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Thread: Laws of Physics changed in 50 years?

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    Default Laws of Physics changed in 50 years?

    I was reading an article about a well insulated house and came across this, "Space heating is a Daikin reverse cycle air conditioner. Amazing piece of gear, has a coefficient of performance of 5. i.e. 800 watts of electrical energy in = 4000 watts of heat out."

    I and many others were taught that energy cannot be created or destroyed. Has this changed in 50 years?
    Last edited by Guiseppe; 14-07-17 at 04:28 PM. Reason: tpo correction
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    Quote Originally Posted by Guiseppe View Post
    I was reading an article about a well insulated house and came across this, "Space heating is a Daikin reverse cycle air conditioner. Amazing piece of gear, has a coefficient of performance of 5. i.e. 800 watts of electrical energy in = 4000 watts of heat out."

    I and many others were taught that energy cannot be created or destroyed. Has this changed in 50 years?

    No, every reverse cycle aircon pumps more heat than it consumes.
    It is not creating any energy, just steals it from outside.
    It is called a heat pump for a reason

    There are limits though.
    They all have issues if the temperature of the outside 'heat' is significantly lower than inside.
    In most parts of Australia they work OK but you can forget northern parts of Europe.
    Last edited by nomeat; 15-07-17 at 12:11 PM.
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    When i started installing Split Systems, it was around 1:3, then 1:3.5 (25 years ago), it wouldn't surprise me at all that its 1:5 now.

    No Laws of Physics changed here.
    You just need to understand whats at play

    The output Kw ratings are kind of arbitrary figures, essentially based on what it would take to create the same amount of Heating from a straight resistive load.
    I guess the Cooling specs are somehow based on the same principle.
    Last edited by oceanboy; 15-07-17 at 12:13 PM.
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    The theoretical limit is 8.8 for 0 to 35˚, so we still have some room for developement.
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    Quote Originally Posted by nomeat View Post
    No, every reverse cycle aircon pumps more heat than it consumes.
    It is not creating any energy, just steals it from outside.
    It is called a heat pump for a reason .
    Quote Originally Posted by oceanboy View Post
    When i started installing Split Systems, it was around 1:3, then 1:3.5 (25 years ago), it wouldn't surprise me at all that its 1:5 now.

    No Laws of Physics changed here.
    You just need to understand whats at play
    I must be having a bad brain day - it seems completely illogical that you can get more out than you are putting in. What about friction, electrical losses, etc?

    EDIT: As an experiment I fired up our LG LGM304V-6. It is nameplated as 9500W heating. The electricity meter states 266.6 revs/kWhr. Timed 13 revs and multiplied by 20 (rough I know) to get 2600 seconds/kWhr. Round figure is 1.5kW/hr. The question now is how can I measure 9500W of heat?

    I should add it in no way feels like I would expect 9500W of silica sheathed radiator to feel.

    Then again consumption is not 9500W either ....
    Last edited by Guiseppe; 15-07-17 at 02:37 PM.
    If Australia is a democracy why, then, is voting compulsory?

    "What has changed between the arrival of the First Fleet and today?"
    "Wearing leg irons is now not required."

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    Quote Originally Posted by Guiseppe View Post
    ...I and many others were taught that energy cannot be created or destroyed. Has this changed in 50 years?
    Yes, the Law of the Conservation of Energy states that 'Energy can be neither created nor destroyed but merely changed from one form to another'.

    A heat pump works by transferring (or pumping) heat from one area to another, i.e. in the case you have mentioned, from the outside air to the inside air. Hence its name, 'heat pump'.

    It's much like using a truck to transport a ton of sand from one location to another. In doing so, a certain amount of energy is consumed, resulting in a certain cost per ton.

    Now, if we make the truck more efficient, i.e. increase the efficiency of each component of the truck, its motor, transmission etc. by the use of more efficient fuel, bearings and lubricants (to reduce energy-consuming friction), the amount of energy and also therefore the overall cost of moving that ton of sand becomes less, when compared to what it was previously.

    Modern air-conditioners use a mechanism referred to as a 'heat pump', i.e. heat is 'pumped' or transferred from one area to another. In the case of cooling the inside of a building, heat is moved from inside to outside. In the case of heating the inside of a building, the reverse applies.

    The amount of energy consumed in doing this is analogous to the amount of energy, and hence also the cost involved, of moving the ton of sand from one location to another. The difference in the case under discussion is that we are transferring or moving heat rather than sand.

    There are a few good video presentations relating to 'heat pumps' on Youtube. Go to . There are more listed in the RHS panel.

    I have not seen an example of the method used to calculate the "coefficient of performance of 5. i.e. 800 watts of electrical energy in = 4000 watts of heat out."

    The amount of (input) energy used by the air-conditioner is easy to measure and I can remember doing an inordinate number of exercises in high school physics lessons in which we had to calculate the amount of energy (BTU's/Calories) used/consumed in performing particular tasks. The same methods have to apply also in the this instance.

    The "4000 watts of heat out" has apply to the increase in inside temperature and the volume of air heated.

