[johnrdila]

I have an old gas-fired steam boiler manufactured by Dunkirk for Carrier. It's a blue-green color with the burners exposed at the bottom (i.e. no burner cover like on the new machines).

The spark ignitor (a plastic housed circuit board) is mounted on a metal plate on the front of the boiler about 6-8 inches above the opening to the burners. The heat from the burners climbs up the face of the boiler and heats the spark ignitor plastic housing and melts it.

I've replaced it once this winter and will need to replace it again before end of winter because it gets so badly melted that it interferes with its functionality. Is this machine supposed to have a cover over the burners (it doesn't look like it, but I have no idea)? If not, any explanations as to why the heat is coming out the front to the point of melting the ignitor housing? Do I need to adjust part of the draft system? I'd appreciate any insights. Pix here to make the problem more obvious.

[SteveKJR]

It appears that the heat from the burners is causing the problem. Check to make sure your gass pressure going to the manifold is correct.

Also, check to see if there is an obstruction in the heat exchanger. This situation could cause flame rollout meaing that not all of the heat from the burners are going up through the heat exchanger.

Looking at the picture, it looks like the front above the burners is getting scorched. I am not that familiar with that particular boiler but I would think the burners should be tucked under the unit more to allow the flames from the burner to go up through the heat exchanger.

SteveKJR

Originally Posted by johnrdila

I have an old gas-fired steam boiler manufactured by Dunkirk for Carrier. It's a blue-green color with the burners exposed at the bottom (i.e. no burner cover like on the new machines).

The spark ignitor (a plastic housed circuit board) is mounted on a metal plate on the front of the boiler about 6-8 inches above the opening to the burners. The heat from the burners climbs up the face of the boiler and heats the spark ignitor plastic housing and melts it.

I've replaced it once this winter and will need to replace it again before end of winter because it gets so badly melted that it interferes with its functionality. Is this machine supposed to have a cover over the burners (it doesn't look like it, but I have no idea)? If not, any explanations as to why the heat is coming out the front to the point of melting the ignitor housing? Do I need to adjust part of the draft system? I'd appreciate any insights. Pix here to make the problem more obvious.

[johnrdila]

Originally Posted by SteveKJR

It appears that the heat from the burners is causing the problem. Check to make sure your gass pressure going to the manifold is correct.

Also, check to see if there is an obstruction in the heat exchanger. This situation could cause flame rollout meaing that not all of the heat from the burners are going up through the heat exchanger.

Looking at the picture, it looks like the front above the burners is getting scorched. I am not that familiar with that particular boiler but I would think the burners should be tucked under the unit more to allow the flames from the burner to go up through the heat exchanger.

SteveKJR

Thanks for the reply. I agree with ur assessment. I found an old manual in the basement. The machine is circa 1981. From the photos I can see that the burner door is missing on my unit. I plan to make one out of metal to replicate the original. Case closed. Thanks again.

[SteveKJR]

Make sure you are getting a good draft at the burners. If you don't have a draft gauge, take a newspaper, roll it up and light it when the burners are lit.

Once it starts to burn blow it out, hold it about 6" away from the burners and see if the smoke is drawn into the flame. If it does, then you have good draft, if it doesn't then you may have a blockage in the heat exchanger or in the flue pipe.

Placing a plate over the burner is ok as long as you have proper draft. If you don't, then the plate will get hot and warp over a period of time.

SteveKJR

Originally Posted by johnrdila

Thanks for the reply. I agree with ur assessment. I found an old manual in the basement. The machine is circa 1981. From the photos I can see that the burner door is missing on my unit. I plan to make one out of metal to replicate the original. Case closed. Thanks again.