What is the real story around heat pumps?

[Someone]

What really disappoints me is in the UK we are still building homes without heatpumps.

That's not the core problem. The core problem is building land has become such a scarce resource that houses are built to get the maximum use of the space available. Also the building has to be constructed cheaply, so the final price, including the land, is somewhat affordable. This is incompatible with heavy insulation. In the 1930s land, in even suburban London, was so available even the cheapest houses could have huge gardens. Now luxury houses have tiny gardens. No space == no room for thick effective insulation. No space == no room to bore for geothermal heat. No space carries an energy burden.

Surface area is the key, although the ground looks like an infinite heatsink to a single user with a very slow time constant, over human time scales and densities it doesn't work without active recharging:
https://www.withouthotair.com/cE/page_302.shtml
But there seem to be (recurring) users on this forum who just can't understand basic physics:
https://www.eevblog.com/forum/chat/what-does-drilling-a-hole-for-water-cost-here-in-europe/?all

[Marco]

Since PV provides a glut of power in summer, recharging is hardly an issue.

[themadhippy]

Gas in the UK is being sold to consumers at a suspiciously low rate compared to electricity

And the gas companys still manage to make record profits,still the new golden hydrogen will change everything.

[coppice]

Heat pumps are viable where electricity is cheap, such as near a hydroelectric or nuclear power station. Areas where electricity is expensive need more investment in nuclear power, then people will choose heat pumps for economic reasons.

Politics aside...

Except your idea of "cheap" is already biased by politics. Gas in the UK is being sold to consumers at a suspiciously low rate compared to electricity. Trigeneration or running your own micro gen should be the answer in those conditions. The unusual situation where gas is much cheaper per unit energy than the open market has settled on.

UK energy prices are rather twisted right now, but before the Ukraine war electricity was about 4 to 5 times as much as gas. Do you think that is unreasonable?

[Someone]

Heat pumps are viable where electricity is cheap, such as near a hydroelectric or nuclear power station. Areas where electricity is expensive need more investment in nuclear power, then people will choose heat pumps for economic reasons.

Politics aside...

Except your idea of "cheap" is already biased by politics. Gas in the UK is being sold to consumers at a suspiciously low rate compared to electricity. Trigeneration or running your own micro gen should be the answer in those conditions. The unusual situation where gas is much cheaper per unit energy than the open market has settled on.

UK energy prices are rather twisted right now, but before the Ukraine war electricity was about 4 to 5 times as much as gas. Do you think that is unreasonable?

Its an anomaly with the UK at an extreme:
https://www.visualcapitalist.com/mapped-global-energy-prices-by-country-in-2022/
Plotted below to quickly see the trends (NL is way off to the right as the opposite outlier, OP is in FR which is also well off the average trend).

Gas is great for non-routine power plants (3:1 or so ratio to include all costs) and has higher value than electricity for some uses due to the inherent storage and high energy density possible. Anyone with access to gas below 3:1 ratio should be sending it to produce electricity and bring down their electricity prices (UK committed their population to long term supply contracts for nuclear??)

[Zero999]

Its an anomaly with the UK at an extreme:
https://www.visualcapitalist.com/mapped-global-energy-prices-by-country-in-2022/
Plotted below to quickly see the trends (NL is way off to the right as the opposite outlier, OP is in FR which is also well off the average trend).

Gas is great for non-routine power plants (3:1 or so ratio to include all costs) and has higher value than electricity for some uses due to the inherent storage and high energy density possible. Anyone with access to gas below 3:1 ratio should be sending it to produce electricity and bring down their electricity prices (UK committed their population to long term supply contracts for nuclear??)

Gas can only provide heat and when used to generate electricity, half of it is lost as heat.

I still think a gas powered heat pump would be best for me in winter. Generating my own electricity from gas is an interesting idea though.  I've thought of solar panels, but not that one.

What really disappoints me is in the UK we are still building homes without heatpumps.  Gas boilers and gas networks continue to be installed.

I should darn well think so, given electric heat pumps are more expensive to run, than gas boilers. If the government really want people to have heat pumps, they need to make electricity much cheaper, think nuclear, then people will be queuing up to get one.

[Someone]

I still think a gas powered heat pump would be best for me in winter. Generating my own electricity from gas is an interesting idea though.  I've thought of solar panels, but not that one.

