the price over a mass amount of units (say 100,000 units)
This almost made me laugh out loud. Exactly how many kettles does the author think sells each year? Multiply by models and again by manufacturers, and you're talking millions of kettles. Even if you consider that one model will last multiple years, manufacturers don't buy supply batches that last for years. Some industries go in the extreme other direction - the local car industry got its stock-on-shelf lifetime down to 48 minutes from part arriving to part being screwed into car.
Similarly, retail markup is generally 20-50% of the final cost. If you think this is too high (it really isn't) then I suggest you use your new formula to undercut the existing market and disrupt away. Other significant costs are transport and wholesalers (who aren't always the manufacturers). Kettles are bulky items that consume a lot of space in storage and transport. On top of all this, every party involved in the transaction is entitled to make some profit, and not just work for costs. There's also regulatory compliance, things like the CE mark.
Looking at an item and stating that the price shouldn't be more than parts + amortised kickback to the designers is naievity, plain and simple.
Say 10% of American households and 80% of British households buy electric tea kettles that last exactly 10 years each.
That's 10 million total market in the US (100 x .1) and about 16 million in the UK (~20 x .8).
So 26 million total market with a level 1/10th per year or 2.6 million kettles per year. At 100k run per year per manufacturer, the market can then support 26 different models easily.
On the second point, It seemed that he was adding the 2x retail markup into his figures. If you'd followed the link on amazon, you'd see that $90 was market down from about $200.
Sometimes it's best to ask "what would you have to believe for this to be right" before you tear into someone for faulty analysis. All of his number easily pass my smoke tests.
Coming from the UK I can't believe that only 80% of households own an electric kettle. The idea of going to someone's house and not finding a kettle seems genuinely ludicrous. Not just houses - almost every break room of every business will have one.
Of course, they cost quite a bit less on average in the UK.
Maybe the other 20% own non-electric kettles, like us, or have one-touch boiling water systems, like my parents.
When our last electric kettle blew up 3-4 years ago, we decided to go with a good, old fashioned metal kettle that we use on the hob. Works well, doesn't ever break, and even makes it a bit more of an 'event' to put the kettle on as you get all the boiling sounds, the whistle going off, etc.
My parents, on the other hand, have a thing that produces boiling water at the touch a button so they just use that to dump water into their mugs instead.
Either way, an electric kettle is far from the only solution .
You mean those old fashioned kettles that are little more than a pot that you put on the hob? Nope. No way do 20% of UK houses have that sort of old fashioned system. That's like claiming 20% of UK houses still have outhouses and don't have indoor toilets.
It always amazes me how the ridiculuous old fashioned non-electric kettles are still popular in USA.
I did also mention boiling water systems like one touch "Quick Cup" type jugs or even boiling water taps as are popular in posher houses now.
Nonetheless, I don't find it so farfetched. We are a wellish-to-do gadget heavy household and we're content with a gas kettle. Other people continue to drive manual transmission cars. Some people even use Internet Explorer! It's a funny old world.
> It always amazes me how the ridiculuous old fashioned non-electric kettles are still popular in USA.
One thing that I find genuinely amazing is that power-companies can spot when there are commercial-breaks in TV programs by people in the country making tea en masse:
Not only can they see the spike, they have to plan for it. I've heard for some popular programmes/events (like a sports event or popular episode), they'll employ someone to watch the TV show and press a button the second the adverts come on, to turn on the power generators that can spin up quickly. There's a power generator that can come fully into operation in 12 seconds[1]
Well here's one data point: my building includes gas in the rent, so there's no incentive for me to buy an expensive and costly to run electric kettle when a stovetop model can boil an unlimited amount of water for zero marginal cost.
(I'm originally from the UK, but I adapted pretty quickly when I moved to the US and saw the price of electric kettles).
Wait, a kettle[1] that you put on the stove and whistles when it's boiling isn't the standard in the UK?
It's what I use for preparing hot water, and I have no issue with it. That's when I want tea or french-press coffee [2]. Sometimes I use an electric percolator[3] for coffee, and what a cup it can make!
I've seen precisely one stove-top kettle in my life, here in the UK: My grandmother owned one before she died, but she spent most of her life on a farm with outdoor toilets and no electricity, and never really adapted from that mindset.
Having said that I've bought only two kettles in my life, once in 1998 when I bought my first flat and realized I didn't own one - all prior rental properties came with one - and one last year when that died.
I remember spending far too much time picking up kettles in John Lewis, and other "fancy" stores, because I knew I'd be using it multiple times a day for many years and wanted something that looked and felt nice.
Drinking tea in the UK isn't about the fun of the kettle. It's a matter of necessity and the whole process is utilitarian. An efficient and predictable water boiler is what is needed, not a 'fun' tea making ceremony. The English largely drink the fannings of tea leaves (poorest quality) it's not about ceremony, fun, or quality, believe me.
We only drink tea when people visit, so the kettle does play a role. Being gas, it takes longer to boil, giving a nice period of often tea-related small talk before it's shrieking for mercy. If one is in an office or one drinks tea because one's addicted to it then yes, the kettle would be more of an inconvenience, but not everyone lives such fast, non ceremonial lives.
It seems inconceivable to me that a US house might not have a microwave (even unfurnished apartments I rented from slumlords in college came with microwaves), but apparently many do not: http://www.eia.gov/emeu/recs/appliances/appliances.html
No. Microwaves are a general cooking thing, and relatively new. Not considered necessary. Tea, in the UK, is so ingrained in the culture, and has been around so long, that kettles are almost like cutlery. I can't imagine a house or business in the UK without one. Hell, you even find kettles in vans out on site. Where there is a Brit, with in about 20m, you'll find a kettle, and a tea bag.
The only exception to that could well be from recent immigrants. They may not be in to tea in the same way, and may not be so wedded to the kettle. Even then, one British thing immigrants quickly pick up, possibly to help integrate, its drinking tea.
In short, dont mess with the British and our tea.
