ANSI Z21.11.2a-2008 pdf download Gas-Fired Room Heaters, Volume II, Unvented Room Heaters
3. An example for determining the volume of a typical area in which the heater may be located and for determining if this area fits the definition of unconfined space.
4. “WARNING: If the area in which the heater may be operated does not meet the required volume for indoor combustion air, combustion and ventilation air shall be provided by one of the methods described in the National Fuel Gas Code, ANSI Z223.1/NFPA 54, the International Fuel Gas Code, or applicable local codes.”
5. The statement, “WARNING: If the area in which the heater may be operated is smaller than that defined as an unconfined space or if the building is of unusually tight construction, provide adequate combustion and ventilation air by one of the methods described in the National Fuel Gas Code, ANSI Z223.1/NFPA 54, Air for Combustion and Ventilation, or applicable local codes.”
6. Unusually tight construction is defined as construction where:
(a) Walls and ceilings exposed to the outside atmosphere have a continuous water vapor retarder with a rating of 1 perm (6 x 1 0 -1 1 kg per pa-sec-m²) or less with openings gasketed or sealed;
(b) Weather stripping has been added on openable windows and doors; and
(c) Caulking or sealants are applied to areas such as joints around window and door frames, between sole plates and floors, between wall-ceiling joints, between wall panels, at penetrations for plumbing, electrical, and gas lines, and at other openings.
c. Adequate clearances for accessibility for purposes of servicing and proper operation.
d. The installation instructions for an appliance for installation on combustible flooring shall specify that when the appliance is installed directly on carpeting, tile or other combustible material, other than wood flooring, the appliance shall be installed on a metal or wood panel extending the full width and depth of the appliance. e. The installation instructions for an appliance for installation at a specified minimum distance above combustible flooring shall specify that the specified clearance shall be maintained from the top surface of carpeting, tile, etc.
f. Minimum clearances to combustible construction as verified by test (see 2.1 7, Wall, Floor and Ceiling Temperatures). In addition to the minimum clearances the installation instructions shall identify the left and right side and front of the appliance. For those clearances where a second side wall is specified, accessibility for purposes of servicing shall also be addressed. g. If applicable, clearances from any projection(s) such as shelves, window sills, fireplace mantles, etc., above the appliance (see 1 .22.8).