Why isn't reversible airconditioning used more for heating in the UK?

I have just installed a unit costing 259 Euro which gives a heat
output 3900 W for an electrical input of 1300 W. I calculate that I
will save more than the cost of the unit in the first year of use.

OK, it only works down to -5 C external temperature but for a few Euro
more you can buy one which will work down to -12 C which will cover
most heating requirement and can be supplimented by other heating in
really cold weather.

Regards,
Russell.

On Sat, 01 Oct 2005 10:56:23 +0200, Russell Eberhardt
wrote:

| Why isn't reversible airconditioning used more for heating in the UK?
|
| I have just installed a unit costing 259 Euro which gives a heat
| output 3900 W for an electrical input of 1300 W. I calculate that I
| will save more than the cost of the unit in the first year of use.

Well electricity is more expensive than gas, so how much would getting the
same amount of heat from gas cost?



--
Dave Fawthrop dave hyphenologist co uk
The London suicide bombers killed innocent commuters.
Animal rights terrorists and activists kill innocent patients.

Russell Eberhardt wrote:

I have just installed a unit costing 259 Euro which gives a heat
output 3900 W for an electrical input of 1300 W. I calculate that I
will save more than the cost of the unit in the first year of use.

That is interesting. What model is it? Is it available in the UK?

"Dave Fawthrop" wrote in message
...
On Sat, 01 Oct 2005 10:56:23 +0200, Russell Eberhardt
wrote:

| Why isn't reversible airconditioning used more for heating in the UK?
|
| I have just installed a unit costing 259 Euro which gives a heat
| output 3900 W for an electrical input of 1300 W. I calculate that I
| will save more than the cost of the unit in the first year of use.

Well electricity is more expensive than gas, so how much would getting the
same amount of heat from gas cost?



Off peak isn't a lot of good unless you can put the higher grade heat energy
into a "heat store" and I don't feel that's very practical.

For every kW of electricity you burn, a further 3 will have gone up a
chimney or in heating the environment in transmission losses.

It's probably more suited to rural places which don't have piped natural
gas.

Overall it's a good idea but not really that green.

"Fred" wrote in message
...

"Dave Fawthrop" wrote in message
...
On Sat, 01 Oct 2005 10:56:23 +0200, Russell Eberhardt
wrote:

| Why isn't reversible airconditioning used more for heating in the UK?
|
| I have just installed a unit costing 259 Euro which gives a heat
| output 3900 W for an electrical input of 1300 W. I calculate that I
| will save more than the cost of the unit in the first year of use.

Well electricity is more expensive than gas, so how much would getting
the
same amount of heat from gas cost?



Off peak isn't a lot of good unless you can put the higher grade heat
energy
into a "heat store" and I don't feel that's very practical.

For every kW of electricity you burn, a further 3 will have gone up a
chimney or in heating the environment in transmission losses.

It's probably more suited to rural places which don't have piped natural
gas.

Overall it's a good idea but not really that green.

Or cheap to run. Gas per kW is approx 1/4 to 1/3 the price of electricty.
The figures quoted were best case examples, which is a COP of three. When
the outsuide temperature drops that COP 3 will drop to around COP 2. So,
for heating, which this country needs more than cooling, they are not cheap,
and complex too. A Myson fan heater is about £300 and works off the CH wet
system, and will heat a large room and quite quickly too being around 9 kW
as opposed to the near 4 kW od this unit, which will tail off when the
oiutside get lower - just when you don't want it too.

Also split a/c units make the outside of a house look downright ugly.

In article ws.net,
Doctor Drivel wrote:
Also split a/c units make the outside of a house look downright ugly.

But you just love those outside water heaters. Is there no end to your
faces?

--
*Why is it that rain drops but snow falls?

Dave Plowman London SW
To e-mail, change noise into sound.

Aidan wrote:

That is interesting. What model is it? Is it available in the UK?

Plenty of heat pump models about:
http://www.uk-airconditioning.co.uk/

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:
Plenty of heat pump models about:

But not that many for =80260.

"Dave Plowman (News)" through a haze of senile
flatulence wrote in message ...
In article ws.net,
Doctor Drivel wrote:

Also split a/c units make the outside of a house look downright ugly.

But you just love those outside water heaters.

I do.

Russell Eberhardt wrote:
Why isn't reversible airconditioning used more for heating in the UK?

I have just installed a unit costing 259 Euro which gives a heat
output 3900 W for an electrical input of 1300 W.

