Update, my tent has never hit 200 degrees. But that is ok, because 180 is HAF. I love my XL. I use it every night. When ambient temp outside is below freezing, it takes more time to get up to temp. Stove is red hot and hits 650-700 degrees. Honestly I get a serious sweat on at 165-170. I did change out my rock cage for a steel pot, loaded all my rocks into the pot. For a change some days will fill the rocks and pot with water and just steam my sauna. It is a more intense heat and I like the different heat. I did hit 185 with the steam.

What is the outside temperature?

Seconding not putting water on the rocks, and also I find a big difference in how fast the sauna heats up based on the wood that I use. Small pieces tend to really crank the heat up for me.

spritz on the rocks 'feels hotter' but it isn't, try not putting water on the rocks. If your stove is glowing you are not low on heat you are loosing heat somehow, or just not waiting long enough. Maybe use the window covers? I actually screwed boards around the outside skit to keep out the wind. Suggestion; when you get it to 160, open the door to the stove and let the stove cool off a bit - I bet the tent goes to 180. At that point I usually just shut it and am happy with the 180. I have also put in more smaller dry oak pieces and have and can crank it up to 200+. It does take some time and a surprising amount of wood. 30 minutes and 3 logs to 200? I would say under ideal conditions. For me I'd say 45 min. and an armload of wood and I can get above 180.