Wireless Modular Multi-Zone HVAC Controller
Group B:
Javier Arias
Ryan Kastovich
Genaro Moore
Michael Trampler
Sponsors:
LiveTV (Tentative)
Introduction
1
Today, there are an increasing number of households running HVAC (heating,
ventilation, and air-conditioning) control systems 24/7. While many of these systems might be
designed to be as efficient as possible, it does not mean that they are smart enough to
accommodate the needs of the user(s) in every possible usage scenario combination. For
example, not every room in a house needs to be set at the same temperature at all times,
especially once everyone has gone to bed. So at night, there are usually no occupants in the
kitchen, living room, or dining room which are still being cooled or heated. Then, a multi-zone
system was introduced to help fulfill the extra needs of consumers. With this new system, users
were given the ability to dictate individual temperatures to different “zones,” whether they be
bedrooms and living rooms, or different floors of an office building. The user could control the
HVAC to cool and/or heat only the room’s occupied, turning off the zones vacant through
installed dampeners to control air flow. Say there are two zones for a HVAC system, if one zone
is vacant, then the user could turn on zone off directing all the air flow to the occupied zone
which will then be cooled or heated faster. So with this system installed, power consumption
will decrease which results in a cut in energy costs.
Motivation
Our goal in this project is to create a low cost, drop-in replacement for a currently
installed HVAC Controller. The controller will be programmable and modular such that it
lowers electrical costs through intelligent control of the AC unit and is adaptable to any
household environment.
Description
The system will be designed such that a consumer will be able to utilize the multi-zone
controllers all while keeping the power consumption low, as well as being eco-friendly and
leaving a small footprint. Although the power consumption will be low, there won’t be any drop
off in precision levels, customizability, or aesthetics. Multiple remote sensor modules (RSM)
will be implemented so the user will be able to control temperature and humidity in certain zones
through an aesthetically pleasing interface. Each RSM will also come with preset modes with
which a user can employ to run throughout the day to further decrease power consumption. But
if those preset modes do not adequately meet the requirements of the user, he/she will be able to
program the RSM to meet his/her own needs. This system will also feature internet connectivity
for the convenience of control anywhere there is internet access. The web interface will give the
user the control features of a RSM, while the user is away.
Specifications and Requirements
2
Display Accuracy
Temperature
Humidity
CO2
0.5˚C
2%
400 ppm
Sensor Accuracy
Temperature
Humidity
CO2
Sampling Rate
0.125 ˚C
2% relative
At least 400ppm
0.5 Hz
System Accuracy
Temperature
Humidity
0.25 ˚C
2%
Budgets and Financing
Item
Sensor Microcontroller
Quantity
Price (of each)
Apprx. Total
10
$5.00
$50.00
8
$3.00
$24.00
10
$5.00
$50.00
CO2 Sensors
8
$15.00
$120.00
Power Supplies
8
$10.00
$80.00
RF Module
8
$10.00
$80.00
N/A
N/A
$40.00
10
$10.00
$100.00
2
$100.00
$200.00
ADC
10
$5.00
$50.00
DAC
8
$5.00
$40.00
N/A
N/A
$40.00
Web Server Controller
1
$100.00
$100.00
Heat Sink/ Misc.
2
$30.00
$60.00
Temp Sensors
Humidity Sensors
Passive Components
PCB
Main Controller
Driving Components
Grand Total
$1,034.00
Main Controller Flowchart
3
Initialize
Alert User to
Check System
Check Safety
Sensors
NO
Shut Down All
HVAC Systems
and Alert User
Check Sub
Systems
O.K.?
NO
Connectivity
Working?
YES
YES
Alert User
NO
O.K.?
Check Thermostat
Communication
YES
Compare Thermo
Data to Current
Values Stored in
Memory
Pull Thermostat
Data
1-2 Sec Delay
YES
Setpoints
Change?
