Become a fan of Slashdot on Facebook

 


Forgot your password?
Close
typodupeerror
×
Technology Science

Company Develops Microwave-powered Water Heater 505

Posted by CowboyNeal from the pacemakers-beware dept.
dponce80 writes "Pulsar Advanced Technologies has announced that, starting next week, they will launch the MK4, a microwave-powered on-demand water heater. Why is this cool? Well, until now, you had two options: electric heaters that keep a large amount of water hot at all times, or natural gas heaters that heat up water on-demand. The first is very costly and wasteful, and the second is not available to everyone, especially those in rural areas. You can't heat water up quickly enough with conventional resistance-based electric elements, as it would require huge amount of electricity. Not so with microwaves. The Vulcanus MK4 can heat water from 35 degrees Fahrenheit to 140 degrees Fahrenheit in seconds and can source multiple applications at once: showers, dishwasher, sink usages and more. The Globe and Mail has an article with a little more information."
This discussion has been archived. No new comments can be posted.

Company Develops Microwave-powered Water Heater More

Company Develops Microwave-powered Water Heater

Comments Filter:

  • ooooh (Score:5, Funny)

    by tonywong ( 96839 ) on Friday November 25, 2005 @02:45AM (#14111593) Homepage
    Another fine product from Wayne Enterprises Military Division...

    • No, another example of cut and paste... (Score:5, Interesting)

      by Constantin ( 765902 ) on Friday November 25, 2005 @09:32AM (#14112833)

      This "article" is a press release being marketed as news by the Globe and Mail. Here is my letter to the editor.

      Reprinting press releases and announcing them as news in your publication is a pretty sad state of affairs. Your "article" fails to analyze the technology even in a rudimentary fashion. For example, if the reporter had turned on a crticial thinking cell, perhaps he/she would have inquired how a micro-wave based tankless water heater was going to be more efficient than a resistance-based one?

      You cannot get around the Physics that it takes 1 BTU to heat a pound of water by 1 degree Farenheit. Tankless electric water heaters have existed for years and are 99.9% efficient at turning electrical energy into heat... just like this microwave technology. So no efficiency gain there, and never mind answering the question where the electrical power comes from in the first place and the conversion efficiency at that end.

      How about comparing the efficiency and energy consumption of a tankless electric water heater (of any kind) to a tank-based water heater that uses a heat pump, a desuperator from a geothermal heating system, or perhaps even an indirect water heater fired with a condensing gas boiler? That probably never occured to your reporter because he/she was under orders to secure advertising from Pulsar Advanced Technologies.

      Yet, heat pump water heaters have been shown to consume a lot less net energy than their electric competition because they harvest "free" energy from the basement or the ground, even if you account for standby losses. Every kWh put into such a heater produces several kWh of heat. See this press release at ORNL [ornl.gov] for more information.

      And, lest we forget, even regular gas fired water heaters achieve a higher thermal gain per net unit energy put in at the front end than any electric unit... as a typical energy plant is 35% efficient. Most of the energy going into that process escapes as waste heat, and I'm not sure that being dependent on the electrical utilities is any more beneficial than relying on the gas utilities.

      Please do better than this in the future.

  • that's more like it (Score:3, Funny)

    by theshowmecanuck ( 703852 ) on Friday November 25, 2005 @02:45AM (#14111595) Journal
    Now I can have a long hot shower in 30 seconds.

    • Re:that's more like it (Score:5, Informative)

      by BigBlockMopar ( 191202 ) on Friday November 25, 2005 @04:50AM (#14111975) Homepage
      This is asinine.

      A hot water heater's element - on demand or tanked - is submerged at all times. Therefore, almost 100% of the heat that it produces is coupled to the water - the only loss *NOT COUPLED* to the water is the heat which travels to the ends of the element where the terminals are. Electric heating of water by immersion heaters is close to 100% efficient. (We'll ignore the heat from the water which radiates through the heater; the energy loss from the hot water will occur with both conventional and microwave heaters.)

      On the other hand, the magnetron, power supply transformer, rectifier diode and capacitor a microwave heater will require *all* dissipate energy, and unless they're all submerged themselves, the heat they produce will be lost.

      How much heat is that? Consider, for a second, that most microwave ovens put out something on the order of 700W of RF power... and that most of their nameplates indicate they consume 1200W-1500W to do it.

      So, watt for watt, will it elevate the temperature of the water more than a conventional resistance element? I can't see how, and I have more than a few University-level engineering courses in thermodynamics, chemistry and electrical engineering under my belt. It might respond faster than trying to heat up a relatively massive heating element, but... there's the magnetron.

