Of course it produces heat.

bob, long time, no see.

I'm very happy with the performance of my heat pump.

Please take a look and decide who make most sense

The basic argument in the thread is for heating a pool:

zl700: Heat pumps don't get any heat from the outside air it's all coming from the compressor. How can you heat 80 degree water with 60 degree air LOL.

jharrell: Heat pumps get most of thier heat from the outside air.

Any thoughts?

I was able to heat my house to 71°F a couple days ago with a Carrier heat pump when the outside air was 35°F. That's a 36°F differential between inside and outside. Auxiliary is not involved (except during defrosting), it's locked-out until the ambient is 25°F. Note also that the system did not run continuously by any means, run-time was approx 15 mins every 15 to 20 mins. I dunno where the heat came from (actually, I do), but it wasn't from air blowing over a hot coil of wire, LOL.

"Please take a look and decide who make most sense"

I read though all of the other post (I was actually reading it as it happened over the weekend), and jharrell makes the most sense since he is correct.

zl700 - the quotes from Aquacal and Trane that you are trying to use to prove your point of view actually prove that you are wrong. From your quote on Thu, Jan 17, 08 at 19:29 - How a Heat Pump Works (Taken right from Trane Corp HP101): "Instead of creating heat, as does a furnace, the heat pump transfers heat from one place to another."

In other words - in heating mode it picks up heat from outside air and discharges it into the inside air, and in cooling mode it picks up heat from the inside air, and discharges it into the outside air.

There are many other descriptions of how a heat pump works from other sources that have been presented to you - all of which say the same thing - heat is moved from one place to another.

Read the description in the following link - it provides a very detailed step-by-step sequence of events on exactly how a heat pump works. (Hint - the compressor is not this mythical, magical device that creates heat from nothing.)

Here is a link that might be useful: How a Heat Pump Works

Contrary to previous postings a Heat pump does not gain heat from outside air. The process internally creates heat that under the AC mode needs to be removed as waste heat. In simple terms heat is produced with an increase of pressure of the freon. Freon is compressed to become liquid. There is nothing magical in this process. A HP utilizes this immutable natural law to produce heat at a lessor cost than resistive heat. The downside is that at present a HP does not work as efficient in outdoor temperatures under approx 42F degrees. At some point the heat pump spends too much time in defrost mode. This is not producing any heat inside the home. Many things can cause a Heat Pump to malfunction and not produce heat. A Heat Pump is an AC unit running backwards

Contrary to previous postings a Heat pump does not gain heat from outside air.
A Heat Pump is an AC unit running backwardsSo, then, conversely, a heat pump running backwards is an AC unit, and the "outside" air becomes the "inside" air. How, then, does an AC unit make the inside cool if it isn't removing (getting) heat from the inside air [and pumping it outside]?

Bob Brown wrote:

"a Heat pump does not gain heat from outside air. The process internally creates heat that under the AC mode needs to be removed as waste heat. In simple terms heat is produced with an increase of pressure of the freon. Freon is compressed to become liquid. There is nothing magical in this process."

Bob once again shows his willful ignorance of HVAC.

Freon is not compressed to become a liquid in any HVAC system. The compressor compresses gaseous freon to produce a high pressure gas, which is hot. The heat is then dissipated in the condenser, which, as its name implies, condenses the gas back to the liquid state, that phase change also gives off heat. The now liquid freon is than passed through the evaporator where, as its name implies, it is vapourized. The energy needed to cause the phase change from liquid to gas comes from the ambient air surrounding the evaporator. In a regular A/C system, the evaporator is inside and the heat is supplied by the air inside the house. In a heatpump in heating mode, the outside unit is functioning as the evaporator and the latent heat of vapourization comes from the outside air. Since the boiling point of freon is -41F for R22 and -63F for R410A a heatpump can extract heat from the air down to a very low temperature.

Thus a heatpump in heating mode extracts heat from the outside air when the outside unit is functioning as an evaporator and rejects heat to the outside air when it is functioning as a condenser in cooling mode. The compressor just moves the heat and boosts it from low to high temperature through the application of Boyle's Law. I think people get confused between "heat" and "temperature".