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    In the real world no motor is 100% efficient.

    In the example there is a compressor < 100% efficient

    Not shown but needed is the fan on the condenser <100% efficient

    Also not shown but needed is the motor needed to pump the hot liquid into the floor coils or radiator <100% efficient

    Also not shown but needed is the motor to bring the heat from the heat source to the evaporator <100% efficient

    So where/how does the magic happen?
    Last edited by Guiseppe; 16-07-17 at 02:01 PM.
    If Australia is a democracy why, then, is voting compulsory?

    "What has changed between the arrival of the First Fleet and today?"
    "Wearing leg irons is now not required."

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    Quote Originally Posted by Guiseppe View Post

    So where/how does the magic happen?
    Evaporation and Condensation is where the Magic Happens
    And a little bit of marketing and incorrect use of figures

    Just be grateful you're not in America mate, they talk in Tons!
    Ie: A 4 Ton AC unit
    Which is not a reflection of the weight of the unit, it is a number that tells how much heat the air conditioner can remove from the house in an hour.
    Last edited by oceanboy; 16-07-17 at 06:50 PM.
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    Evaporation and condensation is simply change of state which, I would have thought, is not 100% efficient.

    I should have added in my post above that, in the example quoted, there are two heat exchangers - again not 100% efficient.

    It would seem that the magic happens, as you say, in the marketing. Is there no independent authority, body or organisation that checks these claims or is the industry "self regulated"?
    If Australia is a democracy why, then, is voting compulsory?

    "What has changed between the arrival of the First Fleet and today?"
    "Wearing leg irons is now not required."

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    Guiseppe, your argument is not making sense in your head, because the question is wrong.
    A Heat Pump, Split System doesn't make 8000Watts of Output, it just doesn't.
    If anything, the output should be represented in Kj, not Kw.

    I believe the Kw or Watt output rating relates to the old way we used to buy and size AC units, in HP.
    You'd buy a 1Hp unit, or a 2.5Hp unit etc

    Your argument is similar to Watts in verse Lumens Out
    When we only had the Incandescent Bulb, it was either 25 Watts, or 60Watts or 100Watts and the light output was in direct correspondence to the power input (more or less).
    Now we have Vapour Discharge Lamps, LEDs, etc

    A 2 Watt LED can have the same Lumen output a 100Watt incandescent had.
    In much the same was a Heat Pump works in comparison to a standard bar radiator.

    But no extra energy is created
    As mentioned, the Kw output is just made up.
    It is either a vague estimate of what a purely resistive heating element would take to create the same heat or in relation to the old way we used to buy AirCons, by Horsepower.
    Last edited by oceanboy; 17-07-17 at 02:02 PM.
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    OK. How should Joe and Jill Average interpret Scroll down a bit and you will see:

    Heating: Power Input 0.8kW Capacity Output 4.90kW, and

    Cooling: Power Input 0.82kW Capacity Output 4.75kW
    Last edited by Guiseppe; 17-07-17 at 05:56 PM. Reason: Rephrased the question.
    If Australia is a democracy why, then, is voting compulsory?

    "What has changed between the arrival of the First Fleet and today?"
    "Wearing leg irons is now not required."

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    As a guide

    Essentially, what is to interpret?
    You measure your room, size the unit to suit.

    If they expressed the Output values correctly, it would in Kj/min or Kj/hr or Btu/min
    Joe Average would have no idea
    Last edited by oceanboy; 17-07-17 at 07:09 PM.
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    I ran this conumdrum past a friend, who has an extensive electronics engineering background, as well as having managed the service department of a very large company supplying, installing and maintaining, among other things, refrigeration and air conditioning equipment etc.

    He responded by e-mail a few minutes ago and tells me that it is all to do with 'ENTROPY'.

    I reproduce his reply verbatim (including a relevant link to look up) below:


    [Quote]
    I donít understand the physics maths but it explains Entropy can get higher efficiencies because you are not using additional energy.

    Entropy, Quantified

    Whole books can be written about the gnarly properties of entropy. Put simply, entropy is a measure of disorder. Strictly speaking, entropy is all about counting the number of quantum-mechanical states that can be occupied at a certain system energy.

    Moving Heat

    A heat pump, rather than creating heat, simply moves heat. It may move thermal energy from cooler outdoor air into the warmer inside, or from the cooler refrigerator interior into the ambient air. It pushes heat in a direction counter to its normal flow (cold to hot, rather then hot to cold). Thus the word pump.

    Read this article...



    Theoretical efficiency limits, so we canít squeeze too much more out of this orange. After all, nothing can be more than 100% efficient, can it? Well, it turns out there is one domain in which we can gleefully break these bonds and achieve far better than 100% efficiency: heat pumps (includes refrigerators). Even though it sounds like magic, we still must operate within physical limits, naturally. In this post, I explain how this is possible, and develop the thermodynamic limit to heat engines and heat pumps. Itís a story of entropy.

    Good luck this is heavy duty physics.
    [End of Quote].

    My advice is, read the complete article, where all will be revealed...hopefully

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    I like that.

