I am trying to find a manual on a Concord furnace. At this time the blower starts but the burners do not light and then the system shuts down until power is cut and then turned on again and the same thing occurs, the rde light flashes 3 times before complete shut down occurs. What does this mean and how can I get a manual?

See if you furnace model number is on this page . If so download it to your computer and read.

Furnace installation Manuals and Replacement Parts Lists