Author Topic: What is the real story around heat pumps?  (Read 389434 times)

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Offline Miyuki

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Re: What is the real story around heat pumps?
« Reply #225 on: February 22, 2024, 06:26:25 am »
That seems contradictory? If nuclear is supposedly cheap electricity, then why would the government have to invest in it? Especially when increasing demand is expected with more heat pumps being deployed, why would it need the government to provide the investment for that cheap electricity?
If the goal is to reduce carbon emissions, then investing in nuclear power, so we have cheap electricity, is a no-brainer. Nuclear plants have a high upfront cost, which few private investors are wiling to pay,

Hu? Where did you get the idea that few private investors are willing to pay high upfront costs with almost guaranteed returns?! I mean, unless you mean "few" as in "most individual people don't have the money to pay for a nuclear power plant"?! I mean, BlackRock have 9 trillion USD of assets under management ... they certainly could find a bunch of people among their clients who would have the cash to build a nuclear power plant and would be willing to do so for reliable returns!? Sounds almost ideal for pension funds! And they obviously aren't the only large asset managers out there.

My best guess is that what you've heard is that few private investors are willing to fund high upfront costs with significant risks. Like, funding billions for medical research where there is a significant chance that nothing comes of it. Which is true. But that is because of the risk, not because of the high costs. And if there is significant risk, then that is exactly the contradiction that I was talking about: How can a nuclear power plant be both a reliable cheap source of electricity (which thus would have reliable long-term returns, if you own the power plant that can produce power cheaper than everyone else) and at the same time a high-risk investment that would need the government to step up?

so it make more sense for the government to invest in it, rather than wasting money on other green schemes such as heat pumps and banning internal combustion engine vehicles.

Why do you think that that is wasting money?

Given cheap, clean, electricity, people will voluntarily switch to heat pumps and electric cars, without subsidies or banning anything. It will also boost the economy, in the form of reduced energy costs to businesses.

Well, that much is obvious, yeah.

Nuclear power will see a return on investment, in the long term.

That part though ... your arguments certainly don't support that conclusion.
Nuclear power has a big problem, you have those same crazy dudes glued to the road also protesting against nuclear.
And as there is no economy of scale nowadays, the cost is enormous.
Current builds will be profitable in 30-40 year horizont (if there won't be any problems). So no investor will go into this because it is beyond their lifetime and when you have investment opportunities with orders of magnitude higher returns. And even after that 30-40 years, those profits are not that great.
And even governments are reluctant because it is controversial, because of those factors.
 

Offline pcprogrammerTopic starter

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Re: What is the real story around heat pumps?
« Reply #226 on: February 22, 2024, 07:59:06 am »
Never heard about De Dietrich. It's probably just some label on some Asian product, like 90% of heatpump brands (including "German" brands like Bosch). Many heatpumps are label over label over label.

De Dietrich is a very old French brand. At some point it joined ventured with Remeha a Dutch brand. I have no idea where the pump offered is fabricated. The reviews seem to be good and put it up at the top with Daikin and Mitsubishi.

Do not use RS-485 for long distances, put a converter near the pump, or an isolator.
Yes, it's made for that, but you do not want that the pump side fails.
With luck you have a machine with multiple circuit boards, but it's a monoblock.
With bad luck there's only one PCB and the driver is integrated to MCU.

My system has provisions for UART with optical isolation. This coupling will be very close to the pump unit. For what I found on it, it is bog standard RS485 and used to connect their brand thermostats. It will be protected against things like lightning to some extend.

Offline pcprogrammerTopic starter

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Re: What is the real story around heat pumps?
« Reply #227 on: February 22, 2024, 08:06:37 am »
Quote
Still waiting for the second quote, but in the mean time I have found options for controlling, or at least read the De Dietrich heat pump with a RS485 interface. A lot of the info is in French, and unfortunately registering to the before mentioned site did not result in the ability to download the mentioned files. But I found a github repository with a python based solution, which gives the needed information.
Are you sure it's a good idea to get something which isn't very well documented? Going by what you've said, that company could be a pain to deal with.

I'm not afraid of a bit of research. If needed reverse engineering is a way to go. The whole thing will become a big experiment to reach a solid and economical solution.

Offline Zarhi

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Re: What is the real story around heat pumps?
« Reply #228 on: February 22, 2024, 08:53:28 am »
That's is situation with air source heat pumps from this morning:
Outside temp 2°C, humidity about 60%, clear sky, no rain, no clouds, no fog.

