How long are the pellets your using? The pdv and pdvc use a 16 second cycle basically the heat range adjustment changes the amount of "on time" per cycle, each cycle represents one "run" + one "stop" in other words if the "on" is 2 seconds, te "off" will be 14 seconds. if the "on"is 4 seconds the "off " will be 12 seconds and so forth it always adds up to 16 seconds. the "feed amounts" are based on approximations , as you know all pellets are not the same uniform size so the "lbs per hour" are not a "set in stone" rate. the "on" time on heat range 9 in "D" mode is 4.77 seconds. the On time in C mode heat range 9 is 5.13 seconds. the other heat ranges have scaled differences between c and d