We have one of the "all-denka" electric plans, where we trade off cheap rates during solar hours for expensive rates during duck curve hours. By having the hot water only run during cheap hours, and having the aircon turned off/down during the expensive hours, we're paying less in energy for our all-electric house than we did in combined electric+gas in our 3x smaller apartment.
We pay approx (before fees, and the rates change slightly by season):
* 8 AM - 10 AM: 35 yen/kWh
* 10 AM - 4 PM: 13 yen/kWh
* 4 PM - 6 PM: 35 yen/kWh
* 6 PM - 8 AM: 19 yen/kWh
Our Mitsubishi has other nice features like it can recirculate the water in the bath through a heat exchanger after you already filled it and got in, so it will keep the water from cooling down to lukewarm, and you can even adjust the bath water temperature if you ended up with filling it with too warm or too cold water. Of course, there's also an app so you can start filling up the bathtub when you leave work for home so a hot bath is waiting for you. There's also an intercom to the kitchen "so mom can tell the kids to get out of the bath, dinner is ready".
edit: the wifi integration does have one actually useful feature: if we had solar panels, then it can use data from them to know when to run "for free", and it can use weather data to predict if it should wait for sun or not to run
I quite like the quarterly pricing, for example today the home-battery charged for 3 hours during the cheapest time (13:00 - 16:00), and discharged again for the most expensive hours (19:00 to 21:00), and kept my house's grid-input at zero for the rest of the day.
Feeding back a few kwh's during the most expensive hours gives me a big kickback, making electricity use for the rest of the day mostly free. (Since there is usually a 150-250% price difference between cheap and expensive timeslots).
(For price-charts, see https://jeroen.nl/dynamische-energie/stroom/prijzen/vandaag or price-predictions upto a week ahead there's https://wattwanneer.nl )
I don't have long-term data yet, as I just implemented this about 6 weeks ago, but last month's bill was 10% lower than the previous month and the same month the previous year. I'm looking forward to seeing the results over time.
I've been trying to think of what other automations I can try out when the price gets high. I thought maybe shorter light timers for automated lights, but all of our lights are LED, so the savings isn't really worth it.
We have quarter-hour pricing here in Vienna and during the sunnier half of the year electricity is cheaper during the day.
It would be interesting to calculate how long it would take to pay off.
How long do you sit in a bath?
> Of course, there's also an app so you can start filling up the bathtub when you leave work for home so a hot bath is waiting for you.
My immediate reaction to this is, “there’s a way for my house to be remotely flooded”.
Another Japan resident here! It is common for a family to share a bath for the evening. (One at a time!) This works because each person showers to get clean before you get in the bath. Many also have folding bath covers, which help to avoid the water from cooling down and to keep the water clean during the showers. Still, nobody wants to be last.
> My immediate reaction to this is, “there’s a way for my house to be remotely flooded”.
A smart reaction! But most baths are also whole-room units, with a floor drain, and are intended to get wet. I myself have forgotten to stop the bath water a number of times (neither I nor my bath are so "smart") and while it is an unfortunate waste of water, there is no danger of flooding, only slight embarrassment.
80kg of meat can hold a lot of heat. It cools quicker than you think it would. Also, Japanese families often share the bathwater within themselves(but everyone showers outside the tub first), and the water will become lukewarm at some point in that use case.
> My immediate reaction to this is, “there’s a way for my house to be remotely flooded”.
Yep, remotely operating a machinery will always have some risks. Every machinery should have someone with an emergency stop button should be monitoring it at all time, ideally. But it's a well engineered tub auto-fill in the shower room, it effectively belongs to "inherently safe" category of equipment.
I'm an American and my answer is at least an hour, maybe more, depending on how I'm feeling. I usually listen to an audiobook. Baths are for hanging out and relaxing in.
We love our baths here in Japan
> My immediate reaction to this is, “there’s a way for my house to be remotely flooded”.
I forgot to mention that it senses and automatically stops filling the bath at a select number of liters, even if you start a bath using the physical button when you're at home.
You can totally remodel bathrooms to be "wet rooms" in the US, it is well worth it.
Kids flooding the bathroom via the tub? Not a problem. Toilet overflowing? Gross, but not a problem.
I wish I would have made all the bathrooms in my home wet rooms.
The entire point of a bath is to relax and soak in it. Otherwise I'd just take a far more economical shower.
These are truly _bath_ rooms. The shower and bath are side by side, with the intent that you wash off before hopping into the bath to soak. Thus if the tub overflowed it would just go down the shower drain.
Huh. Is the heat exchanger located near the bathtub or in the EcoCute unit? And do you need to do anything complex to periodically sterilize the tub side of the pipes and the heat exchanger?
I've also got the ecocute but I was told that it's cheaper to just pump fresh hot water into the bath than recirculate the cooled down water. It uses less energy to pump the already boiled water into the tub than to heat it back up.
