NorthwestBound wrote:
Old-Biscuit wrote:
Fan continues to run after flame is shut off to cool heat exchanger...can run 30-90 seconds
Is that the 'noise' you are hearing???
No, the fan has already come to a stop. Your not able to hear it until the fan is completely stopped.
OK.....
Then it sounds like the 'timed delay relay' buzzing
This is the device that allows fan to run prior to main flame lighting and after main flame has shut down.
It is a bi-metallic coil that gets energized when t-stat contacts make up and then power comes off when t-stat contacts open.....coil then cools off which then shuts-down fan power
Timed delay relay is first component energized in system and the last to loose power.
