Published July 30, 2019 © GPL3+

HVAC Smart Zone

Control a HVAC zone by retrofitting a manual duct damper with a damper actuator motor and installing a thermostat to control it.

BeginnerFull instructions provided2 hours3,454

Things used in this project

Hardware components

Particle Argon

Adafruit Power Relay FeatherWing

Adafruit FeatherWing Doubler

National Control Devices Feather Battery I2C Shield For Particle

National Control Devices TMP112 Temperature Sensor

BELIMO LMB24-3-T

DROK 090187 DC-DC Volt Buck Converter Step-down

24V AC to DC Adapter Power Supply

DC Power Connector, Jack, 2.1 mm, Panel Mount

LeMotech ABS Plastic Junction Box 6.2"x3.5"x2.3"

Optional - All assembled Smart HVAC zone DIY kit w/ free Android App

Software apps and online services

HVAC Smart Zone - Android App

Story

One of the major drawbacks of living in a split level home with forced air is ensuring even temperature through the house. Every spring and fall I had to adjust my HVAC ducts to balance the airflow of heating and A/C throughout the home and that still did not provide an even temperature between the floors. So I created a smart HVAC zone system that can be installed on existing HVAC dampers and controlled using an Android app.

This project walks you through on how to set up a smart zone thermostat and retrofitting your existing HVAC damper system without any changes to the HVAC ducts.

I am not an HVAC expert but the research I have done on a the HVAC system by using the Belimo damper actuator you may not need a bypass damper as these actuators allow you fully control the movement of a branch damper by preventing them from fully closing. Please consult with HVAC professional to ensure you are not compromising your HVAC system.

Prerequisites

Soldering the headers and close the jumper #6 on the underside of the Adafruit Power Relay FeatherWing.

Soldering the headers on the Adafruit FeatherWing Doubler

1. Set Up the Particle Account and Devices

Set up your two Particle Argon devices using the instructed available here (you will need to download the Particle App) https://docs.particle.io/quickstart/argon/

Name your Argon # 1 HVAC Thermostat and flash it with the following code hvacthermostat.ino, TMP112.cpp and TMP112.h

Name your Argon #2 HVAC Zone and flash it with the following code: hvaczone.ino

2. Assembly

Install Argon # 1 HVAC Thermostat in the NCD I2C Shield and connect the NCD temperature sensor.

Assembly the closure and install the Argon # 1 and temp sensor.

Install Argon #2 HVAC Zone in the FeatherWing Doubler along with the Power Relay FeatherWing.

Cut out the two holes on each side of the enclosure. Install the DC to DC converter and the assembled Argon #2 using enclosure standoffs. Install the cable grommet and feed the cables trough (see #1 on picture below). Install a panel DC female jack (see #1 on picture below).

Wire everything up as shown below

3. Install

I am not an HVAC expert but the research I have done on a the HVAC system with the Belimo damper actuator you may not need a bypass damper as these actuators allow you fully control the movement of branch damper by preventing them from fully closing. Adjust damper movement by moving the adjustments screws shown below based on your need.

First, take off the the damper handle or adjusting bolt.

Install a threaded rod coupling (something similar to this - see below). Use Loctite to prevent it from losing up. Close the damper and with a sharpie, mark the position of the damper.

Now install the Belimo actuator make sure the Belimo ring at one of the ends and tighten the ring around the rod coupling. Now is the time to adjust damper movement by moving the adjustments screws based on your need.

Place the HVAC Thermostat in room that controls that damper for that area.

4. Testing

Power up all the devices. Install the Logmor Android HVAC Smart Zone app and login.

To test the system out, first select the AC Mode, set temp swing to 1 and temperature to 0. If your room temperature is above 2 degrees, the damper should start to open if not already opened. If it stays closed, reverse the switch shown below.

Now select HEAT, the damper should start opening. Now go ahead and adjust the settings to your desire temp and enjoy a nice even temperature throughout the house!

// This #include statement was automatically added by the Particle IDE.
#include "TMP112.h"

SYSTEM_THREAD(ENABLED);

TMP112 sensor;
double temperature;
String temperatureString;

bool heat;
float setTemp;
float tempSwing = 1.00;
String setTempString;
String tempSwingString;

String hvacStatus = "";

int setTemperature(String temperature);
int setTemperatureSwing(String temperature);
void setMode(const char *event, const char *data);

int tempSwingEEPROMLocation = 5;
int setTempEEPROMLocation = 1;
int hvacStatusBoolLocation = 0;

void setup() {
    getStoredInfo();
    sensor.setAddress(0,0,0);
    Particle.variable("temperature", temperatureString);
    Particle.variable("HVAC", hvacStatus);
    Particle.variable("SetTemp", setTempString);
    Particle.variable("TempSwing", tempSwingString);
    Particle.function("setTemp", setTemperature);
    Particle.function("setSwing", setTemperatureSwing);
    Particle.subscribe("HVAC_Mode", setMode, MY_DEVICES);
}

void loop() {
    temperature = sensor.temperature();
    temperatureString = String(temperature, 2);
    Serial.printf("Temperature: %f \n", temperature);
    //Running heater
    if(heat){
        if(temperature >= setTemp){
            //Close HVAC DUCT
            Particle.publish("zoneControl", "close", PRIVATE);
            Serial.println("Duct Closed");
        }else{
            if(temperature <= setTemp - tempSwing){
                //Open HVAC DUCT
                Particle.publish("zoneControl", "open", PRIVATE);
                Serial.println("Duct Open");
            }
        }
    }
    //Running AC
    else{
        if(temperature <= setTemp){
            //Close HVAC DUCT
            Particle.publish("zoneControl", "close", PRIVATE);
            Serial.println("Duct Closed");
        }else{
            if(temperature >= setTemp + tempSwing){
                //Open HVAC DUCT
                Particle.publish("zoneControl", "open", PRIVATE);
                Serial.println("Duct Open");
            }
        }
    }
    delay(5000);
}

int setTemperature(String temperature){
    setTemp = temperature.toFloat();
    setTempString = String(setTemp, 2);
    EEPROM.put(setTempEEPROMLocation, setTemp);
    Serial.printf("setTemp: %.2f \n", setTemp);
}

int setTemperatureSwing(String temperature){
    tempSwing = temperature.toFloat();
    tempSwingString = String(tempSwing, 2);
    EEPROM.put(tempSwingEEPROMLocation, tempSwing);
    Serial.printf("tempSwing: %.2f \n", tempSwing);
    
