My dilema, on a recent project, 2 A.O smith boilers were installed. These require 120 volt circuits to power blower and control at each blower. after installation and start up began experiencing prover failures, boilers randomly lock out on comm fail and ignitors are burning up like candles. Manufacturer installation instructions require individual branch circuits. E.C. installed multi wire circuit two hots /one nuetral. one leg powers Fractional horsepower circ pump 120V and other supplies boiler control/fan. manufacturer is voiding warranty claiming improper installation, E.C claims circuits are considered individual per nec 210.4 The two circuits are on individual 20 amp single pole breakers and are not grouped in panel per 210.4d.no handle ties are used. E.C.also states they are installed per engineered drawings.(we all know these can contain mistakes) I feel they should install a seperate circuit (single hot nuetral and ground) to each boiler per Manufacturers instructions. and a sperate one for circ pump. Your opinions would be greatly appreciated
