Cycle control system for boiler and associated burner
AssigneeC. Cowles & Company
InventorsRichard A. Lyons, Christopher L. Murray
Life of this patent
Estimating the term…
Abstract
A cycle control system for use with a boiler having a fluid therein and a method of monitoring a boiler to determine the presence of an adequate level of fluid therein. The cycle control system includes a timing circuit producing a burner control signal having alternating on and off states corresponding to on and off period timers to allow foam to settle so that a probe can accurately check the fluid level in the boiler. A burner monitor circuit monitors when a demand controller turns the burner on and off responsive to demand. The on-period timer is reset whenever the burner monitor circuit indicates the demand control circuit has turned off the burner for a length of time sufficient for the probe to accurately check the fluid level.
Claims20
A cycle control system for use with a boiler having a fluid therein, the boiler including an associated burner and a demand control circuit for turning on and off the burner responsive to demand, the cycle control system comprising:
- a timing circuit for producing a burner control signal having alternating on and off states, the timing circuit including:
- an on-period timer having an on-period for controlling the on state of the burner control signal, the timing circuit switching the burner control signal to the off state at the end of the on-period;
- an off-period timer having an off-period for controlling the off state of the burner control signal, the off-period being of sufficient duration to allow foam and surging fluid in the boiler to settle to allow accurate determination of fluid level in the boiler, the timing circuit switching the burner control signal to the on state at the end of the off-period;
- and
- a burner monitor circuit having an input for monitoring when the burner is on and off, the timing circuit resetting the on-period timer whenever the burner monitor circuit indicates the demand control circuit has turned off the burner for a length of time sufficient to allow foam and surging fluid in the boiler to settle;
- and
- a relay responsive to the burner control signal and connected to enable and disable the burner, the relay permitting the demand control circuit to turn on and turn off the burner when the burner control signal is in the on state and the relay disabling power to the burner when the burner control signal is in the off state.
A method of monitoring a boiler to determine the presence of an adequate level of fluid therein, the boiler having an associated burner and a demand control circuit with a demand control signal to enable and disable the burner responsive to demand, the method comprising the steps of:
- providing a probe at a predetermined level in the boiler, the probe outputting a signal to indicate the presence or absence of fluid at the probe;
- providing a timing circuit having a burner control signal with alternating on and off states to disable the burner for an off-period after an on-period to permit monitoring of the true fluid level in the boiler;
- turning off the burner if the probe signal indicates the absence of fluid at the probe during the off-period;
- monitoring when the demand control circuit turns the burner off;
- and
- resetting the on-period of the timing circuit after the demand control circuit has turned the burner off for a period sufficient to allow foam and surging fluid in the boiler to settle.
Dependencies are inferred from the claim text.