So the energy output is 3 times the input? How is this possible?

cheers

Jacob

wrote in message
oups.com...

Russell Eberhardt wrote:
Why isn't reversible airconditioning used more for heating in the UK?

I have just installed a unit costing 259 Euro which gives a heat
output 3900 W for an electrical input of 1300 W.

So the energy output is 3 times the input? How is this possible?

cheers

Jacob


Remember it's taking most of the heat from the outside.

In article .com,
says...

Russell Eberhardt wrote:
Why isn't reversible airconditioning used more for heating in the UK?

I have just installed a unit costing 259 Euro which gives a heat
output 3900 W for an electrical input of 1300 W.

So the energy output is 3 times the input? How is this possible?

It's a heat pump. You know how the back of a fridge gets warm when it's
cooling the inside? Well the heat pump takes heat from outside and
brings it inside instead. Outside is cooler than inside, which is why
you need a pump to make the heat go uphill :-)

Russell Eberhardt wrote:

Why isn't reversible airconditioning used more for heating in the UK?

Probably because much of it has acess to cheap (ish) gas and expensive
electricity (i.e. four times the cost of the gas).

I have just installed a unit costing 259 Euro which gives a heat
output 3900 W for an electrical input of 1300 W. I calculate that I
will save more than the cost of the unit in the first year of use.

If you are forced to heat with elctricity, then this is a very much
cheaper way of doing it. It is also quite handy for spot heating where
it would not be simple to extend your existing wet system
(conservatories being a good example).

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

wrote:

Russell Eberhardt wrote:
Why isn't reversible airconditioning used more for heating in the UK?

I have just installed a unit costing 259 Euro which gives a heat
output 3900 W for an electrical input of 1300 W.

So the energy output is 3 times the input? How is this possible?

Of course, if you could source a reliable gas fired heat pump, using
an IC engine, then it gets much better.

25% of the energy comes out as shaft power, so you can get maybe 110%
or so of heating, before adding in the 75% of waste heat, for 185% or so
of the heating normally provided by gas.

And this has the side-effect that if you have low temperature sources
of heat, such as low temp solar panels, then you can couple these in, to
improve the output temperature of the system.

Russell Eberhardt wrote:
Why isn't reversible airconditioning used more for heating in the UK?

I have just installed a unit costing 259 Euro which gives a heat
output 3900 W for an electrical input of 1300 W. I calculate that I
will save more than the cost of the unit in the first year of use.

OK, it only works down to -5 C external temperature but for a few Euro
more you can buy one which will work down to -12 C which will cover
most heating requirement and can be supplimented by other heating in
really cold weather.

Regards,
Russell.

COP=3 is youre best case scenarion. When its freezing outdoors you'll
probably find COP=1 or so. Also if its air source, as it probably is,
at cold temps you get ice on the absorber, which drops COP even
further.

Yes its better than plug in fires, and probably better than E7 storage,
but its not as great as it first looks.

Flat plate solar space heating probably gives better returns.


NT

Rob Morley wrote:
In article .com,
says...

Russell Eberhardt wrote:
Why isn't reversible airconditioning used more for heating in the UK?

I have just installed a unit costing 259 Euro which gives a heat
output 3900 W for an electrical input of 1300 W.

So the energy output is 3 times the input? How is this possible?

It's a heat pump. You know how the back of a fridge gets warm when it's
cooling the inside? Well the heat pump takes heat from outside and
brings it inside instead. Outside is cooler than inside, which is why
you need a pump to make the heat go uphill :-)

Are you saying that an electric fridge will produce more heat than an
electric heater working at the same power? If so then you have
discovered a source of free energy which could make fossil fuel,
nuclear power etc all redundant!! There must be a catch.

cheers

Jacob

In article . com,
writes:

Are you saying that an electric fridge will produce more heat than an
electric heater working at the same power? If so then you have
discovered a source of free energy which could make fossil fuel,
nuclear power etc all redundant!! There must be a catch.

The condensor (rear warm element) gives off more heat than the
power consumption of the appliance. The extra heat comes from
the inside of the fridge, which is why it gets cold. Ultimately
of course, that comes from the outside of the fridge due to
the imperfect insulation and opening the door from time to time.
This exactly cancels out the extra heat from the condensor, so
the fridge's contribution to room heating is exactly its power
consumption.