Pictures taken 3-4 minutes after defrost cycle completion.

Anyway in the morning inside temperatures was:
First floor: bedroom - set 22°C, actual 22°C, living room set 24°C, actual 25°C.
Second floor: two bedrooms - set 22°C, actual 23°C.

Last 10 hours electricity consumption: 12kWh

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Online tszaboo

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Re: What is the real story around heat pumps?
« Reply #229 on: February 22, 2024, 09:22:38 am »
Again with your pushing of solutions and completely ignoring/side stepping the practical ones (pretending like no other options exist).

Oversize the solar array, then it will produce enough energy in winter.

Sure not everyone has the physical space for that, but few have the physical space for ground source thermal storage/dissipation.
Almost nobody has place for that here. I have a system that covers my yearly electricity consumption, in fact makes an extra MWh. And I needed 5 GJ heat this december, which is 1400KWh, while my solar made 52KWh, which is a factor of 27. Even with SCOP of 5, it's just not going to be worth it to install 6x the solar on my roof, no space, no money for it.
Which you know... I said (and you quoted). The size of that setup is comparable to the sustainable footprint ground source heating in those cold places where little to no air-conditioning is needed (and solar production falls way off in winter).

Why go straight to extremes with a pure solar setup? its a convenient strawman? Energy supply is almost always cheapest as a mix of things.

Sizing solar arrays to the inverter or export limit is old thinking. Panels are cheap and adding more capacity (vertical for winter production for example) can be cost effective for many.

Also to be pedantic you don't need 5 GJ of energy for heating, you want 5 GJ of energy for heating. That's a choice and how you supply it is up to you (and you can pay for it).
I'm a bit confused, in one comment you say we should oversize solar system to cover winter energy needs. When I show you it's not practical, you say that's not what you said. So then what is your suggestion?
And yes, I do need 5GJ for a winter to be bearable in my home, dropping temperatures lower than most people keep here would be a respiratory hazard. To be pedantic, I don't really care about global warming and polar bears, if I cannot keep temperatures at home high enough to live a quality life. And if the government has a problem with this, we'll overthrow the government and bring out the guillotines for good measure.
 
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Online nctnico

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Re: What is the real story around heat pumps?
« Reply #230 on: February 22, 2024, 09:58:24 am »
Quote
Still waiting for the second quote, but in the mean time I have found options for controlling, or at least read the De Dietrich heat pump with a RS485 interface. A lot of the info is in French, and unfortunately registering to the before mentioned site did not result in the ability to download the mentioned files. But I found a github repository with a python based solution, which gives the needed information.
Are you sure it's a good idea to get something which isn't very well documented? Going by what you've said, that company could be a pain to deal with.

I'm not afraid of a bit of research. If needed reverse engineering is a way to go. The whole thing will become a big experiment to reach a solid and economical solution.
I know this is a great project but try to keep in mind that a generic heating service person needs to be able to fix your heating system. You may go away for a while or become incapacitated. Then your wife is left in a cold home without warm water if your self-build heating system breaks. Most likely a heating service person will either go away or tear your system down and replace it with something the person knows how to deal with (followed by a large invoice).
« Last Edit: February 22, 2024, 10:05:36 am by nctnico »
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Offline m k

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Re: What is the real story around heat pumps?
« Reply #231 on: February 22, 2024, 10:35:57 am »
Quote
Still waiting for the second quote, but in the mean time I have found options for controlling, or at least read the De Dietrich heat pump with a RS485 interface. A lot of the info is in French, and unfortunately registering to the before mentioned site did not result in the ability to download the mentioned files. But I found a github repository with a python based solution, which gives the needed information.
Are you sure it's a good idea to get something which isn't very well documented? Going by what you've said, that company could be a pain to deal with.

I'm not afraid of a bit of research. If needed reverse engineering is a way to go. The whole thing will become a big experiment to reach a solid and economical solution.

I think the only big issue you finally have is how successfully the pump is positioned.
But how big is big is questionable, obviously after the pump itself is generally fine.
Maybe you add a battery backed circulation pump no matter what.
Maybe you must later add some acoustic insulators, but so be it then, even if you must dig under the foundation, it's actually not very big qube.
(how high can engine hoist lift)

What comes to generic heating service persons around here, more experienced ones are many times very aware of many kind of specialities.
Since these things are generally pretty fine over longer periods of times these service fellas must have a wide customer base.
Around here it can include stores, dairy farms, meat packing places and so on, plus considerably old water circulations around different generations of machines.

