How a heat pump works(hvac-learning.com) |
How a heat pump works(hvac-learning.com) |
If he touches on them, it's briefly - if at all, e.g.:
- More expensive units, and more expensive to run power wise. It's always difficult to get adoption of new technology that's "better" but more expensive to buy & repair - to the point where RoI may never happen.
- Power grid implications during very low/record low temps e.g. shortages/blackouts, likely worse than those in summer if heat pump uptake is widespread.
- With a heat pump, you -need- an alternative source of heat - since some days when it's particularly cold, they just won't work, or work very inefficiently. Plus, if the power goes out... you're definitely not powering a whole house heat pump with a small generator like you could a natural gas furnace.
Edit: FWIW, I'd researched this topic heavily & seriously considered getting a heat pump to pair with a solar power setup. For a number of reasons (chief among them: no return on investment before the end of the heat pump's expected service life), I will not be getting a heat pump any time soon. That may change if prices drop dramatically, but that seems unlikely given their increased mechanical/electrical complexity.
> normal Americans
Please revise this phrase. America consists of many different climates and it's very unclear what you mean or why you chose the word "normal."
> More expensive to run power wise
You're comparing new gas HVAC vs new heat pump. However, don't forget about all the folks that are purchasing a heat pump to replace an existing gas unit! For example, my gas unit (Goodman unit used in California) is old and not even energy star compliant! A new heat pump will be more efficient.
> With a heat pump, you -need- an alternative source of heat
By 'you' are you referring to me (or, say, the ~7% of the US population that lives in my small area of the country)? If so, that's not true! It doesn't get too cold here. And I reckon there are quite a few areas in this country where it doesn't get cold enough for a heat pump to eat shit.
When you refer to prices and returns on investment, are you using a unit + professional installation cost (like $18k+ or something)? Or the unit itself (~$4.5k) plus perhaps a DIY installation costs (~$1.5-2k)? There is a big range there in costs, and the ROI is dependent on that.
- Economies or scale will solve the repair and maintenance burden... hell, it's not like a gas boiler is maintenance free...fucking things requiring serving every year and break down all the time in the UK.
- almost noone has a generator when the power goes out anyway. This is a very wealthy American perspective.
Some form of this comment always comes up in these heat pump threads, and I never understand the idea that heat pumps are some elite affectation that doesn't make sense for anyone else. Many millions of Americans live in parts of country where it gets warm enough in the summer to justify central air conditioning and chilly enough in the winter that you need heat but the heating source doesn't need to handle super low temps on a regular basis.
A heat pump is literally one of the simplest ways to address the year round climate control needs for those people since it's a single system that handles both heating and cooling with only marginally more complexity than the air conditioner you'd want anyways. Throw in electric backup heat, which is probably the simplest backup and keeps the system all-electric, and you have a system able to handle a pretty broad range of temperatures all year. As heat pump technology gets better, the applicable temperature range gets colder and colder and makes heat pumps practical for a wider range of "normal Americans".
This isn't just theoretical. Heat pumps account for 17% of heating systems in the US, which isn't huge, but over 40% in North Carolina, South Carolina, and Alabama and a significant percentage in many other states as well. Obviously there are cases where heat pumps are at least currently impractical given the construction, climate, etc, but dismissing them as some effete toy seems a bit silly.
Edit: Interestingly, most states seem to have a significantly higher percentage of homes with electricity as their primary heating fuel than they do homes with heat pumps, suggesting a lot of homes with things like electric baseboard heating. While not all of those homes necessarily have central AC, using Georgia as an example, 85% of homes have central AC and 53% use electricity as their main heating fuel, while only 29% have heat pumps. That suggests quite a few homes with central AC that use electric baseboard or similar. Heat pumps for those homes seem like they'd be very practical.
Modern heat pumps redirect some heat to prevent the coils from freezing. What you wrote is common FUD pushed by the oil & gas companies.
That said, you'd be a fool to live in an area with life-threateningly low temperatures and not have a backup heat source.
It's only a -need- in certain locations. The one I have claims to be fine down to -5 degrees. There is zero chance we will get anywhere close to that in my lifetime. Heck, even getting down to 32 is incredibly rare. So we are fine without an alternative source of heat.
As for other points, we have never had a power loss/blackout in the nearly 3 decades we have lived here. And electric is cheaper than gas due to nearby hydroelectric dams.
[1] from WatchdogReset's profile about
It still feels the wild west for home energy systems - and the costs are quite high for the value they provide.
https://shop-us.getmysa.com/products/mysa-ac
From a technical perspective its just a IR remote with a wifi connection and a touch UI, but for controlling mini-splits it works great in my home.
I understand that its for climate benefits but it feels very coordinated.
edit: didn't realize the attention I would get. Let me add someone answered my question -- a good product market fit and people talking is probably where the push came from. That said HVAC installers / heat pump manufacturers and governments are all pushing this hard right now. I believe in the benefit for most people and the climate benefits are great. I am always concerned on when there is large consensus on a hard push - worth looking at who the winners are and what the trade offs are.
The closest thing is this:
https://rollibot.com/product/mini-split-ac-room-air-conditio...
but it sucks.
I don't understand why these things have to be permanent fixtures of your house, necessarily.
Another caveat is our electricity ranges from 30 to 35 cents per KWh and is probably second to Hawaii in terms of cost.
So I do check the cost of operating a Heatpump in the winter and due to high cost of power I am sticking with our gas furnace.
If and when I go solar, I may reconsider, but for now gas is simply cheaper
Memory is fuzzy but I remember when I was a little kid and even captain planet cartoon showed air conditioners being bad for the environment...
Or is it that heat pumps are better than the fossil fuel counterparts and so if you're going to do something bad you might as well do something less bad?
https://web.archive.org/web/20230210134443/https://hvac-lear...
The archive.org is pretty slow on this one as well, as it is an interactive site.
Compressors themselves have gotten much more energy efficient, although I'm not sure the impact on CoP is all that great since and waste heat from the compressor is being deposited in the home anyway. Variable speed compressors are the most efficient you can get pretty much.
Refrigerants have improved in someways, but not really in others. Since heat pumps could be running with exterior temperatures that are quite low, with the system under pressure, some refrigerant blends would have less than desirable vapor pressures leading to problems running in very low temperature conditions. For the most part, the changes to refrigerant blends have been related to their Global Warming Potential (GWP).
Expansion valves are a very important piece of a refrigerant loop, these used to be fixed orifaces. Nowadays these are dynamic, meaning they can increase efficiency of the system by metering the flow based on system load and other characteristics. These are called TXVs or Thermostatic Expansion Valves. Electronically controlled expansion valves are now hitting the market further increasing efficiency.
Finally there is the design of the interior and exterior coils. I dont think materials have changed much, but the surface area has changed. You may noticed a 2 ton unit from 1997 is about 1/4th the size of a 2 ton unit from 2022. More surface area on the coil for the exterior unit lets you extract more heat from the air without burning a ton of energy running the fan super hard.
Interior air handlers have probably improved some as well, variable speed motors, etc. Variable speed really is nice because you can get much more consistent temperatures in the home and wont get blasted in the face with heat from vents when a regular system cycles on and off.
A contractor should be able to select an appropriate system for you, but if you want to do it yourself, look for yourself, get the 2021 ASHRAE climatic design conditions for your area and choose a heat pump with a minimum operating temperature which is lower than the coldest month 99.6% heating drybulb temperature (DB) (should be the top row, left most temperature).
