EV-based road transportation is not viable

[tom66]

Good diagram.  But, does it account for the difficulty in insulating UK homes to support heat pumps?  Having embarked upon the process of insulating our 1930's detached home, it is definitely not a trivial process usually requiring bespoke techniques for each property.

Heat is heat. There is no difference for heat pump heat or heat from a boiler or gas.

Not really.  Heatpumps have the highest COP when running at lower power outputs.  The ideal heatpump runs all day (when you're awake) at low power outputs, relatively low delta-T at the radiators.  Typical flow and return of 55C and 35C not uncommon, well below that of used for boilers.  If you have insufficient insulation, you need a very large heat pump, which becomes uneconomical.

[nctnico]

So, uhm, that's your argument then? You disregard any data that doesn't fit your narrative and call all those that run with it idiots? 

There is no narrative and there is no argument. Just the fact that heatpumps are not economic to run when it is cold. This is obviously clear from looking at specifications from actual heatpumps. There is no need for yet another fantasy number that is invented to compare heatpumps because it says nothing about the suitability of heatpump for a less insulated home.

[tom66]

Typical winter with this climate, the deltaT is 20-30, entirely possible to provide this even with air source heatpump.

It is not about the temperature delta, but the absolute temperature operating range of a heatpump! And at some point the outside unit will ice up preventing extracting heat from the environment. The graph you posted is way too optimistic. A heatpump simply does not work well in a climate that has close to or sub-zero temperatures.

Below zero most ASHPs cycle and turn the outside radiator into a heating element by extracting a bit of heat from the interior to melt ice.  This typically happens for 1 minute every 15-20 minutes.   I guess some may also use an electric heating element now and then.  For multi split units only one of the units does this, the others shut off entirely.

From someone who I know who owns a cheaper TCL unit (Chinese air conditioner) the bigger problem is the firmware doesn't detect the icing condition soon enough, so efficiency falls off because air flow through the rad drops.  The better units have ice sensors, but the cheaper units just wait until the system doesn't seem to be performing as well as is expected. 

I also wonder if anyone has considered periodically spraying an antifreeze onto the fins, though you'd probably go through a lot of glycol you might be able to recycle it a few times.

[Ice-Tea]

So, uhm, that's your argument then? You disregard any data that doesn't fit your narrative and call all those that run with it idiots? 

There is no narrative and there is no argument. Just the fact that heatpumps are not economic to run when it is cold. This is obviously clear from looking at specifications from actual heatpumps. There is no need for yet another fantasy number that is invented to compare heatpumps because it says nothing about the suitability of heatpump for a less insulated home.

But.... it does. Nobody is arguing that the efficiency of a heatpump goes down when temperature does. That's why you have the SCOP value. It tells you what your seasonal efficiency will be. And it does say something about suitability for less isolated houses as you typically have this value for 35C and 55C feed temperatures. And if 55C doesn't suffise: get crackin' on isolating your barn, please.

[PlainName]

The better units have ice sensors, but the cheaper units just wait until the system doesn't seem to be performing as well as is expected.

Not sure what mine is but probably classed as a cheap unit - when turned on, if the desired temperature is the same as the actual temperature it can get into a permanent defrosting cycle (fix is to just turn up the desired temperature until it recovers, then put it back). When it is cold outside, like below freezing, I do notice it goes into the defrost cycle now and then, but it never actually fails to keep the place warm. Worst case is it feels like it's idling (which, I suppose it is if it's just recirculating air) but it doesn't last long enough to make any difference.

[Monkeh]

Good diagram.  But, does it account for the difficulty in insulating UK homes to support heat pumps?  Having embarked upon the process of insulating our 1930's detached home, it is definitely not a trivial process usually requiring bespoke techniques for each property.

Heat is heat. There is no difference for heat pump heat or heat from a boiler or gas.

Not true. optimum working temperature is different between different systems - heat pumps don't produce the higher temperatures needed to overcome poor insulation. Replacing a traditional pumped water/gas CH system with HP usually requires radiators to be up-sized to get the same output at a lower temperature drop.