Though fresh water and letting out the old will clean the water you are soaking in, which may be valuable.
Interesting! Is there some sort of filter system you can easily clean out, to avoid any issues?
That alone probably will make a huge difference in how often you have to deep clean it.
I'd love to have something like that!
Whenever I take a hot shower I fantasize about putting in a liquid-to-liquid heat exchanger so the hot water can heat up the cold water and you can run the hot water at a much lower temperature.
This application with the bath tub feels way more justified.
Drain heat exchangers are really expensive, this 3” by 48” copper one costs over $1000: https://www.homedepot.com/p/Power-Pipe-3-in-x-48-in-Drain-Wa...
However this is somewhat old fashioned, the most modern tarrifs vary on a 30 minute window, with prices set a day ahead. If there's a lot of solar and little demand on say a sunny sunday afternoon or windy february nighttime, then the prices may even go negative.
You want your consumption to be tied into there. You can do this with batteries -- for example on Tuesday I used 34kWh, 24kWh overnight (mainly to charge the car) and 10kWh in the day. If I had a battery I could have charged that battery overnight and saved a couple of quid, or about £600 a year (depends on what my daytime usage is)
However with a 30kWh battery I could have charged it on Sunday afternoon and been paid for that, and not used any power on Monday, Tuesday or Wednesday for the house. But then the agile rate last night was 25p/kWh. I did look at getting a battery and inverter installed but it wasn't cheap.
On top of that you've got self generation. I have very little solar generation, but in theory I reckon I could have 8kWp on the roof -- I'd want to charge the car (and house battery, and any heatpump or ac) when the sun was shining then, which would be even cheaper than charging at night. Home Assistant will do that, but it feels a little fragile with my car charger (if the HA dies, the charger won't start, and then I can't go anywhere. It's not a great charger)
In fairness it probably works ok for homes insulated to a much higher standard than most British ones.
I was quite confused at the use of "tariff" here, as it meant to me a "tax on a good crossing a political boundary." Turns out, 'tariff' has an older meaning: a published schedule of fees or taxes issued by some authority.
Heat pump conjures up an image of an appliance, but it is a principle of physics. Heat can be created by burning fuel or electric resistance. Cold can't be created. Cold is the lack of heat. Cold is 'created' by removing heat. Fridge keeps the inside cool by moving heat from inside and dumps it outside. This movement of heat is called heat pump (pumping heat in a specific direction).
If we can do this for cold, we can also do this for heat. After all, we always have heat in the environment until we get to 0 degree Kelvin. Which means we can have heat pump water heater in the garage. Or heat pump furnace.
Creating heat from fuel/resistance is at most 100% efficient (most likely a LOT less). Heat pumps are 400% - 500% efficient per unit of electricity, because the idea is just to move heat. In one direction, or another.
All of this is great, until we get to the refrigerant used to transfer the heat. These are very specific chemicals. Mostly synthetic chemicals. Historically, these were Chlorofluorocarbons (CFCs). CFCs caused ozone depletion and have high GWP of 14,400.
What is GWP? CO2 is a warming gas that has Global Warming Potential (GWP) of 1 (the standard). Earth radiates heat back into the atmosphere (exactly the same as get from Sun) and CO2 acts as a barrier for the radiated heat from earth, retaining heat in the atmosphere and warming the planet. Why Greenhouse Gases Make the Planet Warmer: https://www.youtube.com/watch?v=AIBk0pGV_BQ
But, there are lots of other gases that have higher GWP. Fluorinated gases: Hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride are synthetic gases used for refrigeration (maybe other applications). Fluorinated gases replaced CFCs, which were causing ozone depletion. But they have high GWP. HFCs: up to 12,400, PFCs: up to 11,100, NF3: 16,100, SF6: 23,500 (https://www.epa.gov/ghgemissions/fluorinated-gas-emissions)
So, we have to find better alternatives for refrigerants. Because, these leak. And everybody on the planet is going to buy ACs. CO2 is a terrific refrigerant because it has GWP 1 and leaking of CO2 is perfectly okay. With 40 - 60 billion tons of CO2 from fossil fuels, CO2 leaks from refrigerants are less than a rounding error.
I worry in 15 years we will all have crapily made Chinese heat pumps for a fraction of the cost. Noisy, not robust, copying competitor designs not innovating, lower efficiency but easily replaceable. Theres probably an analogy here with software talent and AI but its too early to do that.
* https://en.wikipedia.org/wiki/R-744
It's just not as prevalent in the residential HVAC market (which this product serves?), and more in the commercial/industrial space (probably because of the higher pressures needed to get into a liquid state).
Napkin math based on Amazon/Home Depot prices
You can get a 80"x90"x95% = 2kW output solar heater for $2000
or eight 45"x70"x25% = 1.8kW solar panels for $2800
A regular water heater needs about 12kWh a day, which is about what both systems would produce.
