Chapter 5 Nozzles and Chambers Air Tube Insertion The burner head should be 1/4" back from the inside wall of the combustion chamber. Under no circumstances should the burner head extend into the combustion chamber. If chamber opening is in excess of 4 3/8", additional set back may be required. Figure 5-21: Burner installation, chamber guide “A” = Usable air tube length. Chapter 5—Nozzles and Combustion Chambers 5-21 6. Pack rockwool or vermiculite around the outside of the chamber. 7. Take a piece of smoke pipe slightly larger than the burner air tube, and use it to form the burner air tube opening. Then build up the chamber around it, making sure to observe the proper floor to nozzle center line, and making the end of the smoke pipe recess one quarter inch for the inside face of the chamber. 8. Install the top half of the chamber and pack, making sure that on a dry base boiler the bricks extend at least one course above the dry base. 9. Build up the front of the chamber and finish off the outside with a 50-50 mix of Portland cement and insulating material. 10. Use the same material to cap off the top of the chamber over the packed vermiculite. Form the cap so it is pitched from the chamber up to the boiler. 11. Install the burner with the face of the end cone one-quarter inch back from the chamber face. See Figure 5-21. 12. Snugly stuff the space around the air tube with fireproof rope. 13. Cap off the inside and outside around the air tube with the 50-50 mix. 14. Fire the chamber in short bursts for 10 to 20 minutes to dry the chamber materials. Unlike dry base boilers and furnaces, wet base boilers may be fired without a chamber. The water jacket surrounds the fire zone. The flame from modern burners are self-propagating, they do not need hot refractory reflecting heat back into the flame to burn cleanly. Although a chamber wall is not needed, a target wall with little wing walls is still a good idea. As with chambers, the nozzle must be properly sized so the flame does not impinge on any cold surfaces. There are advantages to chamberless firing: • Target walls are less expensive than chambers. • Heat transfer to the water improves because there is no insulating chamber material between the cast iron and the fire. • Nitrogen oxide emissions are reduced. • Flame temperatures are lowered since there is no chamber to reflect heat back into the fire and the iron absorbs all that heat. Lower flame temperatures produce lower NOx emissions. Finally, when in doubt about nozzles, chamber, chamber design or chamber materials refer to the manufacturer’s instructions, ask your supplier, or call the manufacturer’s technical service hot line.
NORA Oilheat Technicians Manual
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