rberq wrote:I measure stack temperature with a magnetic thermometer on the stovepipe about three feet above the stove outlet, below the barometric damper. My Harman manual says if stack temp is 500 degrees the stove is being fired at its maximum. Do they mean 500 degrees as measured by my stick-on thermometer, or do they mean 500 degrees as measured by a probe (which would be about 250 on the stick-on)?
Yes, basically it is the maximum temp at the center of the pipe. As far as relating the 500* internal probe to a 250* stick on, it would depend on the stick on more rather than less. You could put 5 on the pipe and get 5 different readings. Plus the gas speed would vary the percentage of heat loss from the center. The only accurate way to measure the temp is with a probe. That is not to say you can't operate the stove with a stick on. The changes tell the story, you are just using lower numbers.
By the way, 500* stack temp is nothing for a coal appliance. If you push one real hard, watch the stove pipe. When the color of the steel approaches that of a vigourous coal fire, make up your mind what your going to do because it will be a puddle on the floor in a few seconds.