Author Topic: house outlet ac power  (Read 14882 times)

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Offline TimFox

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Re: house outlet ac power
« Reply #100 on: January 16, 2022, 03:26:10 pm »
Obviously, that reduces the voltage.  Neither type of transformer will increase the power.
 

Offline Zero999

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Re: house outlet ac power
« Reply #101 on: January 16, 2022, 05:52:53 pm »
 

Offline CapernicusTopic starter

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Re: house outlet ac power
« Reply #102 on: January 17, 2022, 01:42:52 am »
playing the fool,  is something i dont understand, i am sorry.

so what do we do,  just lie to all the kids at uni?
 

Online Monkeh

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Re: house outlet ac power
« Reply #103 on: January 17, 2022, 02:35:47 am »
playing the fool,  is something i dont understand, i am sorry.

so what do we do,  just lie to all the kids at uni?

What on earth are you on about?
 
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Offline Munyua44

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Re: house outlet ac power
« Reply #104 on: January 17, 2022, 04:43:49 am »
i would advice you have a look at the basics about electricity. We have too much information on the internet that will allow you to understand why some countries settle for 120v and others 240 v
 

Offline Zero999

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Re: house outlet ac power
« Reply #105 on: January 17, 2022, 08:47:13 am »
playing the fool,  is something i dont understand, i am sorry.

so what do we do,  just lie to all the kids at uni?
Mentioning a step-down transformer, to increase the current, was silly because you know it reduces the voltage, which again is silly, because it's important to keep the voltage the same 230V.
 

Offline BeBuLamar

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Re: house outlet ac power
« Reply #106 on: January 17, 2022, 10:44:18 am »
If your house only have 2400W like someone said you're in big trouble.
 

Offline grumpydoc

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Re: house outlet ac power
« Reply #107 on: January 17, 2022, 11:19:46 am »
If your house only have 2400W like someone said you're in big trouble.
EDF in France go down to a 3kW supply agreement.
 

Offline vk6zgo

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Re: house outlet ac power
« Reply #108 on: January 17, 2022, 11:42:17 am »
Yeh I see now.   because the negative half is a different phase than the positive half, they dont add up to double.    :palm:
Not so much to do with phase as they are different parts of the same waveform, but it is because they are not coincident in time.

If you boil your kettle, it doesn't care if the current through its element flows one way, then the other, it is only the heating effect that is important.

The heating effect is directly related to the power dissipated in the element.

The following is a "mind exercise", only.

You won't be set up to do it safely in real life, as it requires a High voltage DC supply capable of supplying around 3kW of power----a very rare device in any home lab.

Using your nominal 240v ac Mains supply, if you boil a quantity of water, time how long it takes to boil, then let the kettle cool right down to cold, then supply a DC voltage to the kettle of the same nominal voltage, the water will boil in the same time, so obviously the "240v ac" supply is equivalent in work done to the 240v DC supply.

The normal approach to this is mathematical, but the "Empirical" approach above may help to visualise why we use RMS!
« Last Edit: January 17, 2022, 12:00:03 pm by vk6zgo »
 

Offline tooki

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Re: house outlet ac power
« Reply #109 on: January 17, 2022, 12:38:00 pm »
playing the fool,  is something i dont understand, i am sorry.

so what do we do,  just lie to all the kids at uni?
You really, really, really need to erase everything you think you know about electricity, then start learning electricity basics from the beginning systematically. Your half-understandings, with the gaps spackled over with little more than bravado, are doing you — and everyone else — a disservice. You cannot properly learn when your fundamentals are so mangled.
 
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Offline JohanH

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Re: house outlet ac power
« Reply #110 on: January 17, 2022, 01:35:43 pm »
240V 1*40A is not much worse than the Finnish standard, 230V 3*25A. 75A total remains pretty theoretical because balancing the loads that closely is impossible; whereas in single phase system you can utilize the full current no problem.

Yet, all electric heating is usual in many such 3*25A houses. This typically means 3kW (3*4.3A) in hot domestic water buffer tank, and around 10kW peak (3*14A) for heating. If and when they happen to work simultaneously, that leaves some 3*6A for everything else, and that everything else is impossible to get balanced (typical stoves have two "burners" in one phase, two more in the second one, and the oven in third. Turn the wrong two on at the same time, and you are doomed).

