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Company Develops Microwave-powered Water Heater
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."
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.
Really? So none of the electric "tankless" water heaters on this page actually work then?
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.)
Fire and Meat. Yummy.