Hi Monty,
Was the damper open or closed? Was the fire going or not? The factory settings are 185 and 175 (damper opens actually at 174 indicated).
We keep the vent and door to our bedroom closed in order to sleep in the cool. We do not adjust the thermostat.
The temperature display has a "damper open" indication in the form of a dot between the first and second digits, much like a decimal point except on the upper part. Note that this is not necessarily a true indication; it is merely an indication that the signal has been sent to the solenoid in the door. The only way to know for sure if the damper is open, shut, or stuck (in my case, stuck open) is to take the louvered cover on the door which covers the solenoid and damper.
Factory thermostat settings and an indication of 167 degrees should mean that the damper is open, supplying air to the fire. Sounds to me as if the fire goes out due to not enough requirement being placed on the system after your inside thermostat has been turned down. Try not adjusting it and leaving it set in order to troubleshoot.
Are you heating your hot water with the 6048? Is your wood seasoned (dry)?
Best,
Jerry