By the time you're looking at a gas powered heat pump, a trigeneration setup isn't much further. But it's a bet on long term price of commodities given the lifespan/payback of such systems.

[mfro]

...
Its an anomaly with the UK at an extreme:
https://www.visualcapitalist.com/mapped-global-energy-prices-by-country-in-2022/
...

That link shows prices as of March '22. Far from reality in Feb 24.

[Zero999]

I still think a gas powered heat pump would be best for me in winter. Generating my own electricity from gas is an interesting idea though.  I've thought of solar panels, but not that one.

By the time you're looking at a gas powered heat pump, a trigeneration setup isn't much further. But it's a bet on long term price of commodities given the lifespan/payback of such systems.

No doubt it's possible to design a heat pump, which can be powered from electricity, as well as gas. It's just a case of adding an electric motor. It's definitely something I would consider, if my boiler were to need replacing.

...
Its an anomaly with the UK at an extreme:
https://www.visualcapitalist.com/mapped-global-energy-prices-by-country-in-2022/
...

That link shows prices as of March '22. Far from reality in Feb 24.

The copy of the energy bill I posted was for 2023 to 2024. For me gas is around a quarter of the price of electricity. I would have to be mad, to heat my house with anything but gas!
https://www.eevblog.com/forum/chat/what-is-the-real-story-around-heat-pumps/msg5345987/#msg5345987

[Someone]

...
Its an anomaly with the UK at an extreme:
https://www.visualcapitalist.com/mapped-global-energy-prices-by-country-in-2022/
...

That link shows prices as of March '22. Far from reality in Feb 24.

Example of the wide ranging spread of electricity : gas pricing in the real world, so comments from the UK such as gas is 4:1 should be taken with the grain of salt befitting an outlier situation, and not generalised to the rest of the world.

Feel free to put up some more recent figures, or older, or averaged, or whatever. What do you think has changed since those numbers were collected? Over here electricity is cheaper still and gas more expensive, heading further toward a 1:2 ratio.

[soldar]

Natural gas is much cheaper than electricity, even taking into account the lower energy consumption, it doesn't add up.

Well, yes and no but perhaps maybe... Things can get complicated.

Where I am I think heating the entire house with the central gas boiler and radiator system would be cheaper. But...

I do not need to heat the entire house and can manage quite well if I only heat one room where I spend most of my time. I suppose I could install some system to heat that single room with gas but it is not practical and I already have a split a/c heat pump system and I have to say it works really well and really cheaply.

I have my own "manual algorithm" which I suppose I could somehow automate but basically it comes down to pump a lot of heat from outside when the outside temperature is higher outside because this increases efficiency. This means less stable temperature inside but I can live with that because it means less cost. If in the middle of the day it gets hotter than I need, so what? It is heat I am accumulating inside now that it is easy to get rather than in the middle of the night when it is much more expensive.

My "algorithm" aims for minimum cost, not maximum comfort.

[Miyuki]

The problem with generating electricity on a small scale is that the cost does not scale linearly.
And also big engines are easier to reach high efficiency. While big piston engines can reach over 50%, small generator ones are closer to 30% which might not be a big problem if you want the heat anyway.
Then there is here the maintenance problem, every few hundred hours. And that noise issue.

But gas-powered heat pumps might be a nice option for places with cheap gas, even with their low COP of 1.5 - 2.5, there can be a significant reduction in gas usage. I wonder why they are not more common at the domestic scale. Probably only a few places have suitable conditions to use them to be actively developed and manufactured.
And with ever-dropping prices of solar panels, they probably won't be ever viable as they need to be powered by a heat source, so a compressor-driven heat pump is way more versatile and can get some help from solar even during winter.

[m k]

Our recent electricity prices have had few peaks.

Last November some Norwegians gave us a high five.
We have an electric sauna heater, many others also.
Our heater is 6kW thingy and when it goes on electricity heating radiators are blocked, not enough fuses for all.
But 16A wall jacks are still on and luckily I have few portable electric heaters with fans, luckily not too many.
My average electricity for November was less than 4c/kWh.

Our electricity network has two parts, the grid and its energy.
You can buy your energy from where you want, but grid owner is always billing its part.
Old electricity companies are many times county or many counties owned and hidden tax collectors.
Means that electricity transfer cost is as high as it is legally possible, some of them may try to argue against.

