Ashful
Minister of Fire
Get the stove up to temp (700 F at the top) and search with your IR for the hottest spot in the usually accessible front.
Grisu beat me to it. With everyone quoting temps of 400, 500, 700, etc... do keep in mind this guy is running an insert. He's probably quoting a temperature on the front of the surround, whereas those quoting 700, 800, 900 are talking stove top temps.