This module extends Openlayers to provide the capacity for "Ranged Heatmaps". A Ranged heatmap is a map where the color of a feature is set by it falling into a range of values. A traditional heatmap is a smooth graduation of colors, a ranged heatmap can have all sorts of color combinations.
For example, a traditional heatmap might increase saturation based on the value of "population". A ranged heatmap could color regions with population 0-100 in Red, regions with population 101-345 in Blue, and population over 346 as Yellow.
This presents as an Openlayers Behavior. Enable the module, then enable the behavior on your map. Enter the field which contains the value that will determine the coloration, and then enter up to 16 value ranges.