Hearthstone Heritage Flu Gas Temps

Any Heritage owners ever seen your stove do this? Is this normal? I have a 5 year old Heritage (top exit) connected to Excel Ultrablack dual wall stove pipe to our Excel stainless steel chimney. In the stove pipe run I have a damper at 15" and above and a Condor flu gas thermometer at 25".
Before going to bed last night I loaded my stove with 4 logs, which I've done many times before. The stove was hot before I loaded it. I let the wood catch and shut the damper and reduce the air to about 1/8 open (all with in 2 to 3 minutes) and let run for about like that for about 30 minutes. After the 30 minutes I checked the flu gas thermometer and it read 900F and rising. So I shut the air intake to 0 open and flu gas kept rising to 1100F. The re-burn tubes were cranking red hot. The center stone temperature only got up to 400F maybe a little warmer but I've gotten the stove much hotter in the past. So at 1100F and rising I started to get a bit nervous since I have not seen temps like that before and not been able to close the stove and get it back in control. Last night the only thing I could do was to completely block the air intake with some paper and wait until the fire to die out which took a while. Once the fire was out I then unblocked the air intake and resumed the burn with no problems. This mornig I re-loaded the stove and everything seems in controllable.
Any thought are appreciated.

Scott

Yes, I have found this to be fairly normal on my Hearthstone Tribute
when I double-damper (stovepipe damper closed & air flow down).
In this mode I get some of my best burns (hottest burns).

I often do this when loaded-up for an overnight burn, I have
experienced no ill effects from it.

I have a very similar setup except no pipe damper. I routinely run my condar probe meter well past 1000 daily and have seen 1250 more than once. Normal flue cruising temps are very high from this stove typically from 700 to 900 until only coals remain.

Note that the condar probe meters are known to read hotter than actual. By about 20%.

Note that class A chimney is rated for continuous exposure to 1000 degree flue temps.

I wonder if the heritage design just sends more heat up the flue than necessary. My flue temps are always higher than the stove surface temps. Wood consumption appears normal, the stove seems efficient. Some stoves don't send so much heat up the chimney and instead use that heat to heat the room.

I have a damper 6" off the back of a rear vent Heritage and have a probe just off the back of the stove. The only way I can get 450+ is to have flue temps above 1000 and I typically see 1200 and sometimes, briefly, higher than that. I always assumed due to my probe position being so close to the stove I would have "hotter" than normal temps. My pipe goes straight back about 20" and straight up, so I can't read the temp from anywhere else.