However, a heat pump water heater is 4x as efficient, so you could get by with $700 of solar panels.
Except, a heat pump water heater costs $2000 instead of $500 for a regular electric heater.
There's also install, maintenance, and the fact that we're talking about grid prices, not home panels, but those won't fit on my napkin.
For reference: I’m in a household of three. Over the last month (winter, when n case that matters) we averaged 7.9kwh per day.
I recently did the maths on switching to a heat pump hot water cylinder and the payback was surprisingly long at 5-7 years.
So no, switching everyone to a CO2 heat pump will not magically store all our emissions.
I am not a big fan of running lineset with r-410a or r32 in a confined space, too much risk of someone accidentally puncturing it. I would love hydronic systems to be more popular in the US. Being able to run hot/cold water in pex is stupid easy in both new construction and cheap in labor/materials. no noise concerns like forced air and much better routing for MEP imo. combined with an ERV, you can build a very good, high effiency zoned system that is comfortable and flexible.
Will see!
Happy they named it EcoCute, that's so much better than ElectroCute :)
e.g., I'd LOVE to have an API to have dryers/ other high current machines refuse to run if the grid is out and the house run on batteries.
CO2 refrigerant as well.
But having water leave the building envelope is a bit scary on very cold days. There are heat traces and freeze valves so it should be fine, but I do worry about power outages during cold snaps
What does this mean?
A heat pump conjures up an image of an appliance, but it is a principle of physics. Heat can be created by burning fuel or electric resistance. Cold can't be created. Cold is the lack of heat. Cold is 'created' by removing heat. Fridge keeps the inside cool by moving heat from inside and dumps it outside. This movement of heat is called a heat pump (pumping heat in a specific direction).
If we can use a heat pump for creating cold, we can also create heat by pumping heat in the opposite direction. We always have heat in the environment until we get to 0 degree Kelvin. Which means we can have a heat pump water heater in the garage. Or a heat pump furnace.
Creating heat from fuel/resistance is at most 100% efficient (most likely a LOT less). Heat pumps are 400% - 500% efficient per unit of electricity, because the idea is just to move heat. In one direction, or another.
Indoor air quality is just as bad as outdoor air pollution, because we use natural gas for heating and cooking. Anything that burns creates particulate matter. Most homes are closed spaces, the particulate matter never escapes. Cooking can be done by induction, infrared or electric resistance. Heat pumps replace natural gas water heaters and furnaces. We don’t need to build natural gas pipeline infrastructure to every home, which probably costs million(s)/mile.
Household energy bills are fragmented: 2 gas cars, natural gas for cooking, water heater and furnace, and electricity for everything else. EVs replace gas cars. Cooking by induction, and heat pumps replace heating appliances. Now, all the uses of energy are electric. Instead of spending ~$1000+ on 3 different types of energy bills, it creates a clear picture of total electricity consumption. This consolidation makes people think about their energy and how to make the bills disappear. Then they can install solar and make the entire energy bill zero. Forever.
With heat pumps, we gain ~5X efficiency, solve indoor air pollution, save on natural gas infrastructure capex, make everything electric, and let people save money. While getting close to net zero.
Heating and cooling are also very important for demand shifting. Because of thermal mass (and inertia), heating and cooling can be done when energy is cheapest (which is the cleanest source). If heating and cooling is all electric, smart appliances can connect to the grid and figure out when to use energy.
The cost savings of going all electric are going to be significant. There is not only an immediate reduction, but with demand destruction, the price of oil is going to fall precipitously. Oil is priced at the margin, based on demand. If demand is high, people are willing to pay whatever price and costlier sources of extraction (shale, fracking, etc) become profitable. With low demand, Saudi Arabia can supply the world at $10/barrel.
There is a small problem with heat pumps though. It's the refrigerant used to transfer the heat. These are mostly synthetic chemicals. Historically, these were Chlorofluorocarbons (CFCs). CFCs cause ozone depletion and have a high GWP of 14,400.
What is GWP? CO2 is a warming gas that has Global Warming Potential (GWP) of 1 (the standard). Earth radiates heat back into the atmosphere (exactly the same as it gets from the Sun) and CO2 acts as a barrier for the radiated heat from earth, retaining heat in the atmosphere and warming the planet. Why Greenhouse Gases Make the Planet Warmer: https://www.youtube.com/watch?v=AIBk0pGV_BQ
But, there are lots of other gases that have higher GWP. Hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride are synthetic gases used for refrigeration (maybe other applications). These new engineered chemicals replaced CFCs, which were causing ozone depletion. But they have high GWP. HFCs: up to 12,400, PFCs: up to 11,100, NF3: 16,100, SF6: 23,500 (https://www.epa.gov/ghgemissions/fluorinated-gas-emissions)
HFOs break down and produce trifluoroacetic acid (TFA), which is a PFAS. PFAS rains back down, is a forever chemical and bioaccumulates. (vel0city: https://news.ycombinator.com/item?id=49645555)
There are billions without ACs. They are all going to buy them. It is better if we figure out better refrigerants.
