GABLE
VENT
| VENTILATED | |
OPTIONAL | ATTIC | |
INLET (a) | TOP ABOVE | |
INSULATION | ||
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SOFFIT | OUTLET | |
VENT | AIR (a) | |
| GAS | |
| WATER | |
| HEATER |
GAS VENT
FURNACE
AIR SUPPLY OPENINGS AND DUCTS
1.An opening may be used in lieu of a duct to provide to provide the outside air supply to an appliance unless otherwise permitted by the authority having jurisdiction. The opening shall be located within 12” (30.5 cm) horizontally from, the burner level of the appliance. Refer to “AIR SOURCE FROM OUTDOORS AND VENT AND SUPPLY AIR SAFETY CHECK” in these instructions for
| additional information and safety check procedure. |
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2. | The duct shall be either metal, or a material meeting the class 1 | OUTLET |
AIR (b) | ||
| requirements of |
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3. | The duct shall be least the same |
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| area of the air supply inlet opening to which it connects. |
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4. | The duct shall terminate within 12 in (30.5 cm) above, and | INLET |
| within 24 in (61 cm) horizontally from, the burner level of | |
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the appliance having the largest input. | AIR (b) |
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GAS
VENT
|
| OUTLET |
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| AIR (a) |
GAS | FURNACE | INLET |
WATER |
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HEATER |
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| AIR (a) |
VENTILATED
CRAWL SPACE
5.A square or rectangular shaped duct shall only be used when the required free area of the supply opening is
9 in2 (58.06 cm2) or larger. When a square or rectangular duct is used, its small dimensionshall not be less than
3 in (7.6 cm).
6.An air inlet supply from outdoors shall be equipped with a means to prevent the direct entry of rain and wind. Such means shall not reduce the required free area of the air supply opening.
7.An air supply inlet opening from the outdoors shall be located not less than 12” (30.5 cm) above the outside grade level.
GABLE
VENT
SOFFIT
VENT
INLET
AIR (b)
GAS
VENT
VENTILATED
ATTIC
TOP ABOVE
INSULATION
GAS | FURNACE |
WATER |
|
HEATER |
|
INLET AIR (a)
COMBUSTION AIR SOURCE FROM OUTDOORS
1.Two permanent openings, one within 12 in (30.5 mm) of the top and one within 12 in (30.5 mm) of bottom of the confined space, Two permanent openings, shall communicate directly or by means of ducts with the outdoors, crawl spaces or attic spaces.
2.One permanent openings, commencing within 12 in (30.5 mm)of the top of the enclosure shall be permitted where the equipment has clearances of at least 1 in (2.54 cm) from the sides and back and 6 in (15.24 cm) from the front of the appliance. The opening shall communicate directly with the outdoors and shall have a minimum free area of:
a.1 square in per 3000 Btu per hour (6.45 cm2 0.879 kW) of the total input rating of all equipment located in the enclosure.
b.Not less than the sum of all vent connectors in the confined space.
3.The duct shall be least the same
4.The blocking effects of louvers, grilles and screens must be given consideration in calculating free area. If the free area of a specific louver aor grille is not known.
FIGURE 27: Outside and Ambient Combustion Air
Vent and Supply (Outside) Air Safety Check Procedure
Follow the procedure in ANSI Z223.1 National Fuel Gas Code. Refer to the section on the “Recommended Procedure for Safety Inspection of an Existing Appliance” or in Canada
1.Inspect the venting system for proper size and horizontal pitch. Determine that there is no blockage, restriction, leakage, corrosion or other deficiencies, which could cause an unsafe condition
2.Close all building doors and windows and all doors.
3.Turn on clothes dryers and TURN ON any exhaust fans, such as range hoods and bathroom exhausts, so they shall operate at maximum speed. Open the fireplace dampers. Do not operate a summer exhaust fan.
4.Follow the lighting instructions. Place the appliance being inspected in operation. Adjust thermostat so the appliance shall operate continuously.
5.Test each appliance (such as a water heater) equipped with a draft hood for spillage
6.After it has been determined that each appliance properly vents when tested as outlined above, return doors, windows, exhaust fans, fireplace dampers and any other gas burning appliance to their normal condition.
7.If improper venting is observed during any of the above tests, a problem exists with either the venting system or the appliance does not have enough combustion air (Supply Air from outside) to complete combustion. This condition must be corrected before the appliance can function safely.
NOTE: An unsafe condition exists when the CO reading exceeds 40 ppm and the draft reading is not in excess of - 0.1 in. W.C.
8.Any corrections to the venting system and / or to the supply (out- side) air system must be in accordance with the National Fuel Gas Code Z223.1 or CAN/CGA
Ventilated Combustion Air
The ventilated attic space or a crawl space from which the combustion air is taken must comply with the requirements specified in “COMBUS- TION AIR SOURCE FROM OUTDOORS” in this instruction or in Sec- tion 5.3, Air for Combustion and Ventilation of the National Fuel Gas Code, ANSI Z223.1 (latest edition). This type installation requires two properly sized pipes. One brings combustion air from a properly venti- lated attic space or crawl space and a second pipe that extends from the furnace vent connection (top right of unit) to the exterior of the build- ing. Refer to Table 8 for intake pipe sizing, allowable length and elbow usage. Follow all notes, procedures and required materials in the SEALED COMBUSTION AIR SUPPLY section in these instructions when installing the combustion air pipe from the unit and into a venti- lated attic space or crawl space. DO NOT terminate vent pipe in an Attic or Crawl Space.
Ventilated Combustion Air Termination
Refer to Figure 28 for required attic termination for the combustion air intake pipe. For attic termination, use two 90 elbows with the open end in a downward position. Be sure to maintain 12” (30.5 cm) clearance above any insulation, flooring or other material.
A crawl space combustion air installation consists of a straight pipe from the PVC coupling on the burner box that extends into the crawl space and terminates with a 1/4” (0.63 cm) mesh screen and no elbows.
Unitary Products Group | 21 |