BTW,
that earlier mentioned cold water is actually not very cold.
It's from pipes that are around a room temperature and a tap lever is usually lifted straight up, so somewhere around the middle.
Winter stream water is cold, even as cold as tap can give is not really cold, winter times it's probably close to 6C.
People who swim in ice hole would probably argue against the whole concept of cold water.

BTW2,
I had to drop HVAC target temp, the area was closing to 23C and ask was 19C.
The machine has been a bit eager from the beginning.
It's Panasonic E12 series scroll and my educated guess is that it's internal curves are too low for our temp ranges.
Maybe it's because of missing liquid, but if outdoor temps are skyrocketing or dropping equally it sometimes goes bonkers.
Then removing mains for a moment will do the trick, luckily it's indoor unit fed wall plug thing that actually has that plug.
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Offline zilp

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Re: What is the real story around heat pumps?
« Reply #232 on: February 22, 2024, 12:32:42 pm »
To be pedantic, I don't really care about global warming and polar bears,

You are aware that climate change is about your survival, not about the survival of polar bears, right?

I mean, the expectation of having a reasonably heated home is perfectly reasonable, obviously. But then, exactly noone is suggesting anything otherwise, so your whole statement is pretty pointless even in that regard.
 
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Offline NiHaoMike

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Re: What is the real story around heat pumps?
« Reply #233 on: February 22, 2024, 01:42:14 pm »
Politics aside, are there heat pumps which use natural gas or oil, rather than electricity? It won't give the same COP but might be more economical. That might also suit me, although my energy usage is fairly low, so not worth it, until I need a new boiler.
Yep, there are. My understanding is that the Netherlands are betting on natural gas driven heat pumps quite a bit.
Has absorption heat pump technology improved substantially? Last I checked, it's about as efficient as running an electric heat pump from a gas generator. Might as well get a CHP generator and an electric heat pump to get more flexibility.

But as larger systems are more economical, it would work out better to split it up. Have some households with electric heat pumps and some with CHP generators. In colder weather, the CHP generators run more which nicely matches up to the heat pumps also running more.
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Online Siwastaja

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Re: What is the real story around heat pumps?
« Reply #234 on: February 22, 2024, 07:34:05 pm »
I know this is a great project but try to keep in mind that a generic heating service person needs to be able to fix your heating system. You may go away for a while or become incapacitated. Then your wife is left in a cold home without warm water if your self-build heating system breaks. Most likely a heating service person will either go away or tear your system down and replace it with something the person knows how to deal with (followed by a large invoice).

This sort of stuff is usually easy to solve with some kind of manual bypass switch. Or short instructions e.g. "go to menu X and change external control to internal control". Something worth thinking about, yes.
 

Offline zilp

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Re: What is the real story around heat pumps?
« Reply #235 on: February 22, 2024, 07:44:02 pm »
Current builds will be profitable in 30-40 year horizont (if there won't be any problems). So no investor will go into this because it is beyond their lifetime

That is not how investment works.

For one, there are plenty of investors where 30-40 years is not in any way beyond their lifetime. Think insurance companies, pension funds, endowments, that sort of thing. Plenty of investors who wouldn't care if they couldn't liquidate some position for half a century, as long as the returns are worth it.

But also, that is what the secondary securities markets are for. If the profits are as certain as has been suggested, then you can just hold the shares or bonds and then sell them after 30 years or whatever for the time value of the future profits, thus getting your part of the profits before they have been realized.

and when you have investment opportunities with orders of magnitude higher returns. And even after that 30-40 years, those profits are not that great.

And that is the point. It's actually risky. There is absolutely no guarantee that the electricity would be competitive with other sources, and quite a few reasons to think that it wouldn't. And if it isn't, then throwing a pile of tax money at it is just a waste of money. And that especially so given that even if we decided to build a ton of nuclear power plants, they wouldn't be online for at least another 10 years. A lot of solar and wind capacity can be built in ten years, and any generator that is completed pretty much immediately starts saving CO2, rather than in ten years. And also, wind and solar are proven technologies with economies of scale, where the time to compltion is very reliably predictable, as far as the technical side is concerned.
 
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Online Zero999

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Re: What is the real story around heat pumps?
« Reply #236 on: February 22, 2024, 09:14:08 pm »
Your figures for an electric heat pump are wildly optimistic because you used the seasonal average of 350%, when you should use the COP, when it's going to be working hardest and consuming the most power, which will be much lower.

