NTI Boiler loop issues

I installed A NTI TFT 200 boiler with a indirect Hwt last fall. the system worked well throughout the winter. Now that the warmer weather has arrived, the central heat is shut off. I got a call from my customer saying the boiler is still running and the rads are hot. So I went over check it out, found out that when there is a demand for dhw my ch heat loop is getting hot. The ch pump does not come on and i have confirmed this. So I called the NTI tech support to see if they have any solutions and even sent pics to him so he could look at my primary/secondary and dhw loops. He said everything looks fine and said there's no way that the ch loop should be getting hot.



does anybody have any ideas as to what this issue could be?????



thanks