THERMOSTAT OPERABLE FROM VARIOUS POWER SOURCES

• US 20040245349A1
• Filed: 06/03/2003
• Published: 12/09/2004
• Est. Priority Date: 06/03/2003
• Status: Active Grant

• Current Assignee: Tim Simon, Inc.
• Original Assignee: Tim Simon, Inc.
• Inventors: Smith, Blaine M.
• Granted Patent: US 6,886,754 B2
• Time in Patent Office: Days
• US Class Current: 236/10
• CPC Class Codes: F23N 5/203 using electronic means
• CPC Class Codes: G05D 23/1904 variable in time

Abstract

A thermostat is operable from battery, common-wire (“C-wire”), or furnace relay power. The thermostat includes a power source selector, such as a jumper wire, that is set when the thermostat is installed in a heating system. In a gas millivolt heating system, the thermostat operates off of battery power. In heating systems having a C-wire, a diode bridge converter converts alternating-current voltage to direct-current voltage to provide operating power to the thermostat. In heating systems without a C-wire and having sufficient furnace relay current, a triac converter in series with the furnace relay provides voltage spikes to the diode bridge converter to provide operating power to the thermostat when the furnace is on, and the diode bridge converts AC to DC voltage when the furnace is not on. The thermostat can also be used in cooling systems and heating, ventilation, and air-conditioning systems. Thus, the thermostat can be used in a wide variety of applications.

Claims

1. A thermostat comprising:

a heating transformer power terminal;

a heating load terminal;

a common terminal; and

a power source selector configurable to operate the thermostat from alternating-current voltage provided between the common terminal and the heating load terminal when the power source selector is in a first position, and to operate the thermostat from alternating-current voltage provided between the heating transformer power terminal and the heating load terminal when the power source selector is in a second position.

2. The thermostat of claim 1 further comprising a battery wherein the thermostat operates from battery power when alternating-current voltage is not provided to the thermostat.

3. The thermostat of claim 1 further comprising a battery and a low-battery detector that senses battery voltage and indicates a low battery condition when the battery voltage drops below a pre-selected limit.

4. The thermostat of claim 3 further comprising a thermostat controller configured to operate at an operating voltage, the pre-selected limit being greater than the operating voltage by about 0.1 V.

5. The thermostat of claim 1 further comprising:

a power supply;

a thermostat controller;

a diode bridge converter; and

a battery providing a battery voltage to the thermostat controller, wherein the diode bridge converter converts alternating-current voltage to direct-current voltage that is coupled to the power supply, the power supply regulating the direct-current voltage and providing a regulated direct-current voltage to the thermostat controller, the regulated direct-current voltage being greater than the battery voltage.

6. The thermostat of claim 5 wherein the battery has an internal impedance and the power supply has an output impedance, the output impedance being greater than the internal impedance.

7. The thermostat of claim 5 further comprising:

a diode bridge converter; and

a triac converter;

wherein the triac converter provides voltage spikes to the diode bridge converter when the heating transformer power terminal is coupled to the heating load terminal through the triac converter when the power source selector is in the second position, and the heating transformer power terminal is coupled to the heating load terminal bypassing the triac converter when the power source selector is in the first position.

8. The thermostat of claim 7 wherein the diode bridge converter converts alternating-current voltage between the heating transformer power terminal and the heating load terminal when the power source selector is in the second position and the heating load terminal is not coupled to the heating load terminal through the triac converter.

9. The thermostat of claim 7 wherein alternating current is coupled to the diode bridge converter through a limiting capacitor.

10. A thermostat comprising:

a heating transformer power terminal;

a heating load terminal;

a common terminal;

a diode bridge converter;

a triac converter; and

a power source selector configurable to operate the thermostat from alternating-current voltage provided between the common terminal and the heating load terminal when the power source selector is in a first position, and to operate the thermostat from alternating-current voltage provided between the heating transformer power terminal and the heating load terminal when the power source selector is in a second position, the triac converter providing voltage spikes to the diode bridge converter when the heating transformer power terminal is coupled to the heating load terminal through the triac converter when the power source selector is in the second position, and the diode bridge converter converting alternating-current voltage between the heating transformer power terminal and the heating load terminal when the power source selector is in the second position and the heating load terminal is not coupled to the heating load terminal through the triac converter, the heating transformer power terminal being coupled to the heating load terminal bypassing the triac converter when the power source selector is in the first position.

11. The thermostat of claim 10 wherein alternating current to the diode bridge converter is limited by a capacitor.

12. The thermostat of claim 10 further comprising:

a thermostat controller;

a battery providing a battery voltage to the thermostat controller; and

a power supply providing a regulated direct-current voltage to the thermostat controller, the regulated direct-current voltage being greater than the battery voltage.

13. A thermostat comprising:

a heating transformer power terminal;

a heating load terminal;

a common terminal;

a thermostat controller;

a power supply providing a regulated direct-current voltage to the thermostat controller;

a battery providing a battery voltage to the thermostat controller, the battery voltage being less than the regulated direct-current voltage;

a power source selector having a first position and a second position;

a diode bridge converter providing direct-current voltage to the power supply, wherein the diode bridge converter converts alternating-current voltage provided between the heating load terminal and the common terminal when the power source selector is in the first position, and converts alternating-current voltage provided between the heating load terminal and the heating transformer power terminal when the power source selector is in the second position.

14. The thermostat of claim 13 wherein alternating current is coupled to the diode bridge converter through a limiting capacitor.

15. The thermostat of claim 13 further comprising a low-battery detector configured to sense a battery voltage and to indicate a low battery condition when the battery voltage drops below a pre-selected limit.