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Best option for electric heating?

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  • Ebe_Scrooge
    Ebe_Scrooge Posts: 7,320 Forumite
    Part of the Furniture 1,000 Posts Name Dropper Combo Breaker
    Being pedantic, all the energy consumed by the fan is converted into heat (via friction), so there is no waste and no argument.


    Being even more pedantic, it's just converting energy from one form to another. The fan converts electrical energy into kinetic energy ( movement ). Yes, friction will produce some heat, but some of the energy is converted to kinetic energy, so will not produce heat. As I said originally, the amount we're talking about is teeny-tiny - you'd probably even struggle to measure it. But theoretically, a fan heater does not convert 100% of the electrical energy into heat energy.
  • but some of the energy is converted to kinetic energy, so will not produce heat.

    and that kinetic energy, all turns into heat.
    But theoretically, a fan heater does not convert 100% of the electrical energy into heat energy

    A fan heater in reality converts 100% of the electrical energy into heat so a 2KW fan, and a 2KW heater would both produce exactly the same amount of heat.
  • david1951
    david1951 Posts: 431 Forumite
    Fifth Anniversary Combo Breaker
    and that kinetic energy, all turns into heat

    Agreed. All the energy going into an electric heater, at some point, dissipates into heat energy.
  • 27cool
    27cool Posts: 267 Forumite
    As all electric heaters have the same efficiency (100%). The only reason for choosing one type of heater over another is the ease of use.
    That is a decision that you will have to make depending on how and when you want the heat to be available.
  • Kernel_Sanders
    Kernel_Sanders Posts: 3,617 Forumite
    Part of the Furniture 1,000 Posts Combo Breaker
    edited 28 January 2017 at 1:28AM
    A fan heater in reality converts 100% of the electrical energy into heat
    Not quite! Fans aren't silent, so a fraction of the what, 25W they might use must be converted solely into sound.
    I'm not sure if the same applies to the light produced by a halogen heater though. I know that light can't be produced without also generating heat, so is that light in effect 'free', in the same way that the motion of the blades in the kinetic energy example is?
  • Ebe_Scrooge
    Ebe_Scrooge Posts: 7,320 Forumite
    Part of the Furniture 1,000 Posts Name Dropper Combo Breaker
    OK, now I'm genuinely interested !

    Putting aside the fact that, for all practical purposes, all electrical heaters are 100% efficient at converting electrical energy into heat energy ......

    And accepting that we're talking here about minuscule amounts, probably amounts that can't even be measured ....

    But remembering my physics lessons from - quite a lot of - years ago, conservation of energy : energy cannot be created or destroyed, only converted from one form to another ....

    So the aim of a heater is to convert electrical energy to heat energy. A fan heater also creates kinetic and sound energy. A halogen heater also creates light energy. Is this "wasted", in terms of trying to convert the electricity to heat ? Certainly, an incandescent lightbulb "wastes" quite a lot of energy in producing heat, when it could be producing light - the light is what's wanted, the heat is a by-product and cannot be (realistically) used. Hence the raft of new developments in efficient lightbulbs ( first fluorescent tubes, then LEDs, and whatever else ) - trying to turn as much of the electricity into light energy with as few losses as possible.

    Not disagreeing with anyone here, genuinely interested to know the facts. Any Physics professors amongst us ??
  • Apodemus
    Apodemus Posts: 3,410 Forumite
    Ninth Anniversary 1,000 Posts Name Dropper Combo Breaker
    Not a physics professor, but my recollection is that both light and kinetic energy also end up getting converted into heat.

    I've never been quite comfortable with my office's insistence that we turn off lights and computers as much as possible, at the same time as all our heating is thermostatically-controlled electric. We are saving on the waste heat from the appliances and replacing it with deliberate heat from the heating system!
  • I have a physics degree, although not quite a professor...my understanding is that whatever form of energy you come up with (light, sound, etc.) this will, at some point, be convertable to heat energy in the room.

    Light is essentially electromagnetic waves, which heat up whatever they come into contact with (e.g., solar panels). Sound is made up of pressure waves which, again, will cause whatever they hit to heat up (see e.g., ultrasound).

    So the 100% efficiency would appear to be, in theory, correct.

    However, I got confused when starting to think about which efficiency we are talking about. Is it the amount of energy from the heater that is converted into heat in the room, in which case light or sound waves going out the window (or through the walls) will not be converted to heat in the room. I imagine that "efficiency" in the sense of an electric heater can be defined in some way to get around this point...
  • J_B
    J_B Posts: 6,810 Forumite
    Part of the Furniture 1,000 Posts Name Dropper Photogenic
    So, as we are getting technical :D

    We have a house in Cyprus with 'inverter' type A/C units.

    People there tell us that by using these to provide heat in the winter, we get a better efficiency (2 or 3 times better?) than if we use a simple electric heater.

    True or false?
  • Apodemus
    Apodemus Posts: 3,410 Forumite
    Ninth Anniversary 1,000 Posts Name Dropper Combo Breaker
    Assuming these are acting as air-source heat pumps during the winter, then the figures you quote could be correct. Ground-source heat pumps often cite a 1:4 return on the electricity used.

    In energy terms, of course, the bulk of the energy input is from the ambient temperature of the air, it is not being created from nothing...even if it is "appearing out of thin air"!
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