Oh, BTW.
Im British, I can't stand tea. Nasty foul bitter bile. Who the hell likes this stuff? Surely only sadists actually like tea? I like coffee.....
I don't have a microwave. The only use I'd have for one is heating the occasional ready meal for my child, or heating milk for drinks. These are rare so I haven't bothered buying one. I have a fridge but it's not plugged in.
Interestingly I live in the UK and have neither a microwave nor an electric kettle. Incidentally, I am technically an immigrant (from the US), though not with the connotations of what I assume you were envisioning.
"I own a house without a microwave, ask me anything”?
Seriously, though: never saw the point. I do all my cooking from scratch, and heat up leftovers on the stove. Once every few months I find myself doing something where it would be more convenient to have a microwave, but it’s no more often than I find myself wishing I had a sous-vide cooker or a bread machine or electric kettle or any number of other kitchen gadgets. We have a smallish kitchen, and I’d rather have more counter space to work on when I’m cooking.
Thanks for mentioning Sous Vide. I found it interesting that a precisely temp controlled waterbath product only costs a little more than the crude kettles mentioned in the article, and the internet is full of folks who put great effort into creating homemade $40 sous vide rigs.
Also despite what the article claims, water doesn't boil at one temperature, if you program a PID or whatever to keep on firing until the water hits 100C you'll be in for a bit of a surprise in Denver or some mountain towns which are much higher than Denver. I know Big Sky MT is about 9000 ft ASL, water boils at 190F or so.
I guess I'd ask how you got a house without a microwave. I've never lived without a microwave, but I have never purchased a microwave either.
An oven, a microwave, and a fridge are the three appliances I have been able to count on always being present when I move in somewhere. Typically the microwave is build into the cabinetry.
Apparently the previous owner didn’t feel the need to have one either. Note that we are discussing a house that was rebuilt from a barn in 1938 (no one really knows how old the barn was at the time). There are no kitchen cabinets into which a microwave might be built, just open shelves, which I find quite satisfactory.
When I redo the kitchen, I’ll add a range hood, but the next owner will also be buying a house without a microwave.
I think it's a regional thing. Every house I have owned came with the washer, dryer, fridge and stove. Even after I substantially upgraded the stoves in my first two houses, I left them there when I moved. Those houses were built in the 1950's and 1980's. Only my current house, built in the early 2000's came with a microwave.
OTOH, I'm told it's common in other parts of the country (I'm in the upper Midwest) to take major appliances when you move.
Speaking as someone with a commercial-grade sous-vide bath and variable-temperature PID-controlled pouring kettle sitting on his worktop, a microwave is also a useful gadget even for high-end cookery.
It's one of the best ways to cook many green vegetables, for example, and also makes remarkably good poached eggs:
It’s not that I don’t think they’re useful; rather that the marginal utility (for us) of having one isn’t worth the kitchen space that it would cost us. Once every few months I wish we had one, but once every few months I wish I had lots of things. I try not to make a habit of rushing out to buy them.
Heating up a stove takes considerably more energy than using a microwave.
On my microwave, it takes about 96,000 joules (800W x 2') to heat up a plate with leftovers, while doing it on my oven it takes around 432,000J (1800W * 4').
I was pulling reasonable numbers out of the air to do an order of magnitude/what would you have to believe analysis.
It's unclear from that article what "ownership" means, given that a kettle is a household-level item, I'm not sure if it would matter if you did your survey as "do you own a kettle" or "is there a kettle in your house" -- they should sum up to about the same percentage. Maybe a smaller percentage of the population would say they own a kettle than would say they have one in their house due to different interpretations of what it means to "own" something. I'd expect those differences to be within the margin of error of most surveys.
Not to mention work places. If someone doesn't own a kettle at home, but there is a kettle at work that they use to drink tea, then they essentially are part of the UK kettle-culture.
Yeah. In fact, my current kettle cost £2.99. That was 6 ish months ago.
I buy them, and treat them as throwaway. They seem to last as long as £30 ish kettles, so why bother spending more? My cheapo ones last about a year, then I just get a new one. Awful for the environment, but there you go.
For the sake of the previous argument, however, this hardly matters. If the fraction is 100%, then 30 models of kettles can be supported at 100k/year. This is an order of magnitude argument, not a precise census.
Do a google image search on 'kettle' and you'll see that 26 is a laughably small number for the amount of available models.
Strangely, almost all of them are pictured with their spout pointing to the left. It's a bit like a Where's Wally, trying to find one oriented for the left-handers amongst us.
More than 80% of households have a kettle in the UK, I would say 99%. That doesn't count businesses, shops or other places that will certainly also have a kettle.
I worked at a company where they took away our kettle from the office kitchen. (They had just bought a wall heater that produced "quite hot" water, and thought that it would be safer if we just used that.)
I have an electrict kettle and not once though of it as a "tea making device". There are dozens of reasons I might need boiling water and it's most often used for making coffee.
Another good use is dual-core boiling. When I need boiling water for cooking, I put some water in a pot and turn on the stove. But I also put water in my 2 kW electric kettle and will have boilng water within a few minutes.
Good point. I've done this in the past (i.e. back when I was at university) - speed up cooking ramen noodles (or "super noodles") by pouring a boiled kettle into the hot pan.
But these days my kettle is almost solely used as a stand-by "tea making device" :)
It's not even really about our love of tea. I think it's mainly about the US power standard being too low voltage to deliver enough power to boil water in an acceptable time.
While my electric kettle here is only 1kW compared to a standard 3kW in the UK, how else should one boil water for tea? It's still as fast as heating on a hob.
> 10% of American households [...] buy electric tea kettles
No way. I've never seen an electric tea kettle. Tea kettles, sure; but not electric ones. I don't believe anywhere near 10% of US households have one.
We've got plenty of bread machines, waffle irons, electric skillets, toaster ovens, crock pots, and every possible variety of coffee maker, espresso machines, rice cookers, etc. So we're not adverse to electric appliances.
