A fuel-lean mixture burns in rows of flame ports each located between a pair of rows of flame ports burning a fuel-rich mixture. The fuel-rich flames support and stabilize the fuel-lean flames to stabilize combustion and to avoid flame liftoff and noise. The fuel-lean flames reduce the temperature of the overall flame, and thereby reduce the production of Nox compounds produced by the burner. Stepwise and proportional burner control techniques are disclosed.
