Improvements in heating systems using a fuel-burning source

摘要

The rate of dissipation of heat from a heating load is represented by the voltage on capacitors C3a-e. They are charged from a capacitor C4 through a transistor TR1 at the instant that a thermostat (not shown) switches off and so de-energizes transformer X1, which supplies power to the control system. They discharge via a constant current device IC5 and resistor R4. A voltage follower IC6 and load resistor R5 provide a control voltage to charge a capacitor C14, the control voltage being proportional to the time in which the load thermostat is "off". The control voltage which appears on re-energization of the system triggers a Schmidt trigger IC7 after a delay determined by when the capacitor C14 becomes charged to the triggering voltage. Boiler relay L3 is thus energized with a delay inversely proportional to the control voltage.