Myself, I've got a stovetop kettle that I never use. If I want tea, I heat water in the microwave.
I thought that markup was implicitly accepted in blog. I of course do not think that the price should be just the cost of the parts. In fact, I did mention that the fact that both $10 kettles and $39 kettles exist implies that there is some form of price discrimination. The difference in price is the additional markup that the manufacturer can get away with. As I mentioned, my marginal utility does not increase with the markup - a $39 kettle gives me the same utility as a $10 kettle.
As for 100,000 units, yeah, that was probably a mistake. Australia only has 22 million people. No idea why I arbitrarily picked 100,000.
Yeah, I read through in more detail and saw that lurking towards the end. Just came back to edit, perhaps delete the comment but it's already replied-to. :)
The costings at the end are off. Testing is much less that $5/unit for these kind of things, for example. Usually you'll have a common testbench across all products - it'll be much lower per unit, and not tied to a particular model. Also, retailers aren't the only ones in the pricing process - as I say above, wholesalers/distributors and transport also get figured into the cost. It all adds up. Marketing costs are mostly borne by the retailer portion of the price, as the wholesale channel marketing is much more limited and cost-effective (no tv or radio spots, print one catalogue and you're fine for a quarter/year, run a more niche website only for retailers, etc)
The Australia-limited market thing is less of an issue - a kettle will have a market wider than this. But kettles generally last a long time, and there are hundreds of models out there. Though to honest, after a friend's horror story of one day finding a cockroach in her kettle that had been boiled white, I'm much keener on glass kettles now...
Same utility? Not if you fear your $10 plastic kettle so much that, after a single circuit-breaker throw, you have to discard it!
Never mind the $39 kettle. Totaled over ten years, the $150 kettle's seemingly-tiny advantages in reliability, capacity, features, and style over the $10 kettle can be worth way more than its $140 price premium.
Do you have a source for the part about 48mins from part arrival to installation? I find that data point fascinating and would like to learn more about how this is pulled off.
> "The kettle had caused the trip. It was no longer safe to use the kettle"
> You know enough to start designing a temp. controlled kettle, and yet you overlooked the simple (and most likely) possibility that the kettle was on the same circuit with another high draw appliance (hair dryer, electric heater, etc.) and the combination of the two resulted in the trip from overload. And that there was nothing in fact wrong with the kettle at all.
We sometimes forget that our hacker minds can be a weakness :)
RCDs are quite expensive, so its common in the UK for a single RCD to cover several circuits. The most common configuration is to have two RCDs each of which cover half of the circuits. Here's a typical consumer unit...
RCDs detect the slightest earth leak, so they are far more likely to trip than the MCB or the fuse on the plug, which only detect a sustained over-current.
An over current situation would trip the branch. A grounding issue would trip the main switch. If water came into the electric circuit causing a grounding of the current, then the main switch would trip. Nothing wrong with the house wiring.
> A grounding issue would trip the main switch. If water came into the electric circuit causing a grounding of the current, then the main switch would trip.
No it wouldn't.
You could stick the bare wires of a branch circuit in water and it wouldn't trip the main breaker.
The main breaker will trip if there is a short inside the panel (which is all but impossible unless you are working on it live - which is sometimes done). Or if you used so much electricity you simply overloaded it, but if you did that you have the wrong panel for your house (or you are running some crazy equipment - arc furnace, maybe).
Main breakers in the UK are often RCDs, which do in fact trip in the case of grounding issues. The main breaker usually feeds into several circuit breakers.
Generally the wiring goes: mains input -> 1 or more RCDs -> several circuit breakers -> several outlets -> fuse in plug -> appliance.
So a grounding fault can take out many circuits, and many-lots of sockets.
I'm only going on our panel, which is perhaps slightly non-standard due to another UK electricity quirk [1], but was done by an electrician last year so is up to regulations at least.
It has a split in the bus, so there are two RCDs, one on the left with a couple of breakers and one on the right with the rest of the breakers, and a separator in the middle.
Like:
supply in -> R-B-B | B-B-B-B-B-R <- supply in
C R R | R-R R R R C
neutral -> D-K-K | K-K-K-K-K-D <- neutral
[1] The quirk of our board is that the left hand breaker is driven by a separate supply cable from the meter, which is only turned on between midnight and 7am. In this way, we get cheaper electricity at night which is used for storage heaters and immersion water heater. However, we no longer have the storage heaters, so it doesn't really make sense. This set up is called Economy 7 (http://en.wikipedia.org/wiki/Economy_7).
Also, @alextingle, I didn't know that you were meant to have two separate circuits, although that makes sense. Lots of things are required to be RCD protected in the UK, so as you say, it makes sense just to put everything behind an RCD. We don't get any nuisance trips, which I attribute to a generally higher standard of wiring, earthing etc. in the UK, although that could just be jingoism :) (I did once live in the US and some of the literally fraying wiring connected to two pin sockets with no earthing in the house I lived in scared me.)
The regs in the UK say that (pretty much) every circuit must be RCD protected. But they also say that you can't use a single RCD to protect everything, because you might need power to fix whatever has tripped the RCD.
RCDs are expensive, so the most common solution is to have two RCDs, each protecting half of the circuits.
Anecdotal, but I've had an one RCD installed and have only seen it trip once in about 15 years, incidentally when my old kettle broke (I could reproduce it instantly by turning the kettle on).
Newer installations will often have an the RCD integrated with the regular circuit breakers, so you get one for each branch (as well as one the covers the entire installation).
We typically have a ring circuit each for upstairs plugs, downstairs plugs, upstairs lights, downstairs lights, and then perhaps some special purpose ones - oven, smoke alarms. There's a main breaker for the house, then RCDs for each circuit. Each appliance has a fuse in the plug, and it's not uncommon for the appliance itself to have a fuse in its body.
Of course, if you buy something from the store and it trips your RCD you know it's got a fault so you return it. And if something old starts tripping your RCD you know it's developed a fault, and you fix it or replace it.
