A refrigeration system including a refrigerant circuit with a plurality of evaporator paths and a distributor for distributing refrigerants to the evaporator paths. The endoscopic illumination tester includes an optical bridge that is removably interlockable with the lightsource. A method of preventing liquid overflow of a drain pan of an air handling unit comprises monitoring a pressure related to a liquid level buildup within the drain pan and taking an action when the pressure meets a predetermined criteria. An output of the latched comparator provides output signals based upon the captured voltages from the sensor electrode. The invention also provides therapeutics and methods for treating a subject with one or more of diabetes, insulin resistance, impaired insulin secretion, and impaired glucose homeostasis, involving the use of inhibitors of an L-type Ca2+ channel \u03b23 subunit to provide a benefit to the subject. Oxygen gas and hydrogen gas are supplied through the first gas supply pipe 13 and the second gas supply pipe 14, respectively, into the reaction tube 2, and the heater 12 heats the reaction tube 2 at a temperature capable of activating oxygen gas and hydrogen gas.