Help! Live in the NE have electric heat but have burned wood for over 20 years. Last year installed a Clayton Furnace which will burn wood or coal. I have had to replace the control unit 4 times. Here is what is happening. Orginal was an 8". Settings has been 100 degrees and 150 which is recommended for blower to turn off and on. Fan will only run and ciculate heat through trunk line to registers for 10 seconds and then shut off. Keeps cycling until heat builds up in fire box, fan comes on but only runs at this short cycle. Replaced with 11" run for month same problem. Replaced with 8" same thing. Installer check with units being shipped and mfg. now has 5". replaced with 5" two weeks ago and now it is doing same thing. Have emailed US Stove Company. They thought install was not allowing heat to escape furnace but plenum and trunk allows that to occur. Installer says power supply to fan has been cutoff and causing loss of calibration on control unit. That's not the case. Have therometer on flue pipe. When furnace and fan are working properly the temp on flue pipe doesn't reach 300 degrees when temp should be 250 to prevent creosote. Hope my babble makes sense. ANY HELP OUT THERE!