Installation
FURNACE LOCATED IN CONFINED SPACE
When the furnace is in utility room, install two open grilles. (See Fig. 28.) Place them in a wall or door opening to the rest of the house. One grille will supply combustion air.
Locate it near the floor. The other grille is for ventilation. Locate it close to the ceiling. Each grille must have a free area. It should be not less than one square inch for each 1000 BTU/hr. of the total input rating of appliances in confined space.
FOR EXAMPLE: Your furnace is rated at 150,000 BTU per hour. The water heater is rated 30,000 BTU per hour. The total is 180,000 BTU per hour. You need two grilles, each with 180 square inches of free opening. Metal grilles have about 60% free (open) area. Therefore, you need two metal grilles with 300 square inches each of louvered area. The height should be about half the width.
FRESH AIR DUCT CAPACITIES | FIG. 28 |
Fresh air duct capacities for duct supplying fresh air |
|
BTU Per Hour Input*
| 1/4” MESH | WOOD | METAL |
| SCREEN | LOUVERS | LOUVERS |
SIZE | BTU | BTU | BTU |
|
|
|
|
144,000 | 36,000 | 108,000 | |
8 INCH ROUND | 200,000 | 50,000 | 150,000 |
8 X 12 INCH | 382,000 | 96,000 | 288,000 |
8 X 16 INCH | 512,000 | 128,000 | 384,000 |
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|
|
|
* Based on opening covered by 1/4 inch mesh screen, wood or metal louvers.
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