As a reminder of Boyle's Law (actually the Ideal Gas Law):

http://en.wikipedia.org/wiki/Ideal_gas_law

This states that pressure and volume are related to some constants and the temperature of the gas. If you increase the pressure through compression, then you increase the temperature.

Paul in Montreal.

I think we all agree then the compressor in the heat pump mode generates the heat that is capable of being high enough in temp to transfer to a source. In addition the condenser serves as the evaporator to boil off the excess liquid refrigerant after the metering device before returning to compressor. Most people will not deny, including me that the outdoor condenser coil picks up heat but, to believe like JHarrell that the majority of the heat that goes back into the pool in this case comes from the air is the discrepancy.
LetÂs say the refrigerant is returned to the compressor at 60 degrees Fahrenheit and leaves at 140, JHarrell is stating that that temperature rise is coming from the air. Not, it is the mechanical compression of the refrigerant that has created 80% of the heat.

That is the difference in our opinions of heat pumps, and only that.

WhatÂs the opinion of this forum with regards to air heat pumps, place you vote for this simple poll?

1. 80% of the heat generated is from the air?
2. 80% of the heat is generated by the compressor?

(Note I only chose 80% as a base)

Paul...

You've provided the best explaination of heat-pump/AC operation I've read. Thanks for that.

Peace.

Marco

zl700 wrote:

"WhatÂs the opinion of this forum with regards to air heat pumps, place you vote for this simple poll?

1. 80% of the heat generated is from the air?
2. 80% of the heat is generated by the compressor?"

zl700, you are also willfully ignorant - I read your deluded ramblings in the other thread. You obviously don't have the slightest grasp of how the refrigeration cycle works or you wouldn't be posting such mis-informed nonsense in a public forum. I'm surprised you have any customers at all as you have demonstrated your ignorance several times.

In answer to your poll, neither answer is correct, but of the two, answer (1) is closest. If, as I suspect, you think answer (2) is correct, answer this:

For a heatpump with an output of 36,000 BTUh, how much electricity does the compressor use? If it's less than 10.5kw, where does the 36,000 BTUh come from? From your answer (2), if you think 80% of the heat is generated by the compressor, that would be 28,800 BTUh - since 1kWh has 3413 BTUh in it, that would imply the compressor uses 8.4kW - yet if you look at the operating charts of any heatpump manufacturer you'll see something more like 3kW. So just tell us, in simple terms, where you think the missing heat comes from. Sheesh.

Paul in Montreal

"1. 80% of the heat generated is from the air?
2. 80% of the heat is generated by the compressor? "

Wait a minute zl700, you said numerous times in the other forum that 100% of the heat comes from the compressor, now you are admitting some error and saying it's only %80?

Did you not say these things???:

The heat is generated by the compressor and only that"

"how then can a heat pump heat the pool water to 85 if the air temp outside is 60? Gathering heat from the air, dont think so. "

"Don't fall prey to the marketing of heat pumps especially air over claiming to be gaining heat."

"A air heat pump exchanges heat with the air it does not "gather it" as you claim. "

"But according to my other poster, turn on the heat of a heat pump and we capture all this magical heat from the outdoors and he refuses to accept that the compressor is creating it?"

I recall reading years ago that the refrigerant picks up "one unit" of heat (whatever amount that may be in terms of BTU) and the compressor adds "two units" more heat to increase the differential between the ambient and the temp of the refrigerant to facilitate heat transfer, i.e. cooling of the refrigerant via the condensor. What I took that to mean is that the "one unit" of heat is equivalent to the RATED CAPACITY OF THE SYSTEM per hour -- or 1/60 of that amount per minute. Otherwise, how can an AC be rated at removing 60,000 BTU of heat per hour if it isn't picking up that much and moving it out? The "two units" added by the compressor is additional and over that, the so-called waste heat which is to increase the temp differential between the hot refrigerant in the condensor and the ambient so it gives up heat more readily.

