reverse cycle air conditioning heating is more efficient??

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View



A reverse cycle AC dealer was telling me the other day that using the
heating setting on the unit was more efficient than using a cheap blow
heater.

How could this be?

Say both units use 10 amps at 240 V ... That equals 2400W of energy.

Now the inefficiencies in a simple blow heater would be small..... a bit of
noise energy..

But in a reverse cycle AC unit, the ineficiencies would be large....
external pump, more noise, friction and losses in the pipes....

 surely the blow heater is more efficient?

Right??




Re: reverse cycle air conditioning heating is more efficient??


Quoted text here. Click to load it

    An airconditioner (like a fridge), is what's called a 'heat pump'.
In the reverse cycle mode, it moves heat energy from outside to inside.
That's why the external evaporator gets cold. So you get more heat
energy out of it, than the electrical energy you put into it.
    At least that's what I was told. :-)

Bob

Re: reverse cycle air conditioning heating is more efficient??



Quoted text here. Click to load it
No, the reverse cycle air conditioning is up to 250-300% more efficient but
more like on average around 200 - 250%



Re: reverse cycle air conditioning heating is more efficient??



Quoted text here. Click to load it

Reverse cycle A/C extracts latent heat from the outside and passes it to the
heat exchange unit on the inside.  Even when it's cold outside there is
still some latent heat that can be extracted with relative efficiency.
However efficiency in the reverse cycle mode decreases as the outside
temperature approaches 0 deg. C compared to warmer outside temperatures.
Ice can often form on the outside unit, further reducing its efficiency.  In
installations where outside temperatures are likely to go below 0 deg C, a
de-icing element unit should be used.

Cheers,
Alan



Re: reverse cycle air conditioning heating is more efficient??



Quoted text here. Click to load it

Well I believe another term for the refrigerative A/C might be a HEAT PUMP!
When heating it is actually transfering heat from the outside of you house
to the inside, when cooling transfering heat from the inside to the
outside....hmmm....ever wondered why the output ratings of the A/Cs is
higher than the input power consumption? Using electrical energy to move
heat. The little fan heater on the other hand is converting the electrical
energy to heat.

James



Re: reverse cycle air conditioning heating is more efficient??



"Trevor Wilson"  wrote


Nope. You'd be wrong. Almost all heaters are pretty damned close to 100%
efficient. Modern air cons can be up to 500% efficient.


****** I just can't believe that you have single handedly solved the worlds
energy problems for all eternity!!!!!!

500% efficient!!!

The mind boggles!!!


Wota wanker!!!!!!!!!!!


Brian Goldsmith.







Re: reverse cycle air conditioning heating is more efficient??


Quoted text here. Click to load it
Badly explained but sorta .

Re: reverse cycle air conditioning heating is more efficient??



Quoted text here. Click to load it

**Nope. Energy still needs to be expended to heat or cool. There's no such
thing as a free lunch.

Quoted text here. Click to load it

**How do YOU explain the equivalent of 5kW of heating capacity from 1kW of
electrical input? The air condictioning industry calls it EER (Energy
Efficiency Ratio) or COP (Coefficient Of Performance).


--
Trevor Wilson
www.rageaudio.com.au



--

Re: reverse cycle air conditioning heating is more efficient??



Quoted text here. Click to load it

The rest of the world calls it 'marketing', except for scientists, who
call it 'a physical impossibility'.





Re: reverse cycle air conditioning heating is more efficient??


Quoted text here. Click to load it
In fact with reverse cycle the energy consumed in pumping heat from one
place to another needn't approach anywhere near the amount of heat moved ..
  Std laws of physics  and that's not marketing .

Re: reverse cycle air conditioning heating is more efficient??



Quoted text here. Click to load it

**Not really. It was a scientist who invented air conditioning.


--
Trevor Wilson
www.rageaudio.com.au



--

Re: reverse cycle air conditioning heating is more efficient??


Quoted text here. Click to load it
Maybe you should go back to school and learn something about thermodynamics.

Re: reverse cycle air conditioning heating is more efficient??




Quoted text here. Click to load it

I would, but Im too busy building my perpetual motion machine using
thermodynamics :)


Re: reverse cycle air conditioning heating is more efficient??


On Sun, 03 Dec 2006 05:47:35 GMT, swanny

Quoted text here. Click to load it

I kinda remember doing thermodynamics, albeit, i am struggling. Heat
pump is a marketing thing according to thermodynamics.

However, a 'heat pump' is more efficient than an element because as
well as creating heat from using electricity is is also 'moving heat'
from as a side affect of that process, therefore making it more
efficient than a plain electric element heater.

If one thinks these devices are 500% efficient, then go do the math.
Energy is not free (basic physics) and there is still going to be
energy lost. If one was comparing the effeciency compared to a wood
heater, then the RELATIVE difference may well be 500%. Please people,
it's all basic physics, if you wish to make outlandish claims them
plese put it into context so it is then beleiveable.

BTW. IF one was saying 500% percent relative to the power used then a
reverse cycle aircon would be returning power to the grid. IE, the
aircon would cost nothing to run.

Re: reverse cycle air conditioning heating is more efficient??



Quoted text here. Click to load it

**Of course, no one is saying such a thing. An air con with an EER of 5,
will produce as much heat (under ideal conditions) as a 5kW resistive
heater, with 1kW of electrical power input.


--
Trevor Wilson
www.rageaudio.com.au



--

Re: reverse cycle air conditioning heating is more efficient??


Quoted text here. Click to load it

I beg to differ! Heat energy IS free, as supplied from our sun. The part
that is not free is concentrating and directing it for our use. The heat
from a rev cycle AC costs nothing. The electricity to collect and move that
heat is the only thing we pay for. On the other hand, the heat from a
radiator style heater costs heaps due to the fact that electric energy is
converted to heat. Therefore the 500% efficiency figure quoted is realistic
IF compared to a radiator.

Quoted text here. Click to load it



Re: reverse cycle air conditioning heating is more efficient??



Quoted text here. Click to load it

Sure, its 'free' in terms of dollars - but when you talk about efficiency,
you dont talk dollars. You talk energy in vs energy out (in a useful form).



Re: reverse cycle air conditioning heating is more efficient??


Quoted text here. Click to load it

It's all in the terminology and how you measure it.
Reverse cycle aircons have a greater "efficiency" than that of an
equivalent output electric heater. If the electric heater is deemed to
be "100% efficient" then a reverse cycle aircon that produces say 2kW
of *heat energy* for 1kW of electric energy, then it can be said that
the aircon is 200% efficient compared to the electric heater. That is
the way reverse cycle aircons are rated and marketed, but it's *not* a
marketing gimmick. It is the actual practical heat energy output that
heats up a given volume of air.

A 7kW reverse cycle aircon for example actually gives you 7kW of *heat
energy* for only a few kW of electrical energy input. That is much
better than what you can achieve with an electric heater.

It all has to do with how you measure the heat energy in a system.
One formula for heat energy output of a system is :
Heat Energy(kW) = Specific Heat of Air (kJ/kg degK) * Air Mass
(kg/hour) * (Temp differential /3600)

Dave :)


Re: reverse cycle air conditioning heating is more efficient??


Quoted text here. Click to load it

Heat energy IN is free energy, the only thing thats NOT free is the delivery
of that free heat energy.



Re: reverse cycle air conditioning heating is more efficient??



Quoted text here. Click to load it

So if I steal a tank of fuel I can claim my car is infinitely efficient?

Cmon guys.



Site Timeline