EcoRenovator  

Go Back   EcoRenovator > Improvements > Appliances & Gadgets
Advanced Search
 


Blog 60+ Home Energy Saving Tips Recent Posts Search Today's Posts Mark Forums Read


Reply
 
Thread Tools Display Modes
Old 12-29-14, 10:10 AM   #61
Daox
Administrator
 
Daox's Avatar
 
Join Date: Aug 2008
Location: Germantown, WI
Posts: 5,525
Thanks: 1,162
Thanked 374 Times in 305 Posts
Default

I find it odd that your sensors are so far off. When I tested mine, they were pretty accurate.

__________________
Current project -
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
&
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Daox is offline   Reply With Quote
Old 12-29-14, 09:08 PM   #62
Mikesolar
Master EcoRenovator
 
Mikesolar's Avatar
 
Join Date: Aug 2012
Location: Toronto
Posts: 958
Thanks: 40
Thanked 158 Times in 150 Posts
Default

You might want to increase the turn on dT to about 6-8C. Turn off can be 4c. The reason is quite simple, the panel will start at a perceived temp but within in few seconds of flow that temp will change, either up or down depending on conditions. With a small dT, the pump will be on and off too often and it will be hard to get a constant flow.
Mikesolar is offline   Reply With Quote
Old 01-01-15, 05:42 AM   #63
nkuck
Lurking Renovator
 
Join Date: Dec 2014
Location: USA
Posts: 13
Thanks: 1
Thanked 0 Times in 0 Posts
Default

What I ended up doing is modifying the readings:
Ssensor += analogRead(SsensorPin) / 2.5;
and the temps are where I would expect them to be.
nkuck is offline   Reply With Quote
Old 01-01-15, 10:31 AM   #64
Daox
Administrator
 
Daox's Avatar
 
Join Date: Aug 2008
Location: Germantown, WI
Posts: 5,525
Thanks: 1,162
Thanked 374 Times in 305 Posts
Default

nkuck, I would suggest a static offset to correct things. Say your sensor reading is off by 10F, just add 10 to the Ssensor variable. With the current way you're doing it, it may read normal at the temperatures you're reading, but as you get farther from those temperatures your readings will get farther and farther off.

Here is what I would do:

Code:
// read sensor inputs, convert to degrees, and assign to variables
  Counter = 0;
  while(Counter < SensorReadings) {
    Ssensor += analogRead(SsensorPin) / 2;
    Tsensor += analogRead(TsensorPin) / 2;
    Counter++;
    digitalWrite(ledPin, HIGH);
    Delay(250);
    digitalWrite(ledPin, LOW);
    Delay(250);
  }


  // calculate average temp from sensor inputs
  Ssensor = Ssensor / SensorReadings;
  Tsensor = Tsensor / SensorReadings;

  // calibrate sensors
  Ssensor = Ssensor + 10;
  Tsensor = Tsensor + 13;

This is just an example. Replace the 10 and 13 with whatever the readings seem to be off by. This will create a linear offset that won't drift as the temperature varies.
__________________
Current project -
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
&
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Daox is offline   Reply With Quote
Old 01-01-15, 10:48 AM   #65
nkuck
Lurking Renovator
 
Join Date: Dec 2014
Location: USA
Posts: 13
Thanks: 1
Thanked 0 Times in 0 Posts
Default

Good idea. Thank you. Happy New Year.
nkuck is offline   Reply With Quote
Old 01-02-15, 07:58 AM   #66
nkuck
Lurking Renovator
 
Join Date: Dec 2014
Location: USA
Posts: 13
Thanks: 1
Thanked 0 Times in 0 Posts
Default

Here is my current sketch and most everything is working fine, except:
When I activate the external relay (a Reeed Relay Shield) both the Ssensor and the Tsensor temps rise 10-20 degrees and stay high until the relay disengages. Could there be some internal heat being generated by the load? Doesn't seem like it would be high enough to make a difference. Thanks for all of your support and patience.

// Pins
int SsensorPin = 4; // the pin to read solar panel temperature
int TsensorPin = 5; // the pin to read water tank temperature
int RelayPin = 7; // the pin to control the pump relay
int ledPin = 13; // led pin to verify relay on condition
int vref;

// Variables
int Ssensor = 0; // holds the value from SsensorPin
int SensorOnDiff = 0; // holds the Ssensor value plus on differential (OnDiff)
int SensorOffDiff = 0; // holds the Ssensor value plus off differential (OffDiff)
int Tsensor = 0; // holds the value from TsensorPin
int SensorReadings = 5; // number of sensor readings to take
int Counter = 0; // sensor readings loop counter
int OnDiff = 4; // temp diff that must exist to turn pump on (dec F)
int OffDiff = 2; // temp diff that must exist to turn pump off (deg F)

