7
®
FIGURE 3.
4.
AN ACCEPTABLE SCANNER LOCATION MUST ENSURE THE FOLLOWING:
— Reliable pilot flame detection.
— Reliable main flame detection.
— Rejection of pilot flame too short or in the wrong position to ignite the main flame reliably,
thus prohibiting main fuel admission.
Note: Reliable signals must be obtained at all air flows and furnace loads (ranges of fuel firing).
FIGURE 4.
5.
If combustion air enters the furnace with a rotational movement of sufficient velocity to deflect
pilot flame in direction of rotation, position the scanner 0 to 30 degrees downstream of the pilot
burner and close to the periphery of the throat where the ultraviolet radiation is at a maximum.
(See Figures 3 and 4).
Having determined an appropriate location for the sight tube, cut a clearance hole for a 2 inch
pipe through the burner plate. If register vanes interfere with the desired line of sight, the inter-
fering vane(s) should be trimmed to assure an unobstructed viewing path at all firing levels, see
example shown below.
Note: Always check with the burner manufacturer before you trim register vanes.
PRIMARY
COMBUSTION
AIR REGISTER
BLADES
SCANNER
LINE OF
SIGHT
BURNER
THROAT
FLAME
ENVELOPE
SINGLE BURNER SCANNER SIGHTING
BURNER
CENTER LINE
BASE
ZONE
IGNITOR
SCANNER
MAIN
BURNER
CCW ROTATION
IGNITOR
SCANNER
MAIN
CW ROTATION
BURNER
SCANNER LOCATION VS. SECONDARY AIR ROTATION
