I have seen vents painted all kinds of colours. You may be talking about a specific kind of vent. Please let us know where these red vents are,then we may know why they are red.
Firetrucks
School Houses were painted red because it was cheap to use homemade paint that contained a lot of iron oxide which produced a deep, dark red color.
Henri matisse painted the red fish with vivid colors and called it paradise. Matisse(1669-1954) painted it in s figurative style.
Because she found it pretty.
The painting by Georgia O'Keefe was painted in 1924.
Soffit vents can be painted as long as they are appropriately primed based on their existing finish.
There would be 8 will 3 faces painted red, 24 with 2 faces painted red, 24 with 1 face painted red, and 8 that have no faces painted red.
It was painted in Paris, 1908.
When something is painted red, it absorbs most of the colors in the visible spectrum except for red.
Yes heater vents can be painted the same colour as your walls.
Canvas.
Firetrucks
3/6 is red, 2/6 is Blue, 1/6 is yellow
BECAUSE THE BIG RED BOAT MAN PAINTED IT~!!!!!!!
Oil pastels
Paul Klee
Maybe it is painted with red paint.