Overfired Boiler Causing Wet Steam

Bobby D.

Is my burner overfired ?

The reason I ask is, I have checked the pitch of all pipes and rads, cleaned the boiler (by skimming) added a new Main Vent ( hoffman # 75), new rad vents, and I still get wet steam, hissing spitting vents, and surging .

I have an old Dunkirk # 717 Steam Boiler with a circa 1965 Sun Ray Oil Burner Model DSP. The current nozzle is a Red ( Hollow Cone) 1.10 GPH with a 70 Degree angle.

The Ratings on the boiler plaque are NET I.B.R. (oil fired) 430 Steam Sq. Ft. Max Firing Rate 1.60 Gallons.

According to Delavan if I take my steam sq ft of radiation which is 240 sq. feet, add a pick up factor of 1.5 = 360 sq. feet muliply this by 240 = 86,400 divide this by efficiency of burner 75% x 140,000 which is 105,000 I get the number .82 In other words I believe that the burner nozzle should at the maximum be .85 GPH.

With an overfired boiler what are the ramifications, is it slow moving wet steam, short cycling, surging, vents hissing and spitting,

Should I downfire in gradations ?

Any thoughts or suggestions ? Thanks

ta finnegan

Questions

Overfired or oversized to me the problems manifest themselves in remarkably similar symptoms.

For oversized I have had success with more venting and getting the piping around the boiler as near to perfect as possible. Oversized header can help, watch for bullheaded tees as well.

As for the firing issue, the only thing you can try is "tweaking" nozzles, firing rates, air mix etc. Personally I do not like anything over or under fired.

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