INSTALLATION
REMOVING THE OLD FLAME SENSOR
The 3049 flame sensors are manufactured with different termi- nal/panel configurations. Some models have three 1⁄4” spade terminals, while others have two 1⁄4” spade terminals and one pin terminal. Figure 5 illustrates the terminal layout and internal switch action for each variation.
The service technician must identify the terminal configuration on the existing sensor, and confirm that it matches the replace- ment. If the sensor terminals do not match, replacement cannot be made.
Before removing old flame sensor, perform the following:
1.On Type 3049 Flame Sensor - record the color code for each wire attached to the three
2.For both types of mercury flame sensors - inspect the pilot burner, flame sensor bulb, and the adaptors and clips used to hold the bulb within the pilot burner bracket. Note the exact arrangement of clips and adapters so that the same arrangement is used for the replacement flame sensor.
3.For both types of mercury flame sensors - note the exact location and mounting method for the ignition electrode attached to the pilot burner bracket or flame sensor bulb. This location must be used when the replacement flame sensor is installed. Failure to exactly locate the electrode will cause pilot ignition problems.
There are generally three styles of electrode mountings:
A.Electrode and pilot burner manufactured as a one- piece unit. In this case, electrode position should not be disturbed. The flame sensor bulb can be removed without disassembling the electrode.
B.Electrode mounted to the pilot burner via a perforated mounting strap. In most cases using the perforated mounting strap, the electrode will NOT be disturbed when the flame sensor is removed.
3⁄32" to 5⁄32" | Sensing Bulb |
| |
Element | Hood |
type only) | 3⁄32" to 5⁄32" |
|
Clamp
Electrode
C.Electrode mounted using the bracket that attaches to the flame sensor bulb. In this case, the electrode must be removed before the bulb can be pulled from the pilot burner bracket.
4.Carefully remove the flame sensor bulb from the pilot burner bracket noting the positions of the adaptors and the ignition electrode.
5.For flame sensors with
INSTALLING THE REPLACEMENT FLAME SENSOR
1.Check the sensing bulb of the defective flame sensor and note the positions of any
2.Carefully uncoil enough capillary to allow installation of the new flame sensor. Do not kink or sharply bend the capillary to prevent damage.
3.Slip the bulb of the replacement flame sensor into the pilot burner bracket and secure it with the same method used for the defective flame sensor. The bulb should be held by the pilot burner so that movement from side to side is mini- mized.
4.If the ignition electrode was removed or changed position, reinstall it so that it is in its original position. The spark gap should be 3⁄32” minimum to 5⁄32” maximum from the tip of the electrode to the sensing bulb or pilot hood, depending on the original configuration.
5.Carefully uncoil enough capillary to install the switch mecha- nism on the same position as the original unit. Be sure to prevent excessive strain where the capillary enters the bulb.
6.Mount the switch mechanism (for
7.For type 3049 flame sensors, attach the wires to their respective terminals.
8.Energize the system and observe the pilot burner and ignition electrode. Sparking should occur in the middle of the pilot gas stream.
Electrode Mounted | Electrode Mounted Using |
With | Perforated Strap |
Figure 1
The maximum operating temperature as taken by thermocouples attached to the automatic pilot must not be more than shown.
Grooves for
1450°F
Pilot Burner Adaptors
NOTE: Part no.
Electrode
Mounting Bracket
500°F
Avoid Bends at This Point
Mercury Element
Figure 3
Figure 2
2
