Humidity Sensor-Controlled Bathroom Exhaust Fan

Accumulation of moisture in a closed up space like a bathroom can lead to the appearance of mould, which can cause health issues.

Jan 31, 2019

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28701 views

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26 respects

weather

environmental sensing

energy efficiency

Components and supplies

DHT11 Temperature & Humidity Sensor (4 pins)

12v 1A power supply

12V 200mm DIA computer casing fan

MOSFET board

Arduino Nano R3

Jumper wires (generic)

Tools and machines

Hot glue gun (generic)

Project description

Code

Arduino Sketch

arduino

1#include <SimpleDHT.h>
2
3//Declaring digital pin no 2 as the dht11
4  data pin
5
6int pinDHT11 = 2;
7int DHTpower = 3;
8int Fan = 13;
9SimpleDHT11
10  dht11;
11
12void setup() {
13  pinMode(Fan, OUTPUT);
14  pinMode(DHTpower, OUTPUT);
15
16  digitalWrite(DHTpower, LOW);
17  digitalWrite(Fan, LOW);
18  Serial.begin(9600);
19   
20}
21
22void loop() {
23  delay(1000);
24  RHcheck();                        //check
25  Humidity Level
26  delay(15000);                     //wait 15sec
27  }
28
29
30void
31  RHcheck() {                    //Check Humidity Level Function
32  digitalWrite(DHTpower,
33  HIGH);     //On Humidity Sensor
34  delay(5000);
35  Serial.println("============
36  Check Humidity ===============");
37  delay(1000);
38  Serial.println("DHT11
39  readings...");
40   
41  byte temperature = 0;
42  byte humidity = 0;
43  int
44  err = SimpleDHTErrSuccess;
45
46  //This bit will tell our Arduino what to do
47  if there is some sort of an error at getting readings from our sensor
48  if ((err
49  = dht11.read(pinDHT11, &temperature, &humidity, NULL)) != SimpleDHTErrSuccess) {
50
51    Serial.print("No reading , err="); Serial.println(err);delay(1000);
52    return;
53
54  }
55  Serial.print("Readings: ");
56  Serial.print((int)temperature); Serial.print("
57  C, ");
58  Serial.print((int)humidity); Serial.println(" %");
59  delay(500);
60
61  if((int)humidity < 50){
62    digitalWrite(DHTpower, LOW);
63    delay(500);
64
65    Serial.println("Fan OFF");
66    delay(500);
67    digitalWrite(Fan, LOW);
68
69  }else{
70    if ((int)humidity > 58){
71      Serial.println("Humidity > 58%");
72
73      digitalWrite(DHTpower, LOW);
74      delay(500);
75      Serial.println("Fan
76  ON @ full speed");
77      delay(500);
78      digitalWrite(Fan, HIGH);
79    }else{
80
81      Serial.println("50% < Humidity < 58%");
82      digitalWrite(DHTpower,
83  LOW);
84      delay(500);
85      Serial.println("Fan ON @ low speed");
86
87      delay(500);
88      analogWrite(Fan, 150);
89    }
90  }
91 }
92

#include <SimpleDHT.h>

//Declaring digital pin no 2 as the dht11
  data pin

int pinDHT11 = 2;
int DHTpower = 3;
int Fan = 13;
SimpleDHT11
  dht11;

void setup() {
  pinMode(Fan, OUTPUT);
  pinMode(DHTpower, OUTPUT);

  digitalWrite(DHTpower, LOW);
  digitalWrite(Fan, LOW);
  Serial.begin(9600);
   
}

void loop() {
  delay(1000);
  RHcheck();                        //check
  Humidity Level
  delay(15000);                     //wait 15sec
  }


void
  RHcheck() {                    //Check Humidity Level Function
  digitalWrite(DHTpower,
  HIGH);     //On Humidity Sensor
  delay(5000);
  Serial.println("============
  Check Humidity ===============");
  delay(1000);
  Serial.println("DHT11
  readings...");
   
  byte temperature = 0;
  byte humidity = 0;
  int
  err = SimpleDHTErrSuccess;

  //This bit will tell our Arduino what to do
  if there is some sort of an error at getting readings from our sensor
  if ((err
  = dht11.read(pinDHT11, &temperature, &humidity, NULL)) != SimpleDHTErrSuccess) {