*You would also need a fairly large heat pump, perhaps 7 tons (tons here means tons of refrigeration, or how many tons of ice the system can melt per day) depending on how well insulated you are.
Due to your high ceilings, it might be prudent to install ceiling fans to help circulate the heat, but I'm not a heating expert so I recommend asking one.
How much material in a heat pump is recyclable and how much isn't, compared to a furnace?
We are trying to reduce CO2 and methane in the atmosphere. Throwing away the non-recyclable parts of heat pumps isn't as big of a concern. Polluting the ground and water isn't even as big a concern. Certainly they are concerns, but they pale in comparison.
Of course heat pumps emitting no particulates and being able to run on renewables are also good reasons, especially as the health impact of living in cities with high PM2.5 values becomes clearer. But I don't think those are the primary drivers.
Many models are in very high demand. Some of the units I looked at recently were back ordered so far that I was told to pick something else if I expected to have it within the year.
The demand is very high because the technology is good. It’s not a campaign or conspiracy.
Rather, it's a combination wanting to get to net zero, so no emissions, with the big problem of generating enough green electricity. A heat pump system has no emissions and consumes much less electricity than an electric boiler/electric heater.
Companies that sell heat pumps are advertising hard. It's an easy sell for them with rising gas prices.
The US government is "pushing them" by offering tax credits for heat pump systems. This is part of a plan to reduce pollution, improve energy independence/energy security, and save citizens money on their heating bills. No secret there - politicians and public servants are excited about this and they are talking about it. They are also offering tax credits for other high efficiency heating systems, but not that many people are looking at those tax credits because buying a new high efficiency gas furnace doesn't make that much sense when you could buy a more efficient heat pump instead.
Many individual people are also talking about them because they are a great way to help the environment and save money at the same time.
And I think a lot of people just think they are cool technology as well.
I'm always a skeptic on when something gets super hyped. In this case it's more use-case specific that makes me skeptical - majority of people its 100% fit.
Economic but also legal and geopolitical: fuel oil furnaces are getting restricted or banned, and the combination of climate change, air quality standards, and russian instability makes gas look at lot worse than it did 10 or 20 years back.
I mean, yes. They're much more energy efficient than the alternatives and will play a key part of removing our dependence on fossil fuels.
> I understand that its for climate benefits but it feels very coordinated.
That seems like a good thing?
Edit: since i am getting downvoted to oblivion, let me fight back here. I genuinely wished heat pumps would be more efficient and in theory they can be. I would love to not generate heat and just use the outside heat energy and compress it down into a smaller location.
But compressing and decompressing is not an energy efficient task. It takes a lot of work. Mechanical inefficiencies are a huge energy consumption. Gas is simply burning fuel. Yes, we should save gas for rainy days. But I hate to say that it is more efficient and cheap. There is no comparison.
But seriously i think it’s just that awareness hit a critical threshold so the hysteresis kicks in and articles proliferate. In both cases.
If the roof of your house produces enough electricity for the people living it and the heating (and cooling) of all rooms, it is a no brainer to switch to a form of heating that relies on electricity.
Don't you want to resist to turn to explanations like this, that require some invisible force to pull the strings? I think there are more realistic ways to imagine this happening.
If for example a pop star is getting a lot of attention, in multiple countries, what is the mechanism behind that? And is it orchestrated?
But seriously, it's just the next fish to fry after electric vehicles became a solved problem. Heating buildings is somewhere around 10-25% of total emissions and probably the largest remaining single factor not directly addressed by switching the electric grid to renewables, so many people concerned about climate change have converged on it.
For consumers it's also became clear that being slightly more independent from centralized heating and/or energy infrastructure is a good thing
2. Cites like NYC have implemented bans or limits on new gas installations, and it has been proposed at the state level as well. Other cities such as Chicago have had conversations regarding this issue, at least enough for it to get into the news and spark minor outrage.
Because of these recent controversies there has been much talk about Heat Pumps and whether or not they are able to function efficiently or sufficiently in sub zero temperatures regularly seen in the upper Midwest or North East.
Heat pumps are also inexpensive on initial cost and less expensive than straight AC with gas heat.
They are also low maintenance in comparison to straight AC with gas heat.
Very popular units in southern US.
I’m sure there’s others in my position.
The first is your conventional type system, this is usually what AC units are in the US. They run at maybe 1 or 2 speeds. These type of heat pumps are common in the southern parts of the US but also will be found paired with a gas furnace in the northern US. Since they don't adjust their output dynamically they tend to start losing capacity/efficiency significantly around 25-30F.
The second is an inverter driven heat pump. You usually find these in mini splits but they can also be found in a standard air handler form factor that would replace a furnace. The inverter allows the compressor to adjust based on demand and exterior temperature to maximize efficiency. This allow these units to operate efficiently down to -13F depending on the unit. Now there will still be some capacity loss at those temps so during the design of the system this has to be taken into account.
For detailed information on the efficiency of heat pumps I would check out NEEPs website. It is a great resource, it will show you capacity and efficiency (COP) of tons of different units across their operating temperatures.
I don't know what the coefficient of performance is at that temperature though.
Heat pumps require different system design than a traditional setup, where the cooling load is usually the driving force. You might need a bigger heat pump to handle the heating load in very cold weather accounting for the efficiency loss.
Manufacturers are obviously pushing, but many utility companies and municipalities are too. Basically the electric car or solar panels of HVAC. It's one of those things where there are a lot of incentives for everyone involved all the way down the line.
Any reasons to change my mind?
This is, of course, the regulation as it stands today; things can always change. Additionally NYC alone likely doesn't account for the attention. But, other metros and municipalities could have similar legislation.
Having lived in a new, high end apartment that had a heat pump for both heating and cooling for 3 years, I am very unimpressed with the tech. Running nonstop, couldn't heat/cool above/below a certain threshold. Electric bill very high. Clogged and broke a lot. If the general radiant heat and cooling from being in large building didn't exist, I couldn't see this working halfway decent in any place in the midwest. This might work for areas with less variable temperature ranges but for the midwest USA, not seeing it.
There is no conspiracy to push broken technology on to the masses. Heat pump technology has come a long way and modern heat pumps are very good at what they do.
If someone installed a heat pump that doesn’t work in the temperature range of your location, they really screwed up. Modern heat pumps can be selected to work down to very low temperatures, and they’re installed with auxiliary heat when necessary. The design parameters aren’t a mystery.
In the midwest a geothermal heat pump would work wonderfully.
Also, they are designed to run constantly in order to maintain the set temperature -- it's not like a natural gas fired furnace where it quickly reaches the set point.
Firstly the later typically have a higher power rating.
Secondly, if you can lead water around the house and heat via radiators or floor heating you get a much better efficiency.
1. The American market has a lot of incorrect perceptions of heat pumps. Debunking these makes for great viral content! 2. The IRA introduced big incentives for various electrification expenses.
The incentives are the big thing, but the public interest/controversy part is why some enhancements like heat pumps and kitchen electrification ("don't take away my gas stove!") are going more viral than, say, electric vehicles (technology connections guy has some good EV content, but it's not doing quite the same numbers)
At a basic level, governments are full of people who have an interest in public policy, and they read publications that cover public policy matters from around the world. If the EU brings in a policy that encourages an expansion in heat pump usage, it'll probably get written up in The Economist (and a bunch of more specialised publications), and, guess what, bureaucrats and political staffers in the UK, the US, Canada and so on will read it.