      Consider also that the magnetron is a vacuum tube which has a filament. Unless the filament is left on 24/7 (wasteful), it will take a moment to heat up before producing microwaves. A smaller and lighter filament would heat up faster, but would probably fail sooner during the repetitive on/off cycling this thing is going to experience.

      Absolutely asinine. Finally the tankless water heater has one-upped itself in stupidity. Perfect for people with more money than physics knowledge.

      (I come from a Northern climate where the thermostat is set to "HEAT" for 7-8 months of the year. The heat which radiates from the imperfect insulation of my water heater is simply lost *into my house* where it reduces the duty cycle of my furnace. Yet tankless water heaters are all the rage here, and I've installed dozens of them in the past year. They only make sense for compact homes in hot climates.)

      • Re:that's more like it (Score:5, Insightful)

        by hjsb ( 848926 ) on Friday November 25, 2005 @05:48AM (#14112148) Homepage
        I think the point was not that immersion heaters are inefficient in that way (i.e. in the true physical sense), but that because they cannot heat water quickly, they have to keep a large amount of water hot at all times in case it is needed. This is inefficient (not in physical sense) because the vast majority of the heat that is transferred to the water is lost to the atmosphere while the water sits around waiting to be used. Gas heaters, however, can heat water quickly (on demand), and thus no energy is being used to heat the water until it is required.

        • Re:that's more like it (Score:3, Interesting)

          by Alioth ( 221270 )
          I didn't think that this was a problem anyway.

          I have an electric shower. It is a small unit (about 8 inches tall, 5 inches wide and 3 inches deep, which has all the controls and houses the heater) and can adequately heat the water running through it to give a decent shower, and gets hot enough within seconds. It does draw around 10kW on full power, but for a microwave heater to heat the same volume of water would require much more than this (due to the inefficiencies noted).

          So I really don't see what this m

          • Re:that's more like it (Score:5, Interesting)

            by keraneuology ( 760918 ) on Friday November 25, 2005 @08:21AM (#14112540) Journal
            In a former life I lived in Costa Rica for a couple of years. In all that time I saw exactly -two- hot water heaters. (Out near Puntarenas and down in San Isidro the water simply comes out out of the plumbing warm 24/7 without any human intervention.) To get a hot water one had an electric gizmo that threaded onto the end of the horizontal pipe sticking out of the wall in the shower (unless one had this electric ducha one never had a showerhead ofcaug any kind). All showers that I ever saw were constructed to include a large frankenstein-style knife switch in the shower stall with you mounted up in the corner, hopefully away from the expected stream of water. Wiring was one hot, one neutral.

            As the water flows the pressure would close a switch inside the showerhead and heat the water electrically as it sprayed out. Costa Ricas tend to be shorter than Americans so these pipes are invariably mounted about 5'10" off the ground, forcing many to squat down a little bit to get under the head. An accidental brush up against the showerhead with give you a quick reminder to squat back down again. The unfortunately arrival of a moderate earthquake (fairly common) could also bring about a zap.

            In one apartment the occupants (Americans, actually - Costa Ricans aren't this stupid) had spliced the wiring (120V @ 50Hz IIRC +/- 10% to allow for the ever-changing conditions on the line) with masking tape. I happened to be in there at the moment the tape burst into flames making me one of the only people in the history of the world to have been using a shower that caught fire.

      • Here in East Texas we run the AC 7-8 months a year. We, typically, have the hot water heater in the garage so as not to run up the AC bill. What makes the most sense, here, is a solar hot water system. There would likely be only 10 to 15 days a year, if that, where the a solar hot water system would not be able to meet all hot water needs.

        In by gone years a solar hot water system would pay for itself in about seven years. However, with the increase in natural gas prices over the past year I'd be willing to

        • Re:that's more like it (Score:4, Insightful)

          by mpe ( 36238 ) on Friday November 25, 2005 @08:51AM (#14112657)
          Here in East Texas we run the AC 7-8 months a year. We, typically, have the hot water heater in the garage so as not to run up the AC bill. What makes the most sense, here, is a solar hot water system.

          How about having your AC heat up the water?

      • Re:that's more like it (Score:5, Insightful)

        by ShooterNeo ( 555040 ) on Friday November 25, 2005 @06:45AM (#14112284)
        Actually, you are wrong.

                  You forgot about 2 elements to the story.

        1. EXCEPT for cold Northern climates where the heater is properly installed inside the house's heated area (not all of them are, some are in closets in the garage) all the heat used the majority of the time is wasted for a typical heater. Have you ever noticed how much that thing is running during the day when there is minimal demand for hot water? Net efficiency can't possibly be above 50%.

