Is there some way to animate noise in the material, like to simulate heat growing from a hot surface?
otherwise: is there a good practice on how to produce a “heat refraction” material ?
Thank you, so you are not suggesting to use the Noise block though.
I was wondering if this effect could be achieved without a texture
You can use the noise node but it is pretty expensive. With low “levels” setting it might be reasonable. Using some blurry lumpy normal maps with panning textures usually works as well and is much cheaper.
Thank you, this actually solved my question, but just for “theorical” use, can you indicate me how to animate the noise node? because i tried with a panner, but it doesn’t actually move 
Sure no problem. The noise node works by returning psuedo-random values based on the supplied Position input. All you need to do is take “Time” times a vector direction and add the result to your position. That is all panners do internally is add an incrementing vector.