There are also institutions specifically devoted to developing policy advice for national governments, and in the renewable energy space the big one is IRENA. And guess what, they're telling their member governments that, hey, if you want to screw over the Russians, meet your greenhouse targets, and save your citizens a bunch of money, heat pumps are the way to go. And as those things happen to be basically true, national governments are falling over themselves to implement policies to encourage it to happen.
First, it must be told that an off the shelf AC unit is technically speaking also a heat pump. There has been this distinction (and confusion) between AC units and (mostly) ground source heat pumps because, you know the latter actually have a water 'pump' to circulate fluid in the ground piping. Ground source heat pumps are far more expensive that AC units and are nearly impossible to retrofit in existing buildings. Hence, companies came up with a 'middle ground' solution, called air source heat pumps. In these devices the outdoor unit is much like an outdoor unit of a split type AC, but the indoor unit is basically a refrigerant/water heat exchanger with a water pump and some sensors around it. There is also a monoblock type of air source heat pump, where all components are in the outer block and you only connect the piping.
IMHO, the reason air source heat pumps are becoming popular now is because their price went down considerably during the last 5 years, whereas the price of fossil fuel heat sources has gone up. Back then when I had to choose between a gas boiler and a heat pump, the boiler was around EUR 2, off the shelf heat pump (24000 btu) was around EUR 7k and for the DIY option I paid a total of EUR 2.3k. The reason for this was that the market for air source heat pumps was underdeveloped and companies (e.g. Mitsubishi, Daikin, Fujitsu) were charging a lot more in this market segment (rich people with new houses). At some point in time, people started realizing the benefits of a heat pump over a normal AC (less units, no noise, nor air currents, better efficiency, can produce hot water, heating is decoupled from the source and more sources, such as solar can be seamlessly plugged in). Manufacturers albeit slowly responded to this demand.
Now with solar power gaining more traction, they are becoming a very obvious choice.
The winners are consumers, the effort to reduce GHG and particulate emissions, and the drive toward energy independence (whether at the national, local, or hyper-local level).
The losers are fossil fuel extraction industries, because due to the high COP of heat pumps, far more heat is delivered per unit of energy consumed, even if that energy ultimately comes from burning natural gas at a power station. Also, the source of the energy itself gets disintermediated, since electricity can come from multiple sources, including renewables.
The tradeoffs are (for now): Higher upfront installation cost (tempered by the IRA, and potentially lower operating costs), availability of the equipment (supply chain stuff), and long delays in installation due to lack of qualified installers (and resulting high costs).
Based on the lack of political dick swinging I don't think this is a "push". They're legitimately good technology for certain use cases, I'm sure the manufacturers are pushing them. They are also The New Hotness(TM) and they are billed as environmentally friendly. Both those attributes are valuable by themselves to some people.
I think this is more a case of a grassroots-originated circle jerk within certain demographic bubbles.
I get a lot of "air fryer" vibe from the whole thing. And I say this as someone who owns and really likes his air fryer.
Heat pump as every heating or cooling devices, have pro and cons. This is where HVAC knowledge is nice to have, in order to have the best solutions. For example, the maintenance / obsolescence are an under estimated point when it comes to environment and savings
I would never get electrical water heater, stove, and heater for that reason.
I was thinking the solution for me is to put in a heat pump and then run a backup gas generator. But that solution feels like a significant amount of overbuild. I have 3 minisplits already but they aren't valuable in the winter -- where you install your AC units isn't where you would install your heating units .. I.e. the top of my house for AC, the bottom of the house for heat.
Having multiple energy sources to defray risk is helpful.
If he's building the house new, he should strongly consider investing in designing the building envelope in a way that 20kW heat pumps aren't required. It's very possible, especially with new builds.
The models to follow are Passive House [1] and Pretty Good House [2]. There are many examples of large houses built to those standards in cold climates that use a heat pump that only draws 2kW, which could easily be powered by a generator or backup battery. This assumes that by "big house" we mean something still below ~3500sqft and not some kind of mansion.
The basics are to get the building air leakage below 1ACH50 (3-5x better than most codes, but not hard in a new build), and eliminate thermal bridging by using thick exterior insulation around the building perimeter.
It is coordinated. I wish there is more investigative research into who and why they are doing this.
You are not engaging with any of the helpful, generous replies, in fact going as far as to say that you wish you could call it ‘coordinated’.
Why are you even here if you think we are all lying shill for big air compressor?
One doesn't even need to look at climate impact to say gas stoves are bad, but focus the narrative on that one aspect and you can get climate deniers hyperventilating and defending their gas stovetop with statements like "you'll pry my gas stove from my dead hands". But really, economics are going to kill them all the same - induction stoves are dramatically more energy efficient, have the same benefits of fast thermal response, and don't pose a gigantic risk to life and limb every time you turn them on (or leave them off, for that matter).
https://trends.google.com/trends/explore?date=2021-01-10%202...
Yeah, tl;dr: fuel price scares and the French nuclear power plant disaster, as well as government regulations.
To expand: most homes traditionally are heated by either burning something fossil (oil, gas, coal), somewhat half-ish renewable (wood pellets, straight chopped wood), by straight electricity (resistive heating) or by heat pumps (air-to-air, ground-to-air, deep-well-to-air aka geothermal). Some homes particularly in urban areas or in close proximity to a large power plant can also be heated by district heating using one of the aforementioned heat sources.
And all of these classes of heaters have their issues:
- Electricity is the easiest of the bunch from a technical point of view, but you're out of luck when the grid fails for whatever reason, you're tied to grid price hikes in some contract models (as people learned the hard way in Texas' last winter spike), there will be fuel burned as part of the generation and frankly resistive heating is wasteful.
- Wood pellet has the problem that the amount of waste (=sawdust) is finite, which means you're chopping down wood that could be used for construction and burning it instead. That is a waste of money and valuable resources when wood is scarce, fine particulate matter causes smell and health issues, and a lot of wood is unethically sourced.
- Solid-wood or coal heaters are difficult to properly fire up - most people fire it wrong (not enough oxygen / too much fuel load), resulting in higher consumption of wood, higher emissions and a danger of soot buildup which is a fire risk. Additionally, many home fires are started by people disposing not-completely-cooled ash or placing flammable objects too close to the oven or exhaust, and still a lot of people die because of carbon monoxide emissions caused by improper handling.
- Oil stinks to hell and beyond, the boilers need an insane amount of maintenance so they don't clog up, you need to ship tanker trucks to homes, there are risks of spillage and contamination, and the same emissions issues of wood apply (plus, oil generates more CO2 than gas per kWh of heat). Also, it's not renewable at all.
- Gas is relatively easy to ship around when there is a gas distribution network in place, it burns relatively clean, but carries an explosion risk and is fossil in origin (at least for the next decades that it will take to build up power-to-gas infrastructure).
In contrast, heat pumps are pretty awesome:
- all they need is a bit of electricity - a good heat pump can achieve up to 4x ratio, meaning it generates 4 kWh of available heat in the home by using 1 kWh of electricity. That also makes off-grid or local generator fallback solutions more feasible - a 20 kW heat-pump boiler needs a 5 kW generator which can be had for a couple hundred dollars instead of a massive generator unit.
- their heat sources (or rather, cold sinks) are renewable - air, local ground loops or deep wells are virtually infinite. That means, as long as your electricity supply is renewable, your heat generation also is renewable.
- Most heat pumps run at 40-ish degrees. That in turn prohibits the use of old-school convection radiators, so most installations with heat pumps tend to use floor heating which needs less energy to achieve a temperature comfortable for humans (our feet are the most sensitive part, but as heat from a convection radiator rises to the top of the room, it needs a lot of energy for a comfortably warm floor).
