Thermocouple for Mr. Heater & Heat-Star Propane Heaters Part No. 28643 •Fits Model's: MH/80CV & MH200CV. The 28643 Thermocouple fits Mr Heater and HeatStar heaters is supplied with nuts and is 10 inches long. The 28643 Thermocouple fits both the HeatStar and Mr Heater model numbers HS200CV, MH200CV, as well as many other heaters.