A comment after that November day from a grid operator.
He estimated that during that time he learned every spot electricity customers in his grid.
Some burned their main fuses multiple times, billing meter reported them.
Story doesn't tell how those fuses were put back.
Our possibly 3x63A grid fuses are from late 70's and "far away" outside, 3x25A mains switch fuses are under the switch and behind a sealed plate.

[Zero999]

Its an anomaly with the UK at an extreme:
https://www.visualcapitalist.com/mapped-global-energy-prices-by-country-in-2022/

I forgot to say, that link shows gasoline prices. I'm talking about natural gas. I don't know of anyone who uses gasoline to heat their home int the UK. It's very heavily taxed.

Natural gas is much cheaper than electricity, even taking into account the lower energy consumption, it doesn't add up.

Well, yes and no but perhaps maybe... Things can get complicated.

Where I am I think heating the entire house with the central gas boiler and radiator system would be cheaper. But...

I do not need to heat the entire house and can manage quite well if I only heat one room where I spend most of my time. I suppose I could install some system to heat that single room with gas but it is not practical and I already have a split a/c heat pump system and I have to say it works really well and really cheaply.

I have my own "manual algorithm" which I suppose I could somehow automate but basically it comes down to pump a lot of heat from outside when the outside temperature is higher outside because this increases efficiency. This means less stable temperature inside but I can live with that because it means less cost. If in the middle of the day it gets hotter than I need, so what? It is heat I am accumulating inside now that it is easy to get rather than in the middle of the night when it is much more expensive.

My "algorithm" aims for minimum cost, not maximum comfort.

Where did I say you should do the same as I do?

All I did was responded to a comment which implied that electric heat pumps are economical for most people, which I dispute. It certainly isn't the case for me.

Engineering is all about selecting the most optimal solution, for a specific application. In my case a gas powered heat pump is the cheapest to run, but nowhere did I say that's the same for everyone. The original poster currently heats their home with wood, so an electric heat pump will certainly be cheaper, than the status quo.

[soldar]

Where did I say you should do the same as I do?

Where did I say you said that? .... I did not and I cannot see how my post can be understood that way. Relax. We are all friends here.

Engineering is all about selecting the most optimal solution, for a specific application.

"Most optimal"?  Now, those are fighting words!

 

[Zero999]

Where did I say you should do the same as I do?

Where did I say you said that? .... I did not and I cannot see how my post can be understood that way. Relax. We are all friends here.

The way you quoted me saying that gas is cheaper than electricity, could be taken out of context. When the rest of the post is taken into account, it's clear I was talking about my situation, not everyone's. I'm not saying this was intentional of course. It's easily done.

Engineering is all about selecting the most optimal solution, for a specific application.

"Most optimal"?  Now, those are fighting words!

 

Indeed and in this case, what's optimal can change over time. This is why I would be interested in a gas/electric heat pump, that way I'm not locked into using one fuel and can change, if electricity becomes much cheaper than gas in the future.

Anyway, this thread has become too off-topic. The original poster just wants to know the pros and cons of replacing their current wood fired heating with a heat pump.

I wonder if it's easy to power a heat pump from a gasifier. It aught to significantly cut fuel consumption.  It's not something which you'll be able to purchase off the shelf, but is certainly doable from off the shelf components. I'm thinking of a gasifier powering a small internal combustion engine, driving an automotive air conditioning unit. You might have to change the refrigerate so something more suitable for heating than cooling, but it'll work. I don't know what COP you'll get, but it aught to be better than just burning wood.

[nctnico]

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.

[pcprogrammer]

Anyway, this thread has become too off-topic. The original poster just wants to know the pros and cons of replacing their current wood fired heating with a heat pump.

I don't mind, my question has been answered.   

I wonder if it's easy to power a heat pump from a gasifier. It aught to significantly cut fuel consumption.  It's not something which you'll be able to purchase off the shelf, but is certainly doable from off the shelf components. I'm thinking of a gasifier powering a small internal combustion engine, driving an automotive air conditioning unit. You might have to change the refrigerate so something more suitable for heating than cooling, but it'll work. I don't know what COP you'll get, but it aught to be better than just burning wood.

I guess it would be quite the contraption that makes a significant amount of noise, and would still require wood to be hauled around.

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.

[coppice]

...
Its an anomaly with the UK at an extreme:
https://www.visualcapitalist.com/mapped-global-energy-prices-by-country-in-2022/
...

