The boiler seems to start normally. First the auto damper opens, the pump starts, the electronic ignition is heard and then the burners light. At that point it makes a very high pitched harmonic noise. It sounds like a motor with a bad bearing. I have laid on my back trying to pinpoint the noise, and it is loudest near the left burner.

Sometimes we encounter burner doing this but quiet down as they warm. Did you have the boiler professionally installed? If so, call the installer back. It could be a gas pressure issue, bad burner, defective orifice or any of numerous other problems. The installer should take care of it at no charge.

After I read answer #1 I called a gas company. I had used a 1/2" flexible hose and that did not let enough gas pressure. They rerouted some pipe and used a 3/4" flexible hose and it worked perfectly. The problem was low gas pressure to the boiler.

Often flex lines have to be upsized at least one size beyond what one would normally use with pipe. Glad it was that simple.