The hunt for the most efficient heat pump in the world

A new generation of engineers has realized they can push heat pumps to the limit.

See full article...

 

[Flipper35]

We occasionally get an early morning wakeup call from one pecking at our metal roof vents. No idea why.

They also think it is a mating call to bang on thigs that are not trees, especially metal things.

 

[Flipper35]

Ground source heat pump should never need supplemental resistance heat. Glad to hear yours was installed properly!

I was just clarifying that the type of heat pump makes a difference. Though A2A is getting much better.

One thing I would like to do is run an external connector for the genny to run the fridge, well pump and geo unit. for those odd every 5-6 years the storms take the power out. Not having power to the well pump can stink.

Yeah; the install where they used the alley, the building covered 100% of the lot -- dense urban cores build like that. They drilled under the alley, then repaved it so you notice nothing.

If they horizontal bored properly, they shouldn't have needed to repave anything.

 

[Tom the Melaniephile]

I was just clarifying that the type of heat pump makes a difference. Though A2A is getting much better.

Oh, absolutely. There are A2A units on the market which do fine at -30C without supplemental resistance heating. You just need to get the right unit for your climate.


View: https://www.youtube.com/watch?v=_v8vizQXwss


(Just an example, not an endorsement of this particular company or unit)

 

[Tom the Melaniephile]

They also think it is a mating call to bang on thigs that are not trees, especially metal things.

Male woodpecker: "Females love it when I bang hard and loud!"

 

[numerobis]

If they horizontal bored properly, they shouldn't have needed to repave anything.

Everything I know about horizontal boring, they still need to break the surface

 

[numerobis]

Oh, absolutely. There are A2A units on the market which do fine at -30C without supplemental resistance heating. You just need to get the right unit for your climate.


View: https://www.youtube.com/watch?v=_v8vizQXwss


(Just an example, not an endorsement of this particular company or unit)

They aren't the most efficient but they're DIY-friendly, unlike basically all the other manufacturers who (quite reasonably) don't want to deal with individual customers ever.

 

[plectrum]

You are right I do need to do calcs (or get an expert to do them), but there are other complications too. The internal chimney breast is on an inside wall (serving 2 room back to back downstairs, same upstairs for front and back bedrooms) - between the chimney and nearest outside wall, the internal wall is brick connecting to the external wall, which no doubt will act as a cold bridge. That's one of the reasons I looked at external insulation.

Draughts are sorted, I got rid of the leaky aluminium framed double glazing and 90+ year old wood doors (nice and rustic as they were) several years back, for decent upvc framed glazing and composite doors.

In that scenario I'd think about continuing the internal insulation around from the external wall to the chimney breast. You won't completely fix the cold bridge (the inside of the chimney is still connected to the outside, via the roof if nothing else) but what you then have is a cold bridge where the only available path from inside to outside is several metres of brick.

That will reduce the heat flux going through the cold bridge. If the material has a thermal resistance of X per metre, the traditional way is to increase the resistance X (in the UK we talk about U-values which are thermal conductivity, U=1/R) but the other way is to increase the thickness. At some point a thick wall of brick has more thermal resistance than a thin sheet of PIR.

 

[Madaraszvktr]

I think you mean 'buffer' not 'puffer', but something like that might be feasible. The buffer gives you hydraulic separation, ie you can discharge the buffer's 'hydraulic battery' at a different rate to that which the heat pump charges it, which means you can run your emitters at a wider range of flow rates. The downside is that it's not as efficient as a direct connection because you get some mixing of warm and cold water.

So if you're targeting the best COP you want to run without buffer, but the buffer allows flow rates which the HP alone isn't happy with. I don't think it would give you a lot of temporal load shifting (minutes not hours) as the amount of heating/cooling you can store in a 100 litre tank isn't that large.