        Oh, and you still pay a lot more for the 'heat' wasted by the electric hot water heater than you do for heat generated by the fuel burning furnace (whether it uses oil or natural gas). A system that doesn't have that waste heat would be more economical.

        2. Where do you think the energy lost in capictors, magnetron, ect goes? I have a bright idea...let's put the heat sinks for those AGAINST THE WATER TANK COLD SIDE!!! DOH! Where else do you think the heat for a 2000 watt magnetron gets dissipated. Without knowing exactly how this implementation of a fairly obvious idea actually works, I can say that that would take some bigass fans and a huge radiator to get rid of 40% of the heat lost running a magetron this big. It must be a BIG one to heat water in these volumes this fast. It almost certainly MUST vent the excess heat into the cold water coming into the system through a radiator or something. This would have the net effect over a prolonged run-time (perhaps someone is taking a shower) of making the system very efficient. Perhaps 90% net.

        At the least, this kind of system should obsolete electric hot water heaters, as well as electric assists to solar and geothermal systems.

        • Re:that's more like it (Score:4, Informative)

          by Lumpy ( 12016 ) on Friday November 25, 2005 @08:21AM (#14112545) Homepage
          I have a tank style water heater. and I get INSANE efficiency from the old one from the late 80's because of 2 things.

          1 - ALL heat generated is put into the water, the exaust is piped via a PCV pipe ot the outside and it is cool to the touch all the time.

          2 - I regularly flush the tank to get rid of sediment. Sediment is the #1 cause of hot water tank problems. it insulates the bulk of the heat that is hitting the bottom heating plate from the water. after that the chimney that goes up the center has a labrynth in it that sucks out most of the remaining heat left over.

          Gas tank style water heaters are hugely more efficient than electric.

          and then there are things you can do to increase efficency even further. Insulation blanket around the tank, new tanks from today do not need this as they has an insane amount of insulation around them. secondly turn the thermostat down. You do not need 200 degree water at the tap. if the tank style heater only has to maintain 120 degree water and you simply use more of it then do so. Or better yet get a timed thermostat. it cranks the temp up higher in the morning to have more hot water available for showers but reduces it for normal load during the day.

          Even with the impending near 90% price increases Gas heating of ANYTHING is still much more efficient. Nobody reverts to electric unless they absolutely have to, or for convience... I.E. rural areas typically have electric water heaters because it's a PITA to find a fuel oil water heater and some think that using their propane faster is not worth it. (it is, get a propane/butane high efficency water heater and throws out that inefficent electric heater.

          Now Water on demand systems are different and the electric ones are the fastest response but suck down the power like there is no tommorow to instantly heat that much water that fast. and god help you when you burn out the elements because the flow sensor was a little laggy and it overheated.. the element replacement costs nearly as much as a new heater system.
      • (We'll ignore the heat from the water which radiates through the heater; the energy loss from the hot water will occur with both conventional and microwave heaters.)

        That's not a very good idea.

        The radiation heat from a waterheater is very much significant. It is minimal in the mentioned setup because the water is not heated before it is needed. It may be much less efficient watt-by-watt if you use a lot of hot water around the clock - but in a typical residential setting where you only need hot water a few
      • ...that conventional storage water heaters are a religion. I have rarely seen so much energy and emotion expended as their adherent do to fight the evil that is tankless water heaters.

  • Kill germs too? (Score:3, Interesting)

    by jimmyhat3939 ( 931746 ) on Friday November 25, 2005 @02:46AM (#14111596) Homepage
    Microwaves kill various germs too, don't they? They should market this as both a water heater and a sanitizer.
    • That is the very first thing that came to mind.

      2 birds with one radiation treatment, or something.

    • Re:Kill germs too? (Score:4, Funny)

      by Kadin2048 ( 468275 ) <slashdot...kadin@@@xoxy...net> on Friday November 25, 2005 @03:13AM (#14111687) Homepage Journal
      Just think if they heated the water using a critical-sized lump of plutonium -- then it would both heat and irradiate your water! For maximum germ killing power. And it wouldn't just be 'on demand' hot water, it would be hot water all the time whether you want it or not.

      Plus it would be emission free, and a great use of all those Soviet ICBM warhead initiators that are just sitting around, going to waste.

      Just don't turn off the cold water supply....ever.
      • I'm sure in 1985, plutonium is available at every corner drugstore, but in 2005 it's a little hard to come by.
      • Just think if they heated the water using a critical-sized lump of plutonium --

        Yeah, but slow down if you are a contractor beware when driving on the highway with one of these in the back of your truck. If you hit 88mph you will see some serious shit [imdb.com].
    • Microwaves kill various germs too, don't they? They should market this as both a water heater and a sanitizer.

