ESP12F, cant get a relay to work with data from dht11 - arduino

Question

i've been trying to build a system that detects in one room of the house the temperature using an esp8266 and a dht11 sensor, this esp sends the data to a webserver while the ESP12F grabs this data and should turn the relay on when a certain value is reached, however i can't get the relay to work, as soon as i upload the code, the led on the module turns but not at its full power, i tried with another code to see if it was just a faulty relay, but it works perfectly with the same connections. The code from the client side of the system is below:
#include "ESP8266WiFi.h"
#include "ESP8266HTTPClient.h"
#include "WiFiClient.h"
#include "ESP8266WiFiMulti.h"
ESP8266WiFiMulti WiFiMulti;
const char* ssid = "*******";
const char* password = "********";
//Your IP address or domain name with URL path
const char* serverNameTemp = "http://192.168.1.188/temperature";
const char* serverNameHumi = "http://192.168.1.188/humidity";
const char* serverNamePres = "http://192.168.1.188/pressure";
#include "Wire.h"
#include "Adafruit_GFX.h"
#include "Adafruit_SSD1306.h"
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
#define OLED_RESET -1 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
String temperature;
String humidity;
String pressure;
const int relay = 5;
float temp_int = temperature.toFloat();
unsigned long previousMillis = 0;
const long interval = 2000;
void setup() {
Serial.begin(115200);
Serial.println();
pinMode(relay,OUTPUT);
digitalWrite(relay,LOW);
// Address 0x3C for 128x64, you might need to change this value (use an I2C scanner)
if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
Serial.println(F("SSD1306 allocation failed"));
for(;;); // Don't proceed, loop forever
}
display.clearDisplay();
display.setTextColor(WHITE);
int int_temp = temperature.toFloat();
WiFi.mode(WIFI_STA);
WiFiMulti.addAP(ssid, password);
while((WiFiMulti.run() == WL_CONNECTED)) {
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.println("Connected to WiFi");
}
void loop() {
unsigned long currentMillis = millis();
if(currentMillis - previousMillis >= interval) {
// Check WiFi connection status
if ((WiFiMulti.run() == WL_CONNECTED)) {
int int_temp = temperature.toFloat();
temperature = httpGETRequest(serverNameTemp);
humidity = httpGETRequest(serverNameHumi);
pressure = httpGETRequest(serverNamePres);
if(int_temp < 26){
digitalWrite(relay,LOW);
}
else if (int_temp > 26){
digitalWrite(relay,HIGH);
}
Serial.println("Temperature: " + temperature + " *C - Humidity: " + humidity + " % - Pressure: " + pressure + " hPa");
Serial.println(int_temp);
Serial.println(temperature.toFloat());
display.clearDisplay();
// display temperature
display.setTextSize(2);
display.setCursor(0,0);
display.print("T: ");
display.print(temperature);
display.print(" ");
display.setTextSize(1);
display.cp437(true);
display.write(248);
display.setTextSize(2);
display.print("C");
// display humidity
display.setTextSize(2);
display.setCursor(0, 25);
display.print("H: ");
display.print(humidity);
display.print(" %");
// display pressure
display.setTextSize(2);
display.setCursor(0, 50);
display.print("P:");
display.print(pressure);
display.setTextSize(1);
display.setCursor(110, 56);
display.print("hPa");
display.display();
// save the last HTTP GET Request
previousMillis = currentMillis;
}
else {
Serial.println("WiFi Disconnected");
}
}
}
String httpGETRequest(const char* serverName) {
WiFiClient client;
HTTPClient http;
// Your IP address with path or Domain name with URL path
http.begin(client, serverName);
// Send HTTP POST request
int httpResponseCode = http.GET();
String payload = "--";
if (httpResponseCode>0) {
Serial.print("HTTP Response code: ");
Serial.println(httpResponseCode);
payload = http.getString();
}
else {
Serial.print("Error code: ");
Serial.println(httpResponseCode);
}
// Free resources
http.end();
return payload;
}