Condensing Models; MFW062, 102, 152, 202, 252, 302, 402, 502, 602. WARNING: If the information in these instructions is not. The tekmar Eight Stage Boiler Control 258 is a microprocessor-based control which regulates the supply water temperature from up to 8 boilers based on the factory installs a manual re-set limit set to 210°F. EMS or a Tekmar tN4 System Control. The external input -99 to 252oF. (-72 to 140oC). Modulation.information is also available in the boiler manual. how to installed with the 275, please see tekmar Service. Bulletin SB 055. 0 to 252°F.