However, if you could somehow put the fridge condensor indoors
and the rest of the fridge outdoors, now you are stealing this
extra heat from outdoors, and so the net heat output into the
room is more than the fridge's power consuption, and the fridge
will be cooling down the outdoors very slightly as a result of
stealing heat from it. This is exactly how a heat pump heater
works -- you use some energy to pump extra energy from the
outdoors to the indoors. The outdoors is the source of extra
energy -- it's not free because it consumes energy to pump it
inside, but the total energy you get inside is the sum of the
energy stolen from outside plus the energy used to pump it in.

I've mentioned this before, but one of my favourate questions to
put to physics students is: In a perfectly thermally insulated
room, if you were to leave a fridge operating with its door open,
what happens to the room temperature?

***SPOILER SPACE***
Try to answer the question before scrolling down to the answer...





































The 3 different answers show have far the student has understood
this area of thermodynamics...

"The room gets cold"
-- no understanding at all.
"The room temperature stays the same"
-- understands that a fridge transfers heat from the
inside to the outside, so the fridge won't cool the
room.
"The room gets hotter"
-- understands that it requires energy to transfer heat
from a cooler to a warmer location.

--
Andrew Gabriel

wrote:

Running on
economy 7 will be cheaper if the heat is useful at that time of day, and if
you already have the heatpump for use as aircon.

You need to have all your heating satisfied by the E7 schedule, else
its more expensive. Everyone knows its half price at night, but not
everyone knows the daytime tariff on E7 is higher, and the saving
thusly goodly shrunk. Its easy to end up paying more on E7.

NT

On 1 Oct 2005 02:59:00 -0700, "Aidan" wrote:


That is interesting. What model is it? Is it available in the UK?
Airton model AS-12HR53 - bought at Brico Depot in France. They have a
conveniently placed store at Calais tel. 00 333 21 17 07 23

Russell.

On 1 Oct 2005 07:34:47 -0700, wrote:

COP=3 is youre best case scenarion. When its freezing outdoors you'll
probably find COP=1 or so. Also if its air source, as it probably is,
at cold temps you get ice on the absorber, which drops COP even
further.
Where I live the climate is very dry so this is less of a problem.

Yes its better than plug in fires, and probably better than E7 storage,
but its not as great as it first looks.

Flat plate solar space heating probably gives better returns.
Now, what area of solar plate will I need to gain 3900 W? Can I get
one that works at night when it is coldest outside? Can I install it
for 260 Euro?

Russell.

On Sat, 01 Oct 2005 10:49:48 +0100, Dave Fawthrop
wrote:

Well electricity is more expensive than gas, so how much would getting the
same amount of heat from gas cost?
Unfortunately gas is not an option here. Note also that the cost of
gas is rising with the cost of oil and North Sea reserves are low.

Russell

On Sat, 01 Oct 2005 10:56:23 +0200, Russell Eberhardt
wrote:

Why isn't reversible airconditioning used more for heating in the UK?

iirc, there is some scheme in the UK whereby you can claim some/all of
the VAT back if you install a reversible aircon unit.

sponix

wrote:

its more expensive. Everyone knows its half price at night, but not
everyone knows the daytime tariff on E7 is higher, and the saving
thusly goodly shrunk. Its easy to end up paying more on E7.

I always thought that was the case, but when a mate looked into it with
his supplier (I forget which) he found that the day time rate was
actually exactly the same as the suppliers normal tarrif. The sting was
that the E7 tarrif had a higher standing charge.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Russell Eberhardt wrote:

Unfortunately gas is not an option here. Note also that the cost of
gas is rising with the cost of oil and North Sea reserves are low.

What do you think most of the power stations run on then? ;-)

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Huge wrote:
writes:

Rob Morley wrote:
In article .com,
says...

Russell Eberhardt wrote:
Why isn't reversible airconditioning used more for heating in the UK?

I have just installed a unit costing 259 Euro which gives a heat
output 3900 W for an electrical input of 1300 W.

So the energy output is 3 times the input? How is this possible?

It's a heat pump. You know how the back of a fridge gets warm when it's
cooling the inside? Well the heat pump takes heat from outside and
brings it inside instead. Outside is cooler than inside, which is why
you need a pump to make the heat go uphill :-)

Are you saying that an electric fridge will produce more heat than an
electric heater working at the same power?

Until the source of heat is exhausted, yes.

What source of heat? At startup the air temp in and out is the same so
there is no heat differential or 'source of heat' unless you put
something hot in the fridge.

If so then you have
discovered a source of free energy which could make fossil fuel,
nuclear power etc all redundant!! There must be a catch.

