-house-retrofit...
You don't have to do all the the things to improve performance -- you can pick and choose.
Fixing unintended holes in exterior walls is probably also reasonably safe.
However, randomly plugging intended leaks without understanding how the house is supposed to breathe can lead to condensation issues (mold and rot), carbon monoxide poisoning (if you have natural gas) and radon poisoning (if that is a thing where you live).
If you want to do more than I mentioned above, consider hiring an architect, or reading up on house ventilation designs.
- spray foam around windows (requires removing trim)
- caulk joints/spray foam rim joist in basement/crawl space
- spray foam around any attic can lights/duct work
- make sure ducts and air returns are sealed properly
Deleted Comment
Trying to parse the mumbo jumbo, I think these articles are trying to point out and encourage the trend of designing new installations of cooling systems around cooling and heating, with a reversing valve and whatnot. Because it no longer makes sense to lean on a separate heating system that burns fossil fuels. But gosh I wish they would just come out and say this directly instead of beating around the bush as if "heat pumps" are some magical new invention.
My parent’s house had a heat pump then and does so today (albeit much improved over the decades).
Any expert care to explain it in layman's terms?
An air conditioner uses a compressor to convert a refrigerant and sends the compressed fluid through a condenser. The condenser rejects heat from the system into the environment. This is the component of an air conditioner that is found outside. The compressed fluid is then passed through an expansion valve and into an evaporator where it is allowed to expand. Expansion is a process that requires heat. The heat flows into the expanding fluid from the environment inside the home. Air is blown across the evaporator coils to transfer heat energy from the home into the fluid which is then returned outside.
A heat pump is capable of reversing the flow of heat energy. The flow of fluid is reversed from an air-conditioner using something called a reversing valve. The compressor sends compressed fluid into the home where heat is rejected through the evaporator coil. The fluid then flows into the condenser coil and is allowed to expand outside, drawing in heat from the outside environment. The heated fluid is then returned to the compressor and the cycle continues.
In HVAC terminology an Air Conditioner is a one way physical heat pump and a heat pump is a bidirectional physical heat pump. Hopefully that helps clear it up a bit.
If you are able to run this system backwards, you could in theory swap which side is a heat sink (the cold side) and heat source (the hot side). While a traditional A/C cannot do this, heat pumps can electronically switch which side of the system is collecting the heat and which side is releasing it.
This is an improvement over resistive heating (think space heater) because we’re not pumping electricity into some filament that resists current flow and emits off heat due to the resistance. Instead, we are taking heat from inside and moving it out or taking heat from outside and moving it in.
Fun fact, a resistive heating device is a rare case of something being 100% electrically efficient in that all the energy it uses will be turned into heat, whereas heat normally is a byproduct of imperfect conductors, which everything is, and is therefore considered wasted energy in almost all other applications.
There's a process called a "vapor compression cycle" which essentially works by moving energy from a cold area to a hot area (which makes the cold area colder and the hot area hotter).
Air conditioning is when you put the cold side of a vapor compression cycle in a building to keep it cool.
The term "heat pump" most typically refers to a device where the hot side of the vapor compression cycle is put in a building to keep it warm.
However, many heat pumps have an air conditioning mode, where the hot and cold sides of the vapor compression cycle switch places depending on the season. So air conditioner refers only to cooling, while heat pump may refer to heating along or a device which can both heat and cool.
* Heat pumps, when referring to HVAC technology specifically, refer to systems that are essentially the same as A/C units, except they're designed to work in reverse.
* The term "heat pump" when used in Europe, more-often refers to geothermal heat-pumps ( https://en.wikipedia.org/wiki/Ground_source_heat_pump ) which is very different to an A/C-style heat-pump, though achieves similar end-result (livable indoor room air temperature).
As someone who spends a lot of time in the year in both North America and Europe I frequently come across people confusing the two.
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The article says that heat pumps are "compatible with natural refrigerants with lower climate impacts". Why couldn't A/C units use the same natural refrigerants?
Also all refrigerators contain a heat pump.
Heat pumps in particular are getting a push from "green" initiatives because they only use electricity for fuel which can potentially be supplied by "renewable" sources.
ie; it's a buzz word.
They also can operate at >100% efficiency. Under the right conditions (I'll let someone who knows more about it fill that in) they can provide more heat than the same amount of power going into a resistive heater (which is I think per-se 100% efficient right?). Kinda wild.
I guess I'll jump on the bandwagon, while my comment is tangential, it does have to do with the article's focus on reducing greenhouse gases and fuel consumption.
Switching to a heat pump should be done in all cases where a traditional A/C is being replaced, but the biggest bang for the buck is in how the house is constructed in the first place. "Passive solar" orientation and insulation can prevent a HUGE amount of energy consumption. To point to another HN post article:
https://thebaffler.com/salvos/construction-time-again-sisson
I've been saying for 20 years here in San Diego county, that if developers built track housing with passive solar orientation, and covered them with photovoltaic, the neighborhoods would be power plants. They could offer free HOAs and free electricity for the life of the house. Instead, we orient, organize and build for the maximum efficiency of a group of people who are only onsite for about 1 year (the developers) and then leave the people who live there for decades holding the bag.
https://en.wikipedia.org/wiki/Tract_housing
https://brians.wsu.edu/2016/05/25/track-home/
In San Diego
Then this recent rise in popularity elsewhere dispelled that notion.