If it works for Norway, there is really no reason why it wouldn't work for the UK or here.

But it requires significant remedial work to the properties.

My house would be quite impractical to heat with a heatpump: The floors are leaky, and the existing pipework is microbore and fairly severely contaminated by iron oxide buildup. Every radiator and every pipe would require replacement, along with lifting the entire ground floor and insulating and sealing. Oh, yes, all the windows upstairs also need replacing, along with a properly sealed loft hatch.

By the time you've done all this you've not only tripled the cost of the installation, but required the occupants and their belongings to be removed from the house for at least several weeks.

I'd love to go this route. Hell, I'd take the opportunity to fit some AC to a couple of rooms. You supplying the £30,000?

[nctnico]

So, uhm, that's your argument then? You disregard any data that doesn't fit your narrative and call all those that run with it idiots? 

There is no narrative and there is no argument. Just the fact that heatpumps are not economic to run when it is cold. This is obviously clear from looking at specifications from actual heatpumps. There is no need for yet another fantasy number that is invented to compare heatpumps because it says nothing about the suitability of heatpump for a less insulated home.

But.... it does. Nobody is arguing that the efficiency of a heatpump goes down when temperature does. That's why you have the SCOP value. It tells you what your seasonal efficiency will be. And it does say something about suitability for less isolated houses as you typically have this value for 35C and 55C feed temperatures. And if 55C doesn't suffise: get crackin' on isolating your barn, please.

If you look at what SCOP actually means, you'll notice it is not a number that tells you something about the suitability of a unit. Seasonal efficiency doesn't mean that a unit will be able to heat a home when it is cold. The COP might be too low and SCOP doesn't tell you that at all.

Also, you don't need high water temperatures perse. It is relatively easy to retrofit an existing home with underfloor heating (been there, done that) which doesn't need high water temperatures at all.

[tom66]

What I do find nuts is that the UK government is allowing new homes to be built (a) with gas boilers and (b) without good insulation, such that when they do get heatpumps fitted, they will need additional remedial work to make it work properly.  It's bonkers.

[tggzzz]

Good diagram.  But, does it account for the difficulty in insulating UK homes to support heat pumps?  Having embarked upon the process of insulating our 1930's detached home, it is definitely not a trivial process usually requiring bespoke techniques for each property.

And external insulation is very easy to get badly wrong, e.g. https://www.walesonline.co.uk/news/wales-news/victims-home-insulation-scandal-scandal-26076372.amp

One of my relatives is an advisor for people who seek to improve the insulation & lower the carbon footprint of their homes. His conclusion is that it is not worthwhile to re-insulate older homes because the basic structure doesn't allow for it. Better insulation also means adding air treatment to manage the moisture inside a home which means adding ducts and mechanical ventilation. So the only option is to use hybrid heaters (heatpump + boiler) in order to get enough heat into such homes. Heating is not just necessary to keep the people inside a home warm, but also to keep the home itself dry in order not to get problems with mold and wood rot. It is pretty complicated to get right from the start. Let alone trying to do a retrofit.

All plausible, and questions I would want answered before doing anything like that.

IIRC the S Wales situation was exacerbated by grossly incompetent work, allowing driving rain to enter the external insulation. Even if done competently, it sounds like a fragile installation which is certain to deteriorate over the decades.

[tggzzz]

What I do find nuts is that the UK government is allowing new homes to be built (a) with gas boilers and (b) without good insulation, such that when they do get heatpumps fitted, they will need additional remedial work to make it work properly.  It's bonkers.

There's always a balance to be struck w.r.t. planning for a future that might not come. I've known people that put RS232 everywhere in their house so they wouldn't have to retrofit it.

Having said that, the lack of good insulation does seem unsupportable.

[tom66]

It's pretty simple, at the very least properties should be built to support heatpump retrofit, so large radiators or underfloor heating, hot water tank instead of a combi boiler, no electric showers, passive-haus class insulation with room vents etc.  Yet I've looked around 1-2 year old properties and they often don't meet these standards.