And all refrigerants leak. These will cause problems. Many heating/cooling appliances need to be recharged with refrigerants once in a while.
There seem to be several workable alternatives: CO2, isobutane, propane, ammonia. Water is used for district heating. In the middle-east, there is district cooling with water and ammonia.
CO2 is a terrific refrigerant because it has GWP 1 and leaking of CO2 is perfectly okay. With 40 - 60 billion tons of CO2 from fossil fuels, CO2 leaks from refrigerants are less than a rounding error.
Why aren’t we using CO2? (bronson: https://news.ycombinator.com/item?id=49645996) It's because CO2 has to be run at more extreme temperatures and pressures, fine for factory-made connections inside a single unit but a showstopper for field joints.
For example in Turkish, "tarife" means only that: Conditional / Schedule-based pricing, and according to Sevan Nişanyan (a language researcher), Turkish borrowed it from Italian, where it was being used similarly. Import tariffs are a completely different word.
It apparently came to English through Italian -> Spanish -> French.
So I'm not a native English speaker but as far as I understand, import tariffs are just one kind of tariff.
ps. I just f'ing love Etymology.
https://www.etymonline.com/search?q=tariff
Spoiler: the word is originally from Arabic :)
The same word exists in e.g. German or Italian, but mostly just means "pricing scheme" there, like in the article ("import duty" using a different expression in those languages).
Might be a mostly/somewhat "false friend" for a German (pv magazine is german).
Import duty is "gümrük vergisi", and the general list of this is "gümrük vergisi tarifesi" in broad sense. It also has a more technical name here but both I don't remember it, and it doesn't matter in this context.
In the Japan's context we would call it "elektrik fiyat tarifesi", or "elektrik tarifesi" for short, for example.
Cheers,
Your friendly Turkish HN user.
"Tarief" just means price of mainly a service.
I think 'dynamic rate' is the proper translation for the US?
The less common uses show up in examples like "Schedule I drugs" (highly banned) or various schedules in tax laws, appendices of long documents, etc.
Schedules are common in UK legislation as addenda to the main clauses/provisions. Most wouldn't fit in a papyrus strip though!
When I see "tariff", my mind only thinks of 関税 , and I was just as confused as you were. Turns out its just an item in a price schedule.
It's because CO2 has to be run at more extreme temperatures and pressures, fine for factory-made connections inside a single unit but a showstopper for field joints.
I estimate they use less CO2 than is released when burning a tenth of a gallon of gas.
Not significant carbon sequestration, and an insignificant amount to leak to the atmosphere.
After the 2026 heat wave in Europe and elsewhere, and expectations of things getting hotter with global warming and El Niño, it’s already past the time to prepare, but better late than never.
Will governments have to subsidize solar/inverter/battery/heat pump systems to keep people going?
What are people doing to get ready for a “hot house Earth” future around the world?
It seems for refrigerators there are actually specific carve outs in EPA venting regulations to allow R-290 (propane) along with a couple others.
https://www.epa.gov/snap/substitutes-household-refrigerators...
If vendors don't use it, possibly due to flammability, whether a real risk or as imagined by consumers that's a completely different situation. I can't find anything claiming it's banned or even discouraged by the government.
CO2 is not a terrific refrigerant. It requires comparably very high pressures to be effective and has a low critical point reducing their effectiveness in a lot of normal temperature ranges. More modern refrigerants like HFOs usually have a GWP of <1 and don't require anywhere near as high of pressures, with R-454B being around the same as R-410A.
They work really well, with the downside they are very explosive. However stories of airconditioners blowing up are really rare - it seems the risk is probably worth it for the environment.
Thanks! Could've worded it better.
I'm a big fan of Chinese lenses. I reach for Japanese and German lenses when I want to take the highest quality photographs that look like the photographs all the other photographers take. When I want to take a picture like you've never seen before I reach for
https://www.venuslens.net/product/laowa-9mm-f-5-6-ff-rl/?srs...
or
https://findingrange.com/2022/01/14/7artisans-photoelectric-...
It's true a $3000 lens from Sony has better optical quality than a $300 lens from China, like take a picture of a starry sky and you will see light rays bounce around a lot more inside the Chinese lens. But in terms of value and innovation Chinese lenses have a place, and many Chinese manufacturers are looking for this kind of opportunity for whatever they make.
What's the innovation?
Arguably, PRC price / value engineer is their innovation and by far more MORE important than vs minute efficiency differences. Ultimately it's about TCO and global adoption, if JP can't bring their prices down, if they can't fractionalize cost, then they're doing more harm than good for net transition - there's better things to with that 30-50% premium.