I've never had any issue with 3*25A. But I have never had all electrical heating either. Ground source heat pumps are becoming common. That reduces electrical demand. My own pump has three phase connection, but the compressor itself uses one phase (variable speed three phase BLDC motor inside). Motor is max 2 kW, so no issues (6.5kW max heat output). Of course, it does have electrical coil heaters as backup on the two other phases, but they are almost never used. The largest single consumer is the 3-phase sauna stove (6 kW). Electrical car chargers might benefit from larger current, but I'm afraid it won't be less expensive in the future to upgrade from the most common 3*25A.
 

Offline mcz

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Re: house outlet ac power
« Reply #111 on: January 17, 2022, 02:36:47 pm »
240V 1*40A is not much worse than the Finnish standard, 230V 3*25A. 75A total remains pretty theoretical because balancing the loads that closely is impossible; whereas in single phase system you can utilize the full current no problem.

Yet, all electric heating is usual in many such 3*25A houses. This typically means 3kW (3*4.3A) in hot domestic water buffer tank, and around 10kW peak (3*14A) for heating. If and when they happen to work simultaneously, that leaves some 3*6A for everything else, and that everything else is impossible to get balanced (typical stoves have two "burners" in one phase, two more in the second one, and the oven in third. Turn the wrong two on at the same time, and you are doomed).

This arrangement working at all relies on the fuses being really slow and often/typically not blowing until In * 1.4 or something, and people replacing blown fuses. A crappy system. Depending on where you happen to live, upgrade to 3*35A is either free, or prohibitively expensive. Because 3 phase does not have any function in the modern day in itself (since the proliferation of VFDs), having 3-phase forced down to households is only a nuisance. Having whole houses with 1*75A would be superior in every regard (including averaging out better on grid level), except if you really want to run some old industrial lathe you got for cheap and don't want to invest $500 on a VFD.

Well the problem is that running 1x75 Amps requires you to have 2x16sqmm (total 32sqmm) copper wire while 3x25A requires you to have 4x4sqmm. (total 16sqmm)
The ratings are from a table and for buried cables underground. For real we obviously need to consider and calculate voltage drop along the lines.

But it is very well know that 3 phase power delivery is cheaper than single phase for a given power. Which is why it is used everywhere around the world for power transmission.
In the end you get 17.3kW total while the british 40A single phase is just 9.6kW. That's pretty close to half the power. I think the culprit is not your 3 phase power but the fact that your electrical supply is underrated for heating houses with electricity.

Just for comparison I think I've currently got 3x50A coming in an you can get 3x63A here for no additional cost. But I haven't had that discussion with the electrical service provider. And most homes here (>90% if I had to guess) use gas/oil furnace for heating.

edit: changed cable calculation
« Last Edit: January 17, 2022, 02:49:19 pm by mcz »
 
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Offline Siwastaja

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Re: house outlet ac power
« Reply #112 on: January 17, 2022, 05:41:26 pm »
It's a bit of apples vs. oranges comparison, because with 2x16 mm^2 you get more, i.e., the ability to run larger single-phase loads, or unbalanced loads. The whole point is, you can't get 75A total out of the 3*25A system, so actual A / mm^2 is not twice (it's still somewhat better, of course).

You also missed the fact that 4x4mm^2 doesn't suffice and is illegal. Neutral wire needs larger dimensioning. So the calculation is just outright wrong; a good example how 3-phase power is confusing. (See zero sequence harmonics.)

The real solution to the problem obviously doesn't involve a transformer, but simple current transformers & contactors that cut heating temporarily (most simply, just all three phases, or even better, just one phase at the time, the one going overcurrent). Not a new invention, but nevertheless some extra cost.

Power distribution is 3-phase everywhere, including countries (UK, USA) where houses tend to be single-phase. It averages out very well because the neighbor will be in a different phase. It likely averages out better compared to a situation where we have 20 identical houses, built around same time, wired by the same electrician so that the oven is always in the same phase.

With the government subsidy to replace oil burners with air-source heatpumps, which transition into electric heaters at coldest weather to the surprise of the user who were not told about this by the marketing, this 3*25A limitation is becoming as a surprise for many; especially if the load balancing between phases was never considered because there was no need when both heating and domestic hot water was supplied with the burner. Margin in fuses mitigates the problem. If you actually monitored phase currents, you would be surprised how many households regularly and significantly exceed their nominal fuse ratings, being pretty close to actually blowing the fuses but just not barely getting there. This is not the intended way of operation for wiring and fuses, BTW.

