US 5,367,601 A · Supplemental heat control system with duct temperature sensor and variable setpoint

Abstract

A heating system has a primary heat source such as a heat pump, with a capacity that occasionally needs to be supplemented from a supplemental heat source such as an electrical resistance heater. The heating system heats and circulates a medium such as air via supply and return ducts. A thermostat responsive to the heated space has two outputs for operation at different user-selected temperatures defining stages of operation at which the primary and secondary heat sources are normally drawn upon. The invention controls the duct temperature by activating the supplemental heat source according to a further setpoint, that is adjusted by a processor or other control circuit. A temperature sensor allows the control circuit to determine the duct temperature. The control circuit is also coupled to the two thermostat outputs and to a memory register storing the variable duct temperature setpoint. The duct temperature is compared to the duct temperature setpoint and the supplemental heating means is enabled to increase the duct temperature when the duct temperature falls below the variable setpoint. The control circuit adjusts the duct temperature setpoint upwardly upon occurrence of the temperature in the heated space dropping below a lower one of the space temperature setpoints (indicating that the heat pump is not keeping up), and downwardly upon the temperature in the heated space exceeding a higher one of the two space temperature setpoints (indicating that the heating capacity is adequate and use of the resistance heater should be reduced).

Claims18

Dependent claims

In a heater system having a primary heating means operable to heat and circulate a medium via a duct, and a supplemental heating means for further heating the medium when necessary to supplement the primary heating means for maintaining a desired temperature in a heated space, the primary and supplemental heating means being activatable in part by a thermostat responsive to the heated space, having at least two outputs respectively indicating a heated space temperature falling below one of two space temperature setpoints, of which one is the desired temperature of the heated space, a controller comprising:

a temperature sensor coupleable to determine a temperature of the medium at the duct;
a control circuit having inputs coupled to the temperature sensor and to said outputs of the thermostat, the control circuit being coupled to determine the duct temperature from the temperature sensor;
memory means coupled to the control circuit, the control circuit being operable to store in the memory means a variable duct temperature setpoint, to compare the duct temperature to the duct temperature setpoint, and to activate an output to enable the supplemental heating means when the duct temperature falls below the duct temperature setpoint;
wherein the control circuit includes means for incrementally adjusting the duct temperature setpoint stored in the memory means, upwardly upon occurrence of the temperature in the heated space dropping below a lower one of the space temperature setpoints, and downwardly upon the temperature in the heated space exceeding a higher one of the two space temperature setpoints.

1 more element

A heating system, comprising:

a primary heating means operable to heat and circulate a medium via a duct;
a supplemental heating means for further heating the medium when necessary to supplement the primary heating means for maintaining a desired temperature in a heated space;
a thermostat responsive to the heated space, having at least two outputs respectively indicating a heated space temperature falling below one of two space temperature setpoints, of which one is the desired temperature of the heated space;
a temperature sensor coupled to determine a temperature of the medium at the duct;
a control circuit having inputs coupled to the temperature sensor and to said outputs of the thermostat, the control circuit being coupled to determine the duct temperature from the temperature sensor;
memory means coupled to the control circuit, the control circuit being operable to store in the memory means a variable duct temperature setpoint, to compare the duct temperature to the duct temperature setpoint, and to activate an output to enable the supplemental heating means when the duct temperature falls below the duct temperature setpoint;
wherein the control circuit is operable incrementally to adjust the duct temperature setpoint stored in the memory means, upwardly upon occurrence of the temperature in the heated space dropping below a lower one of the space temperature setpoints, and downwardly upon the temperature in the heated space exceeding a higher one of the two space temperature setpoints.

4 more elements

Dependencies are inferred from the claim text.

Supplemental heat control system with duct temperature sensor and variable setpoint

Life of this patent

Supplemental heat control system with duct temperature sensor and variable setpoint

Life of this patent

Abstract

Claims18