Aaah the things you learn on hacker news. I grew up in Australia, and had a trip in the UK about 12 months ago on a broken dishwasher that took out the whole house. I'd brought an electrician in (good guy but poor English) and he said it was fine. I'd kept an open curiosity about why it had behaved that way.
Errr, short-circuiting to ground will cause a RCD to trip immediately - that's what they're there for. You will generally have one RCD on the entire fuse board, and then individual circuit breakers for each branch.
If that's really how they do that - one RCD for a bunch of circuits then I have to retract my words, a ground fault would cause a whole bunch of circuits to lose power.
It seems crazy to me, but if they do that, then they do that.
but if you did that you have the wrong panel for your house
Wrong is relative: here in Portugal we pay a fixed monthly fee that is proportional to the maximum load. Having the "right" panel may cost you more even if you use less electricity, so many people choose to carefully manage their loads instead.
> "The kettle had caused the trip. It was no longer safe to use the kettle"
If the kettle still works, then problem solved.
If the ($10) kettle is broken, then I'm going to say that it's entirely possible to consider that quality of components, design, and build may account for the difference between a $10 and a $40 kettle.
I often end up spending more on something if I have reasonable evidence it will last longer and/or perform better. And I don't write long articles about how I resent spending the "extra" money.
My house had residual current devices in the main circuit board (like the bathroom socket, only centralised). That meant that when devices such as the toaster, kettle, dishwasher and exterior lights developed ground faults, they would take out half the house.
It would lead to much fun as we reset the RCD and then tried each appliance to figure out which one was faulty.
Bear in mind that the price of insurance and UL certification is also built into these devices. Heat, huge amounts of electricity, water, hands: lots of liability.
Is PID control all that expensive? Aren't you talking about a microcontroller, a thermocouple, and a relay?
I was surprised he didn't take these into account. Not to mention quality control, or accounting for market fluctuations in price and manufacturing costs. The price is calculated to be a reasonable bet to pay for periods of really high costs from profits in periods of low costs.
Quality control in a typical product is really a bigger deal than most hackers think. He didn't account for the fact that if you go to china or hong kong and contract a manufacturing organisation to build your kettle, it's very likely you'll get your first shipment, coming in on your boat or plane and half the kettles are dead or defective or dangerous on arrival. There's nothing to do with those but throw them out, or maybe sell them back over to india for recycling, and the cost of those lost sales is built into the price of the not defective kettles.
The maths here assumes you have no shipping costs and no defective products, no manufacturing problems and no price fluctuations. Doesn't seem very realistic.
QC is tabulated under "various manufacturing costs". And yes, you are correct, it doesn't have shipping and dead goods costs. But I still think it's entirely serviceable as a back-of-envelope calculations
I take your point and it's a good one. I Think probably a pitfall is when you never go beyond the level of detail and research of your back of envelope calculation when, say, setting up a kickstarter. Manufacturing has a lot of pitfalls and it is very challenging, especially for electronics, to account for all the things that can go wrong, or all the hidden costs, or the peculiarities of retail infrastructure, supply chains, and retail, if you've never done it before. Not to discourage anyone from trying, but I think this is where a lot of crowdfunded projects can fail.
I once worked on a device that needed UL certification. It was $50,000 per test cycle, so the motivation was there to get your product right before submitting it.
I've never done a PID from scratch, but a friend of mine did for a home espresso setup. I'm suggesting, instead of pricing a PID part, you price the components of a PID. I think the SS relay might be the most expensive part there.
The espresso machine kits traditionally use industrial PID controllers from Fuji and the like, which (did and still do) cost about $200. It looks like there are lots of nice $35 options now... neat.
As your comment above says, the PID loop is probably just an MCU, sensor (for boiling water a diode sensor is probably fine and cheaper than compensating a thermocouple), and a relay and those are relatively inexpensive components.
However, a bimetallic strip rated to switch the current directly is likely an order of magnitude cheaper.
Last time I bought a PID I paid $12 +shipping for a no-name Chinese one. And that was with a case, display and controls. If I just wanted the core components, I think they where about $5.
Why does the author seem to think that a digital solution is required for control over temperature?
The bimetallic approach can be extended to select temperature. An analogue dial can adjust the switch cutoff position (or alternatively, the starting angle of the bimetallic strip) with a screw. All you'd need to do is calibrate the dial, and the added cost shouldn't be more than 50 US cents on the end retail price.
IMO the reason a "good" kettle costs $90+ is because there isn't enough demand to create enough competition and support enough production to amortize the fixed costs. It's essentially a market broken apart into two of Porter's three fundamental strategies, cost leadership and differentiation. The cheapest kettles would be uncompetitive with a temperature selector even if it added only pennies, while the differentiated kettles have specific features for smaller, less cost sensitive markets. Most people simply don't need temperature selection.
I believe the reason he's going for a PID is the ability to reach the target temperature without overshooting. A PID would gradually reduce the power to the heating element as the temperature get closer to the target.
That said, the adjustable bimetallic solution is certain worth a try, it might just work good enough and be far cheaper and much more reliable in the long run.
I don't think he can gradually control the power, just turn it on and off. A thyristor or something for kilowatts of power would be expensive. This makes a PID controller excessive: just heat until it reaches the target temperature and then turn it off. Turn it on again when the temperature has dropped a couple degrees if you want it to keep a temperature.
I do not know about pricing, but they're widely used for espresso machines. That said, my point was merely that it allows for a much more precise control of the temperature - not whether or not it was economical feasible or provided enough value for the money.
Digital thermostats work on electrical resistance which is more accurate than bimetallic thermostats. Also bimetallic thermostats basically only switch at one temperature whereas most digital thermostats can handle a range. If you intend on using a kettle for both coffee and tea, that range is desired since the ideal temperatures between coffee and tea is quite significant.