Id argue that the PRC price / value engineer is only viable because of the development that the innovations in heat pumps have managed to provide. Can't have one without the other. Though once price / value owns the market - innovation dies.
I want to cool the house (so have waste heat) but also want to warm my water, so make heat. In winter I warm my house, except for the fridge where it’s trying to cool its contents.
If there was any overlap or coordination it would surely be possible to have less hardware, working smarter and using less power.
The additional cost barrier being you can't self install or Mitsubishi or get any warranty on a self install, which means you'll likely pay 5-10x when you include install.
China is now at a stage of economic development where it can manufacture products across the entire quality spectrum.
Japan went through a somewhat similar transition: in the 1960s and 70s.
Inferior quality maybe was accurate 5 years ago. Now they're taking over the global automotive market. Only thing preventing them from pulling another Japan-in-the-90s against the US auto market is americans' love of oversized trucks, tariffs, and import controls. If we had a true market economy, we'd see more BYD's than Teslas (and in most global markets that's already the case).
Yes, you can still get cheap Chineesium crap off Amazon for pennies on the competitor's dollar, but it's no longer necessarily true that Chinese = inferior.
As for cars, sales of ICE were down 40℅, BEV grew 1.7℅
What happened since then?
We do need heat pumps deployed at large scale, but sometimes I worry we don't understand they need to be handled with care at the end of their life
CO2 has a GWP of 1 in this context, while other refrigerants are worse - for example, R32 has a GWP of 675 (so 675x worse if it escapes), not sure about R290 (Propane), which I believe is either about 40 or 14…
Regarding EoL: At least around here, household appliances such as fridges are brought to a recycling yard and are properly taken care of in that regard… and as for heatpumps - those are only to be installed by certified professionals, for this very reason.
It's lighter than air so it will go away by itself if allowed to. For a purely exterior instalation it's much better than anything else.
There are indoor devices using propane but they generally come with caveat "must be installed on room at least this m3", precisely so if it leaks it doesn't get to density that allows explosion
You could install your own CO2-based heat pump in a way you wouldn't be allowed to do with a F-gas based one.
This is for the Japanese market so perhaps the cons of the C02 systems are outweighed by the safety aspects.
Compared to other refrigerants it's a paradise:
* https://www.epa.gov/hfcs/technology-transitions-gwp-referenc...
* https://en.wikipedia.org/wiki/Global_warming_potential#Calcu...
Almost anything else you could use as a refrigerant is worse.
Even water vapour is a worse greenhouse gas.
Edit: wait, have I been whooshed? Apologies if so... ;-)
It's exceedingly useful that you can run all your gas appliances at full power at the same time without needing the ridiculous amount of copper or aluminum it takes to carry the same load in electric form, and do all that while the power is out, because the power is up on poles and the gas pipe is in the ground.
Now imagine trying to replace the redundancy by ups or generator. The amount of copper, electronics, and batteries needed to make a ups that can run your furnace or ac and your stove and hot water is just ridiculous. Most people simply won't have it. Wildly impractical luxury.
It's kind of ridiculous to require $billion chip fab infrastructure to make heat, and have your stove be this delicate piece of complex electronics and the burners are all these fixed little circles that don't heat pans evenly because it costs more money to make the fancy burners large enough to cover a whole pan.
Meanwhile a gas stove is just a couple chunks of dead metal and almost no moving parts and doesn't even need electricity let alone any electronics. That is a huge practicality and robustness win.
And heats pans more evenly because the flame does not have this weird artficially sharp 0%/100% border. Even a small simmer burner heats a large pan more evenly because although there is a hotter spot in the center, the flame still spreads out and travels along the pan and up the sides no matter what size it is. It doesn't care what size the pot or pan is, and also doesn't care what the pan is made out of. That is huge.
Electronics and heat are not natural together. It's a constant fight to try to prevent heat from killing elctronics. Every day that one of the thousands of electronic parts of an inductive range sittng above a hot oven and below a hot pan doesn't fail is a lucky day. It's not just reliable by default by just being simple.
It's not a slam dunk all-upsides trade-off.
This is in Europe, might be different on the other side of the pond.
Perhaps look into "air to water" heat pumps.
But if you insist, I believe there are high-temp heat pumps available that will make better use of old-style radiators.
No one likes steam these days because it's old and difficult to install correctly or modify later, but steam has some really cool features.
First, it doesn't require a pump to circulate. That means both the mechanical reliability of not having the electric motor and rotating water seal, or any moving part at all(1), but also you don't need any electricity.
It doesn't even need the usual low voltage circuit for the thermostat and gas valve. These are not common but also not new, there are millivolt systems where the thermostat & gas valve run only on the electricity generated by the thermocouple on the pilot.
