The 31VBER’s boost relay de-energises when the water reaches the temperature governed by the thermostat. This product has a pushbutton switch and neon indicator that indicates when the booster element is operating. Features Booster Element Relays Booster Relay 250V 15A Ideal for a solar hot water element Commonly asked questions Can the 31VBER be time adjusted? The 31VBER can not be adjusted; it operates only on the thermostat’s temperature. Do you have a two-wire time delay switch available? The part number is 31VETR.