|Hot Spot Round||Z-151001 to Z-459999||1995|
|Hot Spot Round||Z-161001 to Z-469999||1996|
|Hot Spot Round||Z-171001 to Z-479999||1997|
|Hot Spot Square (rectangle)||Y-151001 to Y-459999||1995|
|Hot Spot Square (rectangle)||Y-161001 to Y-469999||1996|
|Hot Spot Square (rectangle)||Y-171001 to Y-479999||1997|
Note: There should be 10v.-19v DC between the two red wires coming from the thermostat in order for the low speed pump to come on when the t-stat calls for heat. If there is not, then the thermostat has failed.