Fault-tolerant HVAC system

• US 5,801,940 A
• Filed: 02/12/1996
• Issued: 09/01/1998
• Est. Priority Date: 01/19/1995
• Status: Expired due to Term

• Current Assignee: HVAC Modulation Technologies LLC (Acacia Research Corporation)
• Original Assignee: Gas Research Institute (GTI Energy)
• Inventors: Merry, Nir, Lincoln, Larry A., Russ, Robert M., Glorioso, Charles A., Bassett, William W.
• Primary Examiner(s): RUGGIERO, JOSEPH F
• Application Number:
  US08/598,561
• Time in Patent Office: 932 Days
• Field of Search: 364/138, 364/139, 364/131-134, 364/505, 364/551.01, 364/557, 364/184, 364/185, 364/186, 364/187, 364/506, 364/507, 165/11.1, 165/14, 165/22, 165/32, 165/200, 165/201, 165/205, 165/287, 165/288, 236/46 R, 236/94, 340/825.06, 340/825.07
• US Class Current: 700/9
• CPC Class Codes: G01D 4/004 Remote reading of utility meters to a fixed location
• CPC Class Codes: G01D 4/006 Remote reading of utility meters to a non-fixed location, i.e. mobile location
• CPC Class Codes: G05D 23/1934 each space being provided with one sensor acting on one or more control means
• CPC Class Codes: Y02B 70/30 Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
• CPC Class Codes: Y02B 90/20 Smart grids as enabling technology in buildings sector smart grids supporting the management or operation of end-user stationary applications in general, or like technologies with no associated climate change mitigation effect Y04S20/00
• CPC Class Codes: Y04S 20/244 the home appliances being or involving heating ventilating and air conditioning [HVAC] units
• CPC Class Codes: Y04S 20/30 Smart metering, e.g. specially adapted for remote reading

Abstract

A fault-tolerant HVAC system capable of continued operation in the event of a thermostat malfunction. An HVAC controller controls the operation of an HVAC unit in accordance with a temperature signal output from the thermostat and indicative of air temperature of a conditioned space proximate the thermostat. The HVAC controller detects a thermostat malfunction and, in response thereto, instead controls the operation of the HVAC unit in accordance with a temperature sensor outputting a signal indicative of return air temperature from the conditioned space.

Claims

1. An HVAC system capable of continued operation following a thermostat malfunction, the HVAC system comprising:

a thermostat having an output signal indicative of air temperature of a conditioned space proximate the thermostat;

an HVAC unit having a heat exchanger, a blower for drawing air through the heat exchanger, and at least one of a heating unit and a cooling unit for modifying the temperature of air circulating through the heat exchanger;

a discharge air plenum coupling the HVAC unit to the conditioned space, the discharge air plenum providing a path for air discharged from the HVAC unit to be expelled into the conditioned space;

a return air plenum coupling the conditioned space to the HVAC unit, the return air plenum providing a path for return air from the conditioned space to an inlet port of the HVAC unit;

a temperature sensor having an output signal indicative of return air temperature;

an HVAC controller coupled to the thermostat, the temperature sensor, and the HVAC unit;

means within the HVAC controller for sensing the output signal of the thermostat and for modifying air temperature within the conditioned space based upon the output signal of the thermostat;

means within the HVAC controller for detecting a malfunction of the thermostat; and

means within the HVAC controller for sensing the output of the temperature sensor and for modifying air temperature within the conditioned space based upon the output signal of temperature sensor, in response to detecting a malfunction of the thermostat.

2. The HVAC system according to claim 1 further including at least one positionable air damper associated with at least the discharge air plenum.

3. The HVAC system according to claim 2 further including means to position at least one of the positionable air damper in an open orientation upon detection of a malfunction of the thermostat.