Microwave-powered home boiler

sevenhills

I haven't heard of these before, sounds interesting.

The boiler uses electricity to heat water which can then be pumped through existing radiators and to taps and showers and baths. The company, Heat Wayv, is building prototypes and expects to trial the boilers in homes by the end of 2022, with the first sales to customers targeted for 2024. It says a unit suitable for a three- or four-bedroom home would cost about £3,500, the same as an equivalent gas boiler.

https://www.theguardian.com/environment/2021/mar/16/first-microwave-powered-home-boiler-could-help-cut-emissions?CMP=fb_gu&utm_medium=Social&utm_source=Facebook&fbclid=IwAR1qHy97fEbP3pMH2GqRH6ysR1MaDMNgoSzvgOpwt_tL_EfC5N0bTpUPDOM#Echobox=1615880414

shinytop

You can get electric wet heating systems now but they are very expensive to run.  I can't see this being any different.

Billy_B_North

Microwaves are no more efficient than running current through a wire, so it’s not clear what this offers over a normal immersion heater.
It’ll be far more expensive to buy and maintain too.

coffeehound

One thing that would be a good use of microwave is tumble driers.  They could be used to provide the initial heat to get cold wet clothes up to 40º or whatever.  I looked it up once and apparently the Japanese were starting to use it in commercial machines.  Maybe there are safety concerns or some technical reason why they aren't used in domestic driers.

unforeseen

Magnetron are only around 65% efficient that's assuming that it's into a matched load. If not then efficiency drops fairly dramatically

Billy_B_North

coffeehound said:

One thing that would be a good use of microwave is tumble driers.  They could be used to provide the initial heat to get cold wet clothes up to 40º or whatever.  I looked it up once and apparently the Japanese were starting to use it in commercial machines.  Maybe there are safety concerns or some technical reason why they aren't used in domestic driers.

What advantage would it have over warm air? Again it seems like an expensive way to get worse results.

matelodave

Unless it can produce more energy than it consumes then it's no better than a immersion heater. So far about the only device that does that is a heatpump, assuming  you discount the possibility of your own nuclear generator.

Reed_Richards

If it cost the same as a microwave oven then it might be attractive to small or very-well-insulated dwellings where the cost of the heater is a significant part of the overall cost of the heating.

glennevis

unforeseen said:

Magnetron are only around 65% efficient that's assuming that it's into a matched load. If not then efficiency drops fairly dramatically

I would agree with the poor efficiency. I stuck my 700W microwave oven on a smart power socket with energy monitoring and discovered it uses 1400W.

unforeseen

They say the boiler is 84% efficient in converting electricity into hot water, and another 12% of waste heat is recycled, giving a total efficiency of 96%

They miss the fact that there will be losses when turning that 12% of waste heat into something usable. 
Also, I don't think it really uses microwaves. The process sounds more like induction heating at very high frequencies. 

Reed_Richards

glennevis said:
I would agree with the poor efficiency. I stuck my 700W microwave oven on a smart power socket with energy monitoring and discovered it uses 1400W.

So where is the other 700 W going?  The energy has to be used in either heating something (thermal energy) or turning the turntable (mechanical energy).