Half a croissant, on a plate, with a sign in front of it saying '50c'
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Microwave Hot Water Heater

Heat home hot water faster.
  (+8, -4)
(+8, -4)
  [vote for,

How about a household hot water heater that uses microwaves to heat the water faster? If it was fast enough, the tank could even be smaller. Not sure about efficiency compared to a standard hot water heater using induction coils. Any thoughts?
Nitehawk, Mar 23 2004

Tankless Water Heaters http://www.tankless-water-heater.com/
Not microwave, but your water is hot when you want it. [Worldgineer, Oct 04 2004, last modified Oct 21 2004]

(??) Microwave Water Heater http://www.pmengine...,2732,96706,00.html
claims 99.9% efficiency [FarmerJohn, Oct 04 2004, last modified Oct 21 2004]

Microwave Water Heater http://www.pulsar-at.com
[books97301, Feb 01 2006]

Pulsar Tankless Water Heater http://wanderport-i...dex.php?pg=products
"S" Tube [mikedmonds, Mar 15 2010]


       I am aware of the tankless heaters. Just wondering if microwaves would be faster or more efficient than convential electric tank heaters.
Nitehawk, Mar 23 2004

       "faster": a heating coil can put as much heat as you want into the water, limited only by electric energy provided and surface area of the coil (to avoid boiling).   

       "more efficient": An electric heating element converts electricity to heat at an efficiency of 100%. An electric tankless hot water heater is about 99.5% efficient, probably due to heat lost through the walls of the device.
Worldgineer, Mar 23 2004

       Ok. Hardly baked then. I admit defeat.
Nitehawk, Mar 23 2004

       That's what I thought, but in a different way. Check out microwave home heating.
quibix, Jun 29 2005

       If your water is hot, why do you want to heat it?
ldischler, Jun 29 2005

       In general an electric kettle is more efficient than a microwave for boiling water. This is probably due to the element in the kettle being completely submerged in water and most of the energy produced being put into the water. In the case of a microwave only a percentage of the waves are actually hitting the water. In the case of a microwave water heater, however, I would expect that the water tank would be full and that all the waves would hit the water and you'd end up with similar efficiencies.   

       The microwave water heater will also be able to heat on demand as it can heat the water quick enough that you don't have the standby losses associated with a typical water heater.   

       In addition it should also have the advantage that there is no heating coil to corrode and as a heating coil corrodes the efficiency of the coil - in terms of time to heat and energy required to heat - goes down - probably due to heating up all the corrosion on the coil.
books97301, Feb 01 2006

       Mircowaves are radio waves having frequency where water molecules resonate. The microwave heater transmits these waves inside a shielded box to minimize interference outside the heater.There is no reason the transmitter can't be introduced into a water stream to make hot water on the fly.The problem will be power.
el dueno, Apr 06 2008

       How much are the losses from a large, well-insulated tank of hot water? I'm guessing they are very small.   

       Plus, in all but warm climates, any efficiency improvements in appliances just mean you need to run your home-heating system that bit more.
MaxwellBuchanan, Apr 06 2008

       Awesome idea (bun), but as mentioned earlier, there really isn't much of an advantage other than the ability to heat a lot of water without being limited to any particular heater surface area.   

       As for boiling... There would be nothing wrong with boiling the water right on the heating coils. The heat transfer would be very good, and the bubbles would just collapse in the sub-cooled bulk fluid anyway. I would suggest an accumulator to handle any drastic volume change, however. I believe automotive coolant actually boils in a such a subcooled fashion in the head of the engine, but it can be unstable when you try to pump such a two-phase mixture.
kevinthenerd, Jan 12 2009

       Concerning the Pulsar Tankless Microwave Water Heater: They use an "S" tube that allows the microwaves to pass through the water multiple times. Could this heat the water with less power required?
mikedmonds, Mar 15 2010

       //Could this heat the water with less power required?//   


       The "S" tube provides more surface area of heating element to water, but an ordinary heating element in the same shape should do slightly better.   

       The ad says "High thermal efficiency (projected in excess of 90%)" which is quite a bit less than normal resistive heating of 100%.   

       That said, there may be some time-related heating issues unrelated to efficiency. If you want hot water really fast, you may give up some efficiency for timeliness.
csea, Mar 16 2010

       Yeah, you could stick a microwave beamer up inside a tank that reflects microwaves, but you aren't going to get any better effiency, that's for sure. Wasted energy usually winds up as heat, so you might as well go straight to heat and save the parts.   

       However, you can't lose much, either, as any inefficiency in the microwave gun will just heat the water, so it won't be much less efficient.   

       However, in this part of the country all the heating coils crud up pretty fast from minerals boiling out of the water, and once it starts it goes to hell real fast. I just paid a lot of money to have somebody do a bad job of cleaning out my water heater, and the water is now scalding hot.   

       So make a microwave heater that heats the water all over, with no hot spots for lime-deposit points, and you might have something.
baconbrain, Mar 16 2010

       Is there a fluid that might be a better substance to use other than water. Would a material with more molecules(more surface areas) than water or would less be better (more room to move about).
augiedogie, May 10 2010


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