    Serial.print("No reading , err="); Serial.println(err);delay(1000);
    return;

  }
  Serial.print("Readings: ");
  Serial.print((int)temperature); Serial.print("
  C, ");
  Serial.print((int)humidity); Serial.println(" %");
  delay(500);

  if((int)humidity < 50){
    digitalWrite(DHTpower, LOW);
    delay(500);

    Serial.println("Fan OFF");
    delay(500);
    digitalWrite(Fan, LOW);

  }else{
    if ((int)humidity > 58){
      Serial.println("Humidity > 58%");

      digitalWrite(DHTpower, LOW);
      delay(500);
      Serial.println("Fan
  ON @ full speed");
      delay(500);
      digitalWrite(Fan, HIGH);
    }else{

      Serial.println("50% < Humidity < 58%");
      digitalWrite(DHTpower,
  LOW);
      delay(500);
      Serial.println("Fan ON @ low speed");

      delay(500);
      analogWrite(Fan, 150);
    }
  }
 }

Arduino Sketch

arduino

1#include <SimpleDHT.h>
2
3//Declaring digital pin no 2 as the dht11  data pin
4
5int pinDHT11 = 2;
6int DHTpower = 3;
7int Fan = 13;
8SimpleDHT11  dht11;
9
10void setup() {
11  pinMode(Fan, OUTPUT);
12  pinMode(DHTpower, OUTPUT);
13  digitalWrite(DHTpower, LOW);
14  digitalWrite(Fan, LOW);
15  Serial.begin(9600);   
16}
17
18void loop() {
19  delay(1000);
20  RHcheck();                        //check  Humidity Level
21  delay(15000);                     //wait 15sec
22  }
23
24
25void  RHcheck() {                    //Check Humidity Level Function
26  digitalWrite(DHTpower,  HIGH);     //On Humidity Sensor
27  delay(5000);
28  Serial.println("============  Check Humidity ===============");
29  delay(1000);
30  Serial.println("DHT11  readings...");
31   
32  byte temperature = 0;
33  byte humidity = 0;
34  int  err = SimpleDHTErrSuccess;
35
36  //This bit will tell our Arduino what to do  if there is some sort of an error at getting readings from our sensor
37  if ((err  = dht11.read(pinDHT11, &temperature, &humidity, NULL)) != SimpleDHTErrSuccess) {
38    Serial.print("No reading , err="); Serial.println(err);delay(1000);
39    return;
40  }
41  Serial.print("Readings: ");
42  Serial.print((int)temperature); Serial.print("  C, ");
43  Serial.print((int)humidity); Serial.println(" %");
44  delay(500);
45  if((int)humidity < 50){
46    digitalWrite(DHTpower, LOW);
47    delay(500);
48    Serial.println("Fan OFF");
49    delay(500);
50    digitalWrite(Fan, LOW);
51  }else{
52    if ((int)humidity > 58){
53      Serial.println("Humidity > 58%");
54      digitalWrite(DHTpower, LOW);
55      delay(500);
56      Serial.println("Fan  ON @ full speed");
57      delay(500);
58      digitalWrite(Fan, HIGH);
59    }else{
60      Serial.println("50% < Humidity < 58%");
61      digitalWrite(DHTpower,  LOW);
62      delay(500);
63      Serial.println("Fan ON @ low speed");
64      delay(500);
65      analogWrite(Fan, 150);
66    }
67  }
68 }
69

#include <SimpleDHT.h>

//Declaring digital pin no 2 as the dht11  data pin

int pinDHT11 = 2;
int DHTpower = 3;
int Fan = 13;
SimpleDHT11  dht11;

void setup() {
  pinMode(Fan, OUTPUT);
  pinMode(DHTpower, OUTPUT);
  digitalWrite(DHTpower, LOW);
  digitalWrite(Fan, LOW);
  Serial.begin(9600);   
}

void loop() {
  delay(1000);
  RHcheck();                        //check  Humidity Level
  delay(15000);                     //wait 15sec
  }


void  RHcheck() {                    //Check Humidity Level Function
  digitalWrite(DHTpower,  HIGH);     //On Humidity Sensor
  delay(5000);
  Serial.println("============  Check Humidity ===============");
  delay(1000);
  Serial.println("DHT11  readings...");
   
  byte temperature = 0;
  byte humidity = 0;
  int  err = SimpleDHTErrSuccess;

