pid autotune problem

Hello, I am using pid autotune library: click. I am implementing PID autotuner for my project but I have encountered a problem and I hope you will reply and help me solve it. Here it goes: I want to implement reverse tipe of regulator, because I am triggering TRIAC in dependence of input temperature. If I want temperature to raise, I have to decrease amount of delay from zero crossing to triggering a TRIAC and vice versa. But autotuner is causing me trouble with output steping. If I set output step positive, controller makes delay maximum in the begining and temperature starts to fall. But it seems like trigger line is always set higher than starting point, so input never reaches trigger line and so output never changes. I tryed to solve this problem with seting output step to negative value. Now relay method is working but in the end I get negative parameter values (kp,ki and kd). I assume this is because my negative output step value, but I can't tell. Can you help me with my issue? Thank you!