Coffee machines usually don't boil the water. They heat it enough that there is some evaporation and the vapor pressure pushes the hot water through the drip m

Coffee machines usually don't boil the water. They heat it enough that there is some evaporation and the vapor pressure pushes the hot water through the drip mechanism. It is well below boiling, like maybe 170 or 180 F, and one of the complaints about cheap machines is that they don't get the water hot enough. The issue of coffee tasting bad if kept hot too long is independent of the brewing method though. I generally make coffee manually (pour hot water over a drip cone) and it is an issue then too. I stopped using a thermal carafe because of it.