Well last question first:titleist1 wrote: ↑Tue. Nov. 27, 2018 7:46 amVery interesting idea, using the internal temp probe for feeder control.
Do you still have the distribution blower plugged into the Harman controller to make use of the shut down delay timer?
Where do you power the combustion fan.... from the Harman controller, your controller, or is it running all the time?
It sounds like you had to adjust the feed rate frequently and experienced a lot of outfires when using the Harman controller. You mention babysitting it hourly and I am curious what your timer setting were at that made that necessary?
My timer settings and feed rate settings were every possibility I could make them, and I was at it diligently for weeks if not months. The thing that probably was the biggest problem in getting what I wanted, was that I needed it to put out a very low (but advertised) btu rate, like 5000btus. At those low outputs the beast was not happy at all, and would make me suffer by forcing me to always be on alert for too high coal feeds or too low. Invariably the fact that the coal feed was always coupled to the internal air stoker blower, meant that the coal was always in danger of dumping into the ashpan, instead of being burned in place before needing more.
I really could not get it to work the way Harman wanted it to, UNLESS I increased the btu output to something like 15K or higher, THEN it would work the way it was designed, but not as advertised to be able to go down to 5K or less. Believe me, if I could have tweaked it using the built in controller I would have. I came to conclude that the machine is simply not designed to have a quiescent internal temperature lower than an output of about 10K btus. My redesign of the controller came out of extreme frustration of the embedded controller.
As to the internal thermometer, mine did not have one as part of its design. I had to add a thermocouple type thermometer, mounting it in the little threaded hole right beneath the door (am posting pictures now): I ran the wire up through the internal casing to the chimney stack and out to the controller: I do still have the distribution blower plugged into the Harman controller, to both use its periodically timed "on" state (about 1 minute every 10 minutes) as well as the shut down delay functionality (about 1 minute beyond the internal blower being turned off): I have the wall thermostat plugged into my controller, and my controller's output controlling the internal combustion blower via the Harman thermostat input port (combustion blower is plugged into the Harman controller) and separately controlling the coal feed: My controller keeps the internal temperature between set temperatures (currently between 195 and 215F), activating the internal stoker blower (combustion fan) on and off to keep the internal temp in that range, but NOT feeding any coal into the stove.
Then, at some point, when that internal temp cannot be maintained and goes below 195F, the controller assumes there isn't enough coal on the burn pan, and will only then feed coal into the unit.
So what happens is, the coal that has been fed onto the burn pan stays there and burns up, and until then no more coal is fed. The efficiency goes up, the internal set temp is tighter, and the stove needs no more babysitting. The only thing I think I might eventually add, is the remaining functionality of the pre-existing Harman Vertiflow controller, so I can do away with it entirely.