Log the Data
Apply the Changes
to System
NO
Log New Data
Main Controller Flowchart
4
The flowchart on the previous page shows the process of the Main Controller (MC). To
begin with, the main controller is initialized and starts by running a check mode to make sure the
safety sensors are working properly and there no issues to be found in the system. If there are
issues however, the HVAC System will turn itself off and alert the user of the issue at hand. If
however, there are no problems, the system will then run a self-check on the Sub systems
(Dampener, Fan Control, and connections). If there are problems then the system will alert the
user to check the system before continuing. If the control systems are functioning properly then it
will check the Thermostat communication to make sure the connection is running appropriately
as well as making sure each Thermostat in the system is working and turned on. Once again, if
the connections or Thermostats are not working correctly, the user will be alerted until this has
been resolved. Next, the Main Controller will pull the data from each Thermostat and compare it
to the current values stored in memory. It will then check to see if the set points changed. If they
have then the system will apply the changes, log new data, run through a 1-2 second delay and
go back to checking the safety sensors like before. If however the set points do not change then
the data will be logged, followed by a 1-2 second delay and then return to checking the safety
sensors.
Thermostat Flowchart
5
Initialize
Load Presets
Poll Sensors
NO
YES
AC Mode On?
Temp > Preset
+0.3°C
NO
Temp < Preset 0.3°C
YES
NO
TX Turn Off Heat
& AC
TX Turn On AC
YES
NO
Heat On?
YES
TX Turn On Heat
Sleep Mode 1-2
Sec
NO
Did Presets
Change During
Sleepmode?
YES
6
Thermostat Flowchart
This illustrates the process each thermostat runs through. Starting with an initialization,
it then loads the presets from memory. Then the sensors are polled to see if the temperature is
greater than the preset temperature with a buffer of 0.3 degrees Celsius. If the temperature is
greater than the presets it checks if the AC mode is on and if the preset is less than the
temperature it then checks if the heat mode is on. If the thermostat is in AC mode and the
temperature is higher than the set temperature plus 0.3 degrees Celsius, the thermostat will
transmit a signal which will tell the main controller to send cold air to that particular thermostat’s
zone. Similarly, if the thermostat is in Heat mode and the temperature is lower than the
temperature minus 0.3 degrees Celsius, the thermostat will transmit a signal which will tell the
main controller to send hot air to that particular thermostat’s zone. If neither mode is on, then
there is a command to the main controller to go into sleep mode. It then checks if the presets
have been changed while it’s been asleep. If yes, then it loads the new presets from memory and
repeats this process. If no, then it polls the sensors again and repeats the process.
Main Controller Block Diagram
RTC
To be Acquired
Damper Controller
Research
Wireless TX RX
To be Acquired
Fan Controller
Microcontroller
Research
Research
Embedded Web
Server
Research
Website
Heat Pump
Controller
Research
Heating Coil
Controller
Design
Data Logging
Design
Research
Legend
Michael
Genaro
Javier
Ryan
7
Main Controller Block Diagram
The block diagram on the previous page shows the Main Controller and all of its
subcomponents. More specifically, we can see that the microcontroller has 9 modules which it
will control. The modules include: a Real-Time Clock, a Damper Controller, a Fan Controller, a
Heat Pump Controller, a Heating Coil Controller, a Wireless Transmitter and Receiver for data,
and an Embedded Web server. The Embedded Web server will be run through the main
controller itself as a dedicated server and will serve the web page and will also data log for the
user.
Thermostat Block Diagram
CO2
Research
Humidity Sensor
Research
Display
Research
Inputs
Prototype
Microcontroller
Wireless TX RX
Acquired
To be Acquired
Temperature
Sensor
Prototype
Legend
Michael
Genaro
Javier
Ryan
Thermostat Block Diagram
The above block diagram shows how the Thermostats will be utilized in the HVAC
system. To start, we will use a microcontroller to control all the different aspects of the
thermostat. Within this the Microcontroller will control the CO2 sensor, the Humidity Sensor,
and the Temperature Sensor. The microcontroller will have a display unit attached to it for the
user to see and interact with via push buttons and rotary encoder. The microcontroller will also
have a wireless transmission and receiver to push data to the main controller.
8
Milestones
9