Pop-disc bimetallic thermostats switch at only one temperature, but the property of bimetallic expansion is in no way limited to switching at a single cutoff point.
I'd be willing to make a large bet that a majority of people who brew both coffee and tea do so using boiling water or close to it. Black tea (breakfast tea) is best made with freshly boiled water, while I find coffee made with anything below 90C to be too weak - I generally use water made shortly off the boil when I'm using an Aeropress.
I have zero doubt digital thermostats are more accurate. That wasn't the point.
Thermocouple, RTD, Bi-metallic strip/coil, Silicon Bandgap, Thermistor, and I'm sure there are a few common types that have slipped my mind. Your statements are a gross over-simplification.
Your electric kettle almost certainly uses a thermostat patented by John Taylor [1], who made his fortune with the things. Effectively, your kettle helped pay for the wonderful Corpus Clock [2] - 'the strangest clock in the world' :)
People here are forgetting that you can buy a fully functioning tablet on a retail shelf for less than the cost of a temperature controlled kettle. You can buy a tablet AND a conventional kettle for less than the cost of the temperature controlled kettle. Tablet makers have to deal with QC and retail markup and all of the other things mentioned in this thread as possible drivers of the price so I don't find many of the explanations convincing.
In reality, it's likely that either a) these things are being sold at massive profit margins or b) they're being produced very inefficiently with lots of waste in the production process.
I think a lot of cheap tablets are loss leaders, and the manufacturers don't make any profit (or even lose money) and hope to make more money by bringing them into their retail stores (eg Tesco, Walmart tabs) or on accessories.
That said, I think the kettle thing is mostly a). Companies will price things highly because they've found that people will pay that much, I reckon it's as simple as that.
This is not correct. The boiling point of water is a function of atmospheric pressure [1]. Weather changes the atmospheric pressure by up to 50mbar, which translates to a couple degrees of variation in the boiling point.
The pressure variation due to height is even more severe [2]. At an elevation of 3000m the atmospheric pressure is typically only 700mbar, which means that water boils at 90 degrees.
How does the basic bimetallic strip know the outside pressure and the boiling-point-curve of water so that is knows when to stop the kettle?
I don't think it knows anything about that. Instead I assume once the water starts boiling, the bubbling steam-"padding" around the heating element lowers the heat transfer rate from the heating element to the liquid. This means that the heating element will quickly get a lot hotter until it reaches the threshold temperature of the bimetallic switch.
Thermodynamics was never my favourite subject, but I suspect what happens is that the water boiling at the lower temperature created a higher pressure within the kettle (hence the screaming noise as pressure escapes the small nozzle), allowing the water to heat up to 100degC, and also the bimetallic strip.
Somebody answered this elsewhere, there is a vent that directs steam past the strip. So it isn't heated directly by the water in the kettle, but by the steam that is given off after it boils.
Interesting. I was also wondering about this; how the kettle knows what the boiling point is, since it cannot just measure temperature, because it would boil out the water in the mountains.
I thought there is electronics which simply detects not only absolute temperature, but also change. Once the temperature stops changing and is around 100 degrees, it will stop.
I read the article and most of the comments and I still can't figure out why on earth you would care how hot your teawater is, beyond "boiling"/"not yet boiling." All my life I have made tea with a ~$10 stovetop whistling kettle; no one has ever criticized it and it will never break.
Different tea varieties are best at different temperatures. It doesn't matter much if you use generic black teabags from the store, because the tea is usually quite old has lost most of the subtle tastes.
White, green, oolong or really any kind good black tea might require less than boiling temperatures to extract enough out of tea while preserving the taste or other wished effects of the tea. The temperatures, amount and the steep time might be different by each specific tea or batch.
So a kettle with a temperature control can be helpful and save time with tea or cooking if you want finer control than boiling - not boiling.
You can achieve any temperature with a mix of boiling and cold water. A $0.99 food thermometer will work just fine for that. After a while, you should know what the proper proportions are.
But that's exactly the point the guy in the article makes: he has done that since forever and it's not particularly tiring, but he wants a better solution.
So, for tea at least, and green tea in particular, water temperature is actually very important. This is often overlooked by people (at least in my experience in America). I've had many friends who claimed to hate Green Tea because it is bitter. But they changed their minds when I brewed them a cup and explained that it is important not to burn the leaves with hot water and then over-steep the tea---rather than boiling water you often want water considerably cooler, say 150-180 F, depending on the tea. You also don't want to steep for too long (often just a minute or two, again depends on the tea).
When I was younger I used to hate bitter tastes, I used to shiver when I tasted some. But at some point the only thing to drink at our office was the tea, and sugar ran out quickly so I adjusted. I barely feel bitter taste now and only if I put a tea bag in cup of hot water and drink it after a while without taking out the bag or stirring it.
For black tea too, temperature is really important (it should be boiling). Never order black tea in the States, you'll receive a teabag along with container of tepid water.
Different teas require different water temperatures AND different steeping times for the best taste. Generally the less oxidized the tea the lower the water temperature. I find the worst offense is most Americans over steep their tea which makes it very bitter!
People who use a thermometer are very serious. I just guesstimate.
Also, get some high quality tea, the difference in taste is amazing and its not that expensive, only a few cents a cup.
Re-using tea bags (in the UK & Ireland) is a sign of someone who's very cheap and doesn't want to spend any money. Like someone who cuts their own hair to save money.
That's why he said leaves and not bags. It's ok to reuse the leaves, most of the times the resulting brew will be different from the previous, which is sometimes the desired thing.
An example of this that I recently had was a 北斗一号. The first brew is extremely fragrant - smells of bubble milk tea, but has very weak flavour. The second brew brings out the flavour of the tea.
You're supposed to let the first brew fill the smelling cup[0], and drink the second brew, but I drink both
First of all I said tea leaves and not bags and second of all what the hell is wrong with cutting your own hair if you can do a good job of it? My brother liked simple haircuts (buzzed to a certain length) and my mom always cut his hair in the kitchen because it was just easiest. Anyone who keeps their head shaved probably isn't going to a salon either.