A heat pump may drop in efficiency as load increases and temperature falls, but so does a boiler.  The headline efficiency of 85-90% is only achieved at the point where the return water is below 40C.  Once you demand higher load from a boiler and need a flow of 70-75C, efficiency falls as far down as 70%.  Meanwhile a heat pump will still be achieving a COP around 300%. 
How does the efficiency of a gas boiler drop with temperature? The reverse is true because more heat is extracted from the water being pumped through the radiators. It's more efficient for a gas boiler to heat the water from 25°C to 75°C, than it is for it to heat from 55°C to 75°C. The opposite is true for heat pumps, which need the water to be as lower temperature as possible, hence large pipes and massive radiators, and the COP drops, with the outside temperature.

Unfortunately, it does.  Because condensing boilers don't condense when the return temperature is above 45-50C (roughly). Typically the radiator loop on your system might lose 20-25C between flow and return, but if your radiators are sized so that it can only be properly heated when the flow output temperature is >60C then it will suffer from reduced efficiency in cold weather.  This is currently the case for our house, and it's sadly very common as heating engineers aren't physicists, they just know that they need so many kW per m^2 so install the smallest radiators they can get away with.

When a boiler doesn't condense, the exhaust ends up with plenty of waste heat in it, which isn't heating your property.  Combi boilers also do not condense when providing hot water, as there is no return path.

No such issue occurs for a boiler that is non-condensing, those are rare (especially today) and just generally have all-round bad efficiency.

I question your figure of a COP of 300%. I only use my heating when it's properly cold. It's been mild for the last week or so and my gas boiler has sat idle. 300% seems optimistic, given it'll get used when the temperature outside is close to or below freezing. Even then a COP of 300% is no good, unless the price of electricity were to fall significantly.

A property in the UK will only be approved for the grant when a COP of at least 280% is achieved.   Octopus only install systems >330% COP.  One can surmise from this is most systems installed under the MCS scheme will have a COP of 300% or above.  Octopus are the largest installer of these systems.

You are not the only user of heating systems so I couldn't comment on whether your scenario is going to achieve worse efficiency or not... but it's probably not relevant to the overall economics of heat pumps, most around here use their heating for at least 4-5 months of the year.  It's pretty easy to see the boiler vents on a cold day after all.
Okay, I accept those figures, but they still don't make economic sense for me. It just doesn't add up at the moment.

Nuclear power has a big problem, you have those same crazy dudes glued to the road also protesting against nuclear.
And as there is no economy of scale nowadays, the cost is enormous.
Current builds will be profitable in 30-40 year horizont (if there won't be any problems). So no investor will go into this because it is beyond their lifetime and when you have investment opportunities with orders of magnitude higher returns. And even after that 30-40 years, those profits are not that great.
And even governments are reluctant because it is controversial, because of those factors.
There are also smaller nuclear reactors which are cheaper to build. I believe Rolls Royce are currently developing modular units.
« Last Edit: February 22, 2024, 09:22:39 pm by Zero999 »
 

Online tom66

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Re: What is the real story around heat pumps?
« Reply #237 on: February 22, 2024, 09:16:04 pm »
Current builds will be profitable in 30-40 year horizont (if there won't be any problems). So no investor will go into this because it is beyond their lifetime

That is not how investment works.

For one, there are plenty of investors where 30-40 years is not in any way beyond their lifetime. Think insurance companies, pension funds, endowments, that sort of thing. Plenty of investors who wouldn't care if they couldn't liquidate some position for half a century, as long as the returns are worth it.

But also, that is what the secondary securities markets are for. If the profits are as certain as has been suggested, then you can just hold the shares or bonds and then sell them after 30 years or whatever for the time value of the future profits, thus getting your part of the profits before they have been realized.

Indeed, only 10 years since the UK paid off its last undated bonds, some of which go back to the 1850s.
https://www.gov.uk/government/news/repayment-of-26-billion-historical-debt-to-be-completed-by-government

There are public-private financing schemes on infrastructure which have very long payoff times.  M6toll in the UK was built on a 53 year concession: a private company paid to build it, with the right to take tolls on it for the period of the contract (whilst maintaining it), and the road then returns to the government upon the end of contract. 

The idea that investors are nervous about 30-40 year payback times is nonsense, providing the return is reasonably guaranteed, they love it.
 