      The linked article is only two paragraphs, the second one was...

      "The tankless system uses microwave technology to heat water on demand, saving energy and providing an endless supply of hot water for residential and commercial usage. The technology is designed to eliminate the deadly Legionella Pneumophila, since water will not stagnate, as it does with conventional hot water heaters."

    • Re:Kill germs too? (Score:3, Informative)

      by cnettel ( 836611 )
      No, they basically don't. However, as noted, any quick and thorough heating will be quite efficient in killing them. It's relevant to keep in mind that if the system was tuned to say 40 deg. C/100 deg. F, we would get no germ-killing effect at all.
    • " Microwaves kill various germs too, don't they? "

      No more than hot water. Perhaps you are thinking of UVC? I remember reading somewhere that microwave ovens don't even kill fire ants.

  • Jeepers (Score:5, Insightful)

    by Chairboy ( 88841 ) on Friday November 25, 2005 @02:47AM (#14111600) Homepage
    I'M a conventional resistance-based electric element, you insensitive clod!

    BTW, the article 'summary' contains wholesale copy/pasting from the article linked to, which itself is just a press release that offers no additional data.

    Has anyone considered putting together a submission etiquette guide for the editors to use when greenlighting stuff? Something that includes a dupe check, a Ron P. filter, and perhaps a 'marketfluff' detector? Such a device would come in handy for things like this, "articles" that make Popular Science read like the freakin' Encyclopedia Brittanica in comparison.
  • A conventional heater should do just fine. If it isn't working, give it more surface area and less mass.

    The microwave could be useful with really hard water though. It might not get deposits as much, depending on how it was done.

  • Pssh (Score:2, Funny)

    by doxology ( 636469 )
    From a company with "Pulsar" in its name, I would have expected them to use gamma radiation.

  • microwaves more than 100% efficient? (Score:3, Insightful)

    by joostje ( 126457 ) on Friday November 25, 2005 @02:49AM (#14111607)
    You can't heat water up quickly enough with conventional resistance-based electric elements, as it would require huge amount of electricity. Not so with microwaves.
    So, microwaves need less energy to heat up water the same amount? Strange... The heating with resistance-based methods is already close to 100%; the loss occurs with storage of the warm water. But you do need the same amount of energy (and thus electricity) to heat up water, whether you do it using resistance-based methods, or microwaves.
    • That's the entire point, there is no tank on this unit. Water is heated as it flows through. Try doing that with resistor based elements and you'll get slightly above room temperature water at best. Microwaves are perfect for this since they hit the resonance frequency of water, heating them very quickly with minimal energy.
    • I suspect that the efficiency of electrical resistance heating is lost to radiated environmental heat.

    • Re:microwaves more than 100% efficient? (Score:5, Interesting)

      by G-funk ( 22712 ) <josh@gfunk007.com> on Friday November 25, 2005 @03:16AM (#14111694) Homepage Journal
      That's if you just count kw->BTUs, but that's not what they're talking about. They're talking about a complete system. You can't heat water efficiently for your showers with coils because they take time to heat up, they waste energy when they're cooling down and you're not in the shower, and because it just takes so darn long to do it without a huge amount of coil (which would use more energy in heatup / cooldown), you have to store it hot. And storing something hot is just about the least effecient thing you can do in this universe, and as such "the system" tends to be quite inefficient. With a magnetron it's not seeping heat into the air while it cools down (well not within an order of magnitude the same amount), it's more or less instant-on. So you're not leaking your power into the air in your heater cupboard and the frame of your house. The only thing newsworthy about this though is that it's taken so long for someone to think up and implement a viable microwave solution.

      Of course, my ex housemate ben only knows to get out of the shower when it gets cold, so I apologize for my mate using up all the world's energy when he gets one of these. On the plus side he'll eventually wash down the sink and his missus will turn it off.

      Yes, I understand the OP would definitely know all this, and was just trying to make a point, but I just thought I'd elaborate^W ramble a bit with my AU$0.02

      • Re:microwaves more than 100% efficient? (Score:4, Insightful)

        by devilspgd ( 652955 ) * on Friday November 25, 2005 @04:14AM (#14111864) Homepage
        Okay, stupid question time.

        Prerequisite: I live in an area of the planet where I am heating, rather then cooling my house the majority of the year. None of this applies to anyone with an air conditioner turned on right now.

        I currently heat both my house and my hot water with natural gas. Any heat that my hot water system (tank, pipes, etc inclusive) releases into the environment isn't really lost -- The "environment" into which the heat is being released is also known as my house.