Depending on how "into" tea you are, various teas require steeping for a specific duration of time under a specific temperature. See a website he mentions, steepster.com, where people talk almost exclusively about this topic.
ACK!! Steep is an alien word. In the UK you "brew" tea. "A good brew" is a colloquialism for a nice cup of tea. Honestly, tea geeks, tea is just tea. Unless you paid a large sum of money for the actual product, you put a bag in the cup and pour boiled water on to it. Let it brew. Remove bag. Add milk and sweetener as desired. Done.
Bagged tea is shit tea. Good tea doesn't cost a large sum of money. Good tea tastes better if you don't burn it. Before you ask - yes I'm an Englishman ;)
Also who ruins tea with milk and sweetener? Tea is a beautiful thing on its own. Maybe you think tea is just tea because you can barely taste the tea over the milk and sugar?
Also good tea is still cheap tea - only a few cents a cup.
Would you worry as much about coffee? In The UK tea is a commodity. Google "builders tea". It is unusual to drink "black tea" (any Tea made without milk.)
Black tea with milk is the traditional way of drinking Tea in the UK, so no - I really don't think most people give a shit about what you think. It's a cultural thing and would be like me criticising an Indian for eating a hot Curry or a German for their strict beer making codes.
My choice of words was a mistake, they weren't meant to criticize. I was referring to the post that said "tea is tea" which I was just saying if you put milk and sugar in tea, then yes, you are covering up the true taste and tea is in fact tea at that point and you can't really appreciate a higher quality tea.
Using the word "ruins" wasn't meant to be criticizing, it was meant to be playful tongue in cheek. My own mother takes her tea "the British way," that's what tea was in her family when she was growing up, and I tease her about it. However, I have expanded her taste for tea lately and she has thanked me for it.
>Would you worry as much about coffee?
There's plenty of people who appreciate coffee for coffee. I am not one of them. As much as I try, coffee isn't good to me, the flavor isn't something I can enjoy. I do enjoy flavored fake creamer though, so I add that (probably too much if it...) and cut the actual coffee flavor to something creamy and flavored I can drink. In which case, it doesn't matter the quality of the coffee, it can be the shit cheap stuff or the $50 a pound expensive stuff, I'm covering up the true coffee flavor and I can't appreciate a difference. It's kinda a guilty pleasure, I admit...
It isn't about what I think, I was strictly speaking that one can't say there is no difference in high quality tea and low quality tea while putting milk and sugar in it, as you aren't really tasting the tea flavor at that point.
From what I've seen most British people are way behind on their hard core tea nerding. For most of my British friends tea is something you drink large quantities of, not obsess over.
For we Brits, tea is generally the dust of what was once half-decent tea, bagged up and swaddled in obscene amounts of milk and sugar. Many of us don't know anything other than that!
Add a thermometer to the stovetop kettle and it'd be perfect! :-) I would much rather boil water with gas. It's cheaper and there's no risk that it will overload the circuit breaker.
Buy a container worth of kettles, register goodcheapkettles.com, sell them for a year, and this question will answer itself. Probably cheaper and more useful than studying business in undergrad.
I don't think a good kettle has to cost $90 - There's one one amazon with 80% 5 star reviews for $20. http://www.amazon.com/Courant-Cordless-Electric-Coffee-Maker... . Still there are lots of wealthy people with $100 + to spend so manufacturers will naturally make stuff for those price points if customers will buy it.
I had an expensive kettle which was a gift. It lasted ten years but then started to leak and finally started tripping the breaker. I replaced it with a $20 plastic kettle which does everything the other one did, except boil faster and quieter. Just doesn't look as cool though.
In reality, expensive kettles are like expensive clothes. They are probably made out of better materials, but the rest is just markup to cover the lower volumes and higher marketing costs. And because people will pay it for a brand name and sleek design.
Retail margins are frequently 50%. (50% margin, 100% markup) Unless a company is vertically integrated. Does the author really not understand that? Markup/margin varies by product and retailer but is still one of the largest factors in the price you pay at retail.
For me the perfect kettle is a simple glass kettle because I've found that it doesn't change the taste of water whereas metal or plastic kettles do. Also, I don't like the idea of heated plastic compounds leaching into my water.
Bonus, it looks cool to see the water start to form bubbles and then to go into a full on boil!
I challenge you to a blind trial. I very much suspect that using an electric kettle and a glass kettle you would not be able to taste the difference of the water once cooled. (We'll run the electric kettle twice with clean water followed by a flush, as most manuals state.
> Also, I don't like the idea of heated plastic compounds leaching into my water.
I don't like the idea to getting burned on my kettle. So if anyone is looking for a kettle that should be metal, invest in one with double walls if you want it for the "look" or one that has palstic outside if you want it for the "taste". Having cheap metal kettle is much worse than having even cheaper plastic one in my opinion.
OK. So given all this thinking, where's the 3D printing era, JIT-manufactured, elegant hack in response that fundamentally rethinks the problem domain and is one with kettle-nature?
I guess the author is saying "kettle is a kettle is a kettle" (except for price, certain design features that don't really count).
One thing they left out of the estimate was the cost of passing national electrical safety regulator test regimes. As anyone who has actually produced new electronics can tell you, this can often be an expensive PITA... particularly for lower-volume products. 100,000 is not high volume.
Please contribute your kettle hack ideas in this thread.
A kettle-element where it used sound to listen for the bubbling of water above instead of measuring heat and automatically dropped temperature. It could track immediate temperature variation (for pots within a certain distance) to attempt to detect waterless operation and perform a shutdown for safety (to prevent fire).
A kettle where it doubles as other things. There are a wide variety of essentially similar cooking appliances (pressure cookers, slow cookers, kettles, Iranian-style rice cookers with crispyness-control, standard or Chinese-style rice cookers, stovetops, etc.) which should be possible to combine more elegantly than the wasteful duplication of the present.
