If you are lucky enough to have a gas range, you already know the joys of a dead even heat source that can range from medium-low to blowtorch. None of that cyclic all-on/all-off nonsense of the typical electric range, for example.
However, “low heat” is not something in the typical gas range’s vocabulary. On our Viking, the lowest setting on the smallest burner will keep a small pot of water at a rolling boil and will consistently cause a cup of rice to boil over. And it is a really low flame!
Enter the heat diffuser. A heat diffuser sits between burner and your pan or pot. It effectively acts as a heat buffer and, as the name implies, diffuser.
On a gas range like mine, it allows one to achieve the lowest simmer/heat you might want. On an electric range, a cast iron heat diffuser — you want thermal mass — will nicely even on the all-on/all-off behavior of most ranges.
At ~$20, it is a worthy tool to add to your cooking arsenal!