Online tom66

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Re: What is the real story around heat pumps?
« Reply #238 on: February 22, 2024, 09:18:43 pm »
Okay, I accept those figures, but they still don't make economic sense for me. It just doesn't add up at the moment.

As I said... I don't think they add up either, so I'm not quite sure who you're arguing against!  The problem is the cost savings for heat pumps are maybe 10-20% in the optimal case, and 0% or even negative in the suboptimal case.  The savings need to be something like 50% with say a 10% spread to make them appealing to the masses.  That might happen eventually, especially if efficiencies increase and electricity costs fall as natural gas prices rise, but it's not the case today.

However, if you are building a new home, and have the opportunity to install larger radiators, underfloor heating and adequate insulation (as are often the requirements nowadays anyway) I think you would be foolish to install anything other than a heat pump, and I think we should be mandating heat pumps for all new builds.  The cost of installing a heat pump in every new build home on an estate is far lower than retrofitting one to an existing property.
 
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Online nctnico

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Re: What is the real story around heat pumps?
« Reply #239 on: February 22, 2024, 09:20:23 pm »
Current builds will be profitable in 30-40 year horizont (if there won't be any problems). So no investor will go into this because it is beyond their lifetime

That is not how investment works.

For one, there are plenty of investors where 30-40 years is not in any way beyond their lifetime. Think insurance companies, pension funds, endowments, that sort of thing. Plenty of investors who wouldn't care if they couldn't liquidate some position for half a century, as long as the returns are worth it.

But also, that is what the secondary securities markets are for. If the profits are as certain as has been suggested, then you can just hold the shares or bonds and then sell them after 30 years or whatever for the time value of the future profits, thus getting your part of the profits before they have been realized.

Indeed, only 10 years since the UK paid off its last undated bonds, some of which go back to the 1850s.
https://www.gov.uk/government/news/repayment-of-26-billion-historical-debt-to-be-completed-by-government

There are public-private financing schemes on infrastructure which have very long payoff times.  M6toll in the UK was built on a 53 year concession: a private company paid to build it, with the right to take tolls on it for the period of the contract (whilst maintaining it), and the road then returns to the government upon the end of contract. 

The idea that investors are nervous about 30-40 year payback times is nonsense, providing the return is reasonably guaranteed, they love it.
Indeed. The interest rates on these kind of projects are high and you get a fixed income stream for the decades to come. Ideal for long term investments like pension funds but also small investors are keen on making these kind of investments even though the payback is beyond their grave.
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Online Zero999

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Re: What is the real story around heat pumps?
« Reply #240 on: February 22, 2024, 09:24:50 pm »
Price results from supply *and* demand. Limited supply with decreasing demand still leads to decreasing prices. As the majority of gold demand is from speculators, there is no fundamental reason why demand couldn't decrease (as opposed to technical uses, say, where the practical value of the products that contain gold and where gold is hard to substitute drive the demand). Really, what keeps the value of gold up is exactly such marketing campaigns that mislead people who lack deeper economical understanding into "investing" in it, because that is what generates the demand.

If you buy gold, that's a bet on other people buying gold, and them doing so at a higher rate than gold is supplied to the market, so that you can later sell it to them. That's it.
Just look at the value of gold over the last 100 years. There are peaks and troughs but there's a clear upward trend. Yes I might lose some money, so I certainly wouldn't put all of my money into gold. On the other hand, I know if I replaced my gas boiler with an electric heat pump, it will lose money, so it would be a dumb investment for me. I'm not going to buy a system which will cost a lot of money and cost more to run. It would be like me trying to persuade you into investing in a new paper magazine publication. It will lose money.
https://www.macrotrends.net/1333/historical-gold-prices-100-year-chart

Quote
There is no need to make up my mind, you just have to pay attention.

I am *currently* (as in: most of February so far) heating with a COP of around 600%. As in: Right now, my heat pump draws 476 W electric (pumps and everything included) and outputs 2786 W of heat, so 2786 W / 476 W = 585 % COP.
Well good for you, but I've hardly used any gas this February because it's been so mild. It's possible I would get a COP of 600% or higher at the moment, since the UK is milder in winter than Germany, but if I'm not using it, then it's irrelevant. I've used my heating a bit this evening because the temperature has dropped to 4°C, but the boiler didn't run for long.

Quote
Which I mentioned above to explain why an average of 350% is reasonable, even though the COP can be lower during really cold days.