// initialize the library with the numbers of the interface pins

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup()
{
pinMode(SsensorPin, INPUT);
pinMode(TsensorPin, INPUT);
pinMode(RelayPin, OUTPUT);
pinMode(ledPin, OUTPUT);

Serial.begin(9600);

digitalWrite(RelayPin, LOW); // turn pump off

// set up the LCD's number of columns and rows:
lcd.begin(16,2);
}
void loop()
{

// read sensor inputs, convert to degrees, and assign to variables
Counter = 0;
while(Counter < SensorReadings)
{
Ssensor += analogRead(SsensorPin) / 2;
delay(50);
Tsensor += analogRead(TsensorPin) / 2;
delay(50);
Counter++;
digitalWrite(ledPin, LOW);
delay(250);
}
// calculate average temp from sensor inputs
//Ssensor = (500.0 * Ssensor / SensorReadings) / 1024;
// Tsensor = (500.0 * Tsensor / SensorReadings) / 1024;

Ssensor = Ssensor / SensorReadings;
Tsensor = Tsensor / SensorReadings;

// calibrate sensors
Ssensor = Ssensor - 15;
Tsensor = Tsensor - 16;

// add temperature difference to Ssensor value
SensorOnDiff = Ssensor - OnDiff;
SensorOffDiff = Ssensor - OffDiff;

// Print temps to the Computer
Serial.print("Solar temp= ");
Serial.println(Ssensor);
Serial.print("Tank temp= ");
Serial.println(Tsensor);

// Print temps to the LCD
// set the cursor to column 0, line 1
// (note: line 1 is the second row, since counting begins with 0):
lcd.setCursor(0, 0);
lcd.print("Solar=");
lcd.print(Ssensor);
delay(50);
lcd.print((char) 223);
lcd.print("F");
lcd.setCursor(12, 0);
lcd.print("Pump");

lcd.setCursor(0, 1);
lcd.print("Tank =");
lcd.print(Tsensor);
delay(50);
lcd.print((char) 223);
lcd.print("F");

// if heat source is warmer than heat sink sensor, enable relay
if (SensorOnDiff > Tsensor)
{
digitalWrite(RelayPin, HIGH);
digitalWrite(ledPin, HIGH);
lcd.setCursor(13, 1);
lcd.print("ON ");
delay(500);
}
// if heat source sensor is cooler than heat sink sensor, disable relay
if (SensorOffDiff < Tsensor) {
digitalWrite(RelayPin, LOW);
digitalWrite(ledPin, LOW);
lcd.setCursor(13, 1);
lcd.print("OFF");
delay(500);
}
}
nkuck is offline   Reply With Quote
Old 01-02-15, 08:58 PM   #67
Daox
Administrator
 
Daox's Avatar
 
Join Date: Aug 2008
Location: Germantown, WI
Posts: 5,525
Thanks: 1,162
Thanked 374 Times in 305 Posts
Default

That sounds like a very odd problem. It also sounds more like a wiring problem. Can you describe your setup and possibly provide a wiring diagram?
__________________
Current project -
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
&
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Daox is offline   Reply With Quote
Old 01-04-15, 06:54 PM   #68
nkuck
Lurking Renovator
 
Join Date: Dec 2014
Location: USA
Posts: 13
Thanks: 1
Thanked 0 Times in 0 Posts
Default

I don't have a drawing worked up, but I'm thinking...is there a possibility that the way I am using the digital pins and analog pins, with the serial and lcd display, that there is a conflict going on? The wiring is OK per the pins that I have selected. Thank you for looking at this.
nkuck is offline   Reply With Quote
Old 01-05-15, 02:34 AM   #69
SDMCF
Apprentice EcoRenovator
 
Join Date: Jul 2014
Location: Finland
Posts: 125
Thanks: 5
Thanked 35 Times in 34 Posts
Default

Quote:
Originally Posted by nkuck View Post
// Pins
int SsensorPin = 4; // the pin to read solar panel temperature
int TsensorPin = 5; // the pin to read water tank temperature

...

// initialize the library with the numbers of the interface pins

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
I am no expert, but this code looks odd to me. It seems you are using pins 4 and 5 for the sensors and for the LCD.
Have I read that correctly?
If so, are you sure you can do that?
Do you really have it wired up that way?
SDMCF is offline   Reply With Quote
Old 01-05-15, 04:37 AM   #70
nkuck
Lurking Renovator
 
Join Date: Dec 2014
Location: USA
Posts: 13
Thanks: 1
Thanked 0 Times in 0 Posts
Default

That's precisely my question. I am tryi g to use the analog pins 4 & 5 for the temp inputs amd the digitals for the lcd, but I am not sure if I am setting them up properly and calling them correctly. That may be the reason for my weird readings ��

nkuck is offline   Reply With Quote
Reply


Tags
arduino, controller, differential, thermal

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 05:39 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Ad Management by RedTyger
Inactive Reminders By Icora Web Design