Shockingly, not as much as you would think. The rust is still a conductor so it will still allow current flow. It is always a good idea to maintain the equipment though. Many times, that rust on the burner is just the tip of the iceberg when it comes to combustion issues. Most of the problems that we see are more maintenance related than anything else.
What about a rusty burner surface and how it will affect the flame sensor current.
Shockingly, not as much as you would think. The rust is still a conductor so it will still allow current flow. It is always a good idea to maintain the equipment though. Many times, that rust on the burner is just the tip of the iceberg when it comes to combustion issues. Most of the problems that we see are more maintenance related than anything else.