Add to this our "16A rated" plugs that supposedly melt at 16A and need to be limited by legislation to 8A when charging EVs, instead of fixing the plug ratings, and we have a pretty crappy last-mile + household electrical system compared to the Brits and their excellent massive, fused plugs + switched outlets!
« Last Edit: January 17, 2022, 05:56:52 pm by Siwastaja »
 

Online IanB

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Re: house outlet ac power
« Reply #113 on: January 17, 2022, 05:56:46 pm »
With the government subsidy to replace oil burners with air-source heatpumps, which transition into electric heaters at coldest weather to the surprise of the user who were not told about this by the marketing, this 3*25A limitation is becoming as a surprise for many; especially if the load balancing between phases was never considered because there was no need when both heating and domestic hot water was supplied with the burner. Margin in fuses mitigates the problem. If you actually monitored phase currents, you would be surprised how many households regularly and significantly exceed their nominal fuse ratings.

I was just thinking about this today. With gas prices going through the roof, the future may see a pivot towards electricity and renewable energy. I think the UK government may even be considering a mandate for heat pumps in new builds. That's going to change the perspective on how much electricity is supplied and used.
 

Offline Siwastaja

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Re: house outlet ac power
« Reply #114 on: January 17, 2022, 06:00:09 pm »
I was just thinking about this today. With gas prices going through the roof, the future may see a pivot towards electricity and renewable energy. I think the UK government may even be considering a mandate for heat pumps in new builds. That's going to change the perspective on how much electricity is supplied and used.

Yeah, well for us here, the incentive has been always there and is purely economical, because energy price have had near 1:1 parity between electricity and burnable fossils, thanks to cheap electricity and heavily taxed fossils; causing the COP of the heat pump to translate into money savings almost directly. This is one of the few things we have the right way here, IMHO. The fact that in UK or US you get natural gas (or even oil) for so much cheaper than electricity per kWh, that installing heat pumps makes no financial sense, is just... nuts. Especially since the conditions for air source heatpumps would be just excellent in the UK. We run 'em here even though they are pretty marginal, and they still make financial sense... or made, before the subsidies caused hyperinflation in their install prices.
« Last Edit: January 17, 2022, 06:01:48 pm by Siwastaja »
 

Offline themadhippy

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Re: house outlet ac power
« Reply #115 on: January 17, 2022, 06:10:24 pm »
Quote
I think the UK government may even be considering a mandate for heat pumps in new builds.
sort of,from 2025 gas and oil boilers wont be allowed in new builds.
 

Offline mcz

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Re: house outlet ac power
« Reply #116 on: January 17, 2022, 07:06:07 pm »
It's a bit of apples vs. oranges comparison, because with 2x16 mm^2 you get more, i.e., the ability to run larger single-phase loads, or unbalanced loads. The whole point is, you can't get 75A total out of the 3*25A system, so actual A / mm^2 is not twice (it's still somewhat better, of course).

You also missed the fact that 4x4mm^2 doesn't suffice and is illegal. Neutral wire needs larger dimensioning. So the calculation is just outright wrong; a good example how 3-phase power is confusing. (See zero sequence harmonics.)

The real solution to the problem obviously doesn't involve a transformer, but simple current transformers & contactors that cut heating temporarily (most simply, just all three phases, or even better, just one phase at the time, the one going overcurrent). Not a new invention, but nevertheless some extra cost.

Power distribution is 3-phase everywhere, including countries (UK, USA) where houses tend to be single-phase. It averages out very well because the neighbor will be in a different phase. It likely averages out better compared to a situation where we have 20 identical houses, built around same time, wired by the same electrician so that the oven is always in the same phase.

With the government subsidy to replace oil burners with air-source heatpumps, which transition into electric heaters at coldest weather to the surprise of the user who were not told about this by the marketing, this 3*25A limitation is becoming as a surprise for many; especially if the load balancing between phases was never considered because there was no need when both heating and domestic hot water was supplied with the burner. Margin in fuses mitigates the problem. If you actually monitored phase currents, you would be surprised how many households regularly and significantly exceed their nominal fuse ratings, being pretty close to actually blowing the fuses but just not barely getting there. This is not the intended way of operation for wiring and fuses, BTW.

