Insert here. I usually start closing my primary in increments at or around 300-350. Don't know if your setup will allow, but I take my stove top temp with an IR gun pointed thru where the blower air exits.
![[Hearth.com] What temp do YOU close(begin to)close your damper [Hearth.com] What temp do YOU close(begin to)close your damper](https://www.hearth.com/talk/data/attachments/87/87330-48ac70e29d31494dc71beb9ccdb24e9a.jpg?hash=NnFEnmW5fy)
I also have a Rutland Mag. Thermometer on my doors for reference (not accurate of stove top temps).
![[Hearth.com] What temp do YOU close(begin to)close your damper [Hearth.com] What temp do YOU close(begin to)close your damper](https://www.hearth.com/talk/data/attachments/87/87330-48ac70e29d31494dc71beb9ccdb24e9a.jpg?hash=NnFEnmW5fy)
I also have a Rutland Mag. Thermometer on my doors for reference (not accurate of stove top temps).