Yep. You don't understand.

http://www.energyquest.ca.gov/how_it...nditioner.html

No it seems I don't understand. I know how a fridge/air con works but
if the OP's kit produces more heat than the energy input then it should
be a matter of simple engineering to make the apparatus power itself
and produce heat with no energy input at all - explain!

cheers

Jacob

PS and there are laws of thermodynamics - have they been changed
recently?

wrote in message
oups.com...

If so then you have
discovered a source of free energy which could make fossil fuel,
nuclear power etc all redundant!! There must be a catch.

Yep. You don't understand.

http://www.energyquest.ca.gov/how_it...nditioner.html

No it seems I don't understand. I know how a fridge/air con works but
if the OP's kit produces more heat than the energy input then it should
be a matter of simple engineering to make the apparatus power itself
and produce heat with no energy input at all - explain!

Heat pumps do not generate heat; they move heat from one location to
another. Heat is moved from the outside air, water or the ground into
buildings for heating and DHW. On average heat pumps consume one third of
the electricity of electric resistance heaters. Sounds good so far.

Heat is found in what most people would regard as cool or cold points. Even
on a very cold day there is heat energy in the outside air. The temperature
of air would need to be absolute zero, -273C, for no heat energy to be
available. On a freezing -1C day, the air temperature is -272C above
absolute zero. 20C is 293C degrees above absolute zero. So, a heat pump only
has to raise heat a relatively small amount; the refrigeration cycle does
this.

A heat pump is a large refrigerator compressor. The compressor raises the
pressure of the refrigeration gas and subsequently the gas temperature. Heat
energy is concentrated by the compressor. The absorber has a similar
function to an icebox in a fridge, absorbing heat, being either an outside
air-to-air radiator, a buried pipe in the ground or a water-to-water heat
exchanger in a stream or pond. The emitter, performs a similar function to
the warm pipes at the back of a fridge, is the hot water storage vessel,
heat distribution pipework or ductwork heater battery inside a house.

Heat pumps may incorporate reversible compressors to provide cooling ,
typically incorporated within a forced air ventilation system. Generally in
temperate climate UK, heat pumps are only capable of providing comfort
cooling rather than full cooling, as heating is the prime function. Cooling
is unnecessary in the UK if proper insulation, ventilation and shading is
fitted. In other countries heat pumps may provide full cooling.

The cooling aspect of heat pumps offends environmentalists, who frown on
summer cooling using fossil fuel as the root power source. Although a heat
pump can theoretically recover maybe 7 kilowatts from every kilowatt used,
the overall efficiency from power station to recovered heat is around 30%.

Gas is about 1/4 to 1/3 cheaper than electricity per kW to buy. Heat pumps
on average are 1/3 cheaper to run than electric resistance heaters, bringing
them "near" to the running cost of gas. Electricity from power station to
point of burn is about 30% efficient, because of latentent heat and line
losses. So, may as well burn natural gas at point of use, which is about
86% efficient using the 100% scale. Gas overall is cleaner, cheaper to
install and run.

95% of all Heat pumps in the UK are in commercial installations. They are
not actively encouraged by governments as they use dirty electricity.

"Russell Eberhardt" wrote in message
...
On 1 Oct 2005 07:34:47 -0700, wrote:

COP=3 is youre best case scenarion. When its freezing outdoors you'll
probably find COP=1 or so. Also if its air source, as it probably is,
at cold temps you get ice on the absorber, which drops COP even
further.
Where I live the climate is very dry so this is less of a problem.

Yes its better than plug in fires, and probably better than E7 storage,
but its not as great as it first looks.

Flat plate solar space heating probably gives better returns.
Now, what area of solar plate will I need to gain 3900 W? Can I get
one that works at night when it is coldest outside? Can I install it
for 260 Euro?

Russell.

Solar panel cost only the running of small pump. You can store the heat in
a thermal store and use low temp UFH to use during the night or cloudy days.

Doctor Drivel wrote:
wrote in message
oups.com...

If so then you have
discovered a source of free energy which could make fossil fuel,
nuclear power etc all redundant!! There must be a catch.

Yep. You don't understand.

http://www.energyquest.ca.gov/how_it...nditioner.html

No it seems I don't understand. I know how a fridge/air con works but
if the OP's kit produces more heat than the energy input then it should
be a matter of simple engineering to make the apparatus power itself
and produce heat with no energy input at all - explain!

