Fire!Posted: April 23, 2013
Well of course there’s fire in the burner that’s how it works. After today however the Arduino should be able to sense the fire since I added a photo resistor, commonly known as a flame sensor, bought at a furnace supply store. With the Arduino’s ability to sense flame, the addition of automatic self starting should be enabled. The ability to determine if fuel is building up should also add safety to an already proven safe unit.
The sensor I obtained is a flame sensor used in a normal oil or gas fired burner. The flame sensor allows me to sense the light corresponding to a fire currently burning. The sensor cannot determine if the fire went out or if the flame sensor can no longer see it but functionally it makes no difference to me. I am interested in either condition and the response is the same to both conditions, turn off the fuel feed. If the fire went out, no need to keep feeding fuel, that will simply clog the feed chute and make a mess. If the fuel has backed up the feed chute so much as to shield the flame sensor, there is excess fuel, turn off the fuel feed. Physically the sensor is mounted to “look” through the back of the feed slide. This positions was chosen purposefully to determine if fuel was backing up.
Because the flame sensor is a resistor, I am using a voltage divider circuit to measure the voltage and then using the software to check the voltage with a if – then statement. The software determines if the voltage is high enough to indicate flame or too low indicating dark. I have been recording various sensor data to the micro SD over the heating season, so I will record the voltage overnight and we can see the range of data tomorrow. If anything this should be a good time of year for the test since the fire is needed to maintain the temperature in the building, it is mid 30’s F here today, but the fire is not required to be too vigorous since the temperature is not extremely cold.
Pictures and data to follow.