To compare heating systems, you obviously have to use annual averages, and that certainly is not 600%.
Okay, I accept 350% is a reasonable figure and that I shouldn't just go on the worst case, given others here have told me the same thing.

Quote
Natural gas is a clean fuel, so the exhaust won't be any more dirty than my boiler.

Well, it is clean in comparison to other fuels. But it is not clean as in "doesn't leave any residue". Whether it would be dirtier than your boiler isn't really that easy to say, as the dirt that results from the combustion really depends on the conditions.

Assuming an electric heat pump would give a COP of 300%, a gas one would give a COP of 160%

How did you get to that number?

Given:

The gas engine has an efficiency of 30%

The heat pump system a COP of 300%, i.e. for every 100W of mechanical power from the engine, I get 300W of heat.

Calculate the total COP of the heat pump, driven from the gas engine:

100W of power goes in:

The engine is 30% efficient, thus produces:
30W power to the shaft, which is delivered to the heat pump, which generates three times as much heat 30W*3 = 90W
70W of heat, which isn't wasted but goes into my home.

Total heat to my home 90 + 70 = 160W, hence a total COP of 160%

Quote
and given gas costs a quarter of the price, it would pay for itself within a few years.

What price are you assuming for a gas-driven heat pump, and how did you arrive at it?

I have no idea what they cost, but I would expect them to be even more expensive than electrically driven ones as they are more complex to build (combustion engine vs. electric motor) and more difficult to install (need a gas line i addition to electricity and potentially refrigerant lines)!?
I don't know what the actual cost of a gas powered heat pump is. Yes it would be more expensive, but typically the cost of the heat pump itself is only a small proportion of the total system. At least with a gas powered system, I know it would pay for itself, unlike an electric one. If I've changed my heating to be heat pump compatible and the market changes, I can always move to electric in the future.

EDIT:
Climate change and politics removed.
« Last Edit: February 24, 2024, 02:01:27 pm by Zero999 »
 

Offline Someone

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Re: What is the real story around heat pumps?
« Reply #241 on: February 23, 2024, 01:48:40 am »
Since PV provides a glut of power in summer, recharging is hardly an issue.
It is an issue as there is a relatively short peak power output from solar panels. A common solar panel setup with 12 panels, can deliver around 4kW of output for a couple of hours per day. So either you need a large heatpump capable of taking in 4kW of power and convert this into heat that goes into the ground (assuming the ground can absorb it quick enough) OR have a large battery pack which can smear out putting the energy into the ground over time. Neither is cheap / cost effective. And then you'll still need electricity to get the heat out of the ground again. Where is that coming from? My estimation is that conversion to/from hydrogen (in some form) you can store above ground is more cost effective.
Again with your pushing of solutions and completely ignoring/side stepping the practical ones (pretending like no other options exist).

Oversize the solar array, then it will produce enough energy in winter.

Sure not everyone has the physical space for that, but few have the physical space for ground source thermal storage/dissipation.
Almost nobody has place for that here. I have a system that covers my yearly electricity consumption, in fact makes an extra MWh. And I needed 5 GJ heat this december, which is 1400KWh, while my solar made 52KWh, which is a factor of 27. Even with SCOP of 5, it's just not going to be worth it to install 6x the solar on my roof, no space, no money for it.
Which you know... I said (and you quoted). The size of that setup is comparable to the sustainable footprint ground source heating in those cold places where little to no air-conditioning is needed (and solar production falls way off in winter).

Why go straight to extremes with a pure solar setup? its a convenient strawman? Energy supply is almost always cheapest as a mix of things.

Sizing solar arrays to the inverter or export limit is old thinking. Panels are cheap and adding more capacity (vertical for winter production for example) can be cost effective for many.

Also to be pedantic you don't need 5 GJ of energy for heating, you want 5 GJ of energy for heating. That's a choice and how you supply it is up to you (and you can pay for it).
I'm a bit confused, in one comment you say we should oversize solar system to cover winter energy needs. When I show you it's not practical, you say that's not what you said. So then what is your suggestion?
Ok, so I add back in the original quote tree above rather than your cherry picking and dithering (since you claim to forget why this has happened).

Marco points out that thermal ground sources can be cheaply recharged recharged with solar power when it's running in excess and the price of energy is at its lowest.
nctnico proposes there are only two possible solutions and says since neither of those is economic then the entire idea is a non-starter
I point out that's a dumb simplification as there are other solutions, and include an example
You argue that won't work for you and say it is not practical for the majority
I point out that your generalisation is over dramatic and, wrong on several points.

