CSA RA 350, Installation Manual

Page: 38 / 60

Form I-RA/D 350/500, Page 38
Troubleshooting Continued
Location - The backflow sensor switch is mounted on a bracket on the
hinged viewport cover on the control side of the heater. The location is
important in the operation of this switch. Except for limited observation,
the viewport cover must be kept closed for the sensor (and heater) to
operate properly.
Operation - Underneath the sensor bracket, the viewport cover has a 3/8”
diameter hole. Under normal negative overfire operating conditions, room
air is constantly drawn into that small opening. The temperature-sensi-
tive backflow sensor is “cooled” by the air flow. If for any of the reasons
listed, the furnace pressure becomes zero, or slightly positive, the flow
of air decreases. If this condition persists (10 minutes maximum) the
“uncooled” backflow sensor activates interrupting power to the ignition
controller. The green limit status light will go out, and the heater goes
through the normal post purge and cool down cycle.
After the problem has been determined and corrected, push the manual
reset button on the backflow sensor, and follow the instructions to relight
the heater. Check for proper operation.
Maintenance - A thin film of soot will form on the face of the backflow
sensor. At least once a month and during any routine heater cleaning,
open the viewport cover and clean the soot from the sensor. Check the
wire connections during scheduled maintenance inspections.
Troubleshooting Chart Guide
Symptoms ........................................................... Follow Troubleshooting Chart
With thermostat calling for heat, burner motor never attempts to
run (Green “power on” light is lit; Green “system ready” light is not lit). ............ Chart No. 1, page 41
Chart 1 check completed, but burner motor never attempts to run.
With thermostat calling for heat, burner motor runs momentarily. ..................... Chart No. 2, page 42
System does not attempt to ignite. .................................................................... Chart No. 3, page 43
Burner ignites and burns steadily until system goes into lockout. ..................... Chart No. 4, page 44
Burner operation erratic/unstable flame pattern. ............................................... Chart No. 5, page 45
High temperature limit cycles. ........................................................................... Chart No, 6, page 45
Oil delivery system troubleshooting. .................................................................. Chart No. 7, page 47
CAUTION: The items on the Troubleshooting Charts that are marked with an
asterisk represent events that have occurred due to the improper functioning
of the heater. It is necessary to observe the operation of the heater to determine
what caused these events to occur.