- they are, particularly when compared to oil heating, extremely small and don't cause emissions
- they don't need much maintenance effort to keep running, and no need for chimney sweepers either
- they don't pose an imminent risk of carbon monoxide poisoning or outright fire
Basically, the only issue heat pumps have is you need specially trained people to install them and they are short in supply at the moment since everyone and their dog got shocked to heaven in the last year of that goddamn war and heat pumps are the objectively best way to heat a home.
Those that have the ability to use firewood to heat their homes today can continue doing so if they need to- its not a requirement to close up your chimney permanently to use one.
FWIW I am considering switching to a heat pump, but would still have natural gas fireplaces as a backup.
Using machinery for heating isn’t new. Virtually nobody in the modern world uses firewood from a local vendor to heat their homes.
These conspiracy theorist angles are baffling. Heat pumps are just another variation of AC, which is already ubiquitous. If people don’t use heat pumps, they won’t use firewood. They’ll use a regular furnace or electric heat.
A while ago I ran the numbers, and to meet UK electricity demand from wood would consume every single tree in the country in three months.
Limiting that to heating and giving up on industry would stretch that a bit, but the country is fundamentally dependent on imports to stay alive. We can't not be global.
This is great for the climate but air source heat pump technology simply doesn't work well in cold climates. Most heat pumps in the United States have 100% efficiency down to about 20 degrees F. Below that they "lose efficiency."
What most people don't realize is that "lose efficiency" = blows cool or cold air. So if you live somewhere that routinely gets that low you are likely either going to be really cold, or have to engage aux heat (often natgas or oil-based heating or electric resistance heating).
Additionally, even when operating at 100% efficiency they don't blow air as hot as traditional heating sources. So if you have a poorly insulated room, large space, or even just an unusually cold day, it will often have a hard time keeping up.
I have found that I only use my air source heat pump a little bit during the fall in New England, and I have to run aux heat throughout basically all of winter. Talking to my friends in the region who have heat pumps, they all have similar experiences.
I think we are all very eager to get off of fossil fuels but the technology just isn't there yet, and I am concerned that most people installing heat pumps today don't know the risks associated with them in extreme weather events. If your heat pump can't keep up and you didn't install aux heating you can't live in your house, your pipes will freeze, and you will generally have a bad time. If you did install and use aux heating, you may be surprised at how expensive and inefficient resistive electric heating is as it may need to run all the time.
[1] Massachusetts will pay you $10k to install air source heat pumps and disconnect from natural gas https://www.masssave.com/en/residential/rebates-and-incentiv...
Most things that are already installed are worse than the latest technology that's available.
That's not an argument against the latest technology.
I have a 3000 sqft house in MA with a heat pump as my primary heat, and an electric strip as backup. The heat pump goes into the ductwork for most of the house. I generally haven't had problems. (It did have to be adjusted because it was the first time the installer put one in.) I have solar and usually get 1-2 large bills in January and February, and then March and April are very cheap, if I get a bill at all. My "large" January and February are comparable to what I'd spend on conventional heat.
Last weekend we had a "once in a century" cold snap down to -4. Most of the house was at temp, but one room fell to the high 50s. From what I've heard, plenty of people with conventional heat had far worse issues than a chilly room.
Heat pumps are now the most premium option on units offered by the well known names in HVAC- Trane, Carrier, etc.
In terms of suitability for your climate, they should work just fine for most people- they start to struggle if you are in an area when temps get down to about 10 degrees Farenheit, though they improve in this area each year. Even if you live in an area that cold, there are options to mitigate this- leaving your current furnace hooked up to be turned on during those cold periods, etc. What it comes down to is it just gets more expensive if you live in these colder areas, but over time the energy savings should give you a return on your investment in less than ten years.
My Air conditioner blew this fall, so I am actively in the process of getting bids for heat pumps.
If you're in 1, 2, or 3, heat pumps are definitely the right option. In zone 4 or 5, newer cold temperature heat pumps are a good idea. In 6, 7, or 8 it's less of a sure thing, and you will likely want a backup source for the colder days.
https://www.gradientcomfort.com/pages/products-air-condition...
https://www.achrnews.com/articles/147122-midea-heat-pumps-to...
I'd love for NYC to mandate that ACs must function as heat pumps: the additional parts are cheap, and as America's largest market for window AC units, the NYC market would force competition for much cheaper heat pump window units.
For cooling this exists in many forms: there are the window air conditioners, and "portable" window air conditioners which have a duct that connects to the window. The problem with the latter is that they're loud and the ducts result in a lot of heat loss.
For heating there are some portable air conditioners that use a heat pump but they're subject to the same issue described above. More common is resistive electrical heat in the form of coils or an oil filled container that radiates heat.
A portable mini split, where it connects through the window would give you a similar advantage as a portable air conditioner, but with more efficiency and being less loud.
As a counterpoint to what seems to me like extremely high rates for electricity, as of right now in Vancouver, BC, Canada, I recently calculated that a heat pump would cost about ~2.5-3.5 cents per kWh of heat energy vs ~4.5 cents for gas heating at 80% efficiency. Power on average is about $0.10 USD per kWh here and gas is about $10 USD per GJ.
The average house here uses 74.3 GJ of gas per year, or $ 743 USD of gas. We would save 413 $ per year by switching over.
The neighbours next door spent $ 17000 USD to install a multi-zone heat pump, which still doesn't exactly cover every room. It's a Samsung, so by the general sentiment about their appliances here, we'll assume it doesn't last longer than 15 years and needs to be replaced at a cost of 12000 $ USD down the line.
The hot water, low efficiency 80% boiler has lasted 35 years so far. Total cost of maintenance and repairs has been under $1500 USD. We expect it to last another 30 years easily because there is absolutely nothing special, fragile, or expensive in this system. Most of the spare parts can be found by walking down the alley and seeing which neighbour fell for the "replace your heating system" salesman tactics.
If we replaced it with a "high efficiency" condensing type, we would save at most 20% on our gas bill (143 USD a year). The cost to install will be easily $5000. As a reward for doing so, we will have to pay for maintenance every 5 years at $200, and the device will fail and need to be replaced for another $4000 after 15 years. This is a statistical and practical certainty because condensate is corrosive.
For the next 30 years, the old boiler we have will cost 23790 USD in total.
Upgrading to a high efficiency boiler will cost us $28032 USD in total, not including ANY breakdowns
Using a heat pump will cost $38900 USD in total, not including any maintenance, which you ABSOLUTELY need to do otherwise it smells and grows mould. (we do this maintenance ourselves but the design of the unit is ghastly, I curse the designer out loud every time I think of it, and this is a MAJOR pain to do.)
Based on this math, there is absolutely no reason we would ever consider making any of these changes. A plumber tried to suggest something like this and they seemed to agree.
With this said, I have a heat pump in my room, originally installed because I had too many computers and I needed air conditioning. We bought the absolute cheapest unit we could find at 700 USD and it has been wonderful. It has a capillary tube instead of an EXV because it's cheap, but it works "fine" down to -5 and it rarely goes under that here.
The greatest benefit of a heat pump has nothing to do with energy efficiency or savings. The greatest benefit is that every room can have their own heating and cooling controls that respond FAST. I turn it up and down all the time when I feel like it and it's wonderful.