Yes, thank you, I've meant buffer, it's called puffer in my language, and I skipped my morning coffee =) My buffer has flows both directions, so the heat pump cools the water, sends it into the buffer, it goes to do it's work in the house, and comes back through the buffer, and the heat pump cools back the water from the buffer. It's good because I have the warm water for the taps also produced by the heat pump, and if it would get the warmed up water coming back directly it would need to switch too often. I think it makes 7°c water but only starts to work if the incoming water from the puffer is above 10°c, than it works till it reaches 7°c. You are right that a few 100 litres wouldn't mean much of a buffer, a few m^3 might do the job though, it can be cooled during the cheap period, and can be used during the expensive one. Maybe it should be bypassed during the expensive period if it gets too warm and addittional cooling is needed. Main efficiency loss would be due to imperfect insulation and heat gain of the buffer.

 

[Flipper35]

Everything I know about horizontal boring, they still need to break the surface

True, but they are pretty small holes and I assumed, probably incorrectly, that they started close to the residence and not in a paved area.

 

[Dark Jaguar]

In that scenario I'd think about continuing the internal insulation around from the external wall to the chimney breast. You won't completely fix the cold bridge (the inside of the chimney is still connected to the outside, via the roof if nothing else) but what you then have is a cold bridge where the only available path from inside to outside is several metres of brick.

That will reduce the heat flux going through the cold bridge. If the material has a thermal resistance of X per metre, the traditional way is to increase the resistance X (in the UK we talk about U-values which are thermal conductivity, U=1/R) but the other way is to increase the thickness. At some point a thick wall of brick has more thermal resistance than a thin sheet of PIR.

Indeed, there's a reason brick and stone have been used for thousands of years. They stood the test of time. That said, stone wool insulation definitely supplements that construction quite a bit. From what I read about PIR though, it's some amazing stuff too. I'd prefer it to be an internal layer than external siding because I like stone walls just that much, but that's about it. Before someone says "Hey would you wear a coat outside or stuff that coat in between your skin and bones?" well... living things DO stuff their natural insulation between their skin and bones, and it's called fat. Sorry, just this one house siding salesman I watched used that line ALL the time. Anyway, I love the insulation between metal sheets too for one reason.... it blocks those new police scanners that can see right into your home.

 

[Tom the Melaniephile]

True, but they are pretty small holes and I assumed, probably incorrectly, that they started close to the residence and not in a paved area.

Sounded like it was a "zero lot line" situation where the building is right up to the property line and abuts the alley.

 

[Deleted member 440187]

I'm no expert but I have an A2W heatpump in my home. I would think you could just install a large insulated water tank as a puffer for a surface cooling (water pipes in ceiling) or fancoil or mixed solution. I have a mixed solution as I was worried about condensation shutting down the cooling, and the fancoils help by lowering humidity. I collect 7°c water in a smallish puffer, and the fancoils get their cold water directly from there while the surface cooling gets it mixed with warmer water as it needs higher temperature. I'm pretty sure it would work the same if I would have a puffer of a few 100 litres instead of the 20 something I have now. You'd need a hydro unit which works differently at different time periods, to cool mostly during the cheap times but I think most modern units can handle this.

That engineered system whih thermal buffering could work, but there may he a lot of storage in your home already, or a better way to increase thermal mass, such as brick or masonry walls or artistic features. This video shows one-person's cooling strategy in the Midwest USA. It's not as good as a fully engineered system, but if you are willing to tolerate a bit more fluctuation, it may much easier to implement.

It benefits from not only time of use discounts but also lower night-time temperatures creating conditions for much higher CoPs.


View: https://youtu.be/0f9GpMWdvWI?si=rskauIv8U7sv9-ag

 

[plectrum]

Yes, thank you, I've meant buffer, it's called puffer in my language, and I skipped my morning coffee =) My buffer has flows both directions, so the heat pump cools the water, sends it into the buffer, it goes to do it's work in the house, and comes back through the buffer, and the heat pump cools back the water from the buffer. It's good because I have the warm water for the taps also produced by the heat pump, and if it would get the warmed up water coming back directly it would need to switch too often. I think it makes 7°c water but only starts to work if the incoming water from the puffer is above 10°c, than it works till it reaches 7°c. You are right that a few 100 litres wouldn't mean much of a buffer, a few m^3 might do the job though, it can be cooled during the cheap period, and can be used during the expensive one. Maybe it should be bypassed during the expensive period if it gets too warm and addittional cooling is needed. Main efficiency loss would be due to imperfect insulation and heat gain of the buffer.