Heat pumps do not generate heat; they move heat from one location to
another. Heat is moved from the outside air, water or the ground into
buildings for heating and DHW. On average heat pumps consume one third of
the electricity of electric resistance heaters. Sounds good so far.

Heat is found in what most people would regard as cool or cold points. Even
on a very cold day there is heat energy in the outside air. The temperature
of air would need to be absolute zero, -273C, for no heat energy to be
available. On a freezing -1C day, the air temperature is -272C above
absolute zero. 20C is 293C degrees above absolute zero. So, a heat pump only
has to raise heat a relatively small amount; the refrigeration cycle does
this.

A heat pump is a large refrigerator compressor. The compressor raises the
pressure of the refrigeration gas and subsequently the gas temperature. Heat
energy is concentrated by the compressor. The absorber has a similar
function to an icebox in a fridge, absorbing heat, being either an outside
air-to-air radiator, a buried pipe in the ground or a water-to-water heat
exchanger in a stream or pond. The emitter, performs a similar function to
the warm pipes at the back of a fridge, is the hot water storage vessel,
heat distribution pipework or ductwork heater battery inside a house.

Heat pumps may incorporate reversible compressors to provide cooling ,
typically incorporated within a forced air ventilation system. Generally in
temperate climate UK, heat pumps are only capable of providing comfort
cooling rather than full cooling, as heating is the prime function. Cooling
is unnecessary in the UK if proper insulation, ventilation and shading is
fitted. In other countries heat pumps may provide full cooling.

The cooling aspect of heat pumps offends environmentalists, who frown on
summer cooling using fossil fuel as the root power source. Although a heat
pump can theoretically recover maybe 7 kilowatts from every kilowatt used,
the overall efficiency from power station to recovered heat is around 30%.

Does this mean 30% as against 700%, i.e. still a gain but small?

Gas is about 1/4 to 1/3 cheaper than electricity per kW to buy. Heat pumps
on average are 1/3 cheaper to run than electric resistance heaters, bringing
them "near" to the running cost of gas. Electricity from power station to
point of burn is about 30% efficient, because of latentent heat and line
losses. So, may as well burn natural gas at point of use, which is about
86% efficient using the 100% scale. Gas overall is cleaner, cheaper to
install and run.

Gas fridges are not uncommon - why can't gas be used directly in heat
pumps?

What about my point that apparatus with net power gain could power
itself and produce heat with no energy input at all?

cheers

Jacob

wrote in message
oups.com...

Doctor Drivel wrote:
wrote in message
oups.com...

If so then you have
discovered a source of free energy which could make fossil fuel,
nuclear power etc all redundant!! There must be a catch.

Yep. You don't understand.

http://www.energyquest.ca.gov/how_it...nditioner.html

No it seems I don't understand. I know how a fridge/air con works but
if the OP's kit produces more heat than the energy input then it should
be a matter of simple engineering to make the apparatus power itself
and produce heat with no energy input at all - explain!

Heat pumps do not generate heat; they move heat from one location to
another. Heat is moved from the outside air, water or the ground into
buildings for heating and DHW. On average heat pumps consume one third of
the electricity of electric resistance heaters. Sounds good so far.

Heat is found in what most people would regard as cool or cold points.
Even
on a very cold day there is heat energy in the outside air. The
temperature
of air would need to be absolute zero, -273C, for no heat energy to be
available. On a freezing -1C day, the air temperature is -272C above
absolute zero. 20C is 293C degrees above absolute zero. So, a heat pump
only
has to raise heat a relatively small amount; the refrigeration cycle does
this.

A heat pump is a large refrigerator compressor. The compressor raises the
pressure of the refrigeration gas and subsequently the gas temperature.
Heat
energy is concentrated by the compressor. The absorber has a similar
function to an icebox in a fridge, absorbing heat, being either an
outside
air-to-air radiator, a buried pipe in the ground or a water-to-water heat
exchanger in a stream or pond. The emitter, performs a similar function
to
the warm pipes at the back of a fridge, is the hot water storage vessel,
heat distribution pipework or ductwork heater battery inside a house.

Heat pumps may incorporate reversible compressors to provide cooling ,
typically incorporated within a forced air ventilation system. Generally
in
temperate climate UK, heat pumps are only capable of providing comfort
cooling rather than full cooling, as heating is the prime function.
Cooling
is unnecessary in the UK if proper insulation, ventilation and shading is
fitted. In other countries heat pumps may provide full cooling.