If you do it right, you can heat a house (in UK climates, typical winter day) with less than 500W - that's not one room, that's the whole bloody house.

We do need more homes (complex issue though) but no point putting up homes that are leaky and draughty.

[themadhippy]

Have developers spending money on insulation and doing a decent job instead of slipping a fraction of  the amount to there political chums to keep things as they are,never gonna happen.

[Someone]

crazy, I didn't realize the title of this thread was "heat pumps in houses are not viable"

We had that:
https://www.eevblog.com/forum/renewable-energy/new-world-of-electrical-power-generation/?all
Same people, same completely misleading "arguments" that they cant possibly use heat pumps because:
older heat pumps didn't have enough performance at low temperatures (no longer true for modern units)
massive invested capital in complex Rube Goldberg heating systems, insisting on retaining that system like for like (refusing to trade any benefits against losses in function, stick to your horse and cart and stop complaining....)

[tszaboo]

So, uhm, that's your argument then? You disregard any data that doesn't fit your narrative and call all those that run with it idiots? 

There is no narrative and there is no argument. Just the fact that heatpumps are not economic to run when it is cold. This is obviously clear from looking at specifications from actual heatpumps. There is no need for yet another fantasy number that is invented to compare heatpumps because it says nothing about the suitability of heatpump for a less insulated home.

But.... it does. Nobody is arguing that the efficiency of a heatpump goes down when temperature does. That's why you have the SCOP value. It tells you what your seasonal efficiency will be. And it does say something about suitability for less isolated houses as you typically have this value for 35C and 55C feed temperatures. And if 55C doesn't suffise: get crackin' on isolating your barn, please.

If you look at what SCOP actually means, you'll notice it is not a number that tells you something about the suitability of a unit. Seasonal efficiency doesn't mean that a unit will be able to heat a home when it is cold. The COP might be too low and SCOP doesn't tell you that at all.

Also, you don't need high water temperatures perse. It is relatively easy to retrofit an existing home with underfloor heating (been there, done that) which doesn't need high water temperatures at all.

Why do you think this is happening? Do you think that this is a huge mistake that half the households are doing in these countries? I give you an even better idea. I have district heating, coming from a coal power plant, as I understand it's scheduled to be shut down. And the company maffia organization, Ennaturlijk, was doing absolutely nothing to replace this with something more environmentally friendly. While district heating is the perfect example, with one plant, doing water to water heatpumping, can do enormous energy savings for tens of thousands of households.
But I can already see the people protesting that "it will freeze the fishes" or some other reason, and it's too cold here (clearly not).

[tautech]

New flash in NZ last few days is that our dairy giant Fonterra is partnering with MAN to develop electric heatpump boilers to cease reliance on coal.
https://www.fonterra.com/nz/en/our-stories/media/fonterra-and-man-energy-solutions-enter-into-major-partnership.html

Who says cant ?

[Miyuki]

Just use suitable radiators to have a 45°C system, it is not a problem, they are thicker and have denser fins inside, but they definitely can be fitted to old uninsulated houses.
10 or so years ago was common to install heat pumps rated to 15-25kW output in old uninsulated houses. The cost of the bigger pump was still cheaper than house insulation. And making the heat pump bigger can be relatively inexpensive. Two times bigger compressor does not cost two times but just lower tens of percent more. The evaporator is also relatively cheap and the expensive control electronics remains the same. 

[Monkeh]

Just use suitable radiators to have a 45°C system, it is not a problem, they are thicker and have denser fins inside, but they definitely can be fitted to old uninsulated houses.

'just' replace every radiator in the building and all the pipework. Five minute job.

