Specifications

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between the two settings allows the user to specify to the system how much the
conditions must differ from the set conditions before action will be taken. This
difference is known as the “comfort band.” The setting that has been selected
will be shown to the user on an “energy usage bar” located on the home screen
of the LCD display.
In a standard 3-Ton air conditioning system, any time the inside conditions are
not ideal the entire system is powered on, using about 4000 Watts of power.
With the Efficient HVAC Control and Feedback system, there are multiple
methods available to cool or heat the building. First, if the air temperature is
within the comfort band setting, but the humidity is above the comfort range, the
dehumidifier will be powered on until the humidity is back at a comfortable level.
Typical dehumidifiers use about 500 Watts of power and therefore this option
uses 1/8 of the power that a typical 3-Ton air conditioning system would be using
for this scenario. If the temperature is mildly above the comfort band settings,
the system will use only the 1-Ton air conditioner to cool the building which
typically uses 1500 Watts, or 3/8 of the power that would have been used in this
scenario. If the temperature and humidity are mildly higher than the comfort
band setting, the 1-Ton air conditioner and the dehumidifier will both work to
bring the conditions back to within acceptable range. This will use 2000 Watts
which is ½ of the power that would normally be used. With the temperature
moderately above comfort settings, the 2-Ton air conditioner will be activated,
consuming 2500 Watts, which is 5/8 the power that would normally be used.
With both temperature and humidity moderately above the comfort settings, the
2-Ton air conditioner and the dehumidifier will be activated, using 3000 Watts, or
¾ of the energy of running the entire system. Only on the hottest days of
summer, with the max comfort setting selected will both air conditioners and the
dehumidifier be activated, and the full 4000 Watts of power be used. Breaking
down the HVAC system controls in this way allows the system to consume
significantly less power than a traditional system, hence save the owner money
on the electric bill.
In order to complete the system, we had to do research, shop for parts, and
create a design to implement all of the necessary components. The components
that make up the system include, relays, relay drivers, power supplies, main and
secondary microcontrollers, printed circuit boards, LCD screen, temperature and
relative humidity sensors, and wireless communication chips. The hardware
components of the system will be what make up the total cost to build the
system, as we will be doing all of the software design and coding ourselves. Our,
sponsors, AC3 Development group LLC have specified a budget of $1500 for the
overall design and build of the system, and therefore we had to take cost into
consideration during the hardware design process.
The Efficient HVAC Control and Feedback System has two main components.
The less complex of the two components is the Remote Sensing Unit. The
Remote Sensing Unit has the responsibility of measuring the outdoor
temperature and relative humidity and reporting these values to the other