        The only "lost" heat is that which is carried by water out the drain and into the city's waste system.

        Every bit of heat that is lost due to the inefficiency of storing the water is an equal amount of heat gained by my house, and the result is that my furnace uses that much less energy to keep my house at a comfortable 20C.

        Now in my current house I'm actually using a boiler rather then a furnace. Assuming both my boiler and my hot water tank are equally efficient (which is likely fair, since both appliances do the same job, they heat water), and since they use the same energy source and hence neither is more economical, I don't think I'm losing anything by using a hot water tank rather then an on-demand method, am I?

      • Not every coil-based system involves a big tank of hot water.

        If you want fast heating, use low-mass coils with lots of surface area. Put then at the shower, eliminating the tank and the hot water plumbing.

        If the microwave tube gets hot and is not fully submerged, it will be less efficient than a nice coil system. You could get a very good coil system for less money.

    • I think they factor in the heat dispersion that would occur in the hot-water tank. Heating water with resistance elements also presents the possibility of the elements melting, because of so much power being sent through so little resistance. On the other hand, you cannot make water come into contact with too much heat-exchange area of the resistor, because you would lose pressure.

      Also, most households have clear limits when it comes to maximum power drain: I once calculated that my shower at normal water

  • so we have a mature technology being applied to a new sector. this has the opportunity to save a lot of us money and also the effort required to keep a pilot going. the question is, will it be offered at a fair price?

  • Not true! (Score:4, Informative)

    by Knuckles ( 8964 ) <knucklesNO@SPAMdantian.org> on Friday November 25, 2005 @02:57AM (#14111628)
    You can't heat water up quickly enough with conventional resistance-based electric elements, as it would require huge amount of electricity

    Were I lived (the real world) many people had on-demand heating with conventional gear in the seventies, and still do [plumbingsupply.com].
  • The article, not the idea. It's two paragraphs, and the company that's developing this thing doesn't even have a website up, other than a big shiny logo.

    This is the first time I've bitched about the editors here, but in this case, I think it's deserved. I'd honestly prefer a dupe or something a month old than a story with no substance at all.
  • This device was first seen in the movie "Batman Begins"

  • Some cities may regulate this, as seen by the reaction by the Anchorage Assembly to a home-operated cyclotron [suvalleynews.com], which they are trying to prohibit. Same for other particle accelerators.

    Bummer. If you were thinking of having your own particle accelerator in Alaska, pick another city.

  • You can't heat water up quickly enough with conventional resistance-based electric elements, as it would require huge amount of electricity

    I am placing you under arrest for violating the Second Law of Thermodynamics. You do not have to say anything. Anything you do say will be written down and sold to those guys who spam Usenet with ads for "friction free" bicycle lights.

  • bad science = scam (Score:3, Informative)

    by frovingslosh ( 582462 ) on Friday November 25, 2005 @03:17AM (#14111698)
    You can't heat water up quickly enough with conventional resistance-based electric elements, as it would require huge amount of electricity. Not so with microwaves.

    OK, I'll buy the first part, you can't heat water quickly enough for on-demand use such as a shower, as it would require unreasonably high current, even if the electric water heater was 100% efficent. I've done the math on that. The thing is, that holds true for any way you try to heat water by electricity, including microwave, not just "resistance-based" heating. Assume 100% efficency; do the math. You don't get more than 100% efficency just because you use microwaves. You'll see that you can't heat water fast enough to maintain a flow rate in a shower. So unless you plan to have a tank of water at each point where you use hot water and heat it a few munutes before you need it, this just doesn't pass the math. And, of course, heating tanks of water all around the house isn't pratical either; if you heat a large tank and then just wash your hair you waste a lot of hot water that will cool down before it is needed; if the tank is not large enough then the flow turns cold long before the shower is over.

    Yea, it would be really neat, and I'm sure that some people who really want this will mode me down because they don't like what I'm saying. But the math doesn't work. And I did read the links. Zilch on the official website. The linked article shows no power usage math and get as technical as saying the thing is the size of a "stereo speaker". I have had a lot of stereo equipment over the years but I have absolutely no idea how to translate that unit of measurement.

    • there are electrical tankless water heaters

    • Re:bad science = scam (Score:2, Insightful)

      by Lynx0 ( 316733 )
      OK, I'll buy the first part, you can't heat water quickly enough for on-demand use such as a shower, as it would require unreasonably high current, even if the electric water heater was 100% efficent. I've done the math on that.

      You must be really bad at math, because I had a shower one hour ago using the on demand electrical heater that's been in my apartment for some 15 years. And it was set to "1", because the water is too hot to shower with on the "2" setting.

