16 ms·

I live in Japan and last year when we moved from an apartment to a house we installed a Mitsubishi EcoCute heat pump water heater which already has these featur

I live in Japan and last year when we moved from an apartment to a house we installed a Mitsubishi EcoCute heat pump water heater which already has these features and is also a CO2 heat pump. 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

koolba 6d ago
> 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. 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”.
- fooqux 6d ago
  > How long do you sit in a bath? The entire point of a bath is to relax and soak in it. Otherwise I'd just take a far more economical shower.
  - ibejoeb 6d ago
    Interesting that that's a feature of the water heater and not the tub. It has to travel through the plumbing all the way round-trip to the heater? You must have isolated recirculation plumbing to deal with the grey water, yeah?
    - pbmonster 6d ago
      Technically, you could also just pull refrigerant lines from the heat pump to the bath tub - you probably already run those to the indoor AC units you have in different rooms anyway - or connect the bath tub to the hot water lines you run to the radiators. Both imply a grey water heat exchanger built into the tub. 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...
      - kwarcode 6d ago
        [dead]
    - kalleboo 6d ago
      Typically Japanese homes are laid out economically so the bath is right where the hot water heater is. In our house from the 70's it's probably not more than meter through the wall to the water heater. Even in apartment buildings, typically each apartment has it's own tankless gas water heater on the outside wall of the building so it's easy to meter usage separately.
      - AngryData 6d ago
        That is what I always see in wet saunas/bathrooms around me. The bathing room is a main feature so things like main plumbing and water heaters are all placed around that to keep it simple. Recirculation additions after that would then be two simple connections off the back of the tub, probably near where the faucet goes.
- kalleboo 6d ago
  > How long do you sit in a bath? 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.
- deleted 6d ago
  [deleted]
- Dennip 6d ago
  Most baths (in the UK at least) have overflows right so the primary risk is just wasting a lot of water?
- bluGill 6d ago
  If I'm in the bath I'm either reading a good book, or talking with my wife (I have a tub big enough for two - takes a lot of water to fill) - either way I'm going to be in it for an hour or two. As the other poster said, if I want to get clean I'll take a quick shower. The tub is nice when my muscles get sore and tight from work.
- komega 6d ago
  > How long do you sit in a bath? 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.
  - gwbas1c 6d ago
    A Japanese bath sounds a lot more like what Americans call a hot tub. BTW, Japanese bathing is somewhat visible in My Neighbor Totoro, a really cute movie.
    - ThrowawayTestr 6d ago
      If you look at a picture of one, they're basically tiny hot tubs.
    - Groxx 6d ago
      In most ways, yes. E.g. you clean yourself before you get in, so the water remains relatively clean after a few people. Unlike a hot tub though it's drained between uses, so it doesn't really have some of the nastier issues that hot tubs can acquire (nor does it need higher chlorine content to mitigate it).
  - cynicalsecurity 6d ago
    > (One at a time!) That's unexpected.
  - fransje26 6d ago
    > A smart reaction! But most baths are also whole-room units, with a floor drain Nice concept! Do you have any problems with mold build up?
- fourneau 6d ago
  Barring some catastrophic overflow clogging + drain clogging or other issue, your house will be fine! Your wallet may not be. 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.
- numpad0 6d ago
  > How long do you sit in a bath? 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.
  - germinalphrase 6d ago
    Do you have a water drain in your bathroom floor? This is uncommon in the US, so a bath overflow quickly becomes a significant structural issue.
    - SoftTalker 6d ago
      Bathroom floor drain is common (might even be a code requirement?) in commercial buildings but not in homes.
    - numpad0 6d ago
      The tub sits in a big shower booth. Other bathroom amenities like sink and washing machines are installed outside the booth. Toilet is usually a separate room entirely. So no problem overflowing water onto the floor since that's how you take a shower.
    - pbhjpbhj 6d ago
