Venting a gas furnace out the side of a house is a common practice, but it must adhere to specific regulations and guidelines to ensure safety and efficiency. This comprehensive analysis explores the feasibility and regulations surrounding this practice.
What Type of Venting System is Used for Side Venting a Gas Furnace?
For side venting a gas furnace, the typical venting system used is a direct vent or Category III/IV venting system. These systems are designed to vent combustion gases directly outside through a side wall, rather than using a traditional chimney.
- Direct Vent Systems: These systems use a double-pipe configuration where one pipe carries combustion air from the outside to the furnace, and the other pipe carries exhaust gases from the furnace to the outside. This setup ensures that the combustion process is isolated from the indoor air, reducing the risk of carbon monoxide poisoning.
What Materials and Configurations are Used for Side Venting a Gas Furnace?
- Materials: The vent pipes are typically made of PVC, ABS, or other materials specified by the manufacturer. These materials are resistant to corrosion and can withstand the condensate produced by condensing furnaces.
- Configurations: The venting system must be configured according to the manufacturer’s instructions. This includes ensuring proper clearance from combustibles, avoiding inside corners, and maintaining the required distance from windows, doors, and other openings.
What are the Specific Requirements for Side Venting a Gas Furnace?
- Local Building Codes: Compliance with local building codes and the National Fuel Gas Code (NFPA 54) is mandatory. These codes specify requirements such as vent termination heights, clearances from windows and doors, and prohibitions on venting under certain structures like decks or porches unless specific conditions are met.
- Clearance Distances:
- Windows and Doors: Vents must be at least 6 inches away from windows and doors for inputs up to 10,000 Btu/h, 12 inches for inputs up to 100,000 Btu/h, and 3 feet for inputs exceeding 100,000 Btu/h.
- Mechanical Air-Supply Inlets: Vents must be at least 6 feet away from mechanical air-supply inlets.
- Decks and Porches: Vents cannot terminate under a veranda, porch, or deck unless the structure is fully open on at least two sides and the vent is more than 1 foot above the underside of the structure.
- Vent Termination:
- Height: The vent terminal must be at least 5 feet below eaves, soffits, or overhangs, with a maximum overhang depth of 3 feet.
- Location: Vents must not terminate directly above paved sidewalks or driveways between two single-family dwellings, nor within specified distances of gas pressure regulator vent outlets or other appliances.
- Permits: Installation of a side-venting gas furnace typically requires a permit from local building authorities. The permit process ensures that the installation meets all relevant codes and regulations.
What are the Technical Specifications for Side Venting a Gas Furnace?
- Insulation: If the vent passes through unheated spaces, it must be insulated to prevent freezing. Manufacturers often specify the type and thickness of insulation required.
- Maximum Length: The total length of the venting system must not exceed the manufacturer’s specified maximum length to ensure proper venting performance.
What Relevant Measurements and Calculations are Needed for Side Venting a Gas Furnace?
- Vent Size: The size of the vent pipes must be calculated based on the furnace’s input rating and the manufacturer’s specifications to ensure adequate venting capacity.
- Clearances: All clearances must be measured from the center of the vent terminal to the nearest point of the structure or opening to ensure compliance with codes.
By adhering to these guidelines and regulations, side venting a gas furnace can be a safe and effective method for venting combustion gases.