On my system, when you switch from heating to cooling mode it first runs the water/refrigerant past the fan without using the compressor, so that the water in the loop (including buffer) is dropped to ambient without any cooling in operation - this is more economical than using the compressor to cool 50C water to 7C, it only has to work from outdoor ambient to 7C.

If you were using a buffer as a store then you might end up bleeding away all the heat/cold in the buffer when you switched modes. It might need some valves to bypass the buffer in heating mode so as not to drain its cold.

 

[Madaraszvktr]

On my system, when you switch from heating to cooling mode it first runs the water/refrigerant past the fan without using the compressor, so that the water in the loop (including buffer) is dropped to ambient without any cooling in operation - this is more economical than using the compressor to cool 50C water to 7C, it only has to work from outdoor ambient to 7C.

If you were using a buffer as a store then you might end up bleeding away all the heat/cold in the buffer when you switched modes. It might need some valves to bypass the buffer in heating mode so as not to drain its cold.

That's cool, I don't think my system can do that. I have a small buffer though, and I only switch modes twice a year, so the loss is negligible. The hot water for the taps goes through a big hot water tank, but it has a separate valve from the hydro unit, not attached to the buffer, that's only for the house heating/cooling. If someone would do a huge buffer, your solution would come handy!

 

[Madaraszvktr]

That engineered system whih thermal buffering could work, but there may he a lot of storage in your home already, or a better way to increase thermal mass, such as brick or masonry walls or artistic features. This video shows one-person's cooling strategy in the Midwest USA. It's not as good as a fully engineered system, but if you are willing to tolerate a bit more fluctuation, it may much easier to implement.

It benefits from not only time of use discounts but also lower night-time temperatures creating conditions for much higher CoPs.


View: https://youtu.be/0f9GpMWdvWI?si=rskauIv8U7sv9-ag

You are right, it's probably more sane to just use more insulation, than to build giant buffer tanks for cold water. I have a brick house with good insulation, and I can definately keep the house cool/warm by only heating/cooling a fraction of the day. My wife doesn't like airflow, so we have surface cooling downstairs, and use the fancoils upstairs during the day when we are not there, and it keeps cold during the warm summer nights. I also have a ventillation system with a cross-flow heat exchanger, and in the summer it works during the cold periods, evening and early morning, to bring in colder air. In the winter I'm mostly just trying to dodge air pollution with it as many people still use wood/coal for heating in my area.

 

[85mm]

This seems like an idea that would maximize moisture problems if there’s an effective barrier on the inside. Which there likely is if the inside got done starting about the 1970s until about five years from now when the new idea that vapor barriers are actually bad starts being more widespread.

It's quite comonly done in the UK, though I don't know what mitigations they have to put in for moisture. I think it works because the brickwork will then be inside the heat envilope and the external insulation will ensure that it will stay warm enough to avoid condensation.

 

[plectrum]

It's quite comonly done in the UK, though I don't know what mitigations they have to put in for moisture. I think it works because the brickwork will then be inside the heat envilope and the external insulation will ensure that it will stay warm enough to avoid condensation.

Typically there are two skins with a cavity between. The outer skin is brick and gets wet. The cavity isolates it from the inner skin, which can be brick or aerated concrete block, meaning the inner skin stays dry. Traditionally (1920-1980) the cavity would be open and allow air to circulate to aid drying. Since we discovered insulation is a thing, it's common to blow in insulation into the cavity. That can cause damp problems if the property is subject to driving rain that soaks the bricks and they can't dry. But most sites don't have driving rain, are protected by overhangs and the bricks get enough time to dry. There are maps of affected areas (source):

For condensation, traditionally you'd have porous building materials so that moisture can flow through them in either direction, and then the raised temperature (coal fires, central heating etc) inside would push it through to the outside. Modern non porous coatings prevent that, which can mean condensation builds up in the layers. The modern solution is a vapour barrier on the inside insulation so that humid air stays inside the room and the surface isn't cold.