      But USA bath tubs have overflows (redirecting water into the drain if the taps are left on), surely?
      - compiler-guy 6d ago
        In the US, any tub made past about 1900 or so has an overflow drain that prevents overfilling. The adoption of such drains not quite contemporaneous with the adoption of indoor plumbing, but very soon after. 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.
- BugsJustFindMe 6d ago
  > How long do you sit in a bath? 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.
  - cassepipe 6d ago
    Reading this comment from an hot european bathtub right now, I've been here for two hours
- kazinator 6d ago
  If you have a delayed start dishwasher or washing machine, you already have that.
- brianaker 6d ago
  While in the US making a bathroom a "wet room" is rare, it can be quite common in other countries. 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.
  - MisterTea 6d ago
    This was my biggest takeaway from Japan in terms of home design - the bathroom design. At a small apartment in Tokyo the "bathroom" was in fact three separate spaces: a nook where the washer and sink lived which opened into the living room, one side of the nook featured the toilet closet, the other, and actual bathroom with tub and shower. This lets three people use the plumbing fixtures - toilet, shower/bath and sink. Though not all of the places I stayed at split the sink and bathroom. 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.
- riffraff 6d ago
  Not OP but I used to sit in a bath for a long time reading, gradually adding the hottest water to keep it at a nice temp. It's been a while tho, but I'm sure there's someone like me out there :)
- sellmesoap 5d ago
  Every bathtub I've met has an overflow drain near the top, although maybe that drain is smaller then the output of my faucet, good thing mine isn't connected to the internet :D, YMMV.
gandreani 6d ago
Holy crap that re-circulation feature is luxurious! 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.
- kalleboo 6d ago
  And this is the builder-grade model we got from the house renovation company. There are higher grade ones with fancier stuff...
- OhNoNotAgain_99 6d ago
  [dead]
- londons_explore 6d ago
  Presumably you need a bath with extra plumbing? What happens when the heat exchanger gets clogged with soap and hair?
- bluGill 6d ago
  Many people have thought about the drain heat exchanger. However drains need to be way oversized for various reasons and so you can't get good contact with the water: it is mostly air in the drain pipes.
- shellfishgene 6d ago
  That does exist. Simple versions just have a large, deep drain with coils the cold water runs through. Fancier ones have a proper heat exchanger next to the shower (requires a pump) or in the basement. Water sanitation rules probably make it non trivial to get a design certified.
  - gandreani 6d ago
    Is the deep drain to diminish the air pockets at the exchange surfaces?
bix6 6d ago
Omg the bath features, my dream!
iso1631 6d ago
In the UK we've had off peak power overnight for decades. My current one is something like 1/3rd of the price of daytime power between 2300 and 0700. 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)
- laurencerowe 6d ago
  Economy 7 and storage heaters. Heat up bricks overnight using cheap rate electricity so they can keep your home warm during the day while you’re out working. In fairness it probably works ok for homes insulated to a much higher standard than most British ones.
SenHeng 6d ago
> 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 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.
- bluGill 6d ago
  I don't see how that is possible. Either way you need the same amount of heat added to the tub. Maybe you save a little because the return pipes are not cooling the water, but otherwise the needed heat should be the same. I personally insulated all my hot water pipes which solves that worry. Though fresh water and letting out the old will clean the water you are soaking in, which may be valuable.
  - SenHeng 6d ago
    The way ecocute works is that it heats water at times when electricity is cheap and stores it in a highly insulated tank. So if you’re having a soak in the evening, it’s cheaper to use the water that is already preheated at cheaper rates and stored, than to reheat it again using the expensive to peak time rates. 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.
- londons_explore 6d ago
  I suspect what you were told is a misunderstanding.
  - deleted 6d ago
    [deleted]
UncleOxidant 6d ago
