Temperature drop in a tank after adding a temperature control valve.

Hello

I've been building a model of a tank that heats up till 95 C then it should fill a chamber that exchange heat with an aliuminum comonent before the thermal liquid goes back to the tank. there is a temperature drop when I add the temperature control valve of 10 C.

Can anyone help me to eliminate this drop?

Images are before and after I add the valve.

Thank you