I wouldn't have thought to take apart a simple water boiler (at least not in recent years) so that was enlightening. Sometimes simple but functional designs can be fascinating, after getting to used to doing less with more (arduinos on everything) rather than more with less (completely mechanical control systems).
I have a zojirushi, but only with three temperature settings. Maybe I should mod it to fully variable... although I really want to make a teapot with a built in thermometer more than anything. The water heater wouldn't cool fast enough to really make the variable temp worth it.
>I don’t know how Hamilton Beach did it, and I’m exceedingly curious as to how. The people at Steepster don’t think too highly of it though, so there’s some clues there.
In regards to the $45 variable temperature kettle. The folks at steepster probably didn't care for it because the temperature range is pretty narrow. For high-quality tea, 175-212F simply isn't a wide enough range. It's also not very precise. Many delicate green teas are best prepared at temperatures as low as 140F and in some cases just a few degrees can make a difference.
I bought one recently in the UK - cheapest plastic ones were too flimsy (last couple of kettles died from broken plastic parts [eg in over-complicated lid catches]). Metal ones at the next level up didn't have a level indicator to see how full it is without opening the lid. Next level up from that was about £25-30.
IIRC we paid ~£25 after discount. The best value, of those I found, excluding aesthetics was ~£22 .
An easy way to get temperature controlled water with a standard kettle is to figure out how much cold water you need to add to the bottom of your mug before filling it with (just-boiled) water from the kettle. If you want more accuracy, you can use water from the fridge (which is better at keeping constant temperature than your cold water line).
Why anything but simplest faucets cost 50-200$ and just 2-3 models cost less than 20$?
Because it's reasonably durable decorative item so theres no shortage of people willing to part with their money because it's just 5 times as expensive but 100 times prettier.
The cheap ones are for people that just want faucet. Quality is pretty much the same.
I've wanted a Zojirushi for a few months now. Heard really good things but also heard about the build up of scaling after some usage(I guess that depends on the type of water you use). I only drink black tea (using teabags - nothing fancy) so spending north of $100 seems overkill.
I've had a Zojirushi boiler for about 6 years and have only descaled it twice. It's very easy, you just dump some citric acid in there, set it to the cleaning cycle, and dump the water out. Rinse it a couple times to remove any extra citric acid, though that's only for flavor reasons; it's food-grade citric acid.
The instructions say to dump the water out every day and start fresh in the morning. I don't do that, because I am too lazy.
I've been meaning to buy a kettle, and this post made finally pull the trigger. I absolutely love my Zojirushi rice cooker, I have a Zojirushi thermos for my coffee which is perfect, and now I'm going to have a Zojirushi CV-DYC40 kettle. These (along with my Vitamix) are the only appliances I constantly take with me when I move.
I bought my wife the CV-DSC40 kettle. She drinks green and Jasmine and uses the water for her Bodum coffee press. The scaling is only for really hard water areas.
It is overkill if you don't use it all that much (we use and refill at least once a day). But if you're a hardcore hot beverage drinker, it's truly the Cadillac of kettles.
Me too. The liner being "non-stick" is a bit concerning, but it seems like glass or uncoated metals are impossible to find.
I imagine it has to do with scaling, discoloration, and/or lifetime. I have stayed with my old stovetop kettle until now, simply because it has no plastic/silicone/rubber in contact with the water.
>The most difficult part is the grounding of it – which metal kettles are in sore need of, lest they give you an electric shock.
Appliances like these are generally 2-prong and therefore not connected to safety ground. Rather they are supposed to be "double insulated" for protection.
Pedantic twitch. You wouldn't need the "I"(integral) in PID as we can only drive the system one way. You hardly need the "P"(proportional) either, if you are just trying to figure out when to shut off the power. That leaves shutting off the power based on how fast the water is heating up. So really just "D"(derivative) control. Which is super simple. ... and that is even assuming that there is enough thermal mass in the heating coil compared to the thermal mass of the water to ever make a difference.
It is gotten to the point where I get a twitch whenever I see someone refer to the PID concept. In most cases it gets used in an inappropriate way.
Convenience, mostly -- with an electric kettle you can just hit a button and when it pops back it's ready. Also, if you happen to get involved with something and forget about the kettle, it's not a big deal; not so with the stove.
in 2000 we bought stainless steel kettle for $70. Buying it i felt it was expensive, and there were cheaper plastic ones. My wife overruled. As usually she was right. In 2013 she said that its time to update (though the old one was still in pretty good shape and hadn't produced any issues during those 13 years with everyday usage - at morning once and several times in the evening), and we bought new, stainless steel, for $90 something. This time i didn't even said anything.
Giving the retail markup of say 50% and wholesale markup of say 30%, the difference at the manufacturer of $90 vs. say $50 becomes $31 vs. $17 ($10 vs $5 BOM :)
What do they teach in US schools? The three things I know they teach in UK secondary school physics (11-16s) are how to draw graphs wrong, how to wire a plug and how a kettle works!
Also, who doesn't have a cheap kettle? (I actually have a £20 one, because I wanted a high wattage so it boils quicker, but in my defense I got it free with nectar points[1]. It is still plastic and the on/off LED broke within a week, but it boils enough water for my enormous free hackathon mug in like a minute.)
[1] If you didn't know that Argos accepts nectar points, you're welcome. I have never paid for a kettle or microwave.
The quick answer is supply chain markup. Stuff isn't sold at cost because that's usually not a winning, sustainable strategy. Distributors (if there are any), manufacturers, and retailers will all want to cover their (varying) overheads as well as make a profit. The largest profit is generally made by the the retailer. A bricks and mortar store has markups of about 100%.
All the above is why you sometimes hear people talking about shorting their supply chains because it means lower trade prices, which in turn allows for increased profits, an increased ability to compete on price, or both.
Many startup businesses fail because they underprice their products. They underprice them because they do not account for what all of their costs are going to be.