  //This bit will tell our Arduino what to do  if there is some sort of an error at getting readings from our sensor
  if ((err  = dht11.read(pinDHT11, &temperature, &humidity, NULL)) != SimpleDHTErrSuccess) {
    Serial.print("No reading , err="); Serial.println(err);delay(1000);
    return;
  }
  Serial.print("Readings: ");
  Serial.print((int)temperature); Serial.print("  C, ");
  Serial.print((int)humidity); Serial.println(" %");
  delay(500);
  if((int)humidity < 50){
    digitalWrite(DHTpower, LOW);
    delay(500);
    Serial.println("Fan OFF");
    delay(500);
    digitalWrite(Fan, LOW);
  }else{
    if ((int)humidity > 58){
      Serial.println("Humidity > 58%");
      digitalWrite(DHTpower, LOW);
      delay(500);
      Serial.println("Fan  ON @ full speed");
      delay(500);
      digitalWrite(Fan, HIGH);
    }else{
      Serial.println("50% < Humidity < 58%");
      digitalWrite(DHTpower,  LOW);
      delay(500);
      Serial.println("Fan ON @ low speed");
      delay(500);
      analogWrite(Fan, 150);
    }
  }
 }

Downloadable files

Wiring Schematic

Comments

Only logged in users can leave comments

ahhzen

2 years ago

i came across this post when i looking for a solution for my humidity sensor controlled exhaust fan. Basically i have a DHT11 hook up to arduino nano and a AC relay which will kick ON when humidity reach a certain threshold (which is static programmed). Under ideal situation it works - when it reaches the threshold humidity, then the fan kicked on and sensor/logic will check if the humidity stay above the threshold, if it fell below then the fan will stay on for last 5 mins until OFF, otherwise it keeps on refreshing the 5 mins ON until humidity falls. But the things is, humidity in bathroom fluctuates, causing the fan to not turn on at all (normal condition too dry) or it never switch off (normal condition too humid). any idea what sort of logic we can implement here?

LIMPINGLIM

2 years ago

I suppose you will need to monitor the humidity fluctuation in your bathroom before setting your thresholds for what to happen when? I have used a smart temperature/humidity sensor to keep track and see the trend before implementing this. good luck

Anonymous user

2 years ago

Would i be able to use a DHT 22 of a more accurate (well, wider sensor collection) for this project, just but editing the range in the code

Anonymous user

2 years ago

why there is an LDR in the image

LIMPINGLIM

2 years ago

J'ai mis a jour le code & retire les lignes contenant le LDR.

LIMPINGLIM

2 years ago

Wanted the fan to stop when the light in the bathroom is ON, but i found it a bit redundant since I could pre-set fan speeds for various humidity levels and even stop it if the humidity reaches an acceptable low level.

LIMPINGLIM

2 years ago

c'est dommage que le code ne marche pa pour toi, mais le code est exactement ce qui est charge sur mon Nano. Peu etre l'erreur est dans le circuit shematique.

LIMPINGLIM

2 years ago

I suggest you can watch the youtube video on DHT11. It will guide you step-by-step to set up the sensor.

Anonymous user

2 years ago

je n'ai pas de capteur de luminosité LDR! comme sur le fritzing!

Anonymous user

2 years ago

yes except that on the diagram it is A2, A3 whereas in Sketch it is D2, D3 and it works better

Anonymous user

2 years ago

super merci je vais voir! avec DHT22 Digital Temperature and Humidity Sensor AM2302 ca marche pareil? rien a modifier?

