I'm in the final stages of my shop build, the last two items were the heater and the epoxy paint on the floor. I have installed a older Reznor natural gas45,000 Btu ceiling heater. The heater comes on and heats fine, then will shut off when it reaches the thermostat temp. but will not come back on unless I shut the unit down and restart? I believe it may be the flame sensor but I'm not quite sure. I have also looked into the electric control unit, but they are over $300 for the updated version. Not sure I want to speed that much on a older unit? Does anyone have any experience with these type of heaters? 
I need the heater up and running before I finish the epoxy floor!
I need the heater up and running before I finish the epoxy floor!