I just heat my strike water to ~180° then add it all to the mash tun and let it sit until I get to my desired strike water temp. This pre-heats the mash tun, and gives me about 10 mins to take a breath and relax (which is very important in this hobby). Once the temp is 165°, or whatever I want my temp to be, I dough in and cover it up. Works great, and I lose about 1° by the end of the hour. Me and my mashtun are best friends.