Stepper motor gas valve and method of control

摘要

A controller for a variable heating system is operable to control a stepper motor operated gas valve to adjust gas flow to vary the heating level. The controller includes a first terminal for receiving a thermostat signal requesting heating, an electronic memory, and a microprocessor in communication with the electronic memory and first terminal. The microprocessor detects a thermostat signal requesting heating, and generates a control signal for the stepper motor to operate the gas valve. The microprocessor includes a programmable read-only-memory encoded with an instruction to store a time duration during which the microprocessor detects a thermostat signal requesting heating, and further encoded with an instruction operable to determine a predetermined heating level based on the stored time duration. The microprocessor responds to a thermostat signal requesting heating by determining the number of steps the motor must move to vary the gas flow corresponding to the predetermined heating level.