main flame

Five Reasons Your Boiler Fails on Main Flame

There are numerous reasons that your boiler could fail on main flame instead of ignition. Some of these may seem similar to the symptoms of an ignition failure; however, the causes of the failure are distinct.

1) Dirty Flame Scanner

Flame scanners should be inspected and cleaned at least once per month. Your flame scanner is responsible for sensing the presence of an active flame in the burner compartment. It does this by sensing the release of UV, infrared, or visible light. UV flame scanners can do this in near real time.

After you start your furnace, the flame sensor will activate within a few seconds. If it does not detect a flame, it will cut off the flow of fuel to the boiler, preventing a potentially dangerous buildup of flammable material.

Due to its presence near the flame, this sensor will often suffer from carbon buildup—this is why it needs to be cleaned every month. After cleaning, ensure it is properly aligned to sense the flame.

2) Dirty Fuel Oil Strainer

Your fuel oil strainer is responsible for preventing contaminants from clogging your system. However, if you do not clean or replace your filter regularly, it will eventually lose efficiency, leading to a clog.

This will restrict the fuel, which will result in an inefficient main flame or potentially none at all. For this reason, you should clean and inspect your fuel oil strainer weekly. Your filter gasket should be replaced simultaneously.

3) Out of Oil

This may seem unlikely if your boiler has recently been refilled, but low oil could be responsible for a sudden inability to start your main flame. A refill will be necessary to continue operation. Daily logs of fuel usage should be kept in order to help alert building personnel of possible overheating or leaks that could be responsible for excessive oil usage.

4) Fuel Supply Valve Closed

Even if a low or empty fuel oil supply is not responsible for your boiler failing on main flame, this does not mean a lack of fuel is not the issue. A closed fuel supply is a more common problem than you may think.

Did someone accidentally close the manual oil or gas valve? If so, reopening the valve will solve the problem. Establishing clear lockout procedures and educating personnel will help prevent confusion regarding shutdowns.

5) Broken Linkage

Linkages control the fuel/air mixture being fed to your boiler’s burner. If these are improperly set, broken, or leaking, it may cause several issues, including excessive fuel use, poor operation, or failure of the boiler to fire on main flame altogether.

First, ensure all control linkages on the burner are in place and undisturbed. If necessary, reset them and check for operation. If damaged or worn, linkages may need to be replaced or adjusted.

Linkage control systems are becoming an increasingly obsolete technology. Consider having your burner fit with a linkage-free control system, which may solve your problem and lead to fewer future issues—and significant gas savings.

Conclusion – The main flame fails | Solution: Boiler Maintenance Plan

Your boiler is a critical piece of machinery, and your business often cannot continue in its absence, so you need to diagnose and repair any issues as quickly as possible. To prevent such disruptions, ensure you establish appropriate service intervals and perform regular maintenance.

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