I need your assistance to create a controller for my home heating system.
This device will control a 12 Volt brushless DC air induction fan on a wood-fired boiler.
A K-type thermocouple is installed in the chimney flue; it measures the temperature of the exhaust gasses.
The goal is to maintain a temperature of 450 degrees Fahrenheit (programmable) in the flue when the fan is operating.
At present, I have a PID controlling the fan, but it offers no modulation. The PID works, but it is too choppy.
The operating parameters would be:
Below 400 degrees F, the 12 Volt DC induction fan would operate at 100%.
Between 400 F and 450 F, the speed of the fan would be reduced from 100% to 10% in a linear fashion.
Temperatures above 450 F would maintain a fan speed of 10% (or whatever the minimum speed of the fan is.)
I have tried several sketches (unsuccessfully) and watched many, many YouTube videos. Just can’t seem to get all the pieces to work together.
The 12-Volt fan (Model BFB1012EH) draws about 3 Amps.
Any suggestions/assistance would be greatly appreciated!