Add to this our "16A rated" plugs that supposedly melt at 16A and need to be limited by legislation to 8A when charging EVs, instead of fixing the plug ratings, and we have a pretty crappy last-mile + household electrical system compared to the Brits and their excellent massive, fused plugs + switched outlets!

The conductor thickness comparison was mostly an exercise to illustrate how much more copper is needed for those higher currents. It is a lot. (P=I²*R losses)
Yeah, heavy single phase supply might be nice for you (while I prefer to be able to run 3ph stuff) but it is coming in at a cost.
And what matters in the end is that I can run 17.3kW both from the 3x25A and from 1x75A. Now if that works out in the end depends on the application. We usually calculate with upwards of 30kW supply necessary for electrically heated homes over here.

Pretty sure my incoming cable is a 4x10sqmm copper one. I don't know what legislation would require a bigger neutral but I certainly don't have one. Most residential or even commercial use is not going to run old servers with no PFC and heavy harmonics. And the industrial heavy equipment is mostly 3 phase with no neutral connection. However, your mileage may vary.
I really don't see the point of running larger single phase loads.. I simply haven't found any as those large loads usually tend to be 3 phase. 
 

Offline Gyro

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Re: house outlet ac power
« Reply #117 on: January 17, 2022, 07:16:39 pm »
Quote
I think the UK government may even be considering a mandate for heat pumps in new builds.
sort of,from 2025 gas and oil boilers wont be allowed in new builds.

Although the boiler industry is planning to be fully Hydrogen ready by 2024 - I hope to nurse my cast iron one along until then.  ;)



... but I digress, let's not go there in this thread.
Best Regards, Chris
 

Online bdunham7

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Re: house outlet ac power
« Reply #118 on: January 17, 2022, 07:17:25 pm »
You also missed the fact that 4x4mm^2 doesn't suffice and is illegal. Neutral wire needs larger dimensioning. So the calculation is just outright wrong; a good example how 3-phase power is confusing. (See zero sequence harmonics.)

Are the electric heating loads typically phase-to-phase or phase-to-neutral?? 
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline Siwastaja

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Re: house outlet ac power
« Reply #119 on: January 17, 2022, 07:25:51 pm »
The conductor thickness comparison was mostly an exercise to illustrate how much more copper is needed for those higher currents. It is a lot. (P=I²*R losses)

I can see it was an exercise, but clearly an incorrect one which is why I corrected you. Obviously higher current requires more copper, there is no way around this. This is not related to 1-phase vs. 3-phase. Your example supposedly showed that 3-phase requires lower mm^2 per A - in other words, better utilization - but I showed that your calculation is incorrect, and now you just changed the goalpost to match the reality that the 1-phase 75A use case actually carries more current, which is indeed true.

If you need x A, then you need x A. Single-phase system has optimum copper use, since the current in incoming conductor and return path is always automatically equal.

Perfectly balanced 3~230V equals 1~400V system regarding losses, AFAIK, so it does a bit better. But you could as well use the 400V in a single phase system, or do what our US. of A friends do and use a center-tapped transformer to power "small" trivial loads with lower voltage, and big loads with higher.

3-phase is excellent for large-scale distribution and motors, but what it does not offer is good copper utilization in residential wiring.

In other words, in 3*25A nominal systems it's completely possible and usual that some of the wires carry 30-35A (beyond the design current) while the total is still just say 50. This leads to poor copper utilization. While in 1-phase house wiring, copper utilization is always optimal and geez, if you don't need 75A, then don't wire for 75A.

Now I understand where your confusion is coming from: "3-phase distribution has good copper utilization" is a widely touted claim, because it is true. But you need to understand the scope of this claim. It applies to distribution at wide scale, where balancing the phase currents is well possible; this enables complete elimination of the neutral wire - or utilizing the Earth as neutral - or using very undersized neutral wire.

But at small scale, this completely turns around; due to heavily unbalanced loads and zero sequence harmonics, neutral wire has to be dimensioned larger than phase wires (or, all conductors are just regularly overdimensioned).

Another strong reason for the 3-phase distribution are naturally 3-phase generators, and large 3-phase motor loads in the industry. But again, 1) this does not apply to households, 2) this is slowly changing.