[coppice]

Just use suitable radiators to have a 45°C system, it is not a problem, they are thicker and have denser fins inside, but they definitely can be fitted to old uninsulated houses.
10 or so years ago was common to install heat pumps rated to 15-25kW output in old uninsulated houses. The cost of the bigger pump was still cheaper than house insulation. And making the heat pump bigger can be relatively inexpensive. Two times bigger compressor does not cost two times but just lower tens of percent more. The evaporator is also relatively cheap and the expensive control electronics remains the same.

If you are going to that much expense and disruption, why would you use radiators at all? If you want radiators to run at 45C in most rooms you will need to used forced air. A passive radiator would be huge. You might as well force much cooler air around the entire house, and get a much better COP from the heat pump.

[tom66]

'just' replace every radiator in the building and all the pipework. Five minute job.

Hmm, radiators aren't *that* difficult to change if you're also going to be installing a heatpump.  Doing insulation throughout though, that requires redecoration and most rooms to be emptied out, so isn't really trivial.

[nctnico]

So, uhm, that's your argument then? You disregard any data that doesn't fit your narrative and call all those that run with it idiots? 

There is no narrative and there is no argument. Just the fact that heatpumps are not economic to run when it is cold. This is obviously clear from looking at specifications from actual heatpumps. There is no need for yet another fantasy number that is invented to compare heatpumps because it says nothing about the suitability of heatpump for a less insulated home.

But.... it does. Nobody is arguing that the efficiency of a heatpump goes down when temperature does. That's why you have the SCOP value. It tells you what your seasonal efficiency will be. And it does say something about suitability for less isolated houses as you typically have this value for 35C and 55C feed temperatures. And if 55C doesn't suffise: get crackin' on isolating your barn, please.

If you look at what SCOP actually means, you'll notice it is not a number that tells you something about the suitability of a unit. Seasonal efficiency doesn't mean that a unit will be able to heat a home when it is cold. The COP might be too low and SCOP doesn't tell you that at all.

Also, you don't need high water temperatures perse. It is relatively easy to retrofit an existing home with underfloor heating (been there, done that) which doesn't need high water temperatures at all.

Why do you think this is happening? Do you think that this is a huge mistake that half the households are doing in these countries?

You keep missing the point here which has been explained by several people already. But I will repeat is once more so you may finally understand it: a heatpump can only work for a home that is well insulated.  When the COP bottoms out, it has still has the capacity to provide enough heat through resistive heating. However, in many countries that have relatively mild climates (like UK, NL, Germany), homes (especially the older ones) are not insulated well enough to be heated with a heatpump all year long. It is logical that you see heatpumps in countries with colder climates because those homes are way better insulated already and thus suitable for heating by a heatpump.

It is not about black / white, heatpumps bad / good, it is about suitability. I have been using the word 'suitable' a lot but people keep missing it.

[Miyuki]

'just' replace every radiator in the building and all the pipework. Five minute job.

Hmm, radiators aren't *that* difficult to change if you're also going to be installing a heatpump.  Doing insulation throughout though, that requires redecoration and most rooms to be emptied out, so isn't really trivial.

Peoples are crazy and changing radiators just because they want a modern look or some snake oil salesman telling them these new ones will save them so much money. I see it all around. 
Tossing out perfectly fine cast iron ones just to replace them with fancy sheet metal ones. And similar nonsense. And they replace the old gas boiler with a new one. So system parameters remain the same.   
I agree fan coils will be better for a 45°C system, but for a bedroom, it is a no go.
Big remodel with floor heating will add way more comfortable for many houses but it is a big job and probably will be bodged, just like the insulation is.

So fashionable  And a typical example of where is plenty of space for a big low-temperature one.

[tom66]

You keep missing the point here which has been explained by several people already. But I will repeat is once more so you may finally understand it: a heatpump can only work for a home that is well insulated. In many countries that have relatively mild climates (like UK, NL, Germany), homes (especially the older ones) are not insulated well enough to be heated with a heatpump all year long. It is logical that you see heatpumps in countries with colder climates because those homes are way better insulated already and thus suitable for heating by a heatpump.

So this is not entirely true.  Heat is heat at the end of the day.

