How are clearances and R values determined by mfg's?

essentially the stove is put in a room with thermocouples mounted in the floor and walls, the unit is then fired with "brands" which are small pieces of dried wood intended to get the stove to its maximum temperature, the unit is "fed" until the temperature of the stove hull does not rise for at least 30 minutes, the thermocouples provide during this time the ambient temperature of the test booth as well as surface temperatures around the stove. the walls themselves are movable to allow the testing agency to adjust them to determine clearance (to determine how close the wall can be to the stove). the standard allows the wall to be as close as the minimum distance that records no more than 115F plus ambient after (for example if ambient in the test room was 100F the max would be 215F). the test may last for 4 to 6 hours during this time the temperatures are logged by the test equipment every minute. the clearance is determined when the temperature recorded does not rise for more than 30 minutes during the test.

the floor thermocouples record similar data which is used to determine the R requirement if necessary for the floor protector in essentially the same manner

hope this helps ya!

There was an episode in this old house that had a mantle to close to a fireplace, they brought a guy in to test the fireplace and put those thermocouples all over, I try to dig up the episode.

starts minute one and then again minute 18

I remember watching that episode. Very interesting