I just use the Tatung version of this Newegg-house-brand (http://www.newegg.com/Product/Product.aspx?Item=N82E16896268...), a $30-40 insulated hot water dispenser. If I had the money to buy the perfect Zojirushi, or found one on sale, I might (they're only around $100-150 now; they used to be $200+).
The estimate for cost of electronics is ludicrous. It is a micro controller, a relay, and a PSU. I can build that for $5 at low quantity. PID controllers cost $30 since you pay for low quantity and design. You can build ones from a $1 micro controller, or for even less in analog. Plus you do not need a pid. It makes no sense in that context. It is a thermostat.
They cost what they cost due to product differentiation and similar.
Why would you need a PID controller? All you need to do is power the heating element until your sensor reads the desired temp, then shut it off. A PID (http://en.wikipedia.org/wiki/PID_controller) is way overkill.
Also "PID tuning"? What would there be to tune? There's some serious overcomplication going on here.
$90 isn't bad, I paid $200 for one that steeps the tea as well.
It costs that much because I'd rather pay $200 than spend my weekend making a kettle (producer surplus). Next thing you know someone will be wondering why drinks cost $10 for $1-2 worth of ingredients.
If you want to save money just use a pot and boil the water in that, it's not like you really need a purpose built device for boiling water.
I wonder how much patent licencing adds to the cost. The author mentioned how wonderful of an idea this bimetallic strip was, but that means someone invented it and someone probably holds a patent on it. How much does it cost to use that innovation?
I happen to like the lcd screen console in the Tesla, so it was interesting how quickly the author lost much of the credibility I as the reader had given him when he falsely assumed that I too would agree that it was poor design.
Read "The Design of Everyday Things". A touch LCD screen in a car is a demonstrably worse solution to car controls than old fashioned knobs and buttons that you can use while keeping your eyes on the road. I also see in that picture that the Tesla has a full color speedometer, which is a bad idea because it adds flair around the only thing you really care (current speed/rpm/is something broken?) and unless it has a night mode (which I have every reason to believe it does) it would be very bad for your night vision.
It sure looks slicker, futuristic and trendy, but it's nothing but a gimmick. Also, who needs to browse the web on a car? But I digress.
Having used a tesla interface for over a year. I can't stand the 40 cryptic buttons in a regular car. Also I'm sure you can make similar arguments for a blackberry.
I like to think that often the main difference between cheap and expensive is the amount of QA done so I don't have to do the testing for the manufacturer. Though that's probably very naive on my part.
I'm surprised that someone can simultaneously acknowledge how neat the solution for the $10 kettle is, and then say that "the magic is gone". Seeing this increases the magic for me.
Not necessarily. Different teas brew best at different temperatures. A quick and easy solution of course is to boil the water and let it sit for a while until the temperature drops.
Because that's the price the market will bear for X. Cost has nothing to do with it. If I could sell you a kettle for $100,000 that cost me $100 to build, I would absolutely do it.
Yes, $30 is an insane estimate for the cost of a PID controller. Probably because nobody buys discrete PID hardware anymore because microcontrollers disrupted that market decades ago.
You could easily implement thousands of PID controllers sufficient for this application on a $3 microcontroller with a $2 thermistor. Those are sparkfun prices, so 1/2 that would not be unreasonable for a BOM estimate. Sundry connectors and power transistors would cost more, but those will be present in the analog version as well. Temperature proofing is unnecessary - the sparkfun thermistor is rated to 125C and you can trade latency for max temp by moving it away from the heated parts. In this application you can afford to trade truckloads of latency.
Also, this is not a project for 3EEs + 2 technicians, this is a project for 1 bored EE in an afternoon. I suspect calibrating the digital version would be 10x-100x easier on an industrial scale.
I have no idea why or how he thinks the analog version would work better, so I can't really counter-argue.
The PID controller was definitely the part that stuck out to me. To me, a PID controller is a method of designing a controller and thus essentially "free" to implement in software. Do you happen to know where this $30 number comes from? Also, I highly doubt that there's much variation in the "PID quality". This isn't a use case that should require especially careful controller design/tuning; it's not like your water temperature is going to see large sudden fluctuations.
On a separate note, the price jumps from $16 to $45 going from the analog to digital version, though as far as I can see the only digital-specific additions are the EEs ($7) and PID controller ($10).
On DigiKey I can find a bunch of PID controllers in the >$200 range. I suspect that the $30 figure comes from a discrete package that made economic sense long ago when one had to use op amps and tuning pots to build a PID circuit. Even though microcontrollers have disrupted that market, the ancient PID controllers will stick around in supply warehouses as long as the machines which used them need replacement parts. $30 (or $200) could be significantly above the original manufacturer price if the parts are no longer manufactured but are still in demand. If one has only ever heard of PID controllers as "the semi-magical black boxes used to solve control problems" then one might make the mistake of only looking through the purpose-built controllers rather than looking for the cheapest uC.
As for your separate note, I noticed that inconsistency as well. I never figured it out, although by that point I was ~70% sure the whole analysis was botched so I didn't spend too much time thinking about it.
This almost made me laugh out loud. Exactly how many kettles does the author think sells each year? Multiply by models and again by manufacturers, and you're talking millions of kettles. Even if you consider that one model will last multiple years, manufacturers don't buy supply batches that last for years. Some industries go in the extreme other direction - the local car industry got its stock-on-shelf lifetime down to 48 minutes from part arriving to part being screwed into car.
Similarly, retail markup is generally 20-50% of the final cost. If you think this is too high (it really isn't) then I suggest you use your new formula to undercut the existing market and disrupt away. Other significant costs are transport and wholesalers (who aren't always the manufacturers). Kettles are bulky items that consume a lot of space in storage and transport. On top of all this, every party involved in the transaction is entitled to make some profit, and not just work for costs. There's also regulatory compliance, things like the CE mark.
Looking at an item and stating that the price shouldn't be more than parts + amortised kickback to the designers is naievity, plain and simple.