Company Develops Microwave-powered Water Heater 505
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."
Not true! (Score:4, Informative)
Were I lived (the real world) many people had on-demand heating with conventional gear in the seventies, and still do [plumbingsupply.com].
Re:microwaves more than 100% efficient? (Score:2, Informative)
bad science = scam (Score:3, Informative)
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.
Re:Actually... in Canada, too (Score:2, Informative)
My Dad works at a place that sells these in Canada, and has been selling them for a while (not sure how long exactly, but well over a year). Not the microwave variety like the story talks about, but the electric variety like SETS. He says they work quite well, but it does take people some time to "accept" them.
There are a decent amount of this variety out now [google.ca], it appears. And if they're being sold at Home Depot to your average Joe, then I'd say that at least the electric version of this technology is mature enough.
I would buy one if my water heater wasn't working so darn well right now (I hope I didn't just sentence my water heater to a premature death).
Todd
Electric resistance-based quite common (Score:5, Informative)
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.
Re:microwaves more than 100% efficient? (Score:5, Informative)
Really? So none of the electric "tankless" water heaters on this page [plumbingstore.com] actually work then?
I believe you may be the idiot (Score:2, Informative)
Electric heaters are 100% efficient. (Score:5, Informative)
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
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.
Re:Kill germs too? (Score:3, Informative)
Re:microwaves more than 100% efficient? (Score:5, Informative)
Re:Marketing Crapola! (Score:1, Informative)
This is slashdot, people expect numbers.
It doesn't matter if you use electricity, natural gas, or blowing on it really hard.These on demand electric heaters often require 100 or 200 amp breakers BY THEMSELVES
If you use electricity for purely resistive heating at 100% efficiency, and assuming it's (US) standard 120V:
(I'm completely ignoring AC/DC conversion here, which adds another factor of 1.414.) That's substantially more than 100 or 200 A.Re:microwaves more than 100% efficient? (Score:3, Informative)
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 flow, at about 38 degrees (Celsius, you Neanderthals!), consumed about 27 kilowatts. Consider my 50 square meter flat, in Norway, uses only 1 kilowatt for heating (I've got good insulation though), and you get the picture of how an insane lot of power you need. In Italy there is a mandated limit of 3 kilowatts, beyond which the life-saving circuit clicks and cuts all power. However, this is not going to be any better with microwaves.
Has anyone already mentioned that water exposed to microwaves can go supercritical (above 100 degrees), and start boiling with a big boom? That's why you don't make things boil in the microwave, and why eggs explode. They will need a safe control system, else tubes may get worn out quickly.
Re:that's more like it (Score:5, Informative)
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:microwaves more than 100% efficient? (Score:2, Informative)
Traditional electric water heaters are designed to heat up a stored volume of water over a relatively long period of time. It is certainly possible to design a process where a flow of water is heated electrically - but the power (rate of energy) supply required to heat is beyond practical limitations on the domestic electricity supply.
Deliverable energy to an appliance via a domestic gas pipe is relatively huge. A modern gas combi boiler is typically rated at 100,000 BTU/h (29.0kW). It can provide 14 litres/min at 30C temperature rise or 7 litres/min at 55C rise. To get 29kW from an electrical device, you would need to supply about 120 or 264 Amps (on 240 Volt or 110 Volt supply). Those would be big cables (carrying a lot of current!) I wouldn't want in my house.
So heating a water flow electrically is easy engineering design - just not a practical choice in the domestic arena. The microwave solution still has to get around that problem, it appears to me.
Microwave Heater = Big Product Liability (Score:1, Informative)
Here is the rub, the magnetron must be sparked up to 4000 volts DC folks, with a whopping big capacitor. Many servicement have been killed from a microwave 'kick' .
Mixing water and HVDC electricity - copper pipes, steel sinks+ bathtubs. Nasty! Imagine the situation New Orleans could have had.
Those with a microwave, KNOW cockroaches are drawn to them like magnets, and cockroach urine forms a good conductor - you see where this is leading. Two dissimilar metals and electric current = electrocorrosion = radiation leaks. Nope , you keep it.
Microwave heating may sound cool, but so would a heater powered by a jet engine, or piped from natural geothermic springs. I've seen 100 year old hot water boilers working fine, whereas little used microwave ovens don't go the distance.
