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EV-based road transportation is not viable
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Miyuki:

--- Quote from: tom66 on February 22, 2023, 09:35:26 pm ---
--- Quote from: Monkeh on February 22, 2023, 09:21:16 pm ---'just' replace every radiator in the building and all the pipework. Five minute job.

--- End quote ---

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.

--- End quote ---
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:

--- Quote from: nctnico on February 22, 2023, 09:41:21 pm ---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.

--- End quote ---

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:

--- Quote from: tom66 on February 22, 2023, 09:51:06 pm ---
--- Quote from: nctnico on February 22, 2023, 09:41:21 pm ---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.

--- End quote ---

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.

--- End quote ---
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:

--- Quote from: tom66 on February 22, 2023, 09:35:26 pm ---
--- Quote from: Monkeh on February 22, 2023, 09:21:16 pm ---'just' replace every radiator in the building and all the pipework. Five minute job.

--- End quote ---

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.

--- End quote ---

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:

--- Quote from: nctnico on February 22, 2023, 10:03:36 pm ---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.

--- End quote ---

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.
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