System and method for compressor optimization and system cycling using ambient air for cooling or heating
A system and method are described for conserving energy in HVAC systems. During certain temperature requests, ambient air can be supplied to a conditioned space and the HVAC compressor can be turned off to conserve power. During certain temperature requests, supply air can be adjusted through cycling of heating or cooling elements to conserve power and maintain desired space temperature. In various embodiments, supply air temperature, coil temperature, cabinet temperature and other values can be monitored for their effect on cooling and/or heating, and taken into account for determining how to best cool or heat a conditioned space.
1. A method for operating an HVAC system comprising a heat exchanging coil, one or more compressors, and an HVAC controller, the method comprising:
receiving, at the HVAC controller, a temperature request for a climate controlled space;
determining a basis air temperature of the climate controlled space using at least one sensor in the climate controlled space;
determining an ambient air temperature;
determining a return air temperature using a return air sensor;
determining based on the ambient air temperature and the return air temperature that a mixture of ambient air and return air can be used to fulfill the temperature request;
restricting operation of a compressor;
supplying the mixture of ambient air and return air to the climate controlled space;
determining a supply air temperature using a sensor in the supply airstream;
determining a current temperature of the climate controlled space; and
adjusting the supply air temperature by turning the compressor off and on to extract a maximum amount of energy from the heat exchanging coil and modulate the supply air temperature based on at least the determined supply air temperature, the determined current temperature of the climate controlled space, and the determined ambient temperature.
2. The method of claim 1 further comprising:
determining a humidity level in the space; and
adjusting an operation of the HVAC system based on at least the determined humidity level.
3. The method of claim 1 further comprising;
determining a coil temperature and an HVAC cabinet temperature; and
adjusting an operation of the HVAC system based on at least one of the determined coil temperature and the determined HVAC cabinet temperature.
4. The method of claim 1 wherein restricting operation of a compressor comprises turning off the compressor.
5. The method of claim 1 wherein adjusting an operation of the HVAC system comprises adjusting an amount of refrigerant.
6. The method of claim 1 wherein adjusting an operation of the HVAC system comprises adjusting an operation of a heat exchanger.
7. The method of claim 1 wherein adjusting an operation of the HVAC system comprises adjusting an operation of an enthalpy wheel.
8. The method of claim 1 further comprising:
determining a pressure level; and
adjusting an operation of the HVAC system based on the determined pressure level.
9. An HVAC system for providing conditioned air to a space, comprising:
a cabinet comprising;
an inlet for an ambient airstream;
a supply airstream;
a return airstream; and
at least one heat exchanger;
a supply air temperature sensor;
a space temperature sensor;
an ambient airstream temperature sensor;
a return airstream temperature sensor;
a controller coupled to the cabinet, supply air temperature sensor, the space temperature sensor and the ambient temperature sensor, the controller configured to receive a temperature request, wherein when the request is to heat the space when a determined ambient temperature is greater than a determined space temperature or to cool the space when the determined ambient temperature is less than the determined space temperature, the controller is configured to;
restrict operation of a compressor within the HVAC system;
allow a mixture of return air and ambient air to comprise a portion of the supply air of the HVAC system based on the ambient air temperature and return air temperature;
determine a change in the supply air temperature;
determine a change in the space temperature; and
adjusting the supply air temperature by turning the compressor off and on to extract a maximum amount of energy from the heat exchanging coil and reengaging the compressor when the energy in the heat exchanging coil is insufficient to maintain the supply air temperature.
10. The HVAC system of claim 9 further comprising a humidity sensor, and wherein the controller is configured to adjust an operation of the HVAC system based on at least the determined humidity level.
11. The HVAC system of claim 9 further comprising a pressure sensor, and wherein the controller is configured to adjust an operation of the HVAC system based on the determined pressure level.
12. The HVAC system of claim 9 further comprising a heat exchanger temperature sensor and a cabinet temperature sensor, wherein the controller is configured to adjust an operation of the HVAC system based on at least one of the heat exchanger temperature and the cabinet temperature.
13. The HVAC system of claim 9 wherein the controller is a thermostat.
14. The HVAC system of claim 9 further comprising a thermostat.