Third reason for the "3-phase is superior" claim is that this still lives from the days when it was compared to a 2-phase system (not split-phase; 2-phase with 90deg phase shift). This discussion was relevant over 100 years ago, but back then 3-phase system offered zero neutral conductor current in a motor, while 2-phase system had double the neutral conductor current. Tesla knew what he was doing!

But Brits and Americans are not stupid in their 1-phase house wiring scheme. It is used because it is superior. Our inferior system leads into stupid compromises like manufacturers not willing to design 3-phase loads (they are significantly more complex) and instead design 400V single-phase loads to be connected between two phases, which allows at least to extract 2/3 of the available current without causing massive imbalance. Examples of such systems are some Scandinavian water heaters, and most EVs which come in Europe with a 3-phase plugs, but only utilize 2 of the phases, causing unbalance and arbitrarily limiting their charging power. But 3-phase design would have been prohibitively expensive. No such issue if the house was just 1-phase to begin with.
« Last Edit: January 17, 2022, 07:39:46 pm by Siwastaja »
 

Offline Siwastaja

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Re: house outlet ac power
« Reply #120 on: January 17, 2022, 07:27:31 pm »
You also missed the fact that 4x4mm^2 doesn't suffice and is illegal. Neutral wire needs larger dimensioning. So the calculation is just outright wrong; a good example how 3-phase power is confusing. (See zero sequence harmonics.)

Are the electric heating loads typically phase-to-phase or phase-to-neutral??

In Finland, usually phase-to-neutral, meaning that all significant heaters are built out of three distinct resistors connected in wye, with neutral also connected. In some other Scandinavian countries I think delta wiring is usual, including the typical case of only having one heater between two phases, allowing 2/3 utilization with simple, single heater. (Single-phase system would allow 100% utilization, though).

So basically it's surprisingly common to use the 3~230V system as a 1~400V system which can output more power simply thanks to higher voltage. Designers of such devices (heaters and EVs) prefer to design single-phase loads!
« Last Edit: January 17, 2022, 07:35:59 pm by Siwastaja »
 

Offline JohanH

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Re: house outlet ac power
« Reply #121 on: January 17, 2022, 07:59:11 pm »
Yeah, well for us here, the incentive has been always there and is purely economical, because energy price have had near 1:1 parity between electricity and burnable fossils, thanks to cheap electricity and heavily taxed fossils; causing the COP of the heat pump to translate into money savings almost directly. This is one of the few things we have the right way here, IMHO. The fact that in UK or US you get natural gas (or even oil) for so much cheaper than electricity per kWh, that installing heat pumps makes no financial sense, is just... nuts. Especially since the conditions for air source heatpumps would be just excellent in the UK. We run 'em here even though they are pretty marginal, and they still make financial sense... or made, before the subsidies caused hyperinflation in their install prices.

One thing I've experienced, is that air source heat pumps are not well suited here up north. In the past the house was heated with an oil burner and eventually I also installed an air heat pump, which made it much more comfortable inside, but didn't save much oil. Now four years ago, I ditched the oil burner and installed a ground based heat pump. I pretty much have the same electrical bill as before, but no oil bills! That's because of the much higher efficiency of the ground based heat pump system.

But in places where the weather tends to stay above say -5 ℃, I would imagine air source heat pumps work good and are of course cheaper to buy and install.
« Last Edit: January 17, 2022, 08:04:40 pm by jukk »
 

Online bdunham7

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Re: house outlet ac power
« Reply #122 on: January 17, 2022, 09:00:10 pm »
manufacturers not willing to design 3-phase loads (they are significantly more complex)

That there is the issue that demarcates the dividing line between where 3-phase is the way to go and where it is not.  Distribution?  Yes!  Large motors and very large other loads that are economically viable to design in 3-phase?  Yes?  Toasters, water heaters and home HVAC?  Not so much, especially with the availability of modern PFC/VFD and inverter-drive technologies.  Even the data-center neutral issues with harmonics would have been a non-issue if they weren't trying to use piles of just-above-consumer level single-phase PSUs in a phase-to-neutral configuration.

Even home EV charging is really better done with 1-phase, IMO.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline Zero999

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Re: house outlet ac power
« Reply #123 on: January 17, 2022, 10:00:18 pm »
Yeah, well for us here, the incentive has been always there and is purely economical, because energy price have had near 1:1 parity between electricity and burnable fossils, thanks to cheap electricity and heavily taxed fossils; causing the COP of the heat pump to translate into money savings almost directly. This is one of the few things we have the right way here, IMHO. The fact that in UK or US you get natural gas (or even oil) for so much cheaper than electricity per kWh, that installing heat pumps makes no financial sense, is just... nuts.
How is it nuts?