    • It seems to me that it all boils down (no pun intended) to the different efficiencies between conventional electric water heaters and microwave water heaters.

      If the efficiency of a resistor-based electric water heater is x and the efficiency of a microwave-based electric water heater is y, and y > x, then my math says that a microwave water heater is more cost-effective from an electricity point of view and can heat water faster. Neither of them have to be 100%, and in fact, that's impossible. All th

    • I suspect you must have misplaced a decimal or some such in your "calculations" because what you describe as impossible is a common product used by most households throughout Central and South America. Called a Ducha, it's basically a glorified showerhead with a power hookup that heats the water as you shower.

      When the wiring was slipshod and unsightly it always made me think twice about turning it on.

      Here's a link if you are still incredulous:

      http://www.cpsc.gov/cpscpub/prerel/prhtml04/04044. html [cpsc.gov]

    • Re:bad science = fun (Score:5, Funny)

      by djmurdoch ( 306849 ) on Friday November 25, 2005 @08:49AM (#14112653)
      The thing is, that holds true for any way you try to heat water by electricity, including microwave, not just "resistance-based" heating.

      No, no, no, you don't understand. Heat from microwaves is *more efficient heat*. It's like the difference between LEDs and incandescent light bulbs. The LEDs output almost all their energy as light, whereas the incandescent bulbs output light, but they also waste a lot of energy output generating heat.

      Water heaters are just the opposite. The resistance based ones are basically just big light bulbs. They heat the water, but they also output tremendous amounts of light, which is completely wasted. (You can't see the light because you don't use transparent pipes, do you?)

      The microwave water heaters only output heat (and a little bit of interference with your Wifi network). That's why they're more efficient.
  • The powder will be poured into the water system and then this device will be used to heat the streets of the city, allowing everyone to inhale said hallucinogenic powder for teh win.
  • You can't heat water up quickly enough with conventional resistance-based electric elements, as it would require huge amount of electricity. Not so with microwaves.

    Since Joule we know that energy (e.g. electrical) and heat are equivalent [wikipedia.org]. It doesn't matter how you convert it: bulb,resistor, microwaves...

    • I hate to say it that you do not know what you are talking about (despite being right).

      Microwave emittors do not have the same trouble with efficiency that a bulb or resistor has. Microwaves also penetrate far, and thus can affect larger volumes of mass at the same time, this allows a more consistent heat, in a shorter amount of time, more efficiently
    • Well, apart from heat pumps. And yes, you can get heat pump based water heaters :)
  • Aerogel is an incredible substance made 99.8% air. It's a super insulator (my words). Loosely speaking,it's like Jello in a solid form with the water replaced with air.

    Hot water on demand would require a smaller amount of surface area for the chamber, thus less aerogel needed..a cost improvement. Google aerogel--I see some recent articles in the google 'News' tab as well.

    Nasa/JPL offers a description here:
    http://stardust.jpl.nasa.gov/tech/aerogel.html [nasa.gov]

  • Electric resistance-based quite common (Score:5, Informative)

    by Lynx0 ( 316733 ) on Friday November 25, 2005 @03:25AM (#14111732)
    You can't heat water up quickly enough with conventional resistance-based electric elements, as it would require huge amount of electricity.

    In a lot of countries (like Germany where I live) on demand electric waterheaters (called continous flow heaters) are very common, especially in apartments buildings where there is no central water heating. They work well, and from the (very old) model I have in my apartment you get hot water in less than 30 seconds. Modern units can be set to a fixed water temperature and hold this even with changes in the amount of water flowing.

    Also, as another poster pointed out already, those units do not use up any more energy than other technologies would to heat the same amount of water.

    • In a lot of countries (like Germany where I live) on demand electric waterheaters (called continous flow heaters) are very common

      Not just Germany: Stiebel-Eltron product page [stiebel-eltron-usa.com].

    • Another advantage to tankless heaters is that they can be located closer to the point-of-use than a large central heater. With a central heater, the water must flow for some time to flush the cold water out of the pipes between the tank and the shower or sink, and warm up the pipes so the water isn't cooled on the way. Several gallons are wasted before hot water reaches a tap at the far end of the plumbing.

  • Marketing Crapola! (Score:5, Insightful)

    by GoRK ( 10018 ) on Friday November 25, 2005 @03:25AM (#14111733) Homepage Journal
    This reeks of some marketing crap. There are plenty of on-demand electric heaters with very high flow rates. Yes they require massive amounts of electricity, but I don't know that a microwave based unit would require that much less. Since they don't quote any power rates or even seem to acknowledge their competition's existing and time tested products it leads me to believe that this is a bunch of marketing hoopla to drum up business for their products.

