I looked through the window, and while the color is mostly blue, there are little yellow flashes that come and go quickly. The boiler is running at full (no modulation) during this time; I haven't studied it at lower firing rates.
Are little yellow flashes a sign of anything bad? (I am trying to get a combustion analysis done, but my installer is unresponsive. As I mentioned in another post, I'm gtting rather poor efficiency.)
install my buddy wired up for them*~/:) and helped them with the radiant garge slab layout ...its sorta cool :)condensing and running like a top:) doesnt your gas company have a tech that comes by and makes sure it is running correctly? i thought that was standard in the natural gas industry,sorta a double check on new installs...
My initial thought is that you are sucking dirt/dust into the system, and the yellow flashes are that burning up. You made a comment elsewhere about black stuff in the combustion area, which would be consistent with this as well.
Where is the air intake for the unit? What are the conditions around the air intake?