[an error occurred while processing this directive]
Posted by Eric on March 01, 2004 at 10:53:30:
In Reply to: vibrations posted by Raymond De Ravet on February 29, 2004 at 11:08:03:
I wouldn't just blame the design as the cause of the problem.
Have you checked the combustion throughout the modulating range. Often boilers, firetube and watertube, will vibrate when the combustion goes either very lean or very rich. Even thought the combustion looks good in low fire and high fire, there may be a point where due to damper position and interaction of the airflow on the damper, the burner goes either real lean or real rich. Another common effect is vibration caused by the operating point of the fan: fan curves are not always the smooth curves you find in the book. IN reality, there can be jumps or S turns in the fan curve. This can create an operating point where the fan has 2 pressures for the same flow and it bounces between those operating points.
The problem you describe is very common on larger boilers and finding the solution for it takes more than this forum, I suggest you get a good burner technician that has the necessary equipment to properly investigate the problem.
Good Luck