    If you want to heat 2-3 gallons of water per minute from say 50F to 130F using electricity you need a SERIOUS load. These on demand electric heaters often require 100 or 200 amp breakers BY THEMSELVES which most often means that in order to use them you have to upgrade your home's entire main breaker panel AND you may have to pay the utility company to give you this type of service as they typically do not have not installed equipment and lines capable of providing this amount of power to a home.

    I do se a bit of an advantage in that it's possible that an on demand microwave heater, although ideally less efficient than ceramic/resistance based heaters, could provide both a size and a maintenance advantage over a conventional heater.

    On-demand water heaters have been around a very long time and it seems in the last year or two they have come back in vogue again. They work OK. They can save you money. But most people can also save money with a much less substantial outlay by upgrading their old water heater to a newer model that is better insulated and more thermal efficient. There are even dual gas/electric heaters that let you change fuels to suit whatever is currently cheaper. In many areas such as the one I live in electricity is much less expensive in the winter than in the summer and gas is the opposite.

    • Crapola, or payola? (Score:3, Insightful)

      by Tau Zero ( 75868 )
      There are three possibilities here (see journal for details):
      1. CowboyNeal is a science-illiterate and has no concept of conservation of energy (and should not be editting science stories).
      2. CowboyNeal is just stupid (ditto).
      3. CowboyNeal is taking payments to promote fraudulent products (and should be fired).
      I can't think of any other possibilities here.

  • Possible alternative explanation (Score:3, Interesting)

    by Flying pig ( 925874 ) on Friday November 25, 2005 @03:37AM (#14111763)
    As people have already pointed out, if the article is correct this is a device that claims to disobey the laws of physics. (And BTW the microwave conversion will be much less than 100% efficient, so it should work considerably worse than resistance heating.) However, there is al alternative possibility, and its based on the reference to legionella.

    Although the actual temperature needed for bath or shower water is only around 40-45C, running at that temperature with a conventional system is dangerous because it allows the growth of bacteria in the system, including legionella. Using microwaves will disrupt all the bacteria and mean that low temperature operation is possible, exactly like using a suspended UV lamp in a conventional cold water recirculating system. If the water has only to be heated to around 45C rather than the usual 60, there will be less energy loss and the volume of water that can be heated will be greater.

    However, at the end of the day unless you have a renewables (wind,solar,water) generator, using electricity to heat water is a Bad Thing. By the time it reaches you, the generation efficiency is down to around 30-35% allowing for losses, which means it will always suck badly compared to gas, oil or solid fuel water heating. In terms of sheer efficiency nothing beats a thermo syphonic system running on anthracite - no electricity used, and no water vapor created by combustion to remove latent heat up the stack in steam. A condensing boiler is nearly as good but rarely installed properly. I personally feel the long term energy saving solution lies in more efficient tank heat exchangers with better insulation, and certainly there have been a lot of developments in recent years.

  • You can't heat water up quickly enough with conventional resistance-based electric elements, as it would require huge amount of electricity.



    NEWS FLASH: Heating water requires huge amounts of _power_ (since it has the highest specific heat of any liquid), regardless of the method used to do the actual heating.



    Even if you use microwaves, you'll still need at least 4.19 J/(kg * K).

  • On demand [tanklesswa...direct.com] electrical hot water heaters (known as tankless) have been around awhile.

    Another interesting portable product which I use, and with which I am very happy, is the Coleman Hot Water on Demand [coleman.com]; this one uses propane and is designed for camping.
  • So ... the idea of having a power plant heat up water as well and sending it out to households as a sort of ... "central heating" ... and then having a heat exchanger heat the water locally wouldn't work? Say, send out really really hot water and use something like ... maybe a 2.5 liter exchanger?

    Nah ... couldn't possibly work. I know we never see stuff like that in Denmark. </irony>

  • Electric heaters are 100% efficient. (Score:5, Informative)

    by Futurepower(R) ( 558542 ) on Friday November 25, 2005 @03:57AM (#14111816) Homepage
    Slashdot editors seem to be taking money to run public relations press releases as stories. Here's a quote from the Slashdot story: "You can't heat water up quickly enough with conventional resistance-based electric elements, as it would require huge amount of electricity." ?????

    The energy to heat water is fixed. Normal electric heaters, called "resistance-based electric elements" in this story, use 100% of the energy to make heat. They are 100% efficient.

    A microwave device would waste energy in making microwaves. That wasted energy would be heat, but it might be difficult to put that heat into the water. And why spend more to get another kind of 100% efficiency?

    In Brazil and New Zealand, for example, shower heaters are often 220 Volts at 25 Amps. They heat cold water instantly to shower temperature. The heating elements cost less than $10 local equivalent.

