Troubleshooting Gas Valve; Preventative Maintenance; Main Burners - A.O. Smith VB-500 User Manual

This is a pre-mix burner system. The flame is not supposed to be
directly on the burner. The flame should be just above the burner
deck approximately 1/8" and blue in color, see illustration.
FIGURE 3. - BURNER FLAMES
visually check flame characteristics through the view port
located on the top head of the boiler. The "Burner Flames"
illustration shows the normal flame condition.
These boilers are designed to give many years of efficient and
satisfactory service when properly operated and maintained.
To assure continued good performance, the following
recommendations are made.
The area around the unit should be kept clean and free from
lint and debris. Sweeping the floor around the boiler should
be done carefully. This will reduce the dust and dirt which
may enter the burner and heat exchanger, causing improper
combustion and sooting.

PREVENTATIVE MAINTENANCE

MAIN BURNER
Check main burner every three months for proper flame
characteristics. The main burner should display the following
characteristics:
• Provide complete combustion of gas.
• Cause rapid ignition and carry over of flame across entire burner.
• Give reasonably quiet operation during initial ignition, operation
and extinction.
• Cause no excessive lifting of flame from burner ports.
If the preceding burner characteristics are not evident, check for
accumulation of lint or other foreign material that restricts or blocks
the air openings to the burner or boiler. To check burners:
1. Shut off all gas and electricity to unit. Allow unit to cool.
2. Remove main burner from unit.
3. Check that burner ports are free of foreign matter.
4. Clean burner with vacuum cleaner. Do NoT distort burner ports.
5. Reinstall burner in unit. Ensure that all the screws on the burner
flange are tightened securely so that the gasket will provide a
good seal.
6. Also check for good flow of combustion and ventilating air
to the unit.
After placing the boiler in operation, check the ignition system
safety shut-off devices for proper operation. To accomplish this
with the main burner operating, close the valve on the manifold.
Within four seconds the main burner should extinguish. If this
does not occur immediately, discontinue gas supply by closing
main manual shut-off and call a qualified service agent to
correct the situation. If the burners extinguish, then light boiler
in accordance with lighting and operating instructions.
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