I don't know if this is the right place to look at, But over the last 30 years, in BC, the "Electric power selling price under 5000kw index" has gone from 56.8 to 120.9, about an increase of 110%.
[1] https://www150.statcan.gc.ca/t1/tbl1/en/tv.action?pid=181002...
That seems like it was a useful simplification for a children's cartoon, but things aren't that black-and-white.
1. Without air conditioning (or some other method of cooling and humidity control), almost all high-occupancy buildings would reduce their effectiveness as a work-place or living-place. OSHA has guidelines about office temperature (68-76, iirc), humidity, and overall air quality (e.g. pm2.5 levels).
2. The 1980s-era backlash against air conditioning was likely inspired by then-new knowledge about atmospheric ozone depletion. It was known that CFCs and bromine-containing compounds contribute to ozone depletion. It just so happens that CFC were common refrigerants (and aerosolizing agents). Refrigerant leaks from an air conditioner in those times released nasty stuff. CFCs are very rare (and restricted) in modern air conditioner / hvac systems. We instead use other chemicals which are not ozone depleters. (Though I believe that the theoretical performance of modern refrigerants is often not-as-good as the old CFCs.)
3. Running the air conditioner in a single family home is not terribly efficient, as (in most single family homes) most of the home is just empty space. Cooling bodies directly (e.g. cooling blankets, misting fans, etc) is more energy-efficient in these situations. Perhaps the more nuanced advice would be to use air conditioning to make the space "tolerable" but use direct cooling to make a space "comfortable". (This advice also applies to heating a space. I keep my thermostat between 60 and 65 and use blankets, small electrical resistance heaters, and drinking hot water as ways to temperature-regulate.)
Heat pumps are much better for the environment compared to the other sources of heating. Depending on where you live, you still need to heat your place and if so, heat pumps are better than other traditional methods like natural gas, wood, oil, or electricity.
Similar to air conditioning, if you want to minimize your impact on the climate, you could set your temperature lower in the winter and put on a few more layers and/or set the temperature higher in the summer to minimize your usage of heat pump/air conditioner. This puts less pressure on the grid and demand for electricity generation.
From what I've read, that's not quite feasible yet, since current systems can't produce a high enough temperature.
What are the prospects of that technology becoming viable in the next few years?
I have baseboard in the attic and cast iron rads on the main level. I have the flow set to 126°F until the outside air temp drops below 30°F and then I increase by 2°F for every 4°F change in OAT. So at 2°F OAT, I have 140°F flow.
That’s enough to maintain temp in my fairly poorly insulated 1920s house near Boston. It’s enough to slowly recover temp as well.
140°F is a stretch for air to water heat pumps, but you could reasonably use an A2W for most of the year and supplement with a 9kW (31KBTU/hr) electric boiler as emergency supplemental heat and use that a couple days per year.
What killed it for me (and the reason I have a fairly new gas boiler installed) is the upfront cost was utterly uncompetitive.
If you have a condensing boiler, set the high-limit or flow temp to 130-135°F and see how your house handles it on the cold days. You can measure and calculate all you want, but nothing beats trying it.
The other option that is common in New England is to keep the baseboard oil heat and get mini splits. Then run the mini splits for heat and if they cannot keep up switch to the oil heat.
Is it because baseboard hot-water systems have limited exchange surface surface and thus need very high temperatures to do anything?
It's old tech, it's been around since the 1800s. The only thing that has changed is that heat pumps have gotten cheap and energy has gotten expensive.
There are applications where heat pumps cannot replace boilers - in industrial processes where high temperatures are required or tremendous capacity is needed intermittently.
However, unless your temperatures are routinely below about -20 F, a heat pump is the best choice (and even if temperatures occasionally drop below that, heat pumps are still an excellent choice because those extreme temperatures might only last for a handful of hours out of the year, during which insulation or a cheap electrical resistance heater can keep you warm).
I don't really know how trends and fashions form and haven't thought so much about it. Some aspect of it might look like research into the ising model and phase transitions - small changes in "temperature" everywhere in the mass of people might look like a phase transition in the overall mood.
I have heat pumps through a mini split system. I like them so much I’m redoing my entire HVAC to add ducts with heat pump powered heating and AC. They’re kind of a miracle: they produce great heat (way better than a gas-powered furnace), they’re ultra-efficient, and they’re whisper quiet.
There was also push to do the opppsite to neutralise that threat to fossil profits e.g. Bjorn Lomberg the skeptic saying that we didnt have any tech that could replace gas, so the only response to Crimea was to frack or invent totally new tech, not rolling out renewables and heat pumps faster.
"Fracking Could Free Europe from Putin"
https://www.forbes.com/sites/bjornlomborg/2014/06/23/frackin...
> Still, many EU politicians talk mostly about expanding renewable energies as a way of making Europe independent of Russian energy. Connie Hedegaard, the European Commissioner for Climate Action, said the Ukraine crisis should be a “wake-up call” for European countries to make the switch from Russian gas to clean, renewable sources of energy.
> But this simply ignores reality. According to the International Energy Agency (IEA), Europe gets just 1.3 percent of its energy from renewables like solar and wind, whereas it gets about 75 percent from fossil fuels and most of the remainder from nuclear. Even an extremely optimistic scenario from the IEA suggests that by 2035, Europe will only be able to generate 8 percent of its energy from these renewables. Focusing on them is simply populism without realism.
At that point, climate skepticism was strong enough politically to prevail. They tried to use this latest annexation to promote fracking etc. too but it seems to have largely failed.
With an air-to-air heat pump, you need a backup system for when it gets too cold out for the heat pump to pull enough heat out of the air, and for power outages. With a ground loop heat pump, you only need a backup system for when the power goes out because the ground water will never be too cold for the heat pump to pull heat out of.
When I built my house, I called around and it didn't sound like geothermal works very well where I live. I suspect the reason why I was talked out of it is because my yard is very rocky.
There are lots of different groups looking to push heat pumps for the above reasons. Governments are concerned about both war and global warming. Ukraine supporters are concerned about Russia getting more money (to wage more war). Green activists are concerned about global warming. All have their own reasons to push heat pumps on everyone.
This technology connections YouTuber I've seen pop up in lots of discussions on these topics.
Edit: Nevermind I'm an idiot. From the spec page of that unit: BTU (Cool): 11,000 BTU, BTU (Electrical Heat): 3,500 BTU, BTU (Heat Pump): 9,900 BTU. Though the owner's manual mentions an extremely warm minimum outdoor temp: "The unit should be operated in a temperature range of indoor side 60°F - 90°F (16°C - 32°C), outdoor side 64°F - 109°F (18°C - 43°C)."
This isn't great if you want a building with hydronic heating and forced-air cooling, which is really just the ideal form of both technologies — hydronic cooling creates condensation, while forced-air heating smells bad and leaves you with cold feet.
Also, I found that Home Depot's website tends to be pretty clear about which window units are also heat pumps.
It's not FUD, and you COMPLETELY ignored & omitted the rest of my sentence from your quote. I'm well versed on how heat pumps work. I was not saying heat pumps don't work below freezing. Rather than simply repeat myself, let me rephrase:
1. Heat pump efficiency gets worse the closer you are to the minimum (outside) temperature they're rated down to.
2. Even with the best (and most expensive) technology, that means efficiency of these units approaches that of a $15 space heater.
3. When it gets TOO cold, they can stop working entirely if they don't have a resistive backup heat system (which, again, is effectively a $15 space heater you paid a lot more for).
Both Canada & the northern US experience these temperatures occasionally (-10f to -30f and worse on some occasions).