You can make a heatpump work on a poorly insulated home, but it will need to be much larger and the radiators will have to be large to get the required room heat output.  The challenge is the heatpump output power will begin to decline as the outside temperature falls, so you end up with very large heatpumps serving just a few days a year - and heatpumps don't run as efficiently when cycling or running at lower loads.

There is no reason a heatpump cannot work on a poorly insulated home.  You can just put a bigger and bigger one in.  Unfortunately, a 24kW boiler costs about £2,000 but a 24kW output power heatpump costs about £15,000.  Not economical.

So instead you sometimes see "engineers" try to fit the 12kW heatpump and people complain their home takes forever to heat up (or is too cold in winter.)

A few things need to change for heatpumps to be more economical.  The price needs to fall drastically.  They are a motor, refrigeration system, controller.  Shouldn't cost that much.  And the installers need to get better.  The scheme around F-Gas in this country is a bit bizarre and segmented and too few people do air con systems.

[nctnico]

You keep missing the point here which has been explained by several people already. But I will repeat is once more so you may finally understand it: a heatpump can only work for a home that is well insulated. In many countries that have relatively mild climates (like UK, NL, Germany), homes (especially the older ones) are not insulated well enough to be heated with a heatpump all year long. It is logical that you see heatpumps in countries with colder climates because those homes are way better insulated already and thus suitable for heating by a heatpump.

So this is not entirely true.  Heat is heat at the end of the day.

You can make a heatpump work on a poorly insulated home, but it will need to be much larger and the radiators will have to be large to get the required room heat output.  The challenge is the heatpump output power will begin to decline as the outside temperature falls, so you end up with very large heatpumps serving just a few days a year - and heatpumps don't run as efficiently when cycling or running at lower loads.

There is no reason a heatpump cannot work on a poorly insulated home.  You can just put a bigger and bigger one in.  Unfortunately, a 24kW boiler costs about £2,000 but a 24kW output power heatpump costs about £15,000.  Not economical.

Financially not viable = cannot work. For all intends and purposes it comes down to the same: you'll need a different solution for the problem. There is no semantic discussion necessary on what can work 'in theory' but has no practical application.

[Monkeh]

'just' replace every radiator in the building and all the pipework. Five minute job.

Hmm, radiators aren't *that* difficult to change if you're also going to be installing a heatpump.  Doing insulation throughout though, that requires redecoration and most rooms to be emptied out, so isn't really trivial.

But it's not just the radiators. You cannot get enough flow through a microbore pipe (8 or 10mm OD, typically) with half the bore clogged by the remains of the old radiators to feed these large radiators at such low flow temperatures. This means significant additional work. Even once you've done that, if the house is inadequately insulated or leaks too much cold air, you'll have problems getting things consistently warm.

Heatpumps will work fine, so long as someone ponies up the money to deploy them effectively.

[tom66]

Financially not viable = cannot work. For all intends and purposes it comes down to the same: you'll need a different solution for the problem. There is no semantic discussion necessary on what can work 'in theory' but has no practical application.

Being not viable today doesn't mean not viable in 10-20 years though.  If you could get the cost of the heatpump down then they become a lot more viable.

Fundamentally there's no good reason you could not build much cheaper heatpumps at higher output powers, but there would need to be enough demand for it.  Currently there is limited demand, most heatpumps are sold as air conditioning, used more in summer, so efficiency/power output are seen as less critical.    A 24kW heatpump versus a 3kW air con is a bigger motor, bigger radiator, and a more powerful drive inverter, but the costs for those don't rise in a linear fashion.

This is why the UK government (and EU) should ban the installation of new gas boilers and only allow boilers to be sold as replacements for existing ones, with the objective to phase out the sale of gas/oil boilers in their entirety by a future date. Suddenly you create a huge market for these devices and let capitalism work on the problem.   You need to get the phase out right because it will take a lot longer to fit appropriate heatpumps to the leakiest properties but it will be possible eventually.   As I said, there's no fundamental reason that can't be done.