Energy reducing retrofit method and apparatus for a constant volume HVAC system

摘要

An energy-reducing method and apparatus for retrofitting a single zone, constant volume HVAC system, with or without an economizer, that provides heating, cooling, and ventilation to occupants within a building space. The present invention includes the introduction of a programmable logic controller and variable frequency drive (VFD) that takes control of the existing fan, heating, cooling, and optional economizer operation. The reduction of the fan speed in the ventilation mode when the 100% operation is not needed saves significant energy of the existing constant volume HVAC system where the fan motor is designed to run 100% of the time.

主权项

1. A method for reducing energy consumption comprising retrofitting a preexisting single zone constant volume HVAC system that provides one or more of the following: heating, cooling, or ventilation to an indoor space within a single zone of a building, wherein the indoor space has at least partial occupancy, and the heating, cooling, or ventilation is controlled and operable from a range of not operating to a maximum operation based on preset conditions or on occupancy command, and wherein the preexisting HVAC system comprises a fan, a fan motor associated with the fan, a thermostatic device that references temperature of the indoor space, heating or cooling equipment having equipment control terminations, the method further comprising:
providing a programmable logic controller to receive input from the preexisting thermostatic device and send heating, cooling, and ventilation instructions to the preexisting fan motor to actuate the preexisting fan to ventilate the indoor space within the single zone of the building, and the preexisting heating and/or cooling equipment to send heat or cooling to the indoor space; operably connecting the programmable logic controller to the preexisting equipment control terminations; providing a variable frequency drive (VFD), controlled by the programmable logic controller, and operably connecting the VFD to the preexisting fan motor; operating the preexisting HVAC system in a ventilation mode and a heating or cooling mode, wherein all said modes are controlled by the programmable logic controller; and operating the preexisting fan motor at a reduced speed during the ventilation mode when less than maximum operation in the ventilation mode is required.