So the problem with the sensor is that there's a bad connection to the cable. If I barely nudge the cable where it enters the sensor, the main unit throws an error code that indicates no sensor is attached. So that makes sense that the hotter it gets, the worse the accuracy is gonna be. I have an email in to them asking to exchange it. I also have an email in to them asking for the Klingon symbol to set for the other sensor I bought, figuring I might need options is using this on a non-metallic stove: You're supposed to screw that ring to the flue to monitor its temperature, but I need to monitor the surface temperature of the soap stone. I figured I can either screw it to a heavy washer and lay it on the stove, or I can just stick it under one of the magnet-backed mechanical thermometers I have, since the magnets seem to be perfect heat conductors and the magnet will securely hold onto the end. I have 2 magnet-backed thermometers and one that's not, and the readings are always identical across the stove's entire operating range. I just need to know which symbol to select in the Thermometer unit, although I guess I could do trial & error. edit to add: I just checked. That ring is aluminum, so the magnet idea is out. I could screw something to it and stick it to the magnet...
So I hooked up the Washer Sensor (I got the Klingon Code) and I have the exact same issue I had with the magnetic sensor: the electronic unit reads fine at room temp, but it is consistently 80°-100° lower than the thermometers I have on my wood stove. -The 3 mechanical thermometers I have on my wood stove always agree with each other. -Both sensors on the new electronic thermometer read lower than the 3 stovetop thermometers by 80°-100° -Yesterday I tested the readings with the magnetic sensor and a wood stove thermometer side-by-side on a cast iron griddle over a slow low flame on the stove and had the same outage When I hooked up the washer sensor tonight and saw the same difference, I got out my IR gun. -The temperature read by the IR gun agrees with the electronic thermometer --I took the IR temp of the stove top and of all 3 thermometers --The IR temp read about 100° lower than the temp displayed on the 3 thermometers --The 3 thermometers continue to agree with each other, which is the weird thing The issue with the IR gun is that "emissivity" thing...but it should not be out by 30% or more. 10% would be more reasonable...and the surface of all 3 thermometers and the stove top are within a reasonable range. This is not making any sense. My mind is blown. I have been using this stove for 11 years and now I'm doubting the accuracy of the 3 thermometers I've been using the entire time!!! At least they read high and not low, or I'd have real troubles. But based upon what I sense from the stove's behaviour, I cannot believe that when the thermometers tell me I'm at the upper safe limit I actually have another 100° to go. And how can they agree with each other with no variance yet all of them be so off????? They are 3 different brands, with one being specifically for soap stone stoves with a different design. I don't know what to do next. I can put the sensor in ice water and then boiling water to test 32° and 212°, but I have no way of testing the 3 thermometers, nor do I have a way of making sure that the sensor/electronic unit are accurate at 400° just because they read freezing and boiling OK. I do not have another thermometer I can use to check surface temps. I tried my food thermometers but their pointy ends are valueless on a flat surface. Maybe I could do the griddle test again and put a small stainless steel cup of oil on it so I can measure it's temps with a kitchen thermometer at the higher range (since water is no good over 212°), then run another test in my convection oven. It is advertised as being ±2° accurate. I could use its built-in thermostat in conjunction with my smoker thermometer to verify temp, and put the washer sensor and the 3 wood stove thermometers in it and see what happens. This is insane.
So I couldn't wait until tomorrow to mess with this. I set up the test scenario on the cast iron griddle, and confirmed that the electronic thermometer is accurate and the other ones I have are reading way high. I know the IR gun is accurate on the griddle because it is matte black cast iron, and that's similar to the material that's used to calibrate those guns (100% emissivity.) I'm gonna drive into a wood stove store in Richmond this week to talk to someone. I want to know what they use. The guy I bought my stove from is not gonna be of much value on this. I cannot see running my stove at the temps the electronic thermometer accurately reads, but I don't want to be running it "cold" either. And to think I was ready to write the electronic thermometer off as a mistake and return it.
Could it be that the physical location of the three stove top thermometers are in a different spot than the electronic one? Perhaps the temperature isn’t uniform across the surface you are measuring. A picture of the stove and all thermometers as they are setup in operation would help in a diagnosis from afar. Right now I'm thinking the electronic one is dealing with a heat sink issue maybe. In other words, however the thermocouple is being held in place on the stove, some of the heat is being absorbed into the holder and dissipated into the air which cools it. For a quick test you could put something like a metal pot or a soup bowl over the sensor and see if the indicated temperature rises.
The Infra Red gun verified that the correct temperature is the one that the electronic thermometer reads. I have the washer sensor jammed behind the mounting hardware for one of the thermometer's magnets, so the sensor is reading the exact same spot as that thermometer. I also tested things on the cast iron griddle, which provided a controllable environment. I put a small pan of oil on the center of the griddle so I could use a standard kitchen thermometer in it as yet another measurable data point with yet another thermometer. -The electronic thermometer reading, the housing temp of the 3 thermometers and the stove surface temp are always in agreement. -The electronic thermometer reading, the housing temp of the 1 thermometer, the bowl of oil and the griddle's surface temp are always in agreement. -The displays on the 3 thermometers are always high in both environments. The other data point is that the electronic thermometer sensors both accurately read room temp, and the IR gun also accurately reads objects at room temp.