 

[85mm]

Typically there are two skins with a cavity between. The outer skin is brick and gets wet. The cavity isolates it from the inner skin, which can be brick or aerated concrete block, meaning the inner skin stays dry. Traditionally (1920-1980) the cavity would be open and allow air to circulate to aid drying. Since we discovered insulation is a thing, it's common to blow in insulation into the cavity. That can cause damp problems if the property is subject to driving rain that soaks the bricks and they can't dry. But most sites don't have driving rain, are protected by overhangs and the bricks get enough time to dry. There are maps of affected areas (source):

For condensation, traditionally you'd have porous building materials so that moisture can flow through them in either direction, and then the raised temperature (coal fires, central heating etc) inside would push it through to the outside. Modern non porous coatings prevent that, which can mean condensation builds up in the layers. The modern solution is a vapour barrier on the inside insulation so that humid air stays inside the room and the surface isn't cold.

But in this case we were talking about putting external insulation on a property. That insulation is also waterproof. The job needs to be done competently to avoid damp issues obviously, but it's a perfectly practical solution in a lot of cases and I see a lot of buildings retrofitted in that way.

 

[Dark Jaguar]

But in this case we were talking about putting external insulation on a property. That insulation is also waterproof. The job needs to be done competently to avoid damp issues obviously, but it's a perfectly practical solution in a lot of cases and I see a lot of buildings retrofitted in that way.

Practical, but doesn't look very nice. I can see a lot of people rejecting this upgrade for aesthetic reasons, and others simply because placing the insulation on the outside makes it a lot more vulnerable to being worn down. With all that said, the cost savings alone will be enough to convince many more, if it can be heavily subsidized.

New construction would benefit from using padding that can still leave a small air gap between outer and inner layers of old style stone/brick construction... and sadly now there's a secondary reason for things like metal coated insulation layers, either external or internal, and that's keeping cops from using their new x-ray vision tech (I'm picturing these cops ordering them from the back of a cereal box) to spy on you.

 

[fellow human]

and sadly now there's a secondary reason for things like metal coated insulation layers, either external or internal, and that's keeping cops from using their new x-ray vision tech (I'm picturing these cops ordering them from the back of a cereal box) to spy on you.

So a tinfoil hat for your house.

 

[Dark Jaguar]

So a tinfoil hat for your house.

It's pretty ridiculous isn't it? I also have a tinfoil hat for my... credit card...
What's more ridiculous is that just like how I can no longer in good faith tell people that their TVs and music players aren't spying on them, I can also no longer say cops can't see through your walls, or that someone bumping into you can't read your card through the lining of your purse, or wallet.

But here we are:

View: https://www.youtube.com/watch?v=ZfvmdX631Gc

Because cops love their expensive unnecessary toys.

 

[alisonken1]

It's pretty ridiculous isn't it? I also have a tinfoil hat for my... credit card...
What's more ridiculous is that just like how I can no longer in good faith tell people that their TVs and music players aren't spying on them, I can also no longer say cops can't see through your walls, or that someone bumping into you can't read your card through the lining of your purse, or wallet.

But here we are:

View: https://www.youtube.com/watch?v=ZfvmdX631Gc

Because cops love their expensive unnecessary toys.

The only saving grace with that is they can only "assume" it's you in the house. If you have house guests, they can only tell that someone is in the house, and based on the height/size of the heat plume make a somewhat-educated guess on who that someone is.

Still, the tech is getting closer than you realize.

 

[Dark Jaguar]

The only saving grace with that is they can only "assume" it's you in the house. If you have house guests, they can only tell that someone is in the house, and based on the height/size of the heat plume make a somewhat-educated guess on who that someone is.

Still, the tech is getting closer than you realize.