}

void setMode(const char *event, const char*data){
    String command = String(data);
    if(command.equalsIgnoreCase("AC")){
        heat = false;
        hvacStatus = "AC";
    }
    if(command.equalsIgnoreCase("HEAT")){
        heat = true;
        hvacStatus = "HEAT";
    }
    EEPROM.put(hvacStatusBoolLocation, heat);
}

void getStoredInfo(){
    EEPROM.get(setTempEEPROMLocation, setTemp);
    setTempString = String(setTemp, 2);
    EEPROM.get(tempSwingEEPROMLocation, tempSwing);
    tempSwingString = String(tempSwing, 2);
    EEPROM.get(hvacStatusBoolLocation, heat);
    if(heat){
        hvacStatus = "HEAT";
    }else{
        hvacStatus = "AC";
    }
    Serial.printf("setTemp: %.2f \n", setTemp);
    Serial.printf("tempSwing: %.2f \n", tempSwing);
    Serial.printf("heat: %d \n", heat);
}

#include "TMP112.h"
#include "math.h"

bool TMP112::setAddress(int a0, int a1, int a2){
    
    if(a0 == 1){
        address = address | 1;
    }
    if(a1 == 1){
        address = address | 2;
    }
    if(a2 == 1){
        address = address | 4;
    }
    
    Wire.begin();
    Wire.beginTransmission(address);
    byte status = Wire.endTransmission();
    if(status != 0){
        Serial.println("Serial init failed 1");
        return false;
    }
    Wire.beginTransmission(address);
    Wire.write(0x01);
    Wire.write(96);
    status = Wire.endTransmission();
    if(status != 0){
        Serial.println("Serial init failed 1");
        return false;
    }
    Serial.println("sensor initialized");
    return true;
}

float TMP112::temperature(){
    Wire.beginTransmission(address);
    Wire.write(0x00);
    byte status = Wire.endTransmission();
    if(status != 0){
        return 999.99;
    }
    Wire.requestFrom(address, 2);
    byte a = Wire.read();
    byte b = Wire.read();
    float temp = a;
    temp +=(float)b/256.00;
    
    //Convert to Farenheit
    float tempF = temp*1.8+32;
    return tempF;
}

/* Includes ------------------------------------------------------------------*/

SYSTEM_MODE(AUTOMATIC);

SYSTEM_THREAD(ENABLED);

int triggerRelay(String command);

int relayStatus; 

String ventStatus;

String commandEntered;

String SSID;

String pass;

void ductHandler(const char *event, const char *data);

/* This function is called once at start up ----------------------------------*/
void setup()
{
	Particle.function("controlRelay", triggerRelay);
	Particle.subscribe("zoneControl", ductHandler, MY_DEVICES);
//	Particle.variable("BedroomVents", ventStatus);
	Particle.variable("LastCommand", commandEntered);
	Particle.variable("RelayStatus", relayStatus);
	Particle.variable("SSID", SSID);
	pinMode(D6, OUTPUT);

	
}

/* This function loops forever --------------------------------------------*/
void loop()
{
		SSID = WiFi.SSID(); 
		
		relayStatus = digitalRead(D6); 


	if (relayStatus == 0) {
	    ventStatus = "Open";
	}
	else {
	    ventStatus = "Closed";
	}
 
	
}



void ductHandler(const char *event, const char *data){
    String command = String(data);
    if(command.equalsIgnoreCase("close")){
        Particle.publish("HVAC_Zone", "Closed");
        digitalWrite(D6, HIGH);
        commandEntered = "Close";
    }
    if(command.equalsIgnoreCase("open")){
        Particle.publish("HVAC_Zone", "Open");
        digitalWrite(D6, LOW);
        commandEntered = "Open";
    }
}


int triggerRelay(String command){
	if(command.equalsIgnoreCase("on")){
		digitalWrite(D6, HIGH);
		Particle.publish("HVAC_Zone", "Closed");
		commandEntered = "Close";
		return 1;
	}
	if(command.equalsIgnoreCase("off")){
		digitalWrite(D6, LOW);
		Particle.publish("HVAC_Zone", "Open");
		commandEntered = "Open";
		return 1;
	}
	return 0;
}

Credits

Thanks to Control Everything.

HVAC Smart Zone

Things used in this project

Hardware components

Software apps and online services

Story

Prerequisites

1. Set Up the Particle Account and Devices

2. Assembly

3. Install

4. Testing

Code

HVACThermostat.ino

TMP112.cpp

TMP112.h

hvaczone.ino

Credits

Comments

Embed the widget on your own site

HVAC Smart Zone

HVAC Smart Zone

Things used in this project

Hardware components

Software apps and online services

Story

Prerequisites

1. Set Up the Particle Account and Devices

2. Assembly

3. Install

4. Testing

Code

HVACThermostat.ino

TMP112.cpp

TMP112.h

hvaczone.ino

Credits

Comments

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