Central heating control system - with pump speed variation dependent on difference between actual and desired temp. values

摘要

The central heating control system is for use where the water or other liquid is pumped through a circuit between the boiler and one or more radiators. Pump speed is varied as a function of the difference in temperature between the actual value measured near a heat emission point and a reference value, being increased as the difference increases and vice-versa. Pump speed can be steplessly variable, and there can be a minimum speed such that circulation just continues to exist. An alternating-current motor can be used to drive the pump, speed variation being effected by a phase displacement control.