Hence the need for backup heat - e.g., a pellet or wood-burning stove, backup furnace running propane or natural gas, or even just something cheap and simple like a $150 portable diesel heater. You don't want to be left without heat in a multi-day power outage after a half inch of ice and high winds.
For backup heat, it's more efficient to burn whatever fuel for heat than run a generator outside to power space heaters or a heat pump at those brutally low temps that often follow those hard ice storms.
What part of redirect is confusing?
In the installs I've seen they did it from inside the house i.e. literally cooled the house down.
Cooled the house down, or simply warmed it less than would be possible otherwise, assuming that magic prevented freezing of the coils?
I'll take a reduction in efficiency over a complete lack of function.
Your whole argument is. Heat pumps need a secondary heat source because at the temperatures around 0C they accumulate ice on the heat exchanger outside. To melt the ice they reverse the energy flow so they cool the house and heat that heat exchanger. You asserted that it's just FUD and they can "redirect some heat" instead. This implies they don't cool inside and instead redirect heat from elsewhere (second outside heat exchanger perhaps?).
But it appears there is no second heat exchanger outside and the modern heat pumps work just like heat pumps from couple years ago.
As for keeping the functionality - it's a philosophical question. For me personally, if I turned on the heater because it's cold inside and it started blasting cold air, I'd call the repair people immediately. While it still works in the sense that it makes noise and consumes energy, it stopped performing its function of heating so I'd consider it lost the functionality I am interested in the most.
I personally think geothermal is great, sadly New England's geography makes getting a ground loop installed more difficult. In the midwest lots of people would do a horizontal loop by trenching like 8 feet underground laying pipe in there. In many parts of new england that isn't really viable with all the rock so vertical drilling is used which is significantly more expensive.
Our house was built in 1973 and originally had electric baseboards and then was converted to an oil boiler with hot water baseboard. So retrofitting a heat pump was an interesting task.
A ground-source heat pump typically has a CoP of 5 but the CoP doesn't go down with the outside air temperature. Because the ground water temperature is stable, it will maintain its efficiency when it is cold outside. Of course, depending on the R value of your house, it may need to work harder to make up for the heat loss through the walls, roof and windows.
You really need to find a heat pump installer who has the year round temperature data for your area and can do the math to calculate whether it is worthwhile to spend the extra on a ground-source heat pump.
Typically it makes the most sense to do when you need to replace your system.
My energy bills are 1/2 of what I was paying with an electric furnace last year.
In Seattle are highest usage months for electrical is in the winter, right when you will be maxing out that 50A breaker you had to install in order power that beast; check the notes from Mitsubishi, they are clear that it is not an efficient device in the range you suggest ( and seeing how in Seattle most homes are still at 100A service you must either be living in a newer home or one with an upgraded service ).
You realize that Seattle is now an importer of electricity and is no longer running surplus?
Or how about that the city has been using an unsustainable amount of water? ( i.e. where our power comes from ) Or that our electrical come at the expense of Salmon and the endangered Orca pod that lives in the Sound?
If you replaced your "furnace", which implies a central HVAC system, with a Mitsubishi Hyper-Heat, which I believe is only installed as a mini-split, what are you doing about your air quality?
The Seattle area suffers from "inversions" through out the year; a mini-split does nothing for air quality issues. The smoke that we dealt with in the fall? That wasn't even the worst air quality issue we have had in the last decade.
I am sure your electrical bills are 1/2 of what you were paying for an electric furnace, but unless you are abandoning the use of your heat pump for providing cooling your overall energy yearly costs are unlikely to go down.
I don't know situation, I don't know what options you had when you installed your unit, and I have not listed all of the good and bad that come with the unit that you installed.
There has been a lot of "mini-splits will save the environments" coming out of our City Council; there have been zero reports presented that back up those statements. The local heating and cooling people are happy to install units which have a higher markup/generate more work for them.
The more interesting graph is the total kWh saved per day (8:07). The colder it gets, the more energy he saves. That's because more heat needs to be pumped into the house, so a worse COP multiplied by more total heat equals more electricity savings (at least for the temperatures he's measured).
The only problems I can see are:
-Size/Price ratio: The tonnage (9,000 BTU) is relatively low for its price--it can only condition a ~375 sq foot space. Though the lack of install costs probably makes up for this unless you're doing a DIY job with a Mr. Cool Ductless HP.
-Incentives: Utilities may not want to spend energy efficiency incentive dollars on these, since someone could easily move and take the heat pump outside of the utility territory; which is not a problem with permanent HVAC installations. Might be covered by the IRA's rebates for Heat Pumps though.
if this were popular you'd see old houses retrofitted with pluggable holes where you could feed the lineset through and seal as necessary for temporary heat/cooling, or perhaps even permanent.
the installation would be substantially easier if these were like 6000BTU instead of minimum 12000BTU per head, so it could be run on say, ~8 amps and be plugged inside.
- Gas boilers are far simpler units. Less moving parts, simpler electronics, all in all fewer points of failure than a cutting edge heat pump that can actually produce heat when it's below 20f (-7c, i.e. the only kind of heatpump that might stand a chance at heating throughout the cold winters most of the northern US gets).
- Be that as it may, heat pumps at this time are cost prohibitive - making them largely something only "wealthy Americans" can afford. Many people still run old 80% efficiency units because of similar reasons to boilers: they're cheaper, simpler, and less likely to fail.
My family has one in Poland, it was -20C this winter already and it worked absolutely fine. It's some cheap unit, wouldn't call it "cutting edge". I think there's a simple resistive heater that de-ices the fins at low temps, but it kept the interior of the house at a (very toasty) 24C pretty much non stop even in those low temperatures. I have no idea why people keep saying heat pumps don't work in low temps. I had a basic split unit fitted to my home in UK, literally a basic £600 midea unit and apparently it should work down to -25C without any problem.
>>Gas boilers are far simpler units. Less moving parts, simpler electronics
Have you ever looked inside a modern gas boiler??? I hard disagree that it has less parts than a modern heat pump. A heat pump is like your fridge - there's an inverter, compressor, and a whole bunch of fins, that's about it. A gas boiler has multiple tanks, burn chamber, exhaust recirculation, at least 5-6 probes to measure every part of the process(and they all can fail in surprising ways that renders your boiler dead).
A solution doesn't work in 100% of areas can still be the best one in the 95% of the places that do make sense!
And to your cost concerns, there's a bunch of Federal money (being deployed by the states) in the IRA to specifically pay for low-income Heat Pump upgrades.
If you can afford to have them just for cooling, you can afford to have them for heating as well; in fact, the capital cost may well be lower if people just used their air conditioning systems to heat as well.
The same goes for reliability - we manage to make air conditioning acceptably reliable and the tech is basically the same.
I've lived all around the US, and don't think I've ever lived anywhere with central air. Well, that's not quite true: in New Mexico I had a roof mounted swamp cooler, but that's evaporative cooling and not a heat pump. Elsewhere I've occasionally had and used a portable compressor unit, but rarely. I hadn't realized air conditioning was so overwhelmingly prevalent. Based on people I know and associate with, I would have guessed less than half that rate.
They range from sub-$1K single zone air-to-air wall/window units, to multizone split units, to ground source hydronic boiler/chillers that integrate with baseboard or radiant floors, which can get quite expensive to install, but that's at the high end. Generally speaking they're not really much more expensive than normal air conditioning. I've seen units that come in cooling-only and heating+cooling versions, and the cost difference is marginal (<10%) in those cases.