My 5-ton Carrier pulls between 4K and 5K watts when running based on an electric demand graph I've seen of my house (the baseline without the A/C running is about 1KW on a 5-min sample rate over a 15-min period). So split the difference and say 4,500 watts. Of course, 5 ton capacity, 60,000 BTU is under ideal conditions ... but whatever, it can keep my house at 71°F when the outdoors is 35°F, and run at about a 50% duty cycle.

Assuming full capacity of 60,000 BTU at 4,500 watts, that's 13,333 BTU per KW, which is considerably more than the 3,413 BTU of heat that a KW of electricity contains. Seems like a pretty good deal, LOL!

Again, if all the "heat" is added by the compressor, then how does cooling happen? It's a basic lesson of physics that cold is simply the absence of heat (less energy, molecular motion slows). So where does the heat inside the house go, and how? How does an ice maker freeze water?

I understand all the hoopla of the refrigerant cycles and it properties from the compression states, the expansion and the transferring of heat. After all the simplest way to accept this theory for most is try running an AC system with a failed condensor fan.

Again, as most tend to skip in their readings, I never stated that heat does not transfer, without it happening, it wouldn't work. But soley through exchange with the air and no heat/temperature added by the compressor? Come on!

A compressor is a heat engine that uses energy in the form of electricty to perform work (pump refrigerant) - No one can deny that!

"A human climbing a flight of stairs is doing work at a rate of about 200 watts. An automobile engine produces mechanical energy at a rate of 25,000 watts (approximately 30 horsepower) while cruising. A typical household incandescent light bulb uses electrical energy at a rate of 40 to 100 watts, while energy-saving compact fluorescent lights, which are beginning to replace incandescent bulbs, typically consume 8 to 20 watts."

Mr pyro, a btu is a unit of energy not solely used in electric. We know that combustable gases can have different contents of capable btu's. In addition to fuel btu content, we can have varying ways of converting the btu output, the difference between a 80% and 90%+ furnace.
Using the conversion of 1KW to 3413 Btu's does not apply here unless we were calculating simple resistant heat.

Do you think that that simple principle doesn't apply to electric motors? A compressors basis is an electric motor. With the development of electric motors and high efficiency units over the years, did you think the compressor manufacturers weren't paying attention and applying these principles?

If I think back over the years, I have watched current consumption, amps or watts drop on condensing units or heat pumps for that matter. Aside from larger coils and TXV's, coil designs ..... that effected the SEER, the development of efficient compressors played the biggest part in both energy savings and outputs!

Mr dadoes you are on two something. Now if we can agree to that, that waste heat created by the compressor," The "two units" added by the compressor is additional and over that, the so-called waste heat" is what is rejected to the gas/water ht exch (condensor) that heats the pool.

Once again some of you fall prey to the Missguidings and interpretations on a heat pump.

zl700 rambled thus:

"Mr pyro, a btu is a unit of energy not solely used in electric. We know that combustable gases can have different contents of capable btu's. In addition to fuel btu content, we can have varying ways of converting the btu output, the difference between a 80% and 90%+ furnace.
Using the conversion of 1KW to 3413 Btu's does not apply here unless we were calculating simple resistant heat."

Give it up. You obviously don't have a clue what you're talking about and are just digging yourself into a deeper hole.

1kWh is exactly 3413 BTU as both are a measure of energy. It doesn't matter if the BTU comes from burning gas, oil or the passage of electrons through a wire - 1kWh is the amount of energy required to raise 3413 pounds of water by 1F.

I'm not going to both responding to the rest of your ill-informed ramblings as you are not just simply wrong, you are confused and conflating several different issues. Yes a compressor may be thought of as a heat engine, but that is missing a big part of the picture. The refrigerant was already evaporated by heat from an external source (the air in the case of an ASHP) before having its temperature raised by the compressor. The energy in the refrigerant came from the latent heat of evaporation that was supplied by the air passing over the evaporator - the compressor raised the temperature and also added some energy too - the energy used to run the motor - but that is the "1" input that gives "4" at the output - "3" having come from evaporating the refrigerant in the first place - a process the compressor had no part in.

There are no "misguidings and interpretations on a heatpump". Its rather simple function has already been described from basic physical principals that someone with a high school education in physics could understand. What a shame you demonstrate your palpable ignorance to the public at large. Shame on you. Shame on me for wasting my time with an ignoramus.