It means that when ice has taken down all the power lines in a region, and blocked all the roads for repair crews to fix them at the same time, your heat stays fully working. No air blower, no water pump, not even 24v for the thermostat, and not by dint of having a ups which is just more stuff to fail.
Same goes for the hot water and the stove but that's more about gas than steam.
There is no getting around the huge efficiency of heat pumps of course. It just still kills me that we are accepting it as normal to require TSMC and ASML $billion chip fab infrastructure to make heat. But I guess you could say the same about leds and light so whatever I'm not saying we shouldn't use heat pumps.
(1) there is a moving part in the vent that opens and closes on each radiator, but that is a quality of life and longevity thing. If the vent fails to close or seal, the radiator still works, you still have heat, it just makes a hissing noise and consumes more fresh water which corrodes the boiler faster so it may leak in 5-10 years instead of 20-never.
Then run a wee bit hot water through your cast iron rads for the look of the thing.
I couldn't find a model/calculator that would help visualise typical COP values for particular climatic conditions. However, you'll find in your travels that a COP of ~2-2.5 is typically achieved for ambient (outdoor) temperatures of -15oC (for air sourced heat pumps).
If 300L of water at 15oC is filled into a tank and needs to be heated to 60oC within 2 hours during ambient temperature of -15oC, you get very approximately (no thermal losses considered):
- An output energy need of approximately (4190300(60-15))/(60*120)=~8kW (56MJ/2h)
- An input electricity need of approximately (8/2.2)=~3.6kW
Instead of a resistive heating hot water unit requiring 16kWh to do this job, you could use a heat pump hot water unit requiring 7.2kWh, cutting electricity use in half.
And this is for arguably the most extreme use case for a heat pump hot water unit where it's "cold started" right at the coldest moment in Winter in cool-temperate climates (such as SE Australia). Think for example, arriving at a ski chalet and having to turn on the hot water unit before someone can take the first hot shower.
On a more typical day of the year, perhaps with overnight ambient temperature of 10-15oC, the COP would rise to ~4, equating to an electricity consumption of 2kWh to heat the 300L of water. A lot of units will be set to heat during the warmest part of the day, let's assume an ambient temperature of 25-30oC, where a COP of ~5-6 is more typically achieved. However, there are obviously diminishing returns for COP of 4 vs 5.
In arctic climates, heat pumps are still used, but with a ground or aquifer source rather than ambient air source.[2]
[1] https://en.wikipedia.org/wiki/Coefficient_of_performance
Which means in winter that is extra work for your heating system to compensate for
But in climates where heating only really runs in winter it's great
Because heating water requires higher temperature differences (usually heat pumps get more inefficient then). And with an "ordinary" (propane) heat pump you get such high numbers only in summer time (>=20°C) and for water temperatures of max 50°C.
Contrast this with the all-in-one design where a person taking a shower monopolizes all the plumbing fixtures even while they are not using them. I was on a bachelor party trip with 8 guys and two bathrooms where some inconsiderate people camped out in the shower for 20 minutes while people waking up had to pee so badly they went outside in the bushes. Meanwhile on a trip to Japan with five people we could easily share one or two split bathrooms and never had an issue.
Oh, and the electric bidet is a clear winner in terms of bathroom accessory to buy. Less TP use and no threat of swamp ass that demands you take a shower. Heated seat in winter is a blessing, especially in the morning. After my Japan trip it was the first thing I bought when I got back home.
My rates are 36yen from 6am to 10pm and 19yen on the other end.
Re-reading my earlier post, I should’ve said cost and not energy.
Also gives the same information. BTW the dude is a legend, I had lessons from him in university, he could speak like 12 languages or something.
The explosion risk (in a commercial setting) is mitigated by having gas detection sensors and an exhaust fan that runs when the gas detection alarm trips along with horn/strobes at any entrance to the mechanical room and inside the mechanical room.
In a residential setting, I’d only feel safe if the condenser (outdoor unit) used propane with a liquid to liquid heat exchanger and separate glycol loop that runs inside to the air handler coil.
PRC just doing innovating AND value engineering - they have both. IMO with respect to energy efficiency tech is one of those "any idiot can build a bridge that stands, but it takes an engineer to build a bridge that barely stands". The primary metric for "quality" of energy transition products is efficiency / $, and in that JP fails hard. Only PRC is scaling efficiency / $ effectively, which has much greater value than JP trying to push top end, because frankly that's all they can do. Which has it's economic rational, i.e. TOC in wealthy countries where installation/labour expensive, but its still net, lower "quality" innovation because $ spend on JP premium nets less aggregate efficiency.
* https://www.bryant.com/en/ca/products/heat-pumps/33nm3/
* https://www.arcticheatpumps.com/high-temperature-heat-pump.h...
It does work well, and when it gets cold in the winter and the efficiency of the heat pump drops, he burns wood. But honestly the system is a jungle of pipes and valves, and the guys who did the heat pump installation were unable to wrap their heads around it. Luckily my father is a handy guy so he was able to do it himself.
