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Well I mean heat itself is in fact kinetic energy. It’s emergent on the large scale from the random movements of molecules at the microscopic level and temperature can be calculated statistically from this for instance in a Classical gas etc (is it root mean square or am I remembering wrong?). The larger the movement by and large, the higher the temperature. This is thermodynamics, Boltzmann etc.
Originally Posted by sgosnell
What you might mean is that Electromagnetic radiation (eg radio waves, IR, visual light, IR etc) is emitted by objects in idealised conditions as what is known as ‘black body radiation’. Anything above absolute zero gives off some thermal radiation but the wavelength and therefore the type is governed by the temperature of the object. The higher the temperature the higher the frequency/shorter the wavelength. So yes it can be any frequency depending on temperature. Most warm things we meet in everyday are IR emitters.
In fact I would expect both an iron wood burner like the one in my front room and a heat lamp to be well represented by the physics of black body radiators. We would expect the temperature in both cases to be well within the IR range.
Heat a thing more and you get into the visible light range which is what we call ‘red hot’. Heat more and it moves through the visual spectrum.
Stars are pure black body radiators (as are old fashioned incandescent light filaments.) The sun at ~5600C for example gives off a radiation curve that peaks in the middle of the visual light range meaning we see the light as pure white when the sun is high in the sky. The hottest stars give off mostly ultraviolet radiation and so on (we see them as blue/white.)
(in terms of how the Sun actually heats up the earth… that’s more complicated haha.)
Sent from my iPhone using TapatalkLast edited by Christian Miller; 02-12-2024 at 08:32 AM.
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02-12-2024 08:17 AM
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Well that’s true on both counts…. Originally Posted by SoftwareGuy
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And hence (or thence? Originally Posted by Christian Miller
) the use of temperature (in K) to classify light bulbs: by comparison with the spectrum of light emitted of a black body radiator at the given temperature 
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Exactly Originally Posted by RJVB
And hence (or thence?) the use of temperature (in K) to classify light bulbs: by comparison with the spectrum of light emitted of a black body radiator at the given temperature
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Domestic heating and lighting vs Astrophysics. Basically the same thing.
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Using only infrared radiated heat might exacerbate mould occurrence in unheated parts of rooms.
GuyBoden BEng(hon)
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We don’t have mould in space so can’t comment. Originally Posted by GuyBoden
Using only infrared radiated heat might exacerbate mould occurrence in unheated parts of rooms.
GuyBoden BEng(hon)
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Major? Originally Posted by Christian Miller
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After thinking about is, I think the method of heat transfer (radiation, conduction, convection) is not as important as controlling the temperature and the rate of temperature change.
As long as the temperature (of the guitar) is not extreme and temperature changes are gradual, the guitar will be okay.
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Ground control to major Tom Originally Posted by RJVB
Major?
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"Without Prejudice"
fjärrvärme
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Just for note.... geo. can can produce both heat and cooling. And you.. also just drill small holes straight down. And depending on area... reach a depth that has constant temp. for fluid to circulate. The unit either pulls heat or cold from the constant temp liquid... by changing directions... anyway the units are inexpensive... but bringing in the rig to dill the lines isn't LOL. But it take very little room... 2'x2' at most.
For note... in snowy areas... I've seen lines needing to go down 200' LOL
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Originally Posted by Reg
"In Sweden, most heat pumps were ground-source heat pumps, which required a borehole to be drilled in the yard"
"a really important lesson from Sweden is that transitions like this don't "just happen," and require incentives and policies, both "carrots" and "sticks,It takes deliberate action from not just government [but] from industry, from different stakeholders,"
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My point exactly Originally Posted by Christian Miller
1) any heatpump can "produce" cooling or heating, it just depends in which direction you're letting it pump. But whether or not yet get effective heating or cooling depends on the exchanger technology in the target space. Apparently it has been concluced that heating systems are more energy efficient if they use a circulating fluid as has been used traditionally in central heating (here in Europe), so that's the technology that gets subsidised (in France and IIRC the Netherlands; anywhere else is a bit moot for me). Originally Posted by Reg
With a traditional circuit your heating radiators would turn into cooling sinks with a liquid just above 0°C - doesn't seem very efficient. You could probably change the water in the radiator circuit with the kind of stuff used in fridges; that might give a little bit better cooling (I assume it freezes well below 0°C). But I doubt that's a "drop-in" change that'll work with any old system and I have a hunch you'd have to swap in another liquid for the heating season.
Geo-based pumps tend to use a more horizontal and less deep approach here, if memory serves me well. Or maybe that's only for houses built more or less directly on the bedrock. Neither is very appropriate for individual heating of an appartment that's not on ground level
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Zero Celsius is the freezing point of pure water, which is very, very rare. Water with any impurities freezes somewhere below that. But even pure water won't freeze at zero if it's circulating, and even if it's not moving it takes time. Even in the Arctic, the temperature below the permafrost is above the freezing point of water, so there is nothing magic about that temperature. The water in a circulating geothermal system will remain liquid down to very low air temperatures, far below the theoretical freezing point of pure water.
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I didn't want to mention this because I thought it would be obvious. The water in what I called the radiator circuit doesn't circulate continuously. At least not when used for heating: it will circulate through convection and/or when the (circulation) pump runs; and that's normally only when the central thermostat detects a sufficient different from the configured ambient temperature. I've never seen any indication that a water/air heatpump system would let the cooling liquid run continuously. Even then, any failure in that forced circulation could cause the undercooled water to freeze instantly, like waves crashing on the beach (ever seen that?). Same when someone knocks on a radiator or tube in a far corner where circulation speed isn't high enough. Would you want such a system knowing that a powercut in the middle of a cooling cycle could cause your pipes to burst, knowing that the water that will start coming out is probably far from clean, and that there will be a lot of it? (We've had to deal with a broken heating pipe in my parental home, last summer - not fun I can tell you.) Originally Posted by sgosnell
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Quite interesting - how do you hear a massive stone church efficiently? More info on IR
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Well, we haven’t moved to the new flat yet, so haven’t yet bought a complete system for it. But I did buy a single small “under the desk” IR heater to test it out.
It turned out to be too large for the particular design of my desk, so I use it for heating the whole room.
The heat experience really is like sitting close to a coal fire, in that you can feel as warm as toast, but stand up and walk to an area behind the heater and there is a noticeable drop in temperature. So, two people sitting at opposite ends of the room would best be served by a heater each. However, after an hour, the temperature difference is far less noticeable as the whole room has warmed up.
The feel of the heat is very nice, and my acoustic instruments seem to like it very much. From one month’s usage, I found no adverse effect on the guitars.
So I think they are worth exploring, especially if like me you have asthma or regular headaches. I’ve noticed a big improvement in those areas.
I still have questions over using IR heaters for a whole house. Many reviewers mention having them as a secondary backup to their central-heating system. They work best as ceiling panels, allegedly, with an average double-bedroom requiring two large panels. I’m not sure we would be happy with that setup, or with big white panels on the walls.
So the jury is still out regarding the practicality of having IR as the sole source of heat for a house, but there’s no doubt that the heat is very comforting and healthy, plus the guitars seem happy.
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Make sure the main air resonance is within range? Originally Posted by Christian Miller
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IR heaters are strange. If you feel the warmth delivered to desired items, you're good, I guess.
A friend many years ago found them strange, not heating everything. Maybe it was unrealistic to expect it to heat the room air like forced air heating.
He had buried (in cement) hot water pipe heat in the floors, and those tended to eventually corrode. The fix was to gradually disconnect the failed zones and replace with something like electric baseboard heat. I think he may have had high expectations out of necessity.
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