Another common problem that happens with oil burners in furnaces is a defective protectorelay.
What exactly does it do? The oil that comes out of the burner nozzle turns into a fog. This fog is is ignited with an electric spark that is generated from the transformer.
This spark bounces across electrodes placed in front of the nozzle and is blown into the oil spray a blast of air. The current generated by the fire on the window of the cell is conducted to a protecto-relay and keeps the relay engaged and the burner motor running.
If the fire goes out, the burner will shut down to prevent a build up of un-ignited fuel which has the possibility to create a very explosive condition. This device, also known as a burner relay, also has another function. It has a transformer built into it that transmits a 24 volt current to the thermostat which signals for more heat.
This is a very important item on your boiler or furnace and it has the ability to give you a lot of problems. At times for no reason whatsoever it can lock out which in effect shuts down your heat.
If this tends to happen a lot then you need to look into getting a professional to install a brand new protectorelay on your oil burner. This safety device works great when its working well and can cause major headaches when it is not.
Here are some instructions if you do decide to change it yourself.
Before you rip out the the relay, do yourself a favor first, check or change the cad cell. This is the device the detects the fire when your oil burner lights and tells the protectorelay to keep the burner running. When the cad cell becomes defective it does not send a strong enough signal to the relay to do this.
Once you have done this you can begin fixing your problem. Its not very difficult if you know what you are doing. It will take a matter of minutes.
Caution- turn the power completely off! Make sure of this so that you do not get shocked!
Loosen the two screws on the junction box and slide off the relay. Take a marker and mark the wires and the connection for each one of them. This will make putting the new one on a breeze because you will know exactly how to get the wiring back correctly. Some people even like to have the new protectorelay on hand and connect one wire at a time.
Reconnect the wires to the new control and you are about done. Put it back on the junction box and turn back on the power. Your oil burner in your furnace will now be running like it should.