But I'm thinking if one were to do something like this from scratch, without the history of the existing boiler already being there and installed, I wouldn't bother with it. Just have a few good old school wood stoves with significant thermal mass (masonry heater or whatever you call them in the US) in the house that you can use to provide extra heat when it's cold, and as backup in case there's an electricity outage.
It will suffocate you on account of all that blood pulp in your lungs. And eyes, and nasal mucosa...
Having a high pressure ammonia leak indoors is a death sentence for anybody in the same room. Same building, if it's large enough...
This is probably a little bit "dangerous" in the sense that I'll have high pressure propane in the line sets and minisplits inside the house, but it's a very small volume of propane and not really any more dangerous from a fire perspective than my propane fired condensing gas boiler.
[edit] a little internet sleuthing indicates that hydrocarbon refrigerants "might be" compatible with basically any oil, so I can probably just continue using whatever oil is in it.
This is even simpler: https://warmduscher.de/produkt/warmduscher-original/
Yes, the heat pump will take an efficiency hit for using radiators rather than underfloor heating. I'd say that's just part of the cost of living in an old house.
FWIW, one of the biggest negatives to HFOs is that while they rapidly break down in the atmosphere they end up producing trifluoroacetic acid. This stuff then rains back down, and is a polyfluoroalkyl substance (PFAS).
My understanding is that there are large savings available theoretically at the grid level but the capital to build it is limited and the grid interconnects to make it work are limited.
So globally there are huge amounts of battery storage being added to the grid but this is bottlenecked by capital and grid connections. Oh and land/planning permissions.
Long story short, house level battery storage may be worth it for some people
Having two options during cold winters can pay for itself with one emergency repair though, or be a massive savings if it can't be fixed fast enough and pipes burst.
> Gas is surprisingly, weirdly cheap, often not even metered in apartments.
One of the houses I rented many years ago didn't even have metered gas. We paid a "hookup" fee to the city (like... $40/quarter?), and they didn't care how much we used, as long as it wasn't for commercial purposes. I assume the city had something for detecting extreme use or leaks, but that's probably it. It was a somewhat strange property though.
You do not, to be clear, have a 98% efficient gas boiler. You _may_ have a gas condenser boiler which claims 98% efficiency in absolutely ideal circumstances, but realistically you're likely not getting close to that. AIUI 80% efficiency is fairly normal for real-world condenser boiler usage (non-condensers were more like 70%)
In Ontario Canada; your gas hookup is CAD$29/month (~US$21) every month of the year, on top of a per m3 charge for delivery to you before the gas cost itself. So on a smaller or well insulated residence, capping that pipe really helps push the economics in favour of heat pumps.
https://www.enbridgegas.com/-/media/Extranet-Pages/ontario/r...
I mean you can as long as you make the bathroom a wet room and shower outside the tub, which is exactly how the Japanese do it.
most owned apartments also are not build in a way where it's easy to retrofit. So if you don't do a "in depth" renovation anyway, its often just not a good option from a financial POV. Especially if you have to reroute plumbing (for the floor level wet room sink), especially if beton floor or pre-existing floor heating is involved.
The biggest issue in the west is the room being wet to start with.
If you replaced an R134a fill with R290 you'd need about half as much gas and if it got out, it's got a Global Warming Potential of 3, making it three times as bad as carbon dioxide and about 475 times better than the same amount of R134a.
Even in a very large air conditioning system like in my elderly Range Rover, the 500g or so of propane it would need is about the same as the engine sucks up in about four miles.
The effect of that escaping into the atmosphere is about as bad as the amount of petrol you spilled the last time you refilled your lawnmower.
If you're worried about the ZOMG IT IS GAS IT WILL MAKE A GINORMOUS EXPLODISHION aspect like a lot of people are, ask yourself this - how many aerosol cans are in your car right now? Tin of deicer, tin of magic tyre inflater, maybe a tin of air freshener or WD40 or something? You're already carrying more propane around with you, rattling around loose at your feet.
Any calculations I've done made it unfortunately useless to buy solar and instead favoured investing the money in the stock market.
Nearly all refrigerators/freezers in Europe are isobutane, and have been for 20 years.
https://www.youtube.com/watch?v=uJJvG10tUAw
They're pretty explosive when they have the right mix with air. This can easily happen in, say, a utility closet with a water heater or air handler, or a fridge in a kitchen, etc.
A small leak on the outside unit probably isn't going to be a big risk. A small leak on a unit in a closet with stuff that sometimes makes small sparks...
Yeah, but I'm from the UK so I should be able to detect dry humour. It's something that Americans don't really get.
You know, like affordable healthcare.
So you need backup electricity either way. And in the case of a furnace it's still a significant draw due to fans and/or pumps so to get multi-day resilience you need a big battery. Less than if it was a heatpump, sure, but this battery and inverter system will use all the same amount of electronics either way.