"But soley through exchange with the air and no heat/temperature added by the compressor? Come on!"

zl700 no one is denying some of the heat comes from the compressor, it is exactly 3.413 BTU per watt the rest from the air in an ASHP.

why are you trying to snake your way out of what you said and I quote again:

"The heat is generated by the compressor and only that"

You most definetly said NO heat comes from the air over and over, you called that "magic" heat from cold air.

Now you are arguing in circles trying to act like you didn't say it, just admit you where wrong there is no shame in that, we are all human.

I guess zl700 lost his nerve here.

He's still rambling on the pool forum trying to convince everyone that the compressor generates all the heat and none of it comes from the outside air.

Just reeled in my third, time for weigh in

As I suspected, he just a Troll.

I think we'd all agree that a person could, if he or she wanted, run a heat pump with an old-fashioned belt-driven refrigerator compressor, or a belt-driven car a/c compressor. Wouldn't that prove you were moving heat and not just just picking up the compressor's waste heat, since the motor's (or engine's) heat would not be put into the refrigeration cycle? And, if the compressor were driven by some fuel besides electricity (gasoline engine, etc.), the BTU value of electricity would be irrelevant, but it would still work as a heat pump.

But I have another question about the basic science of this: The waste heat from the compressor that you pick up in the refrigeration cycle, does that, as was said above, correspond exactly to power used, or do you, in fact, not get it all as heat because some did the actual work of compression? This reminds me of a statement I once read that said you could heat your house with incandescent light bulbs just as efficiently as with electric heaters. Obviously you could very nearly do so, as incandescent bulbs are highly inefficient, but would the light produced by the bulb to some degree diminish the heat?

I know he is a troll, 100+ replies in the pool forum thread and he can't give a straight answer, he keeps spouting nonsense to trying to prove that all the heat comes from the compressor, even going to far as saying Trane is lying when I pointed him to a web page on thier site that explains how a heat pump works in layman's terms, LOL.

ky114:

My understanding of why 100% of the mechanical work is converted to heat is that since we all know energy cannot be created or destroyed, the mechanical work that is put into the refrigerant to compress it, is not "lost" in compression, but is converted to heat, compression is a state change in the refrigerant caused by the work, but the work cannot be destroyed, and is instead converted to heat, of course the refrigerant already has heat in it gathered from the evaporator, so both these are added together for the total output at the condensor, that is unless you are zl700 and believe it all comes from the work in the compressor...

Remeber all mechanical work usually ends up back as heat eventually, in your car the mechanical work extracted from the heat of burning gasoline just ends up as heat again from friction against your brakes or drive train or tires or the air.

The same applies to the incandecent light bulb, most of the eletricity is converted into heat some into light, but as the light radiates out and strikes matter it gets converted back into heat unless it escapes into space to stay as light and never hit anything again (which some small amount of it does). So in your house your not only getting the heat from the bulb being inefficent but also the heat from the light striking say your carpet or walls or you.

Gee... I knew how a heat pump worked in high school physics. Oh, wait... that was in Canada, far away from Bob's State of Confusion, where I live now... ;-)

This thread just made my day. LOL

"Remember all mechanical work usually ends up back as heat eventually, in your car the mechanical work extracted from the heat of burning gasoline just ends up as heat again from friction against your brakes or drive train or tires or the air."

Comparing an auto engine to a compressor?

If the heat is generated by the engine, so it is at the compressor.

No engine running no heat - no compressor running no heat

Get it?

No zl700 heat is generated by gasoline burning, an engines job is to turn some of that heat into mechanical work, you can get heat out of gasoline without an engine, just light a match, get it?

No air blowing over the evaporator and all you get is a heater with the same efficiency as a strip heater, that is COP of 1, hmm I wonder why that is, could it be the air adds heat to the system, and with a COP of 4 that would be 3/4 of the heat coming out, nah it all comes from the compressor right, LOL.

zl700 stop trying to argue "no compressor no heat" thats like saying no spark plug no horsepower in a car, are you going to argue the spark plug generates the mechanical work?

