2.5DTI Motor-stamping device

Hello, I had the main thermostat changed at my Omega 2.5DTI and still have problems with the engine pumping it takes a very long time until it has reached operating temperature. After 10 minutes drive the pointer of the display starts to hike. I got the old upgraded thermostat from Opel but that has destroyed the installer, has jumped out of the lead I wonder if he has installed the new thermostat properly. How warm will he get with you my safft on cal like today 80 degrees. Greetings Andreas