As an American reading this I feel like we have fallen far behind when it comes to home HVAC (and bath) tech.
- autoexec 6d ago
  Anyone who has used a nice Japanese toilet knows the US is behind in terms of bathroom tech, but personally I'm glad that nothing my bathroom is controlled by app and that I don't have to spend my time worrying about what time of day it is when I want hot water or air conditioning. I hope my power company never decides to start with "surge pricing" so they can hike up my rates any time it's too hot or cold outside.
  - maigret 6d ago
    Solar + batteries is cheaper than ever. Americans are often full preppers and DIY but when we speak about energy autonomy and efficiency they immediately get some weird allergy.
    - rconti 6d ago
      Some of us still believe in market incentives.
    - foobarian 6d ago
      People keep saying this and yet I struggle to find a decent sized house battery that doesn't cost as much as a new car.
      - maigret 6d ago
        What kind of electricity usage do you have? Because a used electric car probably around 20k provides you with easily 50+kwh in car to grid, + you get a working car for free.
    - kvuj 6d ago
      Electricity here in Quebec is dirt cheap, state owned and 100% renewable. Our first 40 kWh per day is 7 cents per kWh which is roughly 0.05 USD. Any calculations I've done made it unfortunately useless to buy solar and instead favoured investing the money in the stock market.
alufers 6d ago
How does cleaning of the heat exchanger work? From my experience with Jaccuzzi-style baths anything that recirculates bathwater gets very nasty very quick and is a nightmare to clean.
- dathinab 6d ago
  in Japan you tend to shower & wash yourself clean _before_ getting into any bath. In the west people don't do it or do it very half asset. And tbh. a lot of places have combined bath/shower so you kinda can't even do it Japanese style nicely. That alone probably will make a huge difference in how often you have to deep clean it.
  - deleted 6d ago
    [deleted]
  - masklinn 6d ago
    > you kinda can't even do it Japanese style nicely. 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.
    - bigstrat2003 6d ago
      Yes. But then those wouldn't be the places which GP was talking about, where the shower head is set up so you stand in the bath tub to take a shower.
      - masklinn 6d ago
        I’ve used a bunch where the shower head is on a hose not fixed to the wall. Usually with a two-way faucet. The biggest issue in the west is the room being wet to start with.
    - dathinab 5d ago
      my point is most _rented apartments_ are not setup like that and do not provide a reasonable path to have 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.
fransje26 6d ago
> 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 Interesting! Is there some sort of filter system you can easily clean out, to avoid any issues?
- greggsy 6d ago
  It’s like human sous vide
sigio 6d ago
In the Netherlands (and the rest of western europe), we have hourly and quarterly energy pricing (opt-in), next to pricing plans that have one or two fixed tariffs during the day/year. 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 https://jeroen.nl/dynamische-energie/stroom/prijzen/vandaag or price-predictions upto a week ahead there's https://wattwanneer.nl https://wattwanneer.nl )
- westurner 3d ago
  Is this what we call "net metering" here in the US? Unfortunately this region only has "buy-all-sell-all", no intraday prices, and and still not enough storage to store solar from peak at noon until evening commute: https://news.ycombinator.com/item?id=45630917 https://news.ycombinator.com/item?id=45630917 A market economist might remark that perhaps that shouldn't be surprising given the lack of intraday rates and the buy-all-sell-all policies. > In the Netherlands (and the rest of western europe), we have hourly and quarterly energy pricing (opt-in), next to pricing plans that have one or two fixed tariffs during the day/year So your policies create incentives for residential customers to become net producers of electricity (with resilient local storage)?
- enobrev 6d ago
  In Chicago, we have an API where we can get pricing updates every 5 minutes. I recently set up my AC (largest power draw) to cut off when the price goes above a certain threshold. 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.
amluto 6d ago
> recirculate the water in the bath through a heat exchanger after you already filled it and got in 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?
2Gkashmiri 5d ago
you dont have a passive solar water heater?