If you were to use all of the burners on this stove on their highest setting, it would consume more BTUs than a 6-ton Furnace! And it just vents into your indoor air: (https://www.homedepot.com/p/Cosmo-36-in-6-0-cu-ft-Commercial...)
I was surprised when a colleague from Minnesota who moved to the south mentioned never having air conditioning. I'd expect that in many parts of Europe. And I've sweated it out while living there, but it's extremely rare in my experience in the United States.
I've always had central air, along with a gas fireplace for emergency heat which, thankfully, I've never had to use.
I priced out a heat pump versus just an AC and gas furnace in my area, and it was a similar spread a few years ago for me in Texas.
And yet what I see time and again is that initial purchase price is the only focus for construction costs, even rehab work. Those budgets are a separate bucket from utility bills so lower priced projects get approval even if utility bills will be higher.
Anyone doing the math today on a similar purchase should really check out how much they can get from the government: https://www.rewiringamerica.org/app/ira-calculator
Couple "fun" things about a heat pump; You will smell burning the first time the electric strips are used every year moving into the heating season, it's just dust burning off. Once you start moving into colder weather you might notice the system changing into defrost mode so it can melt ice off of the outside coils. There's a variety of sounds that accompany this and you might even see a bunch of steam coming off of the outside unit. It isn't smoke and it's normal. Every year there's a flood of 911 calls about this.
In the US where AC is common, summer is generally peak electricity usage. I suspect this will become true in Europe as well with the heatwaves becoming a regular occurrence.
I'd love to see a source on that. There is very little technological difference between an air conditioner and a heat pump aside from refrigerant reversing valves that allow changing which end is the condenser and which the evaporator.
If you poll the current installed base for HVAC, I suspect you'd find that the (vast) majority of systems are minimum SEER rated (i.e., least efficient) systems, so SEER 13/14 (just became SEER 14 this year).
In comparison, if you're already paying the premium for the heat pump system, likely you also pay an additional premium for a higher SEER unit. Also, what I've seen when doing some online shopping that most heat pump systems marketed seem to be higher SEER. Likely, because the cost associated with additional heat pump stuff drives into a higher end market where you 'might as well' make them higher SEER as well (with inverter compressors, variable fan speeds, etc).
There are government subsidies but it's still much more expensive in the end. I think they are simply too expensive and impractical to install for most people.
BTW my town has an all-electric mandate for new construction already, and there's a lot of that. There's also a bylaw that takes effect in 2025/2026 banning gas-powered landscaping equipment.
I imagine the "proper" heat pump costs a lot because it has to integrate into your central heating - heat and pump water etc. But I also imagine for a lot of people in this country 2-3 mini splits like this one would be absolutely sufficient, wouldn't cost a fortune, and would save them money(plus they can be used for cooling when needed).
Thus Japan acting as a breeding ground for cheaper, replaceable, mini splits. The American manufacturers sold into the HVAC specialist market which was efficiency insensitive but cost sensitive. Thus a bi-partite market.
The only reason mini splits have not bankrupted the American manufacturers yet is many Americans still rely on expensive HVAC specialist to do installs. Thus mini splits extreme cost advantage is buried by expensive installs.
A friend of mine just remodeled their kitchen -- they got all the permits and sign-offs, and their AHJ allowed a gas stove in the island with no venting at all. Inspector told them they should open a window if they were doing a lot of cooking. It's actual madness.
"It's my god given right to poison my family with CO and NOx!"
The house also has an exhaust fan on a timer, paired with small vents on several windows around the house, to cycle in fresh outside air. But practically for much of the year we just open the windows for fresh air since we live in the temperate PNW climate, wildfires aside :(
I looked in to installing a minisplit heat pump system last year, but the quotes I got were outrageous ($25k+) plus as a retrofit it's not the most elegant integration. Someday I'd like to do the conversion and ultimately decommission the gas boiler, but at that price tag it's not happening soon.
In the short term I bought one window AC and one portable AC for a combined ~$1000. It's not ideal but we only have a few weeks a year where cooling is really needed, and a few more where it's a nice luxury but not a necessity.
Condensation is - air conditioners have an integrated drip tray which drains to the outside, but if you ran chilled water through radiators they'd all make puddles of condensation on the floor. Retrofitting drains might be possible but I've never seen one and I can't imagine it'd be cost-effective vs installing mini-splits.
I haven't checked the electricity usage but I can't imagine it is much. The system is literally just a small fan and a solenoid valve. Maybe your parents opted for a steam system, whereas mine is called a flow through style.
Additionally, there are multiple types of restrictions on where geothermal pumps can be installed, and navigating this can add to costs.
I don't see it as a one size fits all solution, there are far too many people for whom the household/company math doesn't add up. However, I agree we should be doing fair comparison against other renewable-friendly options for all new construction. I'm sure heat pumps could win out in a great many situations, and we should use them where they do.
Note that a heat pump cooling a building is essentially the same as an air conditioner. So it's more a matter of how efficient the air conditioner you're replacing is. Cooling a house is much easier than heating, because the temperature differences are lower. In your example, cooling 95 F to 70 F is a 25 F difference, while heating 20 F to 70 F is a 50 F difference. The world record for heat is about 135 F, which is the same difference from 70 F as 5 F, a completely normal winter temperature in much of the world.
GP's comment was about the tech, though, and not the cost of said tech.
It's absolutely not a perfect solution for all heating needs across the globe, the the technology is far better than GP is suggesting.
My main concern is the overall long term efficiency & affordability of renewable-friendly solutions, because competitiveness in those areas is what will lead to mass adoption. The point I was hewing toward is that I feel the heat pump advocates and providers need to make it more clear which situations are best suited for that solution and which are not, because it would benefit everyone.
Not all heat pumps are variable-speed like you describe. My own home, built in 2000, has a single-speed heat pump that kicks on 100% or off, like a regular old AC unit.
Mine is a variable speed unit, but that's not the function that I'm talking about.
Habits are hard to break, though, and there's not much value (if any) of lowering the set-point at night during the winter months. People still do it, though, and then the unit is working overtime in the morning to reach the desired set point.
I'm glad that you're happy with your setup!
Personally, for my home and climate in the area, I disabled aux heat entirely, unless the temperature is below 0f outside, or if it hasn't reached the set point within 2 hours. Recently had some cold weather and these settings worked well for my home.
I'm using an Ecobee, configurations will vary per thermostat. The big settings for me were using manual staging to configure the temperatures to engage aux, temps to lock it out, etc.
OTOH, a few months ago my stepmother installed minisplits after getting quoted $22K to install a whole-home forced air heat pump (going from no forced air at all, so part of that cost was ducting, though it's a single story ranch house so not terribly difficult).
Somewhere between those two points, prices went insane.
Yes, because it fucking works. This isn’t some network effect thing where everyone has to do it correctly.
It’s like saying diet & exercise isn’t a solution to obesity because it’s completely optional and rarely done correctly. Absolute stupidity.
And, since the heating season is there only time you need humidifying on this context, all the "waste" heat is just heating your home.
https://en.wikipedia.org/wiki/Combined_cycle_power_plant
> (CCGT) plant[s] achieve a best-of-class [...] thermal efficiency of around 64% in base-load operation. In contrast, a single cycle steam power plant is limited to efficiencies from 35 to 42%
This is a huge problem in Europe where a house is expected to last a 100 years, in many areas much more.