    And what it shows, is that AC's are very inefficient when you consider the thermal properties
    Yet people are so wound up by the perceived electrical efficiencies
    When if fact, no heating or cooling is actually created at all.
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    "Inevitably, I have to run some machinery to affect this flow of heat ..."

    "That mechanical/electrical/whatever energy also ultimately turns to heat, and if I cleverly send this additional energy to the hot place ..."

    Sorry but it doesn't. Some energy is used in "pumping" the heat and only some will turn to heat - friction, etc of the mechanical/electrical whatever.

    It is a bit like the "proof" we saw at Tech that 1 = 2.
    If Australia is a democracy why, then, is voting compulsory?

    "What has changed between the arrival of the First Fleet and today?"
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    Guiseppe, I mentioned your dilemma to a marine engineer friend, who in another life was involved in the installation/maintenance of on-board mechanical and electrical systems on various naval vessels (RAN).

    His advice was to do some reading about thermodynamics and to pay particular attention to the terms 'enthalpy' and 'entropy'.

    He also stated that it was more efficient to move heat than to create or generate heat and this is the reason for the high efficiency of a heat pump.

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    Or is it high efficiency?
    If you consider that outside your house, there is 80,000watts of potential heat to be extracted from the atmosphere (a wild guess)
    And all we can squeeze out is 8000watts for 1200watts consumed.

    I remember something about this at Fridgy School, in that using different refrigerants allows for a much greater heat transfer, yet these compounds were either explosive, flammable or in some other way not safe to handle.
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    Quote Originally Posted by tristen View Post
    pay particular attention to the terms 'enthalpy' and 'entropy'.
    From I note:

    For example, compressing 1 kg of nitrogen from 1 bar to 200 bar costs at least (hc − ha) − Ta(sc − sa). With the data, obtained with the TĖs diagram, we find a value of (430 − 461) − 300 ◊ (5.16 − 6.85) = 476 kJ/kg.

    Nitrogen is not the refrigerant being used but the concept is valid. Work has to be done (i.e. energy expended) to compress the refrigerant.

    Quote Originally Posted by tristen View Post
    it (is) more efficient to move heat than to create or generate heat
    OK. I can run with that.

    Quote Originally Posted by tristen View Post
    this is the reason for the high efficiency of a heat pump.
    In the real world "something":

    (a) has to compress the gaseous refrigerant (reduce the volume, increase the pressure and temperature) resulting in the hot gas being "pumped" to the heat exchanger, and

    "something":

    (b) has to move the hot air from the heat exchanger into the room to be heated.

    Both of these "something(s)" are less than 100% efficient. The heat exchanger would also be less than 100% efficient.
    Last edited by Guiseppe; 20-07-17 at 06:38 PM.
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    On this forum you will obey the laws for thermodynamics

    I can offer a simplistic view for the average people here.
    I have a magical device called a "heat pump".
    This heat pump, pumps heat (duh) just like water. But it also uses electricity which it converts to heat, in order to operate the pump.

    Lets call our unit of heat BTU's.
    My heat pump pumps 10 BTUs of heat from point A to B and to do this it uses 1 BTU of electricity, which it converts to heat and adds it to the output.

    Input 10 BTU ------+--------> 11 BTU output.
    Electricity 1BTU ---+


    However in this case, for a simple air conditioner, we can consider it a device that just converts electricity into heat.
    If it uses 1000 watts of electricity, then it cannot output more than 1000 watts of heat. That's thermodynamics 101.
    Consider that an air conditioner makes noise. Lets say it's loud and makes 10 watts of noise. 990W of heat is produced.

    In terms of a heat pump. Lets assume the room is 10 degrees. We want to heat it to 20 degrees.
    We might use 10 BTU to do this. However if we have a tank of water we heated to 15 degrees (with the same magical capacity) then we could exchange the heat in the room with that of the tank (It doesn't work like this in reality - it equalizes with diminishing returns).
    But for this example we will just say we get 5BTU from the tank and then use 5BTU of electricity to bring the room up to 20 deg.
    We still used 10BTU, no free lunch in this universe

    IF (energy out) > (energy in) THEN [reality=bullshit]
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    Gosh I am amazed what a complicated and confusing thread this turned out to be.

    In my post #2 I said simply:
    It is not creating any energy, just steals it from outside
    Maybe try to imagine the heat pump a bit like a switched mode power supply.
    Outside you have a large volume of heated* air at a lower temperature like a high voltage at lower amps. It is like mains power(energy for grabs).
    Your switched mode transformer will take some of that energy and convert that to a low voltage (smaller volume of air) at higher amps (higher temperature)
    In both cases no energy is created just transformed, while the transforming device requires some extra energy to function and your condenser(heat exchanger) acts like a resistor for the load.

    * it is way over -273.15˚C so it's molecules contain a considerable amount of kinetic energy.


    As for the principle of heat pumps, there are heaps of explanations on the net but I usually find Wikipedia does the best job:

    and if you like can work you way though the Carnot cycle where it gets really fun
    Last edited by nomeat; 21-07-17 at 02:29 PM.
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