koolba 6d ago

> 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. 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”.

fooqux 6d ago
> How long do you sit in a bath? The entire point of a bath is to relax and soak in it. Otherwise I'd just take a far more economical shower.
- ibejoeb 6d ago
  Interesting that that's a feature of the water heater and not the tub. It has to travel through the plumbing all the way round-trip to the heater? You must have isolated recirculation plumbing to deal with the grey water, yeah?
  - pbmonster 6d ago
    Technically, you could also just pull refrigerant lines from the heat pump to the bath tub - you probably already run those to the indoor AC units you have in different rooms anyway - or connect the bath tub to the hot water lines you run to the radiators. Both imply a grey water heat exchanger built into the tub. 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...
    - kwarcode 6d ago
      [dead]
  - kalleboo 6d ago
    Typically Japanese homes are laid out economically so the bath is right where the hot water heater is. In our house from the 70's it's probably not more than meter through the wall to the water heater. Even in apartment buildings, typically each apartment has it's own tankless gas water heater on the outside wall of the building so it's easy to meter usage separately.
    - AngryData 6d ago
      That is what I always see in wet saunas/bathrooms around me. The bathing room is a main feature so things like main plumbing and water heaters are all placed around that to keep it simple. Recirculation additions after that would then be two simple connections off the back of the tub, probably near where the faucet goes.
kalleboo 6d ago
> How long do you sit in a bath? 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.
deleted 6d ago
[deleted]
Dennip 6d ago
Most baths (in the UK at least) have overflows right so the primary risk is just wasting a lot of water?
bluGill 6d ago
If I'm in the bath I'm either reading a good book, or talking with my wife (I have a tub big enough for two - takes a lot of water to fill) - either way I'm going to be in it for an hour or two. As the other poster said, if I want to get clean I'll take a quick shower. The tub is nice when my muscles get sore and tight from work.
komega 6d ago
> How long do you sit in a bath? 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.
- gwbas1c 6d ago
  A Japanese bath sounds a lot more like what Americans call a hot tub. BTW, Japanese bathing is somewhat visible in My Neighbor Totoro, a really cute movie.
  - ThrowawayTestr 6d ago
    If you look at a picture of one, they're basically tiny hot tubs.
  - Groxx 6d ago
    In most ways, yes. E.g. you clean yourself before you get in, so the water remains relatively clean after a few people. Unlike a hot tub though it's drained between uses, so it doesn't really have some of the nastier issues that hot tubs can acquire (nor does it need higher chlorine content to mitigate it).
- cynicalsecurity 6d ago
  > (One at a time!) That's unexpected.
- fransje26 6d ago
  > A smart reaction! But most baths are also whole-room units, with a floor drain Nice concept! Do you have any problems with mold build up?
fourneau 6d ago
Barring some catastrophic overflow clogging + drain clogging or other issue, your house will be fine! Your wallet may not be. 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.
numpad0 6d ago
> How long do you sit in a bath? 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.
- germinalphrase 6d ago
  Do you have a water drain in your bathroom floor? This is uncommon in the US, so a bath overflow quickly becomes a significant structural issue.
  - SoftTalker 6d ago
    Bathroom floor drain is common (might even be a code requirement?) in commercial buildings but not in homes.
  - numpad0 6d ago
    The tub sits in a big shower booth. Other bathroom amenities like sink and washing machines are installed outside the booth. Toilet is usually a separate room entirely. So no problem overflowing water onto the floor since that's how you take a shower.
  - pbhjpbhj 6d ago
    But USA bath tubs have overflows (redirecting water into the drain if the taps are left on), surely?
    - compiler-guy 6d ago
      In the US, any tub made past about 1900 or so has an overflow drain that prevents overfilling. The adoption of such drains not quite contemporaneous with the adoption of indoor plumbing, but very soon after. 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.
BugsJustFindMe 6d ago
> How long do you sit in a bath? 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.
- cassepipe 6d ago
  Reading this comment from an hot european bathtub right now, I've been here for two hours
kazinator 6d ago
If you have a delayed start dishwasher or washing machine, you already have that.
brianaker 6d ago
While in the US making a bathroom a "wet room" is rare, it can be quite common in other countries. 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.
- MisterTea 6d ago
  This was my biggest takeaway from Japan in terms of home design - the bathroom design. At a small apartment in Tokyo the "bathroom" was in fact three separate spaces: a nook where the washer and sink lived which opened into the living room, one side of the nook featured the toilet closet, the other, and actual bathroom with tub and shower. This lets three people use the plumbing fixtures - toilet, shower/bath and sink. Though not all of the places I stayed at split the sink and bathroom. 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.
riffraff 6d ago
Not OP but I used to sit in a bath for a long time reading, gradually adding the hottest water to keep it at a nice temp. It's been a while tho, but I'm sure there's someone like me out there :)
sellmesoap 5d ago
Every bathtub I've met has an overflow drain near the top, although maybe that drain is smaller then the output of my faucet, good thing mine isn't connected to the internet :D, YMMV.

gandreani 6d ago

Holy crap that re-circulation feature is luxurious! 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.

kalleboo 6d ago
And this is the builder-grade model we got from the house renovation company. There are higher grade ones with fancier stuff...
OhNoNotAgain_99 6d ago
[dead]
londons_explore 6d ago
Presumably you need a bath with extra plumbing? What happens when the heat exchanger gets clogged with soap and hair?
bluGill 6d ago
Many people have thought about the drain heat exchanger. However drains need to be way oversized for various reasons and so you can't get good contact with the water: it is mostly air in the drain pipes.
shellfishgene 6d ago
That does exist. Simple versions just have a large, deep drain with coils the cold water runs through. Fancier ones have a proper heat exchanger next to the shower (requires a pump) or in the basement. Water sanitation rules probably make it non trivial to get a design certified.
- gandreani 6d ago
  Is the deep drain to diminish the air pockets at the exchange surfaces?

bix6 6d ago

Omg the bath features, my dream!

iso1631 6d ago

In the UK we've had off peak power overnight for decades. My current one is something like 1/3rd of the price of daytime power between 2300 and 0700. 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)

laurencerowe 6d ago
Economy 7 and storage heaters. Heat up bricks overnight using cheap rate electricity so they can keep your home warm during the day while you’re out working. In fairness it probably works ok for homes insulated to a much higher standard than most British ones.