The core idea is that you aren’t using 1 unit of electrical energy to create 1 new unit of heat energy. You are using 1 unit of electrical energy to capture several units of pre-existing heat energy from the environment and pump it indoors.
Burning 1 joule of gas would give you 1 joule of heat in a perfect world. That is what a non pump does.
An expensive high efficiency gas furnace might be 95% efficient (most normal furnaces are in the 80's)
1000 x 0.95 = 950 BTU/cuft
A high efficiency natural gas power plant is 60% efficient and a modern high efficiency low temp heat pump can have a COP up to around 2.7 at 17F
1000 x 0.6 x 2.7 = 1620 BTU/cuft
A 40% power pant is still more efficient than a 95% furnace with a 2.7 COP heat pump.
There is obviously more to this, there are some grid losses to account for but has to be compared to piping losses, there is also cost factors and also how much renewable is mixed into your grid supply, but generally once that heat pump is above around 2.5 COP it starts to make sense, this is a no brainer in milder climates which is why I have a heat pump and no gas furnace here in FL even though I have gas to the house for other uses.
Those compressions and decompressions take up immense amounts of energy. They are less efficient than simply burning gas. On the flip side, could we not create electricity generation and heating from Natural gas?
Most of the energy is coming from the ambient air, only a small amount of electricity is used to change what temperature that energy is available at.
[1] A very simple mental model you can use to understand the difference between temperature and energy for a gas is that temperature is the number of times the gas molecules bump into each other in a second, while energy is how fast the gas molecules are moving. So if you have a very low pressure gas, even all of those molecules have a ton of energy in the form of motion, the temperature of the gas will be quite low because the gas molecules won't interact often. But compress that gas down to a small volume, and the molecules will bump into each other all the time even though they don't have much more energy.
>But compressing and decompressing is not an energy efficient task. It takes a lot of work. Mechanical inefficiencies are a huge energy consumption. Gas is simply burning fuel. Yes, we should save gas for rainy days. But I hate to say that it is more efficient and cheap. There is no comparison.
You are very mistaken, the energy required to compress refrigerant is less than the energy captured and delivered if COP > 1, which is the point of a heat pump. At COP 1 it is basically heat of compression and equal to a resistive heater at COP greater than 2 the heat pump captured more heat from the environment than used to compress the refrigerant.
I am not sure if you are arguing in good faith, if so here are some of the simplest resources I can find to explain how a heat pump can exceed a furnace in efficiency even when taking power plant and transmission losses into account, with easy to understand graphics:
https://greenbusinesswatch.co.uk/cop-vs-spf
https://energyeducation.ca/encyclopedia/Coefficient_of_perfo...
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatpump.h...
This should really be taught and drilled in lower education, the difference between heat and temperature and relationship to power, how heat engines work, etc. This stuff basically makes modern society possible and we will never progress in decoupling our power sources from use of the power which is what electrification allows which allows us to transition away from throwing carbon up in the air for energy.
Cost is going to vary greatly on the electricity and gas prices in your area, so it's hard to give a definitive answer there.
With regards to energy efficiency, my understanding is that heat pumps can be up to 400% (300% typical), which is naively much better than gas which is at most 90% efficient (70-80% typical). This doesn't take into account the extra innefficiency of generating the electricity in the first place, but a quick google tells me coal plants are typically 33% efficient, with combined cycle gas plants being typically being 50% efficient. Even at those levels, heat pumps still look to be coming out ahead to me. And that's not even taking into the possibility of green energy generation through renewables or nuclear.
They're a no-brainer in every climate. Newer heat pumps can handle fairly cold temperatures (-13°F) pretty easily, there may be a loss in efficiency but in the majority of the world it doesn't stay that cold. A few days of lower than normal efficiency, and at worst plugging in a few space heaters if it gets extremely cold for a day or two, does not change the overall math of heat pumps being a better solution.
Hell, that's just me talking about air source heat pumps. No reason for new construction to not use ground source and get better efficiency and not worry about ambient outdoor temperatures.
That isn't to say they cannot work I personally have a heat pump in my house and it worked fine through the -15F weather we got. But it requires careful design work initially. Also you run into simply size constraints where residential heat pumps tend to max out at 5 tons (60k BTUs) typically when furnaces can easily get up into the 100k+ BTUs. Which might require multiple heat pumps and separating existing duct work. But definitely new construction should start designing around these constraints now.
I am looking for genuine research, and not from paid mouth pieces.
Majority of the comments here seem like agents of heat pump industry. And HN rules forbid me from calling them that.
In extreme climates, gas burning is cheaper. And quite clean. There are some objections because of delivery leaks, but that is a separate concern.
Switching everyone to heat pumps would lower emissions from heating and cooling in the US by 160m tonnes a year [1], which is something like 30-40%.
It's true that upfront costs of heat pumps can be higher, but thanks to the IRA there are huge subsidies available (and further subsidies in many states) which make up most or even all of that difference. The lifetime costs of heat pumps with these subsidies should be substantially lower than high efficiency natural gas furnaces.
[1] https://www.rewiringamerica.org/circuit-breakers-heat-pumps
(Those subsidies, by the way, are one of the reasons "everybody is talking about heat pumps")
Heat pumps do not create heat, the refrigeration cycle moves heat from point A to point B. For every KWh of electricity used by your refrigerator, air conditioner, or heat pump, 3-4 KWh of heat energy can be moved where you want it to go.
Even if you have a (comparatively) inefficient combined cycle natural gas power plant that is 50-60% efficient, you're still getting 150-200% efficiency for heating with a heat pump compared to 80-95% for a natural gas furnace.
I live in Boise so we have pretty cheap utilities compared to the national average, but here's some math:
1 therm (~30KWh of energy) is ~$0.72 from Intermountain Gas, the furnace in my rental is 90% efficient, so I actually get 27KWh of heat from every therm I burn.
Idaho power has a tiered tariff for residential customers, with a peak charge of ~$0.098 per KWh during the winter for usage over 2,000 KWh in a month.
Every therm my gas furnace burns costs me as much as ~7.5KWh from the electric utility, but those 7.5KWh can provide me with 30KWh of heat with a quality heat pump, which would require a 100% efficient natural gas furnace to reach. Add in that gas furnaces have a much higher TCO because of maintenance and repair compared to a heat pump, and they're not just energy inefficient in comparison but even just plain more expensive to operate even with incredibly cheap fossil fuels.
Gas is burned creating a certain amount of heat, in a furnace some is lost to exhaust the rest goes into your house. That is the furnace efficiency.
When gas is burned at a power plant the same number of BTU is released, but it is used instead in a heat engine to create mechanical power which is then turned into electrical power, the rest is lost to exhaust, this is the power plant efficiency.
Heat pumps are over 100% efficient because they capture heat from the environment around your house which is warmed by the sun. So even though more energy is lost in creating electricity than burning directly in your house, this is more than made up for by using the ambient heat around your house, it is essentially solar assisted (in the case of air source).
I am happy you have an open mind, but the fact that you are trying to tear the technology down when you apparently have no idea how it works or what it even is- hopefully you realize that it is also used for air conditioning, and is essentially just an air conditioner running in reverse... I hope this is a learning experience for you.
At the very least it gives me hope that those trying to tear down this technology are just ignorant, I had real suspicions that they were agents of the fossil fuel industry, or this was something Fox News and the like decided to target and is now being parroted.
Ductless mini-splits remain an option as well. I'd actually like to see somebody make some ground-source exchanger that ductless heads could connect to, because they're much cheaper to install than a multi-zone ducted system.
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