Ventilation Requirements
If the existing boiler or furnace is located in an open area (basement or utility area) and the ventilation is relatively unrestricted, there should be sufficient supply of air for combustion and draft-hood dilution. On the other hand, if the heating unit is located in an enclosed furnace room or normal air infiltration is effectively reduced by storm windows or doors, then certain provisions must be made to correct this situation. Figure 16-9 illustrates the type of modification that should be made in a furnace room to provide an adequate supply of air. As shown, two permanent grilles are installed in the walls of the furnace room, each of a size equal to 1 in2 of free area per 1000 Btu/h of burner output. One grille should be located near the ceiling, and the other near the floor.
If the boiler or furnace is located in an area of particularly tight construction, the heating unit should be directly connected to an When plastering and finishing front, put newspaper over air tube to keep all spotless.
outdoor source of air. A permanently open grille sized for at least 1 in2 of free area per 5000 Btu/h of burner output should also be provided. Connection to an outside source of air is also recommended if the building contains a large exhaust fan.
A conversion burner equipped with a spark ignition system is not suited for use in furnaces or boilers located in areas subjected to sustained reverse draft or where large ventilating fans operate in combination with insufficient makeup air. There is always the danger of drawing flue gases into the structure. (See Installing a Conversion Gas Burner in this chapter.)