That link shows prices as of March '22. Far from reality in Feb 24.

Example of the wide ranging spread of electricity : gas pricing in the real world, so comments from the UK such as gas is 4:1 should be taken with the grain of salt befitting an outlier situation, and not generalised to the rest of the world.

Feel free to put up some more recent figures, or older, or averaged, or whatever. What do you think has changed since those numbers were collected? Over here electricity is cheaper still and gas more expensive, heading further toward a 1:2 ratio.

Prices during a major international upset don't really mean anything about the long term. Some country's energy supplies were disturbed far more than others, so their price rises had a large spread. The chart you posted actually says UK home heating costs were up 3 fold that year. It says 10 cents/kWh for gas. That's less than I have been paying, but its about 3 times what I paid in 2021.

[tom66]

What really disappoints me is in the UK we are still building homes without heatpumps.  Gas boilers and gas networks continue to be installed.

I should darn well think so, given electric heat pumps are more expensive to run, than gas boilers. If the government really want people to have heat pumps, they need to make electricity much cheaper, think nuclear, then people will be queuing up to get one.

Not sure that they are more expensive to run.  Basic maths assuming Ofgem capped rates.

Gas = 7p/kWh
Electric = 29p/kWh

Gas boiler efficiency (net) = ~85% under normal conditions.  90% best case but rarely achieved.
Heat pump efficiency (net) = ~350% seasonal average.

So per kWh of heat, the gas boiler costs 8.2p whereas the heat pump costs ... 8.3p.

There may be some variation either side of these figures but in the UK alone, a heat pump should cost *about as much* as a gas boiler to run.

Going on agile tariffs, like Octopus Tracker, may show more of a difference.  Today's tracker costs are 3.69p/kWh for gas and 16.9p/kWh for electricity.  Giving per kWh equivalents of 4.34p/kWh and 4.82p/kWh.  But still, a pretty close parity, and the heat pump could easily win if the SCOP was better, whereas the gas boiler is already pretty much as efficient as it gets.

The problem is that heat pumps cost so much more to install, so it doesn't really matter even if they cost, say, 2p less per kWh, the TCO doesn't add up if you assume 10 year lifespan before major refurbishment is required.  The cost per kWh of heat needs to be half or less to make them pay off and even then, it's arguable as to how cost effective they are.  And replacing a gas boiler costs ca. £2,000 whereas a heat pump costs at least £5,000 but possibly double that in the worst case.

Really, heat pumps need to fall in price, that will make them a lot more affordable.  I don't personally understand why they cost so much, but I haven't looked in depth at one.

[pcprogrammer]

What really disappoints me is in the UK we are still building homes without heatpumps.  Gas boilers and gas networks continue to be installed.

I should darn well think so, given electric heat pumps are more expensive to run, than gas boilers. If the government really want people to have heat pumps, they need to make electricity much cheaper, think nuclear, then people will be queuing up to get one.

Not sure that they are more expensive to run.  Basic maths assuming Ofgem capped rates.

Gas = 7p/kWh
Electric = 29p/kWh

Gas boiler efficiency (net) = ~85% under normal conditions.  90% best case but rarely achieved.
Heat pump efficiency (net) = ~350% seasonal average.

So per kWh of heat, the gas boiler costs 8.2p whereas the heat pump costs ... 8.3p.

There may be some variation either side of these figures but in the UK alone, a heat pump should cost *about as much* as a gas boiler to run.

Going on agile tariffs, like Octopus Tracker, may show more of a difference.  Today's tracker costs are 3.69p/kWh for gas and 16.9p/kWh for electricity.  Giving per kWh equivalents of 4.34p/kWh and 4.82p/kWh.  But still, a pretty close parity, and the heat pump could easily win if the SCOP was better, whereas the gas boiler is already pretty much as efficient as it gets.

The problem is that heat pumps cost so much more to install, so it doesn't really matter even if they cost, say, 2p less per kWh, the TCO doesn't add up if you assume 10 year lifespan before major refurbishment is required.  The cost per kWh of heat needs to be half or less to make them pay off and even then, it's arguable as to how cost effective they are.  And replacing a gas boiler costs ca. £2,000 whereas a heat pump costs at least £5,000 but possibly double that in the worst case.

Really, heat pumps need to fall in price, that will make them a lot more affordable.  I don't personally understand why they cost so much, but I haven't looked in depth at one.