Anonymous user

2 years ago

tu peut faire un code sans LDR? ca me rendras bien service moi j'ai fait ca , c'est bon? `#include <SimpleDHT.h> //Declaring digital pin no 2 as the dht11 data pin int pinDHT11 = 2; int DHTpower = 3; int Fan = 13; SimpleDHT11 dht11; void setup() { pinMode(Fan, OUTPUT); pinMode(DHTpower, OUTPUT); digitalWrite(DHTpower, LOW); digitalWrite(Fan, LOW); Serial.begin(9600); } void loop() { delay(1000); RHcheck(); //check Humidity Level delay(15000); //wait 15sec } void RHcheck() { //Check Humidity Level Function digitalWrite(DHTpower, HIGH); //On Humidity Sensor delay(5000); Serial.println("============ Check Humidity ==============="); delay(1000); Serial.println("DHT11 readings..."); byte temperature = 0; byte humidity = 0; int err = SimpleDHTErrSuccess; //This bit will tell our Arduino what to do if there is some sort of an error at getting readings from our sensor if ((err = dht11.read(pinDHT11, &temperature, &humidity, NULL)) != SimpleDHTErrSuccess) { Serial.print("No reading , err="); Serial.println(err);delay(1000); return; } Serial.print("Readings: "); Serial.print((int)temperature); Serial.print(" C, "); Serial.print((int)humidity); Serial.println(" %"); delay(500); if((int)humidity < 50){ digitalWrite(DHTpower, LOW); delay(500); Serial.println("Fan OFF"); delay(500); digitalWrite(Fan, LOW); }else{ if ((int)humidity > 58){ Serial.println("Humidity > 58%"); digitalWrite(DHTpower, LOW); delay(500); Serial.println("Fan ON @ full speed"); delay(500); digitalWrite(Fan, HIGH); }else{ Serial.println("50% < Humidity < 58%"); digitalWrite(DHTpower, LOW); delay(500); Serial.println("Fan ON @ low speed"); delay(500); analogWrite(Fan, 200); } } }`

Anonymous user

2 years ago

Hello which library for DHT11?

Anonymous user

2 years ago

bien ,mais le code? le tuto est très bien , mais du coup inutilisable pour les novices comme moi! dommage c'est pas cool

Anonymous user

2 years ago

Hi there, thanks for sharing. I tried it out and was getting no reading from the DHT11 humidity sensor. In your diagram you have the humidity sensor connected to A2 and A3 (analog pins), was not getting the sensor reading, so I changed them to D2, D3 (digital). After these changes the DHT11 produces the temperature and humidity measurements correctly. In your code you have 3 states, full speed, low speed and off. In my testing high and low speed are not distinguishable. So I simplified the code to two states: on if humidity > 60% and off otherwise. Another thing I did differently, is I used two fans in tandem to increase the air flow.

LIMPINGLIM

2 years ago

good job with adjusting to suit your requirements.

kitkat2373

3 years ago

Would i be able to use a DHT 22 of a more accurate (well, wider sensor collection) for this project, just but editing the range in the code

Anonymous user

3 years ago

Hi can I get guidance about humidity controlled fan. There is a project here with deals with temperature controlled fan. I need to change temperature to humidity and simply apply these changes

menzellu

4 years ago

LIMPINGLIM

2 years ago

good job with adjusting to suit your requirements.

siva25143

6 years ago

why there is an LDR in the image

LIMPINGLIM

2 years ago

niermou

2 years ago

yes except that on the diagram it is A2, A3 whereas in Sketch it is D2, D3 and it works better

niermou

2 years ago

super merci je vais voir! avec DHT22 Digital Temperature and Humidity Sensor AM2302 ca marche pareil? rien a modifier?

niermou

2 years ago

niermou

2 years ago

je n'ai pas de capteur de luminosité LDR! comme sur le fritzing!

niermou

2 years ago

Hello which library for DHT11?

Anonymous user

2 years ago

bien ,mais le code? le tuto est très bien , mais du coup inutilisable pour les novices comme moi! dommage c'est pas cool

LIMPINGLIM

2 years ago

c'est dommage que le code ne marche pa pour toi, mais le code est exactement ce qui est charge sur mon Nano. Peu etre l'erreur est dans le circuit shematique.

LIMPINGLIM

2 years ago

J'ai mis a jour le code & retire les lignes contenant le LDR.

LIMPINGLIM

2 years ago

I suggest you can watch the youtube video on DHT11. It will guide you step-by-step to set up the sensor.

LIMPINGLIM

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5 Projects

Intro

Components and supplies

Tools and machines

Project description

Code

Downloadable files