How many Tims have repaired their boiler, Vs Tim's replacing a hot 4000 volt blown fuse. Love to see the insurance angle.
Re:Marketing Crapola! (Score:3, Informative)
No it's not. It's 2 phase did you forget? The amp rating of a breaker is at 240V. (Or equivalently you can say it's 100A or 200A per phase, for 200A or 400A total.) (Is it 480V in EU?)
293.4 / 2 = 146.7. That sounds about right compared to what the gp wrote.
And why would you convert this to DC anyway? And you don't need any 1.4 factor - it's 120V RMS - it's already factored in.
Microwaves aren't tuned to water freqs (Score:3, Informative)
The problem is interference. 2.45 GHz is smack in the middle of a band designated as a free-for-all, so anyone using it for communications has to accept whatever interference they get. Certifying a microwave to operate in a licensed band would cost far too much for no benefit.
Re:that's more like it (Score:3, Informative)
It is fully thermostatically controlled, and you can control the hot water heat just by turning a knob on the front panel (and it'll consistently heat to that temperature regardless of whether you want just a dribble of water or whether you want it to come gushing out to fill a bath).
Looking at the schematic for this heater, it has a small closed hot water loop and a heat exchanger, and the water you're heating is the other side of this heat exchanger. The small hot water loop (I think it contains about a litre of water) acts as a buffer so you don't get wild temperature fluctuations as you change the flow rate. I'd expect that to be a pretty standard design.
Re:that's more like it (Score:4, Informative)
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.
How 'bout checking what's written for errors? (Score:4, Informative)
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
Re:Marketing Crapola! (Score:2, Informative)
I have an electric tankless water heater that I installed myself. It requires 2 240v circuits on 40 amp breakers. I have 150 amp service. It's cut my water heating bill in half. total cost of installation was $650 including wiring. it paid for itself in 2 years.
Re:that's more like it (Score:3, Informative)
This is an over-reaction. Who drinks the water from the hot-water tap, anyway? Blech!
As for breathing in mist when taking a shower, don't forget that unless you're leaving your hot water tank stagnant for long periods of time, you're continuously flushing it with chlorinated water from the mains, which kills the suckers.
The whole thing is marketing bullshit. Just like "anti-bacterial soap" - all soap is anti-bacterial.
Be nice if the reporters at the Globe and Mail got a bit of a basic science education (ditto for the editors here for reposting it)
Re:Kill germs too? (Score:3, Informative)
Put an empty glass in, and it won't heat up much. Ditto for most plastics.
Re:ooooh (Score:1, Informative)
Google before you post (Score:4, Informative)
I think you ought to research your claims before posting here. Instantaneous electric water heaters have been around for years. My mother uses a SETS [sets-systems.com] instantaneous electric water heater to supply water to her entire home. Other examples of tankless electric units include remote washrooms to save on the piping, etc.
Please note that I didn't claim that electric water heaters were 99.9% efficient, I just claimed that 99.9% of the energy consumed by one would actually end up inside it. Obviously, any water heater that incorporates a buffer tank will have some standby losses. Please also note that some instantaneous water heaters have standby losses due to their use of standing gas pilots (common on older systems).
Most significantly, I urge you to research the minimum flow requirements that all instant units impose. If you have a whole house instantaneous water heater, it may be very beneficial to have a small buffer tank to cover low loads like a single faucet being cracked open enough to cause flow, but not enough to allow the water heater to fire.
What you're also missing is that the energy distribution companies are gearing up to disincentivize instantaneous gas and electric water heaters, whereever they are attached to their networks (i.e. methane and electric, LP is a different animal). That's because many distribution networks (gas or electric) cannot handle huge spikes in demand, and instantaneous water heating units do exactly that, creating predictable spikes in the morning and in the evening. How will they kill instantaneous units? Simple, peak demand metering.
Utilities and their distributors prefer the slow,steady demand that a low-recovery, buffer-tank water heater imposes on their systems. As meters get upgraded (and ours just did), the utility company not only knows how much you consume, but when you consume it. Demand metering is already standard practice in the Commercial arena (with VERY heavy-handed penalities) and it's only a matter of time before the distribution companies will try to impose the same kind of demand-control on the residential side of the business.