Model G3B Gas burner — Instruction manual
MNG3B Gas 041015
17
Annual start-up & service
This burner should be started and serviced at least annually
by a qualified service technician. Failure to properly maintain
and service the burner could result in severe personal injury,
death or substantial property damage.
Turn off power to appliance and close main manual gas
valve when servicing burner. See WARNINGS on page 2
and elsewhere in this manual regarding correct procedures.
Failure to comply could result in severe personal injury, death
or substantial property damage.
❏
Discuss burner/appliance operation with user to determine any prob-
lems that may have occurred during the previous season and to verify
user is aware of proper operation and care of the burner/appliance.
❏
Turn off power to appliance and close main manual gas valve.
❏
Remove burner from appliance and inspect flame holder, hot surface
ignitor and burner components.
❏
Inspect ignitor and ignition tube assembly.
1. The hot surface ignitor (HSI) is a silicon carbide element that performs dual
functions of ignition and flame detection. On a call for heat, the ignitor
is powered with 120 vac and is electrically heated to about 2600°F. This
ignites the gas/air mixture when the primary control energizes the gas
valve.
2. The primary control then switches the HSI to the flame detector circuit,
using flame rectification to monitor the flame.
3. The ignitor is positioned in the ignition tube assembly against a factory-
set non-adjustable stop ring for proper ignition and flame sensing.
4. To inspect the HSI, first be sure the 120 vac power supply to burner is
disconnected. Then slide the two silicone insulating boots off of the
insulators.
5. Pull off the quick-disconnect terminals.
6. Remove the four #8-32 screws securing the air tube back plate.
6. Maintenance and Service Procedures
7. Swing the hold-on bracket away and carefully pull out the ignition tube
assembly.
As the white ceramic is exposed, support it using a rag. It
could be HOT. Do not let the hot surface ignitor element bump
into anything. Do not drop the assembly or ignitor element.
The element is very fragile. Even a small hairline fracture will
destroy the HSI.
8. If the ignitor element is damaged in any way, replace it with a new
one.
9. If replacing the ignition tube assembly in the burner, replace the back
plate gasket with a new one. Replace the hold-on bracket and screws.
Ensure the back plate gasket is sealed gas-tight to the burner air tube.
❏
Inspect and clean flameholder.
1. Remove the ignition tube assembly from the burner as described in the
steps for inspecting the hot surface ignitor.
2. Reach in and, with one finger through the center hole of the flameholder,
pull the flameholder out of the burner air tube.
3. Use a small brush to remove dirt and lint from the inside surface of the
flameholder. All holes must be clean and unobstructed.
4. If the flameholder is damaged, dented or defective in any way, replace
it with a new one.
5. Replace the flameholder in the air tube.
6. Replace the ignition tube assembly as described in the steps for inspecting
the hot surface ignitor. Be sure to install a new back plate gasket and
seal assembly to air tube gas-tight.
7. Follow the instructions on page 8 to inspect the hot surface ignitor.
If the inside surface of the air tube needs to be cleaned,
clean with a vacuum cleaner with brush attachment while
the ignition tube assembly is out of the burner.
❏
Check the burner flange gasket. It must be in good condition. Replace
gasket on burner flange and mount burner in appliance, securing to
mounting studs.
❏
Perform the complete checkout procedures of pages 12 through 17,
including system inspection and checks.
Annual start-up & service
(continued)