A good proportion of our electricity is generated using natural gas and other fossil fuels, so it's obviously going to be more expensive, than gas. Electricity being the same price as gas makes no sense. It's like in the USSR when bread was cheaper than grain, at one point, so farmers fed it to their animals. This just shows the insanity of too much state interference in the market.
 

Offline Siwastaja

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Re: house outlet ac power
« Reply #124 on: January 18, 2022, 08:25:07 am »
Yeah, well for us here, the incentive has been always there and is purely economical, because energy price have had near 1:1 parity between electricity and burnable fossils, thanks to cheap electricity and heavily taxed fossils; causing the COP of the heat pump to translate into money savings almost directly. This is one of the few things we have the right way here, IMHO. The fact that in UK or US you get natural gas (or even oil) for so much cheaper than electricity per kWh, that installing heat pumps makes no financial sense, is just... nuts.
How is it nuts?

A good proportion of our electricity is generated using natural gas and other fossil fuels, so it's obviously going to be more expensive, than gas. Electricity being the same price as gas makes no sense. It's like in the USSR when bread was cheaper than grain, at one point, so farmers fed it to their animals. This just shows the insanity of too much state interference in the market.

Because if you turn natural gas into electricity in modern combined cycle facilities and use at least some of the waste heat for district heating with combined total efficiency of, say, 60% (this is a fair approximation, much better numbers have been reported), and then use this 60% to run heat pumps at COP=3, total efficiency (from chemical energy in gas, to heat output inside houses) is 180%. Add renewables to the mix and it only gets better. This is why.

The point you totally miss is extracting free energy. It's similar to PV; the only reason not to install it is, if install costs exceed the savings. Artificial market structures like super-cheap fossils and expensive electricity affect that natural balance of energy choices which should be based on minimizing burning fossils and maximizing extraction of free energy.

This is, if bread was miraculously falling off the sky, it would make sense to feed it to animals, even if small amount of effort would be required to collect and distribute that bread.

If you think it from climate viewpoint, price should be in relation of the CO2 emissions per kWh. The emissions from grid energy are roughly similar to that of locally burning natural gas. (Roughly, because it's really a moving target). Hence the price should be similar. Not exactly the same, but 3x difference in favor of burning fossils is, I repeat, just nuts.

If natural gas is three times cheaper per kWh than electricity, this leads to massive waste of energy due to ignoring heat pumps, which could provide a lot of basically "free" energy.

Finland's tradition of similar price per kWh between fossils and electrical energy (which, on average, has lower CO2 footprint than locally burning fossils) is not only logical and fair, it leads into natural incentive to make energy efficient choices. Now this is partially thanks to the nanny state which I pretty much hate, and we have many of those USSR-like sick mechanisms you mention, but approximate energy price parity is not one of those; this is one of the very few areas where the system accidentally succeeded. Maybe because no one has thought about it, it's not planned, it's more of a coincidence.

Also don't underestimate the amount of politics that went into the cheaply available natural gas! It's an indirect incentive as well. That is the part I call nuts.

Similarly, some countries have sources of cheap oil available to them thanks to political choices of extracting it, or starting wars to gain access to it. We never had this kind of source.

One thing I've experienced, is that air source heat pumps are not well suited here up north. In the past the house was heated with an oil burner and eventually I also installed an air heat pump, which made it much more comfortable inside, but didn't save much oil.

Here in the Southern parts it works fine, but I do switch to oil, below approx. -17 (when COP < 1.5). Still, one of the most important things overlooked by those installing air-to-water units is the total surface area of the distribution (radiator size, or in-floor heating vs. not having one). It completely changes the game. If you need to run 60degC water into the system at mere -10degC, you can't win. Even ground source would struggle to give good savings but it at least somehow works. But the whole game changes if you run 30degC water in massive radiators or in-floor heating. I invested 3000€ in the heat pump and another 600-700€ into upgrading radiators and it's working well and based some modeling and approximate measurements I'm expecting SCOP significantly exceeding 2. The radiator upgrade pays for itself in a year or two. Such "small" details are hugely important.
« Last Edit: January 18, 2022, 08:35:04 am by Siwastaja »
 


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