
This heater shall not be installed in a confined space or unusually tight construction unless provisions are provided for adequate combustion and ventilation air. This appliance is for supplemental heating only. It should not be used as the primary heat source for a dwelling. The National Fuel Gas Code, ANSI Z233.1/NFPA 54 defines a confined space as a space whose volume is less than 50 cubic feet per 1,000 Btu per hour (4.8m3 per kw) of the aggregate input rating of all appliances installed in