The cooling aspect of heat pumps offends environmentalists, who frown on
summer cooling using fossil fuel as the root power source. Although a
heat
pump can theoretically recover maybe 7 kilowatts from every kilowatt
used,
the overall efficiency from power station to recovered heat is around
30%.

Does this mean 30% as against 700%, i.e. still a gain but small?

Gas is about 1/4 to 1/3 cheaper than electricity per kW to buy. Heat
pumps
on average are 1/3 cheaper to run than electric resistance heaters,
bringing
them "near" to the running cost of gas. Electricity from power station
to
point of burn is about 30% efficient, because of latentent heat and line
losses. So, may as well burn natural gas at point of use, which is about
86% efficient using the 100% scale. Gas overall is cleaner, cheaper to
install and run.

Gas fridges are not uncommon - why can't gas be used directly in heat
pumps?

What about my point that apparatus with net power gain could power
itself and produce heat with no energy input at all?

cheers

Jacob


The generation process converts high grade heat into electrical energy. The
maximum efficiency from thermodynamics is:

eff = (T2 - T1) / T1 where T is in Kelvin, ie 273 + deg C

Typically T2 is very high and T1 is hopefully closer to room temperature to
get a high efficiency. Usually there are significant losses such that
overall generating efficiency rarely gets above 40% and is more typically
30%.

When it comes to heat pumps the equation is the other way round where you're
now creating low grade heat.

eff = T1 / (T2 - T1)

Typically ( T2 - T1 ) is a few 10's of degrees in 300 or so in theory the
efficiency should be 1000% or 10 times the energy input. In practice losses
make this nearer the 300% as quoted here.

Ammonia absorption fridges are something else and very complicated. Have a
look at: http://www.nh3tech.org/absorption.html I haven't got any idea how
efficient they are.

"Russell Eberhardt" wrote in message
...
Why isn't reversible airconditioning used more for heating in the UK?

I have just installed a unit costing 259 Euro which gives a heat
output 3900 W for an electrical input of 1300 W. I calculate that I
will save more than the cost of the unit in the first year of use.

OK, it only works down to -5 C external temperature but for a few Euro
more you can buy one which will work down to -12 C which will cover
most heating requirement and can be supplimented by other heating in
really cold weather.


I'm not convinced about the low temperature performance. I doubt it would
work with an outside temperature less than 10 deg C. Anything lower and ice
will form very quickly reducing the heat exchangers efficiency. How quickly
do you think ice will fill the gaps between the fins?

wrote in message
oups.com...

Doctor Drivel wrote:
wrote in message
oups.com...

If so then you have
discovered a source of free energy which could make fossil fuel,
nuclear power etc all redundant!! There must be a catch.

Yep. You don't understand.

http://www.energyquest.ca.gov/how_it...nditioner.html

No it seems I don't understand. I know how a fridge/air con works but
if the OP's kit produces more heat than the energy input then it
should
be a matter of simple engineering to make the apparatus power itself
and produce heat with no energy input at all - explain!

Heat pumps do not generate heat; they move heat from one location to
another. Heat is moved from the outside air, water or the ground into
buildings for heating and DHW. On average heat pumps consume one third
of
the electricity of electric resistance heaters. Sounds good so far.

Heat is found in what most people would regard as cool or cold points.
Even
on a very cold day there is heat energy in the outside air. The
temperature
of air would need to be absolute zero, -273C, for no heat energy to be
available. On a freezing -1C day, the air temperature is -272C above
absolute zero. 20C is 293C degrees above absolute zero. So, a heat pump
only
has to raise heat a relatively small amount; the refrigeration cycle
does
this.

A heat pump is a large refrigerator compressor. The compressor raises
the
pressure of the refrigeration gas and subsequently the gas temperature.
Heat
energy is concentrated by the compressor. The absorber has a similar
function to an icebox in a fridge, absorbing heat, being either an
outside
air-to-air radiator, a buried pipe in the ground or a water-to-water
heat
exchanger in a stream or pond. The emitter, performs a similar function
to
the warm pipes at the back of a fridge, is the hot water storage vessel,
heat distribution pipework or ductwork heater battery inside a house.

Heat pumps may incorporate reversible compressors to provide cooling ,
typically incorporated within a forced air ventilation system. Generally
in
temperate climate UK, heat pumps are only capable of providing comfort
cooling rather than full cooling, as heating is the prime function.
Cooling
is unnecessary in the UK if proper insulation, ventilation and shading
is
fitted. In other countries heat pumps may provide full cooling.

