Stovepipe probe thermometer instructions

Directions for use

Condar's FlueGard (3-39) thermometer is designed for insertion into a double-wall stovepipe, with the end of the probe approximately centered inside the flue for accurate readings.

To install a FlueGard Thermometer, drill a 14 inch hole in the outer wall, and a 316 inch hole through the inner wall. Position so the thermometer can be read easily at a glance. Slide the magnet then the eyelet onto the stem of the thermometer; and insert into the hole.

When properly installed, the FlueGard accurately reads flue-gas temperatures, with an error margin less than 5%. If placed closer than 18 inches from the top of your stove or furnace, the thermometer will read slightly higher. Creosote on the stem of the thermometer will have little effect on the readings. When used on horizontal stovepipes, add 6% to temperature readings due to lower heat transfer. Before cleaning your flue pipe, remember to remove the thermometer.

Guidelines for probe thermometer temperature readings

Consult your stove manufacturer's manual for precise temperature recommendations. See below for approximate guidelines, if the FlueGard is installed properly on the flu pipe. Note that flue-gas readings are approximately 50% higher than surface temperature readings:
  • 100℉ to 400℉: Temperature too low. Incomplete combustion, causing smoke, soot and hazardous creosote. Open draft and/or add dry fuel.
  • 400℉ to 900℉: Safe operating temperature. Complete combustion and best efficiency.
  • 900℉ to 1200℉: Wasting energy, possibly overheating. While high temperatures are often reached on initial firing, should not be maintained for normal operation. Reduce draft.