SenHeng 6d ago

> 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 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.

bluGill 6d ago
I don't see how that is possible. Either way you need the same amount of heat added to the tub. Maybe you save a little because the return pipes are not cooling the water, but otherwise the needed heat should be the same. I personally insulated all my hot water pipes which solves that worry. Though fresh water and letting out the old will clean the water you are soaking in, which may be valuable.
- SenHeng 6d ago
  The way ecocute works is that it heats water at times when electricity is cheap and stores it in a highly insulated tank. So if you’re having a soak in the evening, it’s cheaper to use the water that is already preheated at cheaper rates and stored, than to reheat it again using the expensive to peak time rates. 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.
londons_explore 6d ago
I suspect what you were told is a misunderstanding.
- deleted 6d ago
  [deleted]

UncleOxidant 6d ago

As an American reading this I feel like we have fallen far behind when it comes to home HVAC (and bath) tech.

autoexec 6d ago
Anyone who has used a nice Japanese toilet knows the US is behind in terms of bathroom tech, but personally I'm glad that nothing my bathroom is controlled by app and that I don't have to spend my time worrying about what time of day it is when I want hot water or air conditioning. I hope my power company never decides to start with "surge pricing" so they can hike up my rates any time it's too hot or cold outside.
- maigret 6d ago
  Solar + batteries is cheaper than ever. Americans are often full preppers and DIY but when we speak about energy autonomy and efficiency they immediately get some weird allergy.
  - rconti 6d ago
    Some of us still believe in market incentives.
  - foobarian 6d ago
    People keep saying this and yet I struggle to find a decent sized house battery that doesn't cost as much as a new car.
    - maigret 6d ago
      What kind of electricity usage do you have? Because a used electric car probably around 20k provides you with easily 50+kwh in car to grid, + you get a working car for free.
  - kvuj 6d ago
    Electricity here in Quebec is dirt cheap, state owned and 100% renewable. Our first 40 kWh per day is 7 cents per kWh which is roughly 0.05 USD. Any calculations I've done made it unfortunately useless to buy solar and instead favoured investing the money in the stock market.

alufers 6d ago

How does cleaning of the heat exchanger work? From my experience with Jaccuzzi-style baths anything that recirculates bathwater gets very nasty very quick and is a nightmare to clean.

dathinab 6d ago
in Japan you tend to shower & wash yourself clean _before_ getting into any bath. In the west people don't do it or do it very half asset. And tbh. a lot of places have combined bath/shower so you kinda can't even do it Japanese style nicely. That alone probably will make a huge difference in how often you have to deep clean it.
- deleted 6d ago
  [deleted]
- masklinn 6d ago
  > you kinda can't even do it Japanese style nicely. 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.
  - bigstrat2003 6d ago
    Yes. But then those wouldn't be the places which GP was talking about, where the shower head is set up so you stand in the bath tub to take a shower.
    - masklinn 6d ago
      I’ve used a bunch where the shower head is on a hose not fixed to the wall. Usually with a two-way faucet. The biggest issue in the west is the room being wet to start with.
  - dathinab 5d ago
    my point is most _rented apartments_ are not setup like that and do not provide a reasonable path to have 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.

fransje26 6d ago

> 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 Interesting! Is there some sort of filter system you can easily clean out, to avoid any issues?

greggsy 6d ago
It’s like human sous vide

sigio 6d ago

In the Netherlands (and the rest of western europe), we have hourly and quarterly energy pricing (opt-in), next to pricing plans that have one or two fixed tariffs during the day/year. 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 https://jeroen.nl/dynamische-energie/stroom/prijzen/vandaag or price-predictions upto a week ahead there's https://wattwanneer.nl https://wattwanneer.nl )

westurner 3d ago
Is this what we call "net metering" here in the US? Unfortunately this region only has "buy-all-sell-all", no intraday prices, and and still not enough storage to store solar from peak at noon until evening commute: https://news.ycombinator.com/item?id=45630917 https://news.ycombinator.com/item?id=45630917 A market economist might remark that perhaps that shouldn't be surprising given the lack of intraday rates and the buy-all-sell-all policies. > In the Netherlands (and the rest of western europe), we have hourly and quarterly energy pricing (opt-in), next to pricing plans that have one or two fixed tariffs during the day/year So your policies create incentives for residential customers to become net producers of electricity (with resilient local storage)?
enobrev 6d ago
In Chicago, we have an API where we can get pricing updates every 5 minutes. I recently set up my AC (largest power draw) to cut off when the price goes above a certain threshold. 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.

amluto 6d ago

> recirculate the water in the bath through a heat exchanger after you already filled it and got in 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?

2Gkashmiri 5d ago

you dont have a passive solar water heater?