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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."
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.
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.