Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Stack CO concentration trend. 24 h March day emulation run without thermal storage. The dotted red line in this figure illustrates the 400 ppm (air-free) limit used in certification test codes for natural-gas-fired appliances, illustrating the much higher CO levels normal with wood pellet firing under cycling conditions.