The cooling aspect of heat pumps offends environmentalists, who frown on
summer cooling using fossil fuel as the root power source. Although a
heat
pump can theoretically recover maybe 7 kilowatts from every kilowatt
used,
the overall efficiency from power station to recovered heat is around
30%.

Does this mean 30% as against 700%, i.e. still a gain but small?

Gas is about 1/4 to 1/3 cheaper than electricity per kW to buy. Heat
pumps
on average are 1/3 cheaper to run than electric resistance heaters,
bringing
them "near" to the running cost of gas. Electricity from power station
to
point of burn is about 30% efficient, because of latentent heat and line
losses. So, may as well burn natural gas at point of use, which is
about
86% efficient using the 100% scale. Gas overall is cleaner, cheaper to
install and run.

Gas fridges are not uncommon - why can't gas be used directly in heat
pumps?

They are slow to operate and recover.

What about my point that apparatus with net power gain could power
itself and produce heat with no energy input at all?

A Perpetual Motion Machine. No one has managed that yet.

A heat pump can output more energy than what it takes to operate (in fact it
only moves heat). But the problem is changing the heat it outputs (energy)
back to a form of energy that can turn the heat pump. The energy state
change from heat to electricity saps up any surplus energy. You have the
notion of a heat operated heat pump. The output of the heat pumps is not
hot enough to drive an absorption refrigeration system.

A machine that outputs more than what it takes to run, is referred to
over-unity. A heat pump is not over-unity as it "moves" heat.

If I have a 100 litre cylinder full of 80C water and another cylinder cold,
I could run a small cheap pump to move the hot water from one cylinder to
the other. That is a quite a bit of heat energy that the pump has moved for
little energy input to run the pump. The heat moved in reality is not the
pump output, although it appears that way.

John Rumm wrote:
wrote:

its more expensive. Everyone knows its half price at night, but not
everyone knows the daytime tariff on E7 is higher, and the saving
thusly goodly shrunk. Its easy to end up paying more on E7.

I always thought that was the case, but when a mate looked into it with
his supplier (I forget which) he found that the day time rate was
actually exactly the same as the suppliers normal tarrif. The sting was
that the E7 tarrif had a higher standing charge.

I guess it varies then, when I was on E7 it was more money in day time,
we changed to flat rate and saved money.

Last time I looked at leccy prices there was a wide variety in
different regions.


NT

"Fred" wrote in message
...

Ammonia absorption fridges are something else and very complicated. Have
a
look at: http://www.nh3tech.org/absorption.html I haven't got any idea
how
efficient they are.

They are ideal candidates for cars as they can use waste heat from the
engine rather than consume power from the crank as the current a/c systems
do. The problem was that they are slow to respond so were never taken up.
If the car is baking hot inside and you want the inside cool ASAP an
electric compressor can do that. An absorption a/c will take a long time, so
not that practical for cars. But, PV cells integrated on the roof of a car
can keep the absorption a/c system ticking over and a slow moving fan
running to keep the interior cool while parked. When the engine starts up,
a heat accumulator (as on the US Toyota Prius) storing high grade heat, can
give the a/c system a boost until the waste heat from the motor kicks in.
All now feasible with few moving parts.

"Fred" wrote in message
...

"Russell Eberhardt" wrote in
message
...
Why isn't reversible airconditioning used more for heating in the UK?

I have just installed a unit costing 259 Euro which gives a heat
output 3900 W for an electrical input of 1300 W. I calculate that I
will save more than the cost of the unit in the first year of use.

OK, it only works down to -5 C external temperature but for a few Euro
more you can buy one which will work down to -12 C which will cover
most heating requirement and can be supplimented by other heating in
really cold weather.


I'm not convinced about the low temperature performance. I doubt it would
work with an outside temperature less than 10 deg C. Anything lower and
ice
will form very quickly reducing the heat exchangers efficiency. How
quickly
do you think ice will fill the gaps between the fins?

Wirh air sourced heat pumps, heat is extracted from the outside air. Most
domestic air sourced heat pumps in the UK have a maximum output of around
5kW (17,000 BTU/h). The problem with air source is that outside air
temperatures may fluctuate widely affecting heat pump performance.

Air-source heat pumps work very well down to around 7C, below, efficiency
depends on the heat loss of the building being heated. If a building is well
insulated with a low heat loss, an air-source heat pump can efficiently heat
a house with an outside temperature down to -4C, or lower. A poorly
insulated house will require a supplemental heat source to assist at an
outside temperature around freezing.

