As I recall.. 3 burners fire at first.. and then after an extended
runtime (how much I don't know), the other two come on. The theory
is that it may only take 3 to get the house to the desired temp ---
and then the others come of a bit later.

There is some black box -- about 1.5" square that has a dial on it
that says something about delay time.

It's a Maytag -- natural gas.