VENTILATION & COMBUSTION AIR
WARNING: AIR OPENINGS TO COMBUSTION AREA MUST NOT BE
OBSTRUCTED. BY FOLLOWING THE INSTRUCTIONS BELOW, ADEQUATE COMBUSTION AIR CAN BE MAINTAINED
COMBUSTION AIR REQUIREMENTS
(MINIMUM SQUARE INCHES OPENING)
| *UNCONFINED AREA | **CONFINED AREA | ||
| OUTSIDE | INSIDE | OUTSIDE COMBUSTION AIR | |
MODEL | COMBUSTION | COMBUSTION | VERTICAL | HORIZONTAL |
NUMBER | AIR 1 SQ. IN | AIR 1 SQ. IN. | DUCTS | DUCTS |
MGB | /5000 BTU/HR | /1000 BTU/HR | 1 SQ. IN. | 1 SQ. IN. |
| (SEE FIG. 4) | (SEE FIG. 3) | /4000 BTU/HR | /2000 BTU/HR |
MGB 38 | 8 | 100 | 10 | 19 |
MGB 50 | 10 | 100 | 13 | 25 |
MGB 75 | 15 | 100 | 19 | 38 |
MGB 100 | 20 | 100 | 25 | 50 |
MGB 125 | 25 | 125 | 32 | 63 |
MGB 150 | 30 | 150 | 38 | 75 |
MGB 175 | 35 | 175 | 44 | 88 |
MGB 200 | 40 | 200 | 50 | 100 |
MGB 225 | 45 | 225 | 57 | 113 |
MGB 275 | 55 | 275 | 69 | 138 |
MGB 300 | 60 | 300 | 75 | 150 |
*Unconfined area: A space whose volume is not less than 50 cubic feet per
1000 BTU per hour of all appliances installed in that space (cubic feet of space = height x
width x length).
** Confined area: A space whose volume is less than 50 cubic feet per 1000 BTU per hour of all appliances installed in that space (cubic feet of space = height x width x length).
1.Ventilation of the boiler room must be adequate to provide sufficient air to properly support combustion per the latest revision of the National Fuel Gas Code, ANSI Z223.1 section 5.3.
2.When a boiler is located in an unconfined space in a building or conventional construction frame, masonry or metal building, infiltration normally is adequate to provide air for combustion and ventilation. However, if the equipment is located in a building of unusually tight construction (See the national Fuel Gas Code, Ansi Z223.1 section 1.7), the boiler area should be considered as a confined space. In this case air for combustion and ventilation shall be provided according to part 5 on page 5. If there is any doubt, install air supply provisions in accordance with the latest revision of the National Fuel Gas Code.
3.When a boiler is installed in an unconfined space, in a building of unusually tight
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