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What is the real story around heat pumps?

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Zero999:

--- Quote from: Someone on February 24, 2024, 11:10:47 am ---
--- Quote from: Zero999 on February 24, 2024, 10:45:39 am ---
--- Quote from: Someone on February 24, 2024, 02:04:47 am ---
--- Quote from: johansen on February 24, 2024, 01:31:25 am ---Is this what this forum has become?  5% useful posts on actual heatpump data, 95% argument?

--- End quote ---
Something about heatpumps brings out the crazies, not just this forum. So the OP asking for honest answers (being overwhelmed by the noise) is fully understandable.

--- End quote ---
Because it's political. I'm not going to get into who's right and wrong in this post, just explain why many get emotional about it, briefly outlining both points of view.
--- End quote ---
But the only politics seems to be in the supply/price of natural resources. Nothing to do with the heat pump.

All it needs is people plainly stating the reason why they think their position, instead of non specific unarguable generalisations.

Most of this thread is UK people dodging the fact that their energy costs are abnormal, while making all sorts of big claims about the rest of the world. Obnoxious colonialism vibes.

--- End quote ---
And from my position, I see this thread as a load of Europeans lecturing us Brits telling us what to do.

Are you trolling now by mentioning colonialism? It's irrelevant. It has nothing to do with colonialism and all to so with people making generalisations, which is inherent to human nature.  The Europeans and Americans do the same thing.

I accept what might be the most economical solution for me, won't be the case for others. For the purposes of this thread, it doesn't matter why energy prices are what they are. It's outside the scope of this forum.

coppice:

--- Quote from: Zero999 on February 24, 2024, 11:20:56 am ---And from my position, I see this thread as a load of Europeans lecturing us Brits telling us what to do.

--- End quote ---
Nobody can tell someone from another part of the world how to deal with resource hungry things (e.g. energy), or their environment. Supply chains and environments are so location specific. This probably has a lot to do with people misinterpreting what they see and read, because they are projecting from their own position.

Siwastaja:

--- Quote from: Zero999 on February 24, 2024, 11:20:56 am ---And from my position, I see this thread as a load of Europeans lecturing us Brits telling us what to do.

--- End quote ---

Not at all. You would be a fool not to take advantage of the very cheap natural gas. That said, on the level of country, it's sad to see how expensive electricity is for you, because electricity is so flexible and useful.

AVGresponding:
As it happens, we are installing an air-source heat pump at a community youth centre we are rewiring. I shall provide some pics and COP info at some point in the near future...

zilp:

--- Quote from: Zero999 on February 24, 2024, 10:27:53 am ---
--- Quote from: zilp on February 23, 2024, 02:38:44 pm ---
--- Quote from: Zero999 on February 22, 2024, 09:24:50 pm ---I'm just not going to discuss net zero, propaganda and taxes. They're political and will just result in pages of arguing, with neither of us agreeing. I just don't support it. You clearly do. We'll just have to disagree and leave it at that.

--- End quote ---

That is simply a lie. You did discuss just that, as I quoted above. You just don't want to defend your position when challenged. If you didn't want to discuss it, you wouldn't have mentioned it in the first place.
--- End quote ---
Now it appears you're tying to provoke me, which will not work. I'm more than capable of defending my position.

--- End quote ---

You really need to pay attention. I didn't say you wouldn't be capable of defending your position. I said you didn't want to defend your position. Look at it, it's right there in the quote that you are responding to. Now, you aren't trying to tell me that you wrote "I'm just not going to discuss net zero, propaganda and taxes" because you wanted to tell me that you were intent on defending your position, are you?


--- Quote from: Zero999 on February 24, 2024, 10:27:53 am ---Indeed I consider it to be fairly obvious.

--- End quote ---

I supposed as much. But you do notice how that is a pointless statement to make, right?


--- Quote from: Zero999 on February 24, 2024, 10:27:53 am ---I just do not want to discuss the matter here any more.

--- End quote ---

Which might be true or not. But that doesn't change that it is dishonest to first throw out a statement that you know is controversial, to say the least, and then pretend that it's a claim that you don't want to talk about. Obviously, you would be willing to talk about it further if you were getting agreement. If it were in fact something that you didn't want to talk about, you wouldn't talk about it. But you obviously did talk about it. And you obviously weren't forced to, either.


--- Quote from: Zero999 on February 24, 2024, 10:27:53 am ---For one it's against the rules of this forum and secondly I know from previous experience it's impossible to discuss such matters in a logical manner with those who resort to accusations of lying.

--- End quote ---

It's funny how the problem apparently is that someone is pointing out that you are in fact lying, isn't it?


