Arrangement, in a weather-dependent advance controller of temperature of a heating installation, for facilitating adjustment of controller characteristics to heating characteristics
The arrangement comprises a Wheatstone bridge to which an operating potential is applied and whose diagonal is connected to a differential amplifier controlling a final control element for the temperature of the heating medium. One half of the bridge is constituted by a potentiometer, adjustable to effect parallel shifting of the controller characteristic curve, relating the outside temperature to the advance heating temperature of the heating medium, connected at a first junction point to a temperature sensitive resistor subjected to the temperature of the heating medium. The other half of the bridge is constituted by a first arm comprising a temperature sensitive resistor subjected to the outside temperature connected at a second junction point to a fixed resistor, and a second arm comprising two further fixed resistors connected to each other at a third junction point. An adjustable voltage divider is connected between the second and third junction points, and comprises a series connection of a second potentiometer and a limiting resistor. The adjustable tap of the second potentiometer is connected through a third potentiometer to the third junction point and is also connected to one input terminal of a threshold value switch whose other terminal is connected to the third junction point. The adjustable tap of the third potentiometer is connected to one input of the differential amplifier and the other input of the differential amplifier is connected to the first junction point. The second potentiometer is operable to adjust the slope of the controller characteristic curve in accordance with a preselected outside temperature, and the third potentiometer is adjustable in accordance with a selected advance temperature. The output of the threshold value switch is used to provide an indication as to whether, in case of an erroneous adjustment, the first potentiometer is to be used to effect a parallel shift of the curve or the second potentiometer is to be used to adjust the slope of the curve.
