- Combination operating and high limit with manual reset (90000CEL)

- Add step control for low/high/low operation (99000C)

- Add proportional control for full modualtion operation (99000E)

- Microprossesor based for optimal performance and real time diagnostics

- Standarized on manual reset high limit

- EZ to read LED's for status and diagnostic

- Multiple sensors for built in redundancy

- Pre-wired with boiler control for easy installation

- Only utilizes one tapping

- EZ to adjust modulation range