National Products BW3 - Manual (Page 5)

7. Table 2 shows minimum clearances from combustible materials.
8. Equipment shall be installed in a location in which the facilities for ventilation permit satisfactory combustion of gas, proper venting, and
maintenance of ambient temperature at safe limits under normal conditions of use. Equipment shall be located so as not to interfere with
proper circulation of air. When normal infiltration does not provide necessary air, outside air shall be introduced as described in Fresh Air
for Combustion section.
9. Advise owner to keep air passages free of obstructions. Ventilation and combustion air must enter boiler room without restrictions.
10. The boiler shall be installed such that the automatic gas ignition system components are protected from water (dripping, spraying, rain , etc.)
during appliance operation and service (condensate trap, control replacement, etc.).
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FRESH AIR FOR COMBUSTION
Provision for combustion and ventilation air must be in accordance with Section 5.3 of NFGC, Air for Combustion and Ventilation, or applicable
provisions of local building codes.
Canadian installations must be installed in accordance with NSCNGPIC and all authorities having jurisdiction.
WARNING: Be sure to provide enough fresh air for combustion. Enough air ensures proper combustion and
ASSURES THAT NO HAZARD WILL DEVELOP DUE TO LACK OF OXYGEN. Failure to follow this warning can cause a fire,
personal injury, or death.
You must provide for enough fresh air to assure proper combustion. The fire in the boiler uses oxygen. It must have a continuous supply. The air
in a house contains only enough oxygen to supply the burner for a short time. Outside air must enter the house to replace the oxygen used by the
burner. Study the following examples to determine your fresh air requirements.
CAUTION: Air for combustion must not be contaminated by halogen compounds, which include fluoride, chloride,
bromide, and iodide. These elements are found in aerosol sprays, detergents, bleaches, cleaning solvents, salts, air
fresheners, and other household products. Excessive exposure to contaminated combustion air will result in safety and
performances related problems.
CAUTION: If a fireplace or a kitchen or bathroom exhaust fan is used, an outside air intake should be installed. These
devices rob the boiler and water heater of combustion air.
PROCEDURE 1—BOILER LOCATED IN UNCONFINED SPACE
EXAMPLE 1:
An unconfined space is defined as a space whose volume is not less than 50 cubic feet per 1,000 Btu per hour of the total input rating of all
appliances installed in that space.
If your boiler is in an open area (unpartitioned basement) in a conventional house, the air that leaks through the cracks around doors and windows
will usually be adequate to provide air for combustion. The doors should not fit tightly. Do not caulk the cracks around the windows.
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Table 1—Room Large In Comparison With Boiler
BOILER SIZE
(SECTIONS)
BOILER VOLUME
(CU FT)
MINIMUM ROOM
VOLUME REQUIRED
TO BE LARGE
ROOM
(CU FT)*
2 4.3 68.7
3 5.6 89.0
4 6.8 109.3
5 8.1 129.5
6 9.4 149.8
7 10.6 170.1
* For room with single boiler only.
Table 2—Minimum Clearances From Combustible Materials and For Servicing
PART OF BOILER
ALCOVE OR ROOM
NOT LARGE
IN COMPARISON
WITH BOILER (IN.)
ROOM LARGE
IN COMPARISON
WITH BOILER (IN.)
Top 6 6
Rear 6 6
Control Side 8 6
Opposite Control Side 6 6
Front 18 18
Flue/Vent Connector 6 6
Boiler Piping 1 1
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