What blu said, you want to always keep the flat away from the hot side. So point pointing at firebox, flat end pointing at exhaust.
Thermo isn't going to give you an accurate reading of what grate temp is.
One more thing. Sizzling is a good thing. That means it's cooking. You should never attempt to lower temps because you hear sizzling. You'll be cooking at 180F and meat will never get done. Anywhere from 250-325 F is a great temp for brisket. 220 is not a magic cooking temp.
Modded Brinkmann Gourmet. Basic UDS. Rescued 22.5" OTS. SJS Mini-WSM. Stubbs. B&B Oak Lump.
Cannondale 2009 F8 (for burning off all the great BBQ)