deactivated at t ih to prevent excessive temperature about the heater 12 if desired the heater 12 could be deactivated at some higher temperature and still provide the desired protection if count is equal or greater than a threshold n e g 2 the blockage indicator 26 is activated and remains so whether air is flowing through the dryer 10 or the heater 12 is on or off in this way the operator has a much better opportunity to notice the blockage indicator 26 when the inlet temperature 16 drops below an inlet low limit temperature t il e g 100 u00b0 c the heater 12 is reactivated and the process continues fig3 shows a flow chart of a method according to the invention for measuring the dryness of the load 14 in the dryer 10 initially all variables are initialized and the heater 12 is activated the controller 20 compares the measured exhaust temperature 18 to an exhaust high limit temperature t eh this temperature may be for example 55 u00b0 c for cotton or 40 u00b0 c for knits if the exhaust temperature 18 exceeds t eh the heater 12 is deactivated the controller 20 then compares the measured inlet temperature 16 to a threshold dryness temperature t id this temperature may be for example 55 u00b0 c if the inlet temperature 16 drops below t id the dryness.