Regulator Replacement parts for the Air and Oil Regulator on the CB 500 series burner models CB 500, CB 550, CB 550-S2, CB 525, CB 525-S, CB 525-S2, Saturn A2 and CB 100. Also works on boiler burners CB 551-H3 and CB 551-H5. Includes: Diaphragm, Poppet Seat, Poppet O-Ring, Poppet Valve, Poppet Spring. These burners are original to the following furnace models, CB 1400, CB 1500, CB 1750, CB 1800, CB 2500, CB 2800, CB 3250, CB 3500, CB 5000, CB 140 Saturn 140/230 or boiler models; CB 200 CTB, CB 350 CTB, and CB 500 CTB.