It is known that HVAC (heating, ventilation, and air conditioning) is the technology of indoor and vehicular environmental comfort. Typically, air conditioning large buildings, such as hotels requires the use of compressor-based cooling plants. These systems employ multiple machines, and are the most common method of providing cooling for medium and large commercial and institutional buildings and also for many industrial processes. These systems employ a chiller to remove heat from a liquid via a vapor-compression or absorption refrigeration cycle. Chillers are usually electric driven, but may also be driven by an engine or other power source. Electric driven water chillers are used extensively in buildings, campuses and district cooling plants to provide chilled water for comfort conditioning.
Often, the vapor-compression-based systems enable an HVAC unit to reliably chill inside environments well below ambient temperatures. When operated as an air conditioner, the compressor converts the refrigerant from gaseous to liquid form, thereby extracting considerable heat from it. That heat is then transferred to the outside air. The newly chilled liquid is then circulated to the evaporator under high pressure through insulated tubing. Once it reaches the evaporator, which is located inside an air handler in which the air is conditioned by being forced past the evaporator by a fan, the pressure on the liquid is removed, at which point the liquid reconverts into a gas, thereby absorbing heat from the air being blown across the evaporator. The refrigerant is then transported in gaseous form back to the compressor to repeat the cycle. Thus heat is transferred from the air in the conditioned space to the refrigerant, and then from the refrigerant to the outside air.
Typically, individual rooms in a hotel employ thermostats to enable the occupants to adjust the temperature to a desired level. However, this latitude to freely set the temperature is often abused, as the occupant excessively lower the temperature on the thermostat. This creates a large waste of energy, especially for larger buildings, such as hotels. The chiller must work at high power levels to perpetually cool the recirculated fluid from the HVAC system.
The inventor has been working in the field of motor control units for over seven years. The inventor recognized that large users of energy such as hotels, office buildings and the like have found the need to conserve energy is now critical to profitability. Public and non-profit facilities such as schools, universities, hospitals, and civic buildings must divert limited financial resources from their primary missions to pay for energy. Therefore, many energy conservation strategies and devices have been developed over the past several decades. On a smaller scale, individual families are faced with ever-increasing utility bills, sometimes forcing the choice between living needs and paying for electricity, gas, or oil.
The inventor decided to invent a system and method for taking the excessive set point out of the hands of the occupant by overriding the thermostat. The inventor knew that chillers and the pumps that circulate fluid in an HVAC unit are the largest consumers of electricity. He had to enable the return line to return with cooler water so that the chiller would not have to exert maximum energy, and thus consume excessive energy. The inventor decided to override the thermostat in each room, figuring that the cumulative effect of restricting temperatures in each room would lead to large savings over a duration. The inventor initially, manually went into unoccupied rooms and adjusted the thermostat to a more reasonable setting.
However, he realized that a more automated system was needed. After trial and error, the inventor decided to override the thermostat with a bypass feature having a reasonable and comfortable predetermined temperature. However, the room would not be allowed to fall below this predetermined temperature, no matter at which setting the room occupant set the thermostat. The overriding function was done with a control unit that integrated into the HVAC unit.
A temperature sensor in the control unit sensed the temperature in the room, and if the room temperature fell below the predetermined temperature, the temperature sensor would trigger a control relay to shut off a cooling valve going into the room. Repeated over many rooms, the return fluid was cooler since it did not have to work so hard in each room; and thus the chiller did not have to operate at high power to cool the return fluid for reentry into the HVAC units and rooms. The inventor used a wire harness to enable the control unit to be retrofit into a variety of HVAC units—especially older HVAC units with no intelligence.
HVAC optimization systems have been used for reducing energy consumption in cooling and heating systems in the past, yet none with the present characteristics of the present invention. See Patent numbers: U.S. Pat. No. 8,457,802; U.S. Pat. No. 7,878,236; and U.S. Pat. No. 8,511,576.
For the foregoing reasons, there is a need for a system that optimizes energy consumption in an HVAC unit by minimizing chiller activity with a control unit that overrides a thermostat in a room.