The temp won't remain constant at 225 because of the analog controller. The SIs will heat to a point above your set temp, and then shut off (the click you heard) and cool to a point below your set temp at which point the unit will turn back on (the click again). Most of us see temp swings in the +/- 15 to 25 degree range, so for a set temp of 225F, you might see smoker box temps ranging from 200 to 250 (+/-25). Not a problem, though, as the SI will average out at 225.