What Tempperature Is Considered "Overfiring"

I've seen in some posts where guys are worried that they are overfiring there stoves at 200* to 300*. Maybe other stoves are different. But this is from the manual for a Harman SF 250
"When and if the chimney pipes or
connectors reach 500 degrees
fahrenheit (maximum temperature),
the stove is being over-fired. We recommend
the purchase of a Harman
Magnetic Te m p e r a t u re Gauge to
monitor the stove and stack temperatures
relative to the amount of draft
the customer permits the stove to
operate."

My Keystoker Kaa-2 boiler running flat out has stack temps of a little over 300F measured midstream before the baro damper (with a turkey thermometer).

At idle, it keeps around 175F.

I would not let my stove get above about 460*-480* (magnetic stick-on thermo about 12" above the stove on the stack) I rarely run it above 350*-375* even on the coldest days.

It is easy to mix apples and oranges here. I would expect to be able to see (potentially) higher stack temps on a hand fire than a stoker and probably higher temps on a stove than a boiler. A stoker is considered over firing when you are pushing burning coal off of the grate before it can burn fully.

My hand fired boiler will run up to 6-700* on a long run, measured with a 12" probe style thermometer @ the center of the stovepipe. I'm sure a magnetic stick on would read about 200* or more lower.

Another thing is measuring before or after the Baro, the baro will drop the stack temp 50-100 degrees.

I have seen 450-500 on the stove itself (Mag Thermometer on the front of the stove), but the pipe temp (inside probe) after the baro is only 250 degrees on a good full grate burn.

I have a cheap magnetic temp gauge ( which won't stick to 304ss ) resting on the elbow which comes directly out of the stove. Even being that close to the stove, it's never gone over 275*.

With my old Mark I, I had the gauge about 2' away from the stove on the pipe right next to where it entered the chimney, & that never went above 300*. Those gauges are of questionable accuracy -- I just use it as a reference