| 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.