No air blowing over the evaporator and what you get is a blown compressor not moving any heat, thats all

{{gwi:1544058}}

Don't you guys think some of your disagreement might have to do with semantics? As the prime mover in a refrigeration system, the compressor is responsible for moving and concentrating the heat. I could seem where someone could therefore say it "creates" the heat, even though technically it doesn't. The people who design the heat pumps aren't necessarily the best at installing them, just as an auto engineer might totally screw up your car if he or she turned a wrench on it.

Saltcedar:

Please remove my picture from your post.

Thank you.

"Please remove my picture from your post."

LOL Right away! :-)

nutty buddies, gosh I hope noone takes this garbage serious. Mods restrict this thread so that noone under the age of 65 can view it and warp their young minds.

"No air blowing over the evaporator and what you get is a blown compressor not moving any heat, thats all"

I thought you said it generates the heat what is this about moving it?

So a modern scroll compressor can't tolerate some slugging and continue to run(albient inefficiently)? A working TXV can't use the heat of compression to superheat enough to keep the refrigerant above boiling point even with no air flow? again you might as well use a strip heater, but the compressor won't instantly blow it just be a very expensive resistance heater.

You act like if a heat pump frosts over the compressor will instantly blow. When in reality it's effiency just drops off, wonder why that is, could it be it lost the BTU's it was pulling from the outside air, nah that's just magic right?

ky114,

I wish this argument was just a matter of symantics, but this is the post from zl700 I originally responded to in the pool forum, does this look like just a matter of symantics to you:

"However, dont be fooled that heat pumps gather heat from the air or ground. The heat is generated by the compressor and only that."

Then later:

"Again my point is a heat pump doesn't "gather" or gain heat from the air and, the only heat generated is by the electric compressor that is more efficient to run and is capable of generating heat for less than electric resistance heating."

And so on, zl700 seems pretty clear on his position.

WOW!!! I read this whole thing and it's like watching Jerry Springer but a whole lot more informative. I really appreciate that!

I have a pretty good understanding of refrigeration and I can't see why moving heat from cold air over a condenser turned evaporator to an evaporator turned condenser should be so hard to understand. There is always heat avaiable unless the source is at absolute zero. This of course if all conditions are ideal which is not nearly the case in the real world. I just wanted to say that.

What I actually have for you is a question about Geo-Thermal heat pumps. To keep it simple what are the advantages of a geo-thermal heat pump over one that just uses air for cooling the condenser/evaporator, outside of the fact that it just eliminates the condenser's/evaporator's fan motor. To me it seems like a minor advantage. I can't understand all the hoopla over a very expensive geo-thermal system just to eliminate the use of a little fan motor. I wanted to start a new thread on this subject, but some of you seem to be very knowledgeable, so I thought this may be a good place to get an answer.

Thanks,

Jim

Unless you have a ground DX system, yes there is a pump or circulator to exchange the fluid temps (ground, pond, well) with the refrigerant circuit which replaces the fan motor thus, stil a energy user in the system.

However on a closed loop geo system, many times the current draw of a circulation pump can be less than a fan motor on a air system.

The benefits are the stable ground temps, unlike air temps over a outside coil. As most have agreed, as the temp outside drops on an air heat pump so does the efficiency & output.

What?????????

Jim,

The outdoor fan motor is relatively minor in the overall energy consumption of a heat pump, amounting to about 5% of the total.

As zl700 said the outdoor air temperature will fluctuate much more over the seasons than the ground will just a few feet down.

The reason being the thermal mass of the ground versus the air. 1 BTU will raise a cubic foot of air 55 degrees F while it takes 22 BTU's to raise a cubic foot of concrete just 1 degree and 62 BTU's to raise a cubic foot of water 1 degree. Ground is somewhere between concrete and water in thermal mass but it varies widly based on it's composition.

Since as *most* of us know a heat pump moves heat "uphill" from a cooler source to a hotter sink the ground will accept or reject many more BTU's with less temperature change and is therefore a much better place to put heat into in the summer and pull heat from in the winter requiring less work to do so, therefore less electricity.