Weil Mclain boiler flame flashback

[UP North]

Greetings all from Michigan. First time posting. Thanks in advance for any information. Weil Mclain Gold CGA boiler with pilot light, 23 years old and burning propane. Last night I heard an unusual startup of the burner (louder than normal) and when I looked at the boiler (with the front cover still on) there was significantly more sound coming from the burner and a bright orange light was visible. I immediately shut down the boiler with the power switch and began researching the issue. As I did not have the front cover off when this was happening, I could not see the burner tubes but I suspect it had flashed back and was burning at the orifices. There was definitely a hot smell in the room (basement). This model boiler has a flame rollout fuse located on the left side on the metal plate that has the pilot light access hole and separates the combustion chamber from the front portion of the boiler. I let it cool down and then inspected the burner tubes for debris. They were clean. Plenty of propane in the tank and about 5 degrees outside. Today I am going to inspect again and check each orifice for any blockage. I will also check the gas pressure with a manometer. I have lived here 12 years with no previous issues. What I don't understand is why the rollout fuse did not trip out the boiler. Either the fuse is not functioning or the area of the boiler it is located at did not get hot enough to trip it. It sure smelled hot enough. The boiler started back up fine and is working as it should. I am going to replace the rollout fuse out of caution but there is no way of knowing whether it is bad until I have a new one and can test the old one. Any input on this issue is greatly appreciated. Thank you. Rick

 

[Fitter30]

Greetings all from Michigan. First time posting. Thanks in advance for any information. Weil Mclain Gold CGA boiler with pilot light, 23 years old and burning propane. Last night I heard an unusual startup of the burner (louder than normal) and when I looked at the boiler (with the front cover still on) there was significantly more sound coming from the burner and a bright orange light was visible. I immediately shut down the boiler with the power switch and began researching the issue. As I did not have the front cover off when this was happening, I could not see the burner tubes but I suspect it had flashed back and was burning at the orifices. There was definitely a hot smell in the room (basement). This model boiler has a flame rollout fuse located on the left side on the metal plate that has the pilot light access hole and separates the combustion chamber from the front portion of the boiler. I let it cool down and then inspected the burner tubes for debris. They were clean. Plenty of propane in the tank and about 5 degrees outside. Today I am going to inspect again and check each orifice for any blockage. I will also check the gas pressure with a manometer. I have lived here 12 years with no previous issues. What I don't understand is why the rollout fuse did not trip out the boiler. Either the fuse is not functioning or the area of the boiler it is located at did not get hot enough to trip it. It sure smelled hot enough. The boiler started back up fine and is working as it should. I am going to replace the rollout fuse out of caution but there is no way of knowing whether it is bad until I have a new one and can test the old one. Any input on this issue is greatly appreciated. Thank you. Rick

Pull the burners, if their cast dump the rust out of them, run a wire through the holes or slots. If made from sheet metal dump the dirt out of them. Run water from the top of the burner they get dirty from the bottom. The orifices take a piece of strained wire push it through the holes. Check the pilot orifice if it has one blow it out. Of that doesn't resolve the problem need a flue brush top of the boiler has to come off to inspect the sections. Pull burners, brush between the sections, vacuum out where burner sit.

 

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[Fitter30]

Greetings all from Michigan. First time posting. Thanks in advance for any information. Weil Mclain Gold CGA boiler with pilot light, 23 years old and burning propane. Last night I heard an unusual startup of the burner (louder than normal) and when I looked at the boiler (with the front cover still on) there was significantly more sound coming from the burner and a bright orange light was visible. I immediately shut down the boiler with the power switch and began researching the issue. As I did not have the front cover off when this was happening, I could not see the burner tubes but I suspect it had flashed back and was burning at the orifices. There was definitely a hot smell in the room (basement). This model boiler has a flame rollout fuse located on the left side on the metal plate that has the pilot light access hole and separates the combustion chamber from the front portion of the boiler. I let it cool down and then inspected the burner tubes for debris. They were clean. Plenty of propane in the tank and about 5 degrees outside. Today I am going to inspect again and check each orifice for any blockage. I will also check the gas pressure with a manometer. I have lived here 12 years with no previous issues. What I don't understand is why the rollout fuse did not trip out the boiler. Either the fuse is not functioning or the area of the boiler it is located at did not get hot enough to trip it. It sure smelled hot enough. The boiler started back up fine and is working as it

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[UP North]

Thanks Fitter30 for your reply. I cleaned the burner tubes and the orifices. The tubes were not dirty as I had cleaned them last year. The orifices seemed clean but it is hard to tell. But I cleaned them with a welding torch tip cleaner (Oxweld #18 for a #56 drill). The pilot light orifice is very small (.01) and required a 30 gauge piece of wire. The pilot light now has a smoother sounding burn. Before I go into it any further, I will try it as is for a while. There are 6 burner tubes and the 3 on the right have been very hot based on the color change. So it appears that not all of the tubes had flashback. If anything changes, I will report back.