But gas boiler manufactures state 103 to 107% efficiency for the condensing systems.    (How to fool your customers)

I don't see either why the heat pumps need to be so expensive. A small car can probably be bought for the price of the De Dietrich GSHP 12 MR-E. (11066,95 Euro including 5,5% TVA or in English VAT  )

[Zero999]

What really disappoints me is in the UK we are still building homes without heatpumps.  Gas boilers and gas networks continue to be installed.

I should darn well think so, given electric heat pumps are more expensive to run, than gas boilers. If the government really want people to have heat pumps, they need to make electricity much cheaper, think nuclear, then people will be queuing up to get one.

Not sure that they are more expensive to run.  Basic maths assuming Ofgem capped rates.

Gas = 7p/kWh
Electric = 29p/kWh

Gas boiler efficiency (net) = ~85% under normal conditions.  90% best case but rarely achieved.
Heat pump efficiency (net) = ~350% seasonal average.

So per kWh of heat, the gas boiler costs 8.2p whereas the heat pump costs ... 8.3p.

There may be some variation either side of these figures but in the UK alone, a heat pump should cost *about as much* as a gas boiler to run.

Going on agile tariffs, like Octopus Tracker, may show more of a difference.  Today's tracker costs are 3.69p/kWh for gas and 16.9p/kWh for electricity.  Giving per kWh equivalents of 4.34p/kWh and 4.82p/kWh.  But still, a pretty close parity, and the heat pump could easily win if the SCOP was better, whereas the gas boiler is already pretty much as efficient as it gets.

The problem is that heat pumps cost so much more to install, so it doesn't really matter even if they cost, say, 2p less per kWh, the TCO doesn't add up if you assume 10 year lifespan before major refurbishment is required.  The cost per kWh of heat needs to be half or less to make them pay off and even then, it's arguable as to how cost effective they are.  And replacing a gas boiler costs ca. £2,000 whereas a heat pump costs at least £5,000 but possibly double that in the worst case.

Really, heat pumps need to fall in price, that will make them a lot more affordable.  I don't personally understand why they cost so much, but I haven't looked in depth at one.

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 gas powered heat pump is a more economical solution. It wouldn't cost much more and would be cheaper to run, so would eventually pay for itself.

[coppice]

But gas boiler manufactures state 103 to 107% efficiency for the condensing systems.    (How to fool your customers)

In the UK the boiler makers quote figures in the low 90s for their condensing boilers. Perhaps the 103% to 107% is a comparison with non-condensing boilers, but that seems too low. The improvement should be well above 3%.

[pcprogrammer]

But gas boiler manufactures state 103 to 107% efficiency for the condensing systems.    (How to fool your customers)

In the UK the boiler makers quote figures in the low 90s for their condensing boilers. Perhaps the 103% to 107% is a comparison with non-condensing boilers, but that seems too low. The improvement should be well above 3%.

The guy who tried to persuade us to buy a oil burner stated that the condensing one, he was going to offer, had an efficiency of 107%. He clearly had no idea what he was talking about.

But indeed they use it to compare non condensing with condensing types. Don't know how they get these figures, but they are useless.

[tszaboo]

But gas boiler manufactures state 103 to 107% efficiency for the condensing systems.    (How to fool your customers)

In the UK the boiler makers quote figures in the low 90s for their condensing boilers. Perhaps the 103% to 107% is a comparison with non-condensing boilers, but that seems too low. The improvement should be well above 3%.

The guy who tried to persuade us to buy a oil burner stated that the condensing one, he was going to offer, had an efficiency of 107%. He clearly had no idea what he was talking about.

But indeed they use it to compare non condensing with condensing types. Don't know how they get these figures, but they are useless.

His numbers might be OK, but it's calculated differently. I know how it sounds, the efficiency is still less than 100% physics wise. it was probably a condenser boiler, that includes latent heat in the calculation and that's how you reach "more than 100%".

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.

I don't think it's an issue because my solar system delivered ~1KWh during the last one week daily, about 1/25th of a summer day. You certainly shouldn't size a system for that.

Something else I just looked up. An Air source heatpumps uses something like 25KG of copper. So our entire copper reserves worldwide are only enough for 45 million heatpumps if we use all of it for that, which is about the number of households in Germany  .Geothermal uses that as well. I guess it's also time probably to use Aluminium for these, otherwise the great plans might be in peril.