Reddy heater model 28725

Propane heater uses a hot surface ignitor. this operates off 120 volts and glows red/orange when actuated. it stays lit throughout the heater on operation.  on the backplate of the combustion chamber is a high limit with two wires coming off it.  these two wires connect to the spade connectors on the flame detector cappillary.  Once you establish a fire, the flame detector generates a 750 millivolt signal which is applied to the pilot/main valve assembly.  My diagram will show this.