"The hand test may sound a little primitive for our technological age, but it provides a more accurate and universal gauge of heat than any modern gadget made for the grill," write Cheryl and Bill Jamison in "100 Grilling Recipes You Can't Live Without." For testing a fire's intensity, the Jamisons suggest holding your hand a few inches above the grill's cooking grate and counting the number of seconds until the fire's heat forces you to pull your hand away. A high fire is 1 to 2 seconds, a medium-high fire is 3 seconds, a medium fire is 3 to 4 seconds and a medium-low fire is 5 to 6 seconds.