Yep! Though that "saving grace" isn't much when it's all the excuse an officer needs to break down the door or shoot at someone they're assuming is "you" through the walls. I'm even more horrified at the notion a house guest is going to get shot on my behalf than if it was just me in there. The fact the image is a fuzzy mess that requires AI to even make sense of makes these an even more dangerous tool. It's like cops found the perfect "eyes" to fit their own methods.

 

[numerobis]

Yep! Though that "saving grace" isn't much when it's all the excuse an officer needs to break down the door or shoot at someone they're assuming is "you" through the walls. I'm even more horrified at the notion a house guest is going to get shot on my behalf than if it was just me in there. The fact the image is a fuzzy mess that requires AI to even make sense of makes these an even more dangerous tool. It's like cops found the perfect "eyes" to fit their own methods.

It’s not like police needed those tools to start shooting blindly at a building.

 

[Dark Jaguar]

It’s not like police needed those tools to start shooting blindly at a building.

True, but this time they'll be shooting at a figure they know the location of in the building, because they were "holding a knife"... in their kitchen.

 

[85mm]

Practical, but doesn't look very nice. I can see a lot of people rejecting this upgrade for aesthetic reasons, and others simply because placing the insulation on the outside makes it a lot more vulnerable to being worn down. With all that said, the cost savings alone will be enough to convince many more, if it can be heavily subsidized.

New construction would benefit from using padding that can still leave a small air gap between outer and inner layers of old style stone/brick construction... and sadly now there's a secondary reason for things like metal coated insulation layers, either external or internal, and that's keeping cops from using their new x-ray vision tech (I'm picturing these cops ordering them from the back of a cereal box) to spy on you.

It can be finished in any number of ways, but just plain render is not ugly if you want to keep it cheap.

 

[alisonken1]

It can be finished in any number of ways, but just plain render is not ugly if you want to keep it cheap.

And if you use tilt-wall (concrete walls poured flat about 3"-6" thick, then tilted up to form the wall), you can also use molds to pre-form brick shapes into the concrete. Only thing left is paint to match.

 

[Dark Jaguar]

And if you use tilt-wall (concrete walls poured flat about 3"-6" thick, then tilted up to form the wall), you can also use molds to pre-form brick shapes into the concrete. Only thing left is paint to match.

Concrete isn't nearly so long lasting as true stone and brick solutions, which to me is a major downside, though admittedly there are many cases where shelter isn't expected or desired to last centuries.

 

[Tom the Melaniephile]

Concrete isn't nearly so long lasting as true stone and brick solutions, which to me is a major downside, though admittedly there are many cases where shelter isn't expected or desired to last centuries.

Depends on your concrete. If you want it to last centuries, design it without steel reinforcement. Steel is the Achilles heel of modern concrete construction. Eventually it corrodes and causes the concrete to crack/spall. Also use a pozzolan in your mix design, low water:cement ratio and low permeability.

There is Roman concrete which is ~2,000 years old and still in good shape. Romans used natural volcanic ash pozzolans. While you can get some today, it's more common to use fly ash.

 

[Golgo1]

Depends on your concrete. If you want it to last centuries, design it without steel reinforcement. Steel is the Achilles heel of modern concrete construction. Eventually it corrodes and causes the concrete to crack/spall. Also use a pozzolan in your mix design, low water:cement ratio and low permeability.

There is Roman concrete which is ~2,000 years old and still in good shape. Romans used natural volcanic ash pozzolans. While you can get some today, it's more common to use fly ash.

This guy 'cretes

 

[scarletjinx]

Concrete isn't nearly so long lasting as true stone and brick solutions, which to me is a major downside, though admittedly there are many cases where shelter isn't expected or desired to last centuries.

Nerd correction - concrete as we generally formulate it nowadays isn't long lasting at all. And offgasses CO2 among other things.

However, if you don't wanna go cheap on it, you could use something like the ancient Roman recipe using volcanic ash, where it self-heals and sort of fossilizes into something like true stone over the centuries.

Roman concrete - Wikipedia

en.wikipedia.org

Riddle solved: Why was Roman concrete so durable?