If the home owner has natural gas? They should could get a natural gas generator, that way they have a continuous supply of fuel if the grid fails.
Grid and gas failure? That happens only after a significant event, like a major earthquake. Not much you can do about those sorts of events. ( The person lives in Ohio… so not as much concern. )
Cost-wise? They would be better with a dual fuel system for heating. They live in Ohio, they probably have AC so moving to dual fuel when the AC system needs to be replaced is the smarter option.
Depends on setup, of course. If there's a central AC blowing hot/cold air through ducts, you're stuck using a grey water loop. But it is the least attractive setup...
What you're describing is closest to "actually fair" I think we can get. A neighbour of someone I know leaves their apartment empty for long periods of time and when they're gone they just shut off their heating completely and leave all of their neighbours to pick up the bill - each apartment has their own heating system but they share walls, floors, and ceilings.
BTW, Japanese bathing is somewhat visible in My Neighbor Totoro, a really cute movie.
Nice concept! Do you have any problems with mold build up?
Bath rooms in smaller apartments, and also in hotels, tend to be, literally, whole-room plastic/resin structures, so it dries easier and if mold appears it's in the plastic surface and easy to get rid of it.
I have a friend with a very big fancy apartment, and his huge bath room is covered mostly in tile and has very good ventilation. The bath even has a waterproof TV so you can watch a movie meanwhile!
It's fun in the winter when you're running humidifiers but forget to turn off your house ventilation and don't understand why you're still so dry.
Do they have Mechanical Ventilation and Heat Recovery (MVHR) or is this more like Aircon? I've recently moved somewhere more humid and I'm looking to get a grip on what other countries do.
That's unexpected.
Looks like 30-50% less efficiency.
This is uncommon in the US, so a bath overflow quickly becomes a significant structural issue.
Basically a spa experience every day.
It's the metal plate usually just below the faucet that looks like it might be useless. But it has an opening underneath to let the overflow water in. These are always sized to handle more water than the faucet can output.
This is basically a non-concern in anything but very, very old, unremodeled bathrooms.
The sinks do as well, but it is more obvious.
I think a lot of European houses have floor drains in the bath, you can basically hose the bathroom down.
More on topic. Outside of the US R290 (propane) heat pumps are common. But illegal in the US because the refrigerant manufacturers control the code bodies. You can have a 20lb propane tank hanging off a BBQ which in normal operation is literally on fire. But you can't have an R290 monoblack cause it's too dangerous.
Unless you live in the artic where it's freezing year round, these things make sense. During the summer they reduce your cooling load and during the winter they are effectively heated by whatever your home heater is. Meaning if it's gas, then they are gas powered. If you have a heat pump outside then it's still pretty efficient. Even in the worst case of a resistive heater you are basically just running a slow resistive heater.
And for the normal ones, at least they are leveraging outside temperature parts of the time while everything else stays at 1 in 1 out.
Most homes in Japan for decades have been designed for Tankless Gas Water Heaters stuck on the side of the building so there is no room indoors for a water tank.
The condenser unit for this literally just looks like the same one as for a regular mini split air conditioner, just a little bit larger.
I have a tankless in my house and I'm not going back... I wish someone made a heat pump tankless water heater (I don't know if that is possible)
I was worried going from living with tankless to a tank that we would run out of water like we did in my parents house as a kid but so far it's just never been a problem. I think it helps that while the physical water capacity of our unit is 370 liters, the internal temperature is 80 C and it uses a thermostatic valve to blend the output, so the "hot water capacity" is more like 500 liters.
So no, not possible. Theoretically you might be able to do it with a stupid enough system of coils and a very ridiculous amount of power, but it wouldn't be efficient or practical.
The tl;dw is that it is significantly slower than a resistive or gas-powered water heater, and lowers the temperature of the room by a few degrees, but nothing major. You have to over-provision them compared to your needs. And they are way bigger.
This was TC being a weirdo. He bought a 120V hot water heater. Had he done a regular 240V water heater the recovery time would be comparable to pure resistive water heaters.
But the takeaway about cooling is important. These things barely chill the room they are in.
I just wish dish washers and dryers were more common in Japanese households. I'm in Okinawa where dryers are a lot more "standard", but dish washers are relatively rare.
truly bizarre
But the sibling comment to this one, where a sink had an overflow, but it was not connected, did not meet code [also 1].
Go figure. There must be some reasoning there, but I'm confused as to what it is.
https://forms.iapmo.org/email_marketing/codespotlight/2018/m...
So if you have old two-prong outlets in your house from back when, those are allowed.
If you replace them with a three-pronged outlet which is ungrounded, that breaks code.
If the three-pronged outlet is a GFCI outlet labeled with NO ELECTRICAL GROUND, that is allowed.