Yet another Hacker News

Hitachi launches CO2 heat pump water heaters with solar-friendly tariff controls

51 points thelastgallon 22 hours ago 38 comments

throw0101d 22 hours ago | parent

CO2 as a refrigerant isn't new:

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).

Lwerewolf 54 minutes ago | parent

There are resident systems, and they're of exactly the type listed in the article (i.e. water heaters). Residential... area heating pumps, so to say, are moving towards propane (afaik). I've been looking into getting a propane monoblock air-to-water pump, with an antifreeze loop towards an indoors heat exchanger / water tank.

adaml_623 22 minutes ago | parent

Trends for new refrigerant depends on country... some to R-454B, and some to Propane, doesn't seem like C02 is very common which is a pity because I love the idea of a non-toxic non-flammable super cheap refrigerant.

This is for the Japanese market so perhaps the cons of the C02 systems are outweighed by the safety aspects.

alex_duf 41 minutes ago | parent

It's useful though, as I think (correct me if I'm wrong) that the gases generally used in HVAC tends to have much worse warming effect than co2 per volume.

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

PunchyHamster 35 minutes ago | parent

If it is outside you can just use propane as refrigerant. Low warming value and it leaking to outside doesn't matter, not gonna catch on fire.

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

jabl 9 minutes ago | parent

I believe there are propane using split AC systems where propane is used only in the outside unit. The outside unit has a heat exchanger transferring the heat to some glycol-water solution which is what then circulates through the inside unit.

moepstar 32 minutes ago | parent

Yes, that dangerous effect is indexed as GWP - global warming potential.

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.

jabl 11 minutes ago | parent

Per the latest IPCC report, GWP of propane is estimated to be 0.02, previously it was estimated to be around 3.

raisedbyninjas 1 minute ago | parent

R32 is on the safe side of common refrigerants. R410 just started its phase out in the US and carries a GWP of >2000.

callmemclovin 25 minutes ago | parent

That's true, old school refrigerants like R-12 are awful. The downside of modern replacement refrigerants are high operating pressure (>100 bar for R-744/CO2) or high flammability for natural refrigerants like R-290 (Propane) and R-600a (Isobutane). But these are solely engineering problems, and I'm happy to know that my R-290 heat pumps at home (Panasonic L & Wolf FHS) and A/C (Midea Xtreme Save Blue) aren't awful to the environment, once they reach EOL.

PowerElectronix 14 minutes ago | parent

Yeah, ammonia can also be used, it's, IIRC, more efficient to use it and a bit safer because you don't high pressure, buuut enough ammonia in the air will suffocate you.

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.

codeduck 3 minutes ago | parent

I feel like potential suffocation is not what I'd be most concerned about if I were in an atmosphere with high concentrations of gaseous ammonia.

arpinum 32 minutes ago | parent

CO2 does better with large temp deltas, like hot water tanks. Radiators don't produce large deltas - the inlet to outlet diff is typically under 10 degrees. But they run at higher pressures, making the manufacturing more expensive.

objektif 58 minutes ago | parent

“Hitachi has not yet disclosed full efficiency specifications for the two new models. Their predecessors, the BHP-FV37WD and BHP-FV46WD, have annual hot-water and heat-retention efficiency ratings under Japanese Industrial Standards (JIS) of 4.2 and 4.1, respectively.”

What does this mean?

alex_duf 50 minutes ago | parent

If I'm not mistaken, it means 1kWh of electricity moves 4.1kWh of heat into your hot water tank. Heat pumps are amazing.

PunchyHamster 34 minutes ago | parent

well, in case of water heater it moves it from your room to the water.

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

slau 25 minutes ago | parent

Technology Connections has recently published an in-depth piece of the advantages and disadvantages of in-room heat-pump water heaters [1].

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.

[1]: https://youtu.be/F_7B2shTPPU

cogman10 12 minutes ago | parent

> significantly slower than a resistive or gas-powered water heater

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.

ZeroGravitas 18 minutes ago | parent

This specific model appears to be a split system that has an external unit to extract the heat from the outside air.

Dlemlo 15 minutes ago | parent

The one mentioned in the article has an outside unit.

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.

cogman10 2 minutes ago | parent

Technically your refrigerator heats up your kitchen in the same fashion adding extra work for your AC to compensate.

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 of it's gas, then they are has 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.

onedognight 42 minutes ago | parent

I believe that for every joule of electricity used, 4 or 4.1 joules are pumped from the environment into the water. This is contrast to conventional water heaters which are bounded by an efficiency of 1, where, for example, burning gas directly heats the water with some heat leaking into the environment instead of the water.

elgertam 54 minutes ago | parent

> Some Japanese utilities have introduced tariffs designed to encourage daytime water heating as growing volumes of solar generation enter the grid. [Emphasis added.]

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.

Aboutplants 42 minutes ago | parent

US utilities also have Tariffs. It’s the statement of how the utility operates and charges users for service. Anytime a utility needs to adjust costs/rates, they need to file a Rate Case with the public utility commissions, and resulting in changes to the Tariff.

_joel 40 minutes ago | parent

I've seen 'tariff' used a fair amount here in the UK on price lists (taxi etc)

world2vec 16 minutes ago | parent

Same in Portugal: a "tarifa" can mean a price charged for a rendered service or a tax on imported products.

koito17 39 minutes ago | parent

The Japanese word used in the context of price lists would be something like 料金表 or 料金メニュー.

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.

myrmidon 28 minutes ago | parent

It's an arab loan word for ~"price list" (originally strongly suggesting an import-duty-like meaning).

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).

bayindirh 17 minutes ago | parent

Tarif/Tarife means price list of anything. Your barber, restaurant, taxi service, hospital can have one. tariff as in the meaning of custom tax is a very narrow meaning considering the usage of the word in general (but that's OK).

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.

egeozcan 24 minutes ago | parent

I've read that the word is borrowed from Arabic, meaning notification, and I think at first it was price notifications and then people started using it to mean that the prices were bound to some schedule or condition.

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.

thevillagechief 13 minutes ago | parent

Big fan of Etymology as well, mostly because my brain seemingly needs to understand the origin/history of terms to feel like I've fully grasped concepts.

trescenzi 16 minutes ago | parent

It’s confusingly super common in the US for that usage when talking about trucking and shipping. Where of course the other kind of tariffs are also common.

Neil44 10 minutes ago | parent

In the UK you can get agile tarrifs now where the price changes through the day according to demand and supply predictions. There's an API you can use to control chargers, heaters, bitcoin miners etc.

EspadaV9 36 minutes ago | parent

I'm actually in need of a new hot water tank and have been looking for a heat pump one. Wonder if these will be available in Australia, and how they compare to the current range.

XorNot 23 minutes ago | parent

I have a heat pump hot water unit in Australia - Sanden: https://www.sanden-hot-water.com.au/

CO2 refrigerant as well.

boringg 16 minutes ago | parent

Japan is so far ahead the rest of the world for quality and innovative heat pumps. Quiet, robust, high efficiency in cold climates. I wish they could bring the prices down though.

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.

PaulHoule 7 minutes ago | parent

Not everything from China is crap.

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...

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.

post_break 3 minutes ago | parent

China figured out how to make thermal imaging sensors as well. Why would you buy a $4,000 Flir with less resolution when you can get a $400 Topdon. What's funny is now it appears Flir has cut their prices dramatically to compete.