Researchers have discovered ancient Roman concrete-manufacturing strategies that incorporated self-healing. Applying this knowledge toward modern cement production, they hope to improve the material’s environmental impact.

news.mit.edu

/Edit - man I love/hate Ars commentators. They're too damn smart. Ninja'd already

 

[Tom the Melaniephile]

Nerd correction - concrete as we generally formulate it nowadays isn't long lasting at all. And offgasses CO2 among other things.

Close, but no. Making cement offgasses CO2. Concrete slowly absorbs CO2 over time. This is one of the two main mechanisms allowing eventual steel corrosion. Alkalinity passivates steel and prevents corrosion. CO2 progressively reduces the alkalinity in the concrete.

The other main mechanism is chloride penetration. When the combination of pH and chloride hit a critical level, the steel is no longer passivated and begins to corrode. I'm sure someone has a graph showing at what point various combinations allow corrosion, but I can't be arsed to go look it up.

There's a really interesting new technique (research stage) - you take old, pulverized concrete, separate out the aggregate and use the remaining cured cement paste as flux on your electric arc steel (recycling) mill instead of using limestone. This converts the concrete back into cement clinker. Basically a "two for one" on the energy usage. Cement plants normally burn stuff (tires, coal, methane, etc) for process heat in making cement clinker.

Engineers push to make zero emissions steel and cement from a single process

WHAT if it were possible to make cement as a byproduct of recycling steel – and power its production with green energy? This is the focus of a new two-year project involving researchers and industry from across the UK who are working to prove that two materials which are fundamental to society...

www.thechemicalengineer.com

Edit: Example of a company which sells natural pozzolans for use in concrete (among other things)

CR Minerals - Natural Pozzolan and Fly Ash Products

CR Minerals offers several grades of Tephra® to serve the construction and oil and gas industries as a natural pozzolan.

www.crminerals.com

And I just found out today that the Falcon Dam on the Rio Grande (Texas/Mexico border) used a natural pozzolan when it was constructed in the 1950s:

Pozzolana - Falcon Dam | UTRGV

 

[Dark Jaguar]

Close, but no. Making cement offgasses CO2. Concrete slowly absorbs CO2 over time. This is one of the two main mechanisms allowing eventual steel corrosion. Alkalinity passivates steel and prevents corrosion. CO2 progressively reduces the alkalinity in the concrete.

The other main mechanism is chloride penetration. When the combination of pH and chloride hit a critical level, the steel is no longer passivated and begins to corrode. I'm sure someone has a graph showing at what point various combinations allow corrosion, but I can't be arsed to go look it up.

There's a really interesting new technique (research stage) - you take old, pulverized concrete, separate out the aggregate and use the remaining cured cement paste as flux on your electric arc steel (recycling) mill instead of using limestone. This converts the concrete back into cement clinker. Basically a "two for one" on the energy usage. Cement plants normally burn stuff (tires, coal, methane, etc) for process heat in making cement clinker.

Engineers push to make zero emissions steel and cement from a single process

WHAT if it were possible to make cement as a byproduct of recycling steel – and power its production with green energy? This is the focus of a new two-year project involving researchers and industry from across the UK who are working to prove that two materials which are fundamental to society...

www.thechemicalengineer.com

Edit: Example of a company which sells natural pozzolans for use in concrete (among other things)

CR Minerals - Natural Pozzolan and Fly Ash Products

CR Minerals offers several grades of Tephra® to serve the construction and oil and gas industries as a natural pozzolan.

www.crminerals.com

And I just found out today that the Falcon Dam on the Rio Grande (Texas/Mexico border) used a natural pozzolan when it was constructed in the 1950s:

Pozzolana - Falcon Dam | UTRGV

Sounds very nice! If we can get back to using that kind of material in modern concrete it sounds like it'll get it's old long-lasting nature right back AND have low CO2 impact. I still wouldn't want to use it for vertical walls outside of, say, a parking garage, but that's just because I know just how long lasting a good stone wall can be and I like to use "the old reliable" for it's aesthetics as well as it's durability.