Kevin, this is based on 20 yrs of selling and installing HHT gas direct vents with 5 yrs as a factory technical rep. for this mfr. Let me assure you the exhaust temps reach 500+. I agreed with you about the moisture issue and have seen many decks rotted because of this. FYI, rotten wood ignites easier than fresh wood.

Yes, the metal gets that hot. That's why they stamp the word HOT into it!
Bob

__________________
Keep the fire in the fireplace.