Precisionâ   Instruction Manual SERVICE (Contd.) HEATER DATA Heater Resistance Cat.  No.        Model                  Wattage                   Voltage                       (Ohms) 66630 180 225 120 64 66557 181 225 120 64 66564 181 225 240 256 66643 182 300 120 48 66617 182 300 240 192 66551 183 400 120 36 66553 183 400 240 144 66648 184 600 120 24 66618 184 600 240 96 66562 185 600 120 24 66563 185 600 240 96 66634 186 2(600) 120 24 66647 186 2(600) 240 96 66552 188 2(400) 120 36 66554 188 2(400) 240 144 Heater Resistance Procedure: WARNING: Disconnect the bath from its power source. Refer to the appropriate wiring diagram and the table above for resistance values at room temperature.  Resistance is measured between terminals on the heater element. Be sure to disconnect at least one lead of each heater before taking an ohmmeter reading. If the heater is open (infinite resistance), it should be replaced. Heater Replacement: WARNING: Service should be performed by qualified service personnel. -7-