    Disgusting nonsense quote from the referenced article: "The technology is designed to eliminate the deadly Legionella Pneumophila, since water will not stagnate, as it does with conventional hot water heaters."

    Here is accurate information [middlebury.edu]: "Legionella ... requires complex nutritional requirements such as high cysteine levels and low sodium levels to grow. "

    You don't get Legionaire's disease from water heaters! The high heat in water heaters kills bacteria. The linked article about Legionella says that it can live in shower heads, but that is at a cool temperature, on the outside.
  • Well, until now, you had two options: electric heaters that keep a large amount of water hot at all times, or natural gas heaters that heat up water on-demand.

    My parents have a bathroom with two "water-heaters", working in exactly opposite manner:
    1. an electric one that heats up water on demand (but I admit the water's not too hot, which, btw, saves a lot of water cuz nobody wants to take long showers then :P ).
    2. gas-based one that stores some hot water all the time (it's enough for a 5 minutes-long s
  • I recently researched buying an electric on-demand water heater for my own home. Such heaters consume around 10-20kW and can demand 100 amps of current, they are however very efficient (as someone else noted) and so there is little waste to squeeze out of the system (a few percent at most I expect). Using microwave generating magnetrons is likely to be less efficient imo, so it is very hard to see how this company can live up to its claims. Whether by microwave or resistive heating, the same amount of ener
  • I've used on-demand electric hot water systems in both the UK and Japan.

    I'll grant they're a bit like being piddled on by a cat.

  • The British, Great Innovators.... (Score:5, Funny)

    by Budenny ( 888916 ) on Friday November 25, 2005 @07:15AM (#14112356)
    The British, great innovators and world leaders in matters of plumbing, as all visitors know, have invented something interesting on this subject.

    Its stated in the article that there are two methods.

    Method 1 is to heat water and store it and draw it off as needed. In the UK this is usually done with the aid of one massive tank in the roof, to store the cold water for the hot water store. And a second, to store the cold water for the working fluid, which is used to heat the water in the water store. And then of course, there is a third tank, in which the actual hot water itself is stored.

    Are you with us so far?

    Well, there is a variant on this method, which consists of having a mains fed hot water store. The advantage of this method is that you no longer need tanks in the roof. The disadvantage is that if this tank, which is under pressure, ever blows up, it takes the house with it. A very small chance however.

    Method 2 is to heat it on the way through, either by gas fire in a heat exchanger, or by running it over a hot resistive electric heater. In this case you do not have all those hot and cold water stores in your roof space and closets.

    British heating engineers have invented a third way. This interesting method has the great merit of being even more more complicated than the multiple tanks in your roof. In this method, you first circulate the working fluid through a tank of hot water, thus heating it up via a heat exchanger. But you do not bathe in this!

    No, you draw cold water in a second heat exchanger through that hot water. In this way you have the benefits of both of the first two systems. You have a constant store of hot water in your closet, and two cold water storage tanks in your roof. And, you get to have hot water on demand heated up for you when needed. And as compared to the variant on method 1, you get to have mains pressure hot water, without having a pressurized tank anywhere in the house.

    It is very surprising that this system has never been exported.

  • Mandatory Scotty quote (Score:3, Interesting)

    by Ancient_Hacker ( 751168 ) on Friday November 25, 2005 @08:04AM (#14112475)
    "But captain, I can't change the laws of physics!"

    As others have noted, this microwave heater is a really terrible idea, for many reasons:

    • Your basic $69.95 resistance heater does the job with 99%+ efficiency.
    • A microwave heater is going to be at best 60% efficient.
    • A 20KW magnetron is going to cost serious money!
    • A 20KW power transformer is $$$ and heavy too!
    • Many houses don't have the extra 40% power available to waste.
    Silly, counterproductive, expensive, ridiculously bad idea. Scotty would cry.
  • "...[U]ntil now, you had two options: electric heaters that keep a large amount of water hot at all times, or natural gas heaters that heat up water on-demand. The first is very costly and wasteful, and the second is not available to everyone, especially those in rural areas."

    This makes utterly no sense. Here in the US, and I assume in a fair number of places, we have oil or natural gas water heaters that are hot all the time, and I believe I've read (in the Whole Earth Catalog) of oil on-demand heaters. In either case, drive around outside the big cities, and you'll see house after house with 550 gal. propane tanks, like the one we had in our immobile home 19 years ago.

    "Natural gas not available outside cities"?

                    mark
         

Slashdot Top Deals

Adding features does not necessarily increase functionality -- it just makes the manuals thicker.

Close