Air sourced heat pumps operate at temperatures colder than 7C degrees for
much of the winter. When the temperature is -7C degrees and below,
efficiencies drop off sharply, with a COP 3 rated heat pump being closer to
COP 2 or COP 1 than COP 3. When outside temperatures fall below 5C the heat
pump may require periodic defrosting. The heat pump extracts heat from the
house to heat the outdoor coils lowing efficiency further.

In article ,
"Fred" writes:

Ammonia absorption fridges are something else and very complicated. Have a
look at: http://www.nh3tech.org/absorption.html I haven't got any idea how
efficient they are.

Not as efficient as a compressor heat pump.
And neither are Peltier effect heat pumps.

--
Andrew Gabriel

"Doctor Drivel" wrote in message
eenews.net...


Wirh air sourced heat pumps, heat is extracted from the outside air. Most
domestic air sourced heat pumps in the UK have a maximum output of around
5kW (17,000 BTU/h). The problem with air source is that outside air
temperatures may fluctuate widely affecting heat pump performance.

Air-source heat pumps work very well down to around 7C, below, efficiency
depends on the heat loss of the building being heated. If a building is
well
insulated with a low heat loss, an air-source heat pump can efficiently
heat
a house with an outside temperature down to -4C, or lower. A poorly
insulated house will require a supplemental heat source to assist at an
outside temperature around freezing.

Air sourced heat pumps operate at temperatures colder than 7C degrees for
much of the winter. When the temperature is -7C degrees and below,
efficiencies drop off sharply, with a COP 3 rated heat pump being closer
to
COP 2 or COP 1 than COP 3. When outside temperatures fall below 5C the
heat
pump may require periodic defrosting. The heat pump extracts heat from the
house to heat the outdoor coils lowing efficiency further.


I'm not familiar with methods of running an air source heat exchanger at
very low temperatures without the problem of icing. Any icing would rapidly
reduce efficiency to 100%.

Another reason for poor low temperature working is like to be from the
choice of refrigerant.

"Andrew Gabriel" wrote in message
.. .
In article ,
"Fred" writes:

Ammonia absorption fridges are something else and very complicated. Have
a
look at: http://www.nh3tech.org/absorption.html I haven't got any idea
how
efficient they are.

Not as efficient as a compressor heat pump.
And neither are Peltier effect heat pumps.

If you are using heat that normally would be wasted, they are very efficient
in running costs.

"Fred" wrote in message
...

"Doctor Drivel" wrote in message
eenews.net...


Wirh air sourced heat pumps, heat is extracted from the outside air.
Most
domestic air sourced heat pumps in the UK have a maximum output of
around
5kW (17,000 BTU/h). The problem with air source is that outside air
temperatures may fluctuate widely affecting heat pump performance.

Air-source heat pumps work very well down to around 7C, below,
efficiency
depends on the heat loss of the building being heated. If a building is
well
insulated with a low heat loss, an air-source heat pump can efficiently
heat
a house with an outside temperature down to -4C, or lower. A poorly
insulated house will require a supplemental heat source to assist at an
outside temperature around freezing.

Air sourced heat pumps operate at temperatures colder than 7C degrees
for
much of the winter. When the temperature is -7C degrees and below,
efficiencies drop off sharply, with a COP 3 rated heat pump being closer
to
COP 2 or COP 1 than COP 3. When outside temperatures fall below 5C the
heat
pump may require periodic defrosting. The heat pump extracts heat from
the
house to heat the outdoor coils lowing efficiency further.


I'm not familiar with methods of running an air source heat exchanger at
very low temperatures without the problem of icing. Any icing would
rapidly
reduce efficiency to 100%.

Another reason for poor low temperature working is like to be from the
choice of refrigerant.

In a humid climate the icing problems are more pronounced.

Russell Eberhardt wrote:

Now, what area of solar plate will I need to gain 3900 W? Can I get
one that works at night when it is coldest outside? Can I install it
for 260 Euro?

As dribble says, that would be the cost of "only running a small pump"...

So compared to the 200 quid heatpump aircon, all you need is a couple of
grands worth of panels and their installation, say a grand and a half
for the thermal store setup and control logic, and a grand to retrofit
UFH in the conservatory.

But then he has a unique ability to see "value" in situations that pass
us mere mortals by! ;-)

--
Cheers,

John.

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