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A set of primary colors consists of colorants or colored lights that can be mixed in varying amounts to produce a gamut of colors. This is the essential method used to create the perception of a broad range of colors in, e.g., electronic displays, color printing, and paintings. Perceptions associated with a given combination of primary colors can be predicted by an appropriate mixing model (e.g., additive, subtractive) that reflects the physics of how light interacts with physical media, and ultimately the retina.
Primary colors can also be conceptual (not necessarily real), either as additive mathematical elements of a color space or as irreducible phenomenological categories in domains such as psychology and philosophy. Color space primaries are precisely defined and empirically rooted in psychophysical colorimetry experiments which are foundational for understanding color vision. Primaries of some color spaces are complete (that is, all visible colors are described in terms of their primaries weighted by nonnegative primary intensity coefficients) but necessarily imaginary (that is, there is no plausible way that those primary colors could be represented physically, or perceived). Phenomenological accounts of primary colors, such as the psychological primaries, have been used as the conceptual basis for practical color applications even though they are not a quantitative description in and of themselves.
Sets of color space primaries are generally arbitrary, in the sense that there is no one set of primaries that can be considered the canonical set. Primary pigments or light sources are selected for a given application on the basis of subjective preferences as well as practical factors such as cost, stability, availability etc.
The concept of primary colors has a long, complex history. The choice of primary colors has changed over time in different domains that study color. Descriptions of primary colors come from areas including philosophy, art history, color order systems, and scientific work involving the physics of light and perception of color.
Art education materials commonly use red, yellow, and blue as primary colors, sometimes suggesting that they can mix all colors. From the perspective of modern color science, no set of real colorants or lights can mix all possible colors.

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  1. Robjolla

    Tee off primary Flow and Return

    Hi new to the forum here and after some advise please. I have done a garage extension and need heating in the room. I am in a town house with no Rads on the ground floor. (Underfloor heating). My boiler (not combi) is downstairs, but megaflow tank is upstairs along with rads upstairs. I have...
  2. R

    Just come across a job where both primary and secondary

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  3. MarkWillGreen

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    Hi All, Thanks for your time. Planning a complete house refurb, where the utility/WC/bathrooms sit right next to the riser which will take the primary up to the cylinder in the loft. It would be easiest to take these towel rads off this primary. All the other rads are on the opposite side of...
  4. P

    Aga w/ Primary feeds (Draining)

    Afternoon ladies and Gents, got a query I’m hoping some of you can help me with. Mate and work colleague is doing some work at a house renovating areas of it. I’m doing some standard bits and bibs there but he has asked me about something I’m actually unsure of. it’s regarding an AGA with...
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  5. C

    How easy is it to replace a primary pump in a BoilerMate A Class OV?

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  6. P

    Primary Ventilated Stack Replacement - DIY or Professional?

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  7. soother

    Ideal logic primary heat exchanger leak sealant success?

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  8. P

    Replacing DHW primary circulating pump

    Hi everyone I have a dead pump on my DHW This monster pushes water around the heating coil of s 210 litre unvented cylinder. That's all It used to be 2 cylinders, and will be again at some point (I have questions about that too but I'll create a new thread) My question is - does anyone...
  9. D

    Gurgling from primary circuit, Y plan system

    I've noticed that my hot water primary circuit has started gurgling a lot. My system is a conventional 'y' plan and the controller will not allow heating without hot water. The gurgling is at it's worst when there is only hot water demand. I'm pretty sure there's no air in the system and in any...
  10. I

    Megaflo CL170 2 port valve on primary circuit

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  11. R

    Comparative heights of primary and cold water storage cisterns

    I have a job coming up in a house where the primary F&E is in the loft and has a tap pouring into the top of it (!) and also a combined feed and vent in 15mm. Am planning to fit FOV, add a 22mm vent, and an overflow. My concern is that the combined cold water storage and indirect-cylinder feed...
  12. C

    Worcester Greenstar 37CDi Combi Boiler - air lock in primary circuit?

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  13. A

    Pre-payment meter

    Can someone please inform me of the reason why a pre-payment meter used as the primary meter can not feed a secondary meter? Kind Regards
  14. K

    Flow and return pipes

    Hi, Im currently replacing the central heating system in our house and have the following question. Our house has solid floors downstairs so both the upstairs and downstairs radiators will be supplied from 22mm flow and return pipes routed between the upstairs floorboards and downstairs...
  15. A

    TRV on Primary coil inlet?

    Went to a property this week, customer was saying that the hot water was too hot. In the airing cupboard the flow to the heating coil had a TRV on it with a remote sensor stuck on to the cylinder. The TRV was set to 2. I turned it down to 1. Asked if he'd call me back to see if there was any...
  16. Worcester

    Towel Rails on the DHW primary circuit

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  17. M

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  18. J

    potterton power max he pressure vessel

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  19. H

    Air in gravity primary feed and return

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  20. E

    is it ok

    to pressurise the primary side i.e. heating on a vented cylinder. I was told it is ok but it doesnt sit right with me I would prefer one system or another but of cours I am probably wrong. eddie
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