There are many ways to get more thermal energy when it's needed. But there are no universal solutions that fit all, or situations that apply to all (beyond the laws of physics...).

Always jumping to single solutions for energy are putting up strawmen, 100% solar, 100% wind, 100% CO2 capture, heating only from seasonal storage. They're all as dumb as each other. Most people can and do leverage the diversity of the gird to provide their energy needs, backed with things that are impractical on a domestic level like pumped hydro and nuclear power.

Talking about thermal ground sources without considering the energy recharge is just abusing another finite resource, which has little to no oversight. Pretty much the same as logging national parks to burn the wood (there are people doing that too). Tragedy of the common.

And yes, I do need 5GJ for a winter to be bearable in my home, dropping temperatures lower than most people keep here would be a respiratory hazard.
You're not needing that, its a want. As has been said repeatedly and in this thread even if heating is a need for health, heating the whole house is still a want.

But it seems this thread is now just the (outlier) UK gas price discussion, and the rest of the world still cant talk openly about heat pumps.
 

Offline NiHaoMike

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Re: What is the real story around heat pumps?
« Reply #242 on: February 23, 2024, 03:14:29 am »
I don't know what the actual cost of a gas powered heat pump is. Yes it would be more expensive, but typically the cost of the heat pump itself is only a small proportion of the total system. At least with a gas powered system, I know it would pay for itself, unlike an electric one. If I've changed my heating to be heat pump compatible and the market changes, I can always move to electric in the future.
How about compare it to just a CHP generator? If gas is so cheap compared to electricity, you could make a profit heating your house. It also wouldn't need any redesign of the plumbing for lower temperature, actually engines don't like to run too cool and so there would be valves to regulate the temperatures.
Cryptocurrency has taught me to love math and at the same time be baffled by it.

Cryptocurrency lesson 0: Altcoins and Bitcoin are not the same thing.
 
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Offline m k

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Re: What is the real story around heat pumps?
« Reply #243 on: February 23, 2024, 07:46:00 am »
That's is situation with air source heat pumps from this morning:
Outside temp 2°C, humidity about 60%, clear sky, no rain, no clouds, no fog.

Pictures taken 3-4 minutes after defrost cycle completion.


Looks can be misleading.

The structure is what it is because air is not dense enough that lesser surface area would be enough.
Actual operation happens between refrigerant and inner wall of the pipe.
So the machine doesn't know that there is frost, generally it only knows that compression is fine or not.

Condenser/evaporator can be insufficient when general operation changes from the normal sufficient operation.
It can still be fine with visually not so fine looks.
Advance-Aneng-Appa-AVO-Beckman-Danbridge-Data Tech-Fluke-General Radio-H. W. Sullivan-Heathkit-HP-Kaise-Kyoritsu-Leeds & Northrup-Mastech-OR-X-REO-Simpson-Sinclair-Tektronix-Tokyo Rikosha-Topward-Triplett-Tritron-YFE
(plus lesser brands from the work shop of the world)
 

Online tom66

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Re: What is the real story around heat pumps?
« Reply #244 on: February 23, 2024, 08:14:34 am »
Depending on the model, some heat pumps just detect that they have fallen in efficacy (due to airflow drop) whereas others do actually measure for ice on the fins.
 

Offline Zarhi

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Re: What is the real story around heat pumps?
« Reply #245 on: February 23, 2024, 08:26:26 am »
That's is situation with air source heat pumps from this morning:
Outside temp 2°C, humidity about 60%, clear sky, no rain, no clouds, no fog.

Pictures taken 3-4 minutes after defrost cycle completion.


Looks can be misleading.

The structure is what it is because air is not dense enough that lesser surface area would be enough.
Actual operation happens between refrigerant and inner wall of the pipe.
So the machine doesn't know that there is frost, generally it only knows that compression is fine or not.

Condenser/evaporator can be insufficient when general operation changes from the normal sufficient operation.
It can still be fine with visually not so fine looks.

Evaporator was fully clogged, no air passes at all. And fan operates at very high speed.

In this situations heat pump works with COP slightly under 1. Heat dissipated in compressor are transferred to inside unit. Power needed for fan is lost.
 

Offline Marco

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Re: What is the real story around heat pumps?
« Reply #246 on: February 23, 2024, 09:19:52 am »
Defrost circuitry can be very stupid.
 

