Of course heating the house may or may not be separate from hot water delivery also. Gonna stick with some solar hot water for that because most of the year it's pretty efficient. Then electric heating for the rest of the time.
a new era of low cost, accessible and efficient heating?
- Thread starter Jacob
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John Brown
Freeloading Social media influenza
No.
John Brown
Freeloading Social media influenza
I apologise for that terse reply, but the simple facts are that, unless you're utilising heat from ground or air sources(hear pumps), energy in = energy out. Any inefficiency in an electrical device, be it a fan heater or a microwave, will manifest itself as heat. Even light or sound, from a radiant electric fire, or a noisy fan heater will, in an idealised windowless, soundproof environment, be eventually converted to heat. Heat is but movement at molecular level(as I understand things). So while a microwave might be very efficient at heating a bag of frozen peas, or a forgotten cup of coffee, its main advantage is focus. It doesn't have to heat the entire oven cavity and half of your kitchen in the process.
@Stevekane
My 800W microwave oven draws about 1300 Watts from the mains. That's about 60% efficient.
Most gas boilers are 70 to upper 80's % efficient.
The "most efficient" claim is probably in the context of cooking. The simple example above shows it isn't very efficient in absolute terms.
My 800W microwave oven draws about 1300 Watts from the mains. That's about 60% efficient.
Most gas boilers are 70 to upper 80's % efficient.
The "most efficient" claim is probably in the context of cooking. The simple example above shows it isn't very efficient in absolute terms.
John Brown
Freeloading Social media influenza
For a gas boiler, some of the inefficiency may depart via the flue. For a microwave oven, any inefficiency will end up warming your kitchen in one way or another.
Terry - Somerset
Established Member
There are some very basic concepts over which greater clarity is required.
Efficiency expressed in financial or environmental terms will not always align. An example - PVs have far less impact on climate, yet cost more than gas generation.
Improving insulation/controls will reduce energy consumption irrespective of how it is generated.
Financial - costs of improving insulation is compared to costs of energy saved. Environment - pollution from materials used to insulate is compared with those used in power generation.
There can be a disconnect between the financial and environmental - eg: spending (say) £50k to retrofit insulation to a small house may be environmentally beneficial, but financially foolish.
Accepted science is that energy cannot be created or destroyed, only transformed from one form to another. Microwaves, induction hobs, infrared heaters etc cannot produce more energy than is input - although the way it is used may deliver the benefits more effectively.
Even a heat pump with a coefficient of efficiency of (say) 3-4 obeys this basic law - we focus on the internal building temperature and ignore the energy dumped or used from the atmosphere.
Efficiency expressed in financial or environmental terms will not always align. An example - PVs have far less impact on climate, yet cost more than gas generation.
Improving insulation/controls will reduce energy consumption irrespective of how it is generated.
Financial - costs of improving insulation is compared to costs of energy saved. Environment - pollution from materials used to insulate is compared with those used in power generation.
There can be a disconnect between the financial and environmental - eg: spending (say) £50k to retrofit insulation to a small house may be environmentally beneficial, but financially foolish.
Accepted science is that energy cannot be created or destroyed, only transformed from one form to another. Microwaves, induction hobs, infrared heaters etc cannot produce more energy than is input - although the way it is used may deliver the benefits more effectively.
Even a heat pump with a coefficient of efficiency of (say) 3-4 obeys this basic law - we focus on the internal building temperature and ignore the energy dumped or used from the atmosphere.
Stick to Solar PV, even if you then use the generated power solely to feed an electric immersion heater for hot water £ for £ including initial investment it's more efficient than Solar thermal water heating.
Jacob
New Luddism. Wake up and resist.
The attraction of solar thermal is that it is low tech and could potentially work "off grid" when climate change s**t finally hits the fan. This can't be said of the various highly technical alternatives like heat pumps which are very vulnerable to breakdown, need regular specialised service and good infrastructure.
Solar thermal at its simplest means glass - fight the greenhouse effect with greenhouses!
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Stevekane
Established Member
Re the Microwave questain, its correct to say that its efficiency claim that I read somewhere was probably in relation to warming food and it was just an idle thought that perhaps it could heat central heating water as well as forgotten coffee,,but Im sure your all correct. Intrestingly there is a company that was trying to produce microwave boilers, two models on offer, but I couldnt find anything after the initial publicity and as a guess it never got off the ground.
Steve.
Steve.
Jacob
New Luddism. Wake up and resist.
This could run and run!
https://www.bbc.co.uk/news/articles/c88n4p48vgmo
https://www.ecowatch.com/electric-wallpaper-radiant-heat.html
and there may be next generation heat pumps on the way? https://www.timeshighereducation.co...eat-pump-could-cut-energy-bills-and-emissions
https://www.bbc.co.uk/news/articles/c88n4p48vgmo
https://www.ecowatch.com/electric-wallpaper-radiant-heat.html
and there may be next generation heat pumps on the way? https://www.timeshighereducation.co...eat-pump-could-cut-energy-bills-and-emissions
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John Brown
Freeloading Social media influenza
"a 30 to nearly 100% energy reduction"!!!
What next? Electric heating that feeds power back into the grid?
What next? Electric heating that feeds power back into the grid?
Jacob
New Luddism. Wake up and resist.
Cooking the books.
But it's interesting to look at how heat is actually delivered. It gets overlooked when looking just at bare figures; kwh, efficiency etc.
e.g. I've just come out of our long narrow kitchen on a cold evening and having the electric fan heater is brilliant for a short spell of pot washing. It must be cheaper . The gas CH just couldn't compete - they call them "radiators" but they hardly radiate at all. Its all convection up to the ceiling and you might be lucky to feel the benefit after it's been running for some time and heated everything else in the room first.
John Brown
Freeloading Social media influenza
https://www.bbc.co.uk/programmes/m001dxtx
Of course some of you won't believe a word of it, because it's the BBC.
Of course some of you won't believe a word of it, because it's the BBC.
All improvements add up so this is welcome, but does it count as "next generation" when it claims just a 3.7% improvement in efficiency ?
This in a thing that is seeking / claiming 300 to 400% CoP or "efficiency" in the sense of using a small amount of energy to move a bigger amount of energy from the environment to where you want to use it.
Jacob
New Luddism. Wake up and resist.
3.7% at least sounds honest and realistic!
Woody2Shoes
Impressive Member
To be fair, the "lost" 500W would all have been heating up the space around the machine.
Microwaves are very good at warming up water molecules - which ring like a bell at around 2.4GHz - whether those water molecules are within a potato or living tissue. I wouldn't want to heat my house with microwaves - there are other safer and more manageable ways to turn electrical energy into heat.
Woody2Shoes
Impressive Member
If you were installing an air source heatpump, and had some additional land, one idea to improve efficiency in cold weather might be to draw the air through an underground tunnel - to pre-heat it to 8-10C (avoids having to waste energy defrosting the heat exchanger exposed to the incoming air).