--- Quote from: Zero999 on February 24, 2024, 10:27:53 am ---
--- Quote ---It's just that you don't actually know that. Whether replacing a gas boiler with an electric heat pump now is a net profitable decision depends heavily on the development of energy supply costs and the purchase price and installation costs of heat pumps over the lifetime of that (hypothetical) heat pump. And as you don't know any of these to a particularly high degree of certainty, you also can't necessarily know whether installing a heat pump now would lose you money.
--- End quote ---
I have done the calculations,  as has someone else here, who is also an advocate of heat pumps.
https://www.eevblog.com/forum/chat/what-is-the-real-story-around-heat-pumps/msg5347484/#msg5347484

--- End quote ---

Nowhere in that post that you are linking to is there any attempt to model the future costs of the respective systems, so that obviously is not a relevant response to what I wrote. And also, it is obviously nonsensical to say that you have done the calculations in response to me pointing out that you don't know the numbers that you would need to do the calculation without saying a single word about how you do know the numbers after all.


--- Quote from: Zero999 on February 24, 2024, 10:27:53 am ---
--- Quote ---One thing that is pretty likely, though, for a variety of reasons, is that the price differential between gas and electricity will shrink, and possibly even invert, which at the very least means that betting on gas is not a particularly safe bet.
--- End quote ---
And guess what. If it becomes economical for me to buy an electric heat pump, then can do it. It's just uneconomical at the moment. I don't see why you appear to be having difficulty understanding that.

--- End quote ---

Because that isn't how economics works. To make an obvious example to illustrate the problem: If gas goes to 50 p per kWh tomorrow and stays there for the next ten years while electricity doesn't change, then the total costs of an electric heat pump installed at current prices would probably be lower than a gas boiler. But at that point, because of that change in gas price, the installation costs for heat pumps will shoot up, because the supply of heat pumps and of heat pump installation work is close to fixed in the mid term, so the massively increasing demand will drive the price up (to the new equlibrium point), so you can't actually buy a heat pump at that price then anymore.

You are essentially saying that you can still buy gold tomorrow if you see that the price has increased.

And just to be clear: No, 50 p per kWh tomorrow is not likely. The point is to create an obvious example to illustrate the problem. Though we did see similar scenarios play out at the start (or whatever you want to call February 2022) of the Ukraine war: People who had installed heat pumps or solar systems recently at prices where they weren't expecting break even any time soon, if at all, at the then-current energy prices suddenly realized that they had made a profitable investment, while others, who got the idea to avoid the increased energy prices by putting in renewable sources found that the prices for doing so had adjusted to the point where it wasn't a clear win anymore.


--- Quote from: Zero999 on February 24, 2024, 10:27:53 am ---
--- Quote ---... which assumes that the exhaust will be at outdoor temperature (i.e., your heating water return is below outdoor temperature?) and at the same absolute humidity as outdoor air (which indeed would be likely with outdoor-temperature exhaust ... but not so much in reality)!?

Also, I don't know all that much about the power regulation of combustion engines, but I think that they at the very least have a relatively narrow band of rotational speed where they reach maximum efficiency, and I suspect that exhaust temperature is part of that equation and thus can not be varied continuously to match the water heat exchanger without sacrificing mechanical efficiency!?

Which is to say: It seems highly optimistic to me to assume that you could capture 100% of the waste heat for heating purposes.
--- End quote ---
Not highly optimistic, only a little optimistic to assume all of the heat from the engine will heat my home. Perhaps 85%, is a more reasonable figure, similar to a condensing gas boiler. This still a COP of around 150% and is much cheaper to run than electricity of a condensing gas boiler.

--- End quote ---

It's just that I don't see any reason to assume that you would be able to achieve that efficiency, which is what I was trying to tell you. The efficiency of a condensing boiler comes from low temperatures, which is what allows the condensation to happen. But for one, it isn't obvious that you can actually control the exhaust temperature that well without sacrificing mechanical efficiency, because, see above. But also, you then have the choice to either use the exhaust to heat up the return before the heat pump, which is at the lower temperature and thus allows for more condensation, but which drives up the return temperature seen by the heat pump and thus reduces the efficiency of the heat pump, or you can heat up further at the output of the heat pump, in which case you get higher efficiency of the heat pump, but higher temperature in the exhaust heat exchanger and thus less condensation and thus lower efficiency in the use of waste heat.


--- Quote from: Zero999 on February 24, 2024, 10:27:53 am ---To be honest, changing to a heat pump, whether it's powered from electricity, or gas wouldn't be worth it for me at the moment because my energy usage is too low for it to matter. It's really a thought experiment.

--- End quote ---

Well, yeah, sure, but I would think that it wouldn't be an obvious economic win even if your heat use was closer to the average.

(And for that matter, it wouldn't necessarily be an ecological win either to swap out a working gas boiler that isn't used that much overall ...)

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