Online tszaboo

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Re: What is the real story around heat pumps?
« Reply #247 on: February 23, 2024, 11:47:04 am »
Always jumping to single solutions for energy are putting up strawmen, 100% solar, 100% wind, 100% CO2 capture, heating only from seasonal storage. They're all as dumb as each other. Most people can and do leverage the diversity of the gird to provide their energy needs, backed with things that are impractical on a domestic level like pumped hydro and nuclear power.
A private individual can only do so many projects at home. Solar is one of them, heatpump is another (which I'm not against, just pointing out how it's not practical for existing homes, after my government forces millions of homes to use). Combined heat and power is feasible, if the government keeps their dirty hands away from our individual freedom, and allows us to connect to the gas grid.
So yes, maybe it's possible to resolve these with solar or nuclear or burning peat underground or whatever. I have zero control over that. Solar is great, because it's free as in beers. Any time I need to import energy is just more leverage on my life that I want as much reduced as possible. All the other solutions are just asking for more taxes, fees utility bills. It leads to energy poverty. We want to resolve this global warming situation without causing yet more damage to the standards of living.

And yes, I do need 5GJ for a winter to be bearable in my home, dropping temperatures lower than most people keep here would be a respiratory hazard.
You're not needing that, its a want. As has been said repeatedly and in this thread even if heating is a need for health, heating the whole house is still a want.

But it seems this thread is now just the (outlier) UK gas price discussion, and the rest of the world still cant talk openly about heat pumps.
I'm done with this part of the discussion. I have the right for this declared by the UN article 25.
"Everyone has the right to a standard of living adequate for the health and well-being of himself and of his family"
I'm sick and tired of people flying in private jets to meeting in Davos, trying to tell us that we have to lower our standards of living, and convincing millions of useful idiots of this. You should stop being a useful idiot. There are ways we can resolve global warming without "depopulation" or "great reset".
So I'm going to be very clear about this: You have no right whatsoever to tell me, or anyone else, what I can or cannot have for my standard of living.
« Last Edit: February 23, 2024, 11:48:51 am by tszaboo »
 

Offline coppice

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Re: What is the real story around heat pumps?
« Reply #248 on: February 23, 2024, 12:41:06 pm »
That's is situation with air source heat pumps from this morning:
Outside temp 2°C, humidity about 60%, clear sky, no rain, no clouds, no fog.

Pictures taken 3-4 minutes after defrost cycle completion.


Looks can be misleading.

The structure is what it is because air is not dense enough that lesser surface area would be enough.
Actual operation happens between refrigerant and inner wall of the pipe.
So the machine doesn't know that there is frost, generally it only knows that compression is fine or not.

Condenser/evaporator can be insufficient when general operation changes from the normal sufficient operation.
It can still be fine with visually not so fine looks.

Evaporator was fully clogged, no air passes at all. And fan operates at very high speed.

In this situations heat pump works with COP slightly under 1. Heat dissipated in compressor are transferred to inside unit. Power needed for fan is lost.
Where is this located? A heat pump's exchanger needs to be in a place with very freely circulating air. Anything closing it in not only reduces efficiency, as the air recirculates, but condensation builds up much faster.  I see lots of people putting the heat exchanger in some dark corner of the world, so it doesn't look obtrusive or to make the noise less obtrusive. Good aesthetics tends to give poor operation.
 

Offline Zarhi

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Re: What is the real story around heat pumps?
« Reply #249 on: February 23, 2024, 01:05:37 pm »
Where is this located? A heat pump's exchanger needs to be in a place with very freely circulating air. Anything closing it in not only reduces efficiency, as the air recirculates, but condensation builds up much faster.  I see lots of people putting the heat exchanger in some dark corner of the world, so it doesn't look obtrusive or to make the noise less obtrusive. Good aesthetics tends to give poor operation.

One unit is south of the house, second unit is east. Both are in the same condition on same time.

But this is no matter. In 2 °C, 60% relative humidity and atmospheric pressure about 1000 hPa dew point is about -4.9 °C. So evaporator will build ice quickly no matter of location, air circulation and so on.

This morning was 3 °C, 30% relative humidity and 1012 hPa. Both outside units was clean, no ice at all, and no signs of water underneath them. So last night they doesn't look to defrost at all.

PS: Defrosting is clearly seen on graphs.
« Last Edit: February 23, 2024, 01:11:05 pm by Zarhi »
 


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