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Preventing Service Calls
This guide is not a replacement for your owner’s manual. If at anytime you feel uncomfortable with what you are doing, or are unsure of how to put things back together, it is time to call a service technician. Be sure not to reset the primary control too many times (3 or more without any ignition).
If you have recently run out of oil or cleaned your oil filter(s), refer to your owner’s manual for oil pump priming.
Understanding the Primary Control
The primary control on a waste oil furnace is a safety feature to prevent the furnace from running when there is no flame. The only reason you will have to push the reset button is due to the furnace not seeing a flame for a period of 15 seconds. If you have had to reset your furnace, understanding that fact will give you a place to start troubleshooting from.
The primary control uses a cad cell eye to see the presence of the flame. The eye translates the brightness of the flame into a resistance that lets the control know there is a flame. Sometimes the eye will become dirty, and although there is a bright flame inside the chamber, the control does not see it. The brighter the flame, the greater the ohm reading, therefore a bright flame is the best.
Many different reasons will cause a loss of flame, for example low oil pressure, plugged nozzle, insufficient combustion air, faulty igniter, dirty electrodes, etc. It is always a good idea to try a few easy things to be sure you really need a service call.
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Adjusting the flame
It is always important to check the flame inside your furnace to make sure it is burning properly. On most furnaces, there are three things you can adjust; air pressure, oil pressure, and the air band. Some furnaces use a self-metering pump, and therefore you cannot adjust the oil pressure.
A proper flame should be bright in color, almost reaching the target wall, but not allowing the flames to touch the target wall. Every furnace has an oil and air pressure setting written on it, but realize that these are simply a ballpark number to work from. Throughout the year, these setting will probably need to be changed as you burn different oils, as ash build up occurs inside the chamber, and due to many other factors. You can view the flame through the view port, but it is important to wear safety glasses. Make minor adjustments to the settings until you get your desired flame.
Oil Pressure – In general, the oil pressure affects the size of the flame. An oil pressure that is low will give you a flame that is far too short. A high oil pressure will fill the chamber with flames, usually dark orange flames. (If you are not getting any oil pressure, or it is very sporadic, refer to your manual for priming the oil pump.)
Air Pressure – In general, air pressure affects the intensity of the flame. Air pressure set too low will create orange flames that are too wide. An air pressure set too high will cause the flame to form into a point at the end.
Air Band Setting – An air band setting that is not letting enough air in will cause dark orange flames throughout the chamber and cause the furnace to smoke.
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Cleaning the nozzle, retention head, and electrodes
The nozzle of a waste oil furnace is the smallest orifice the oil passes through. Debris can get past the filter and plug the nozzle.
The retention head is the part of the burner the spins air around the outside of the nozzle and has a significant effect on the flame quality. Overtime, if the furnace is not burning correctly, the retention head will build up the layer of carbon. This carbon will block the airflow from the blower, causing poor burn quality.
The final component is the electrode ends. The same carbon the builds up on the retention head can also effect the electrode ends. As more carbon builds up collects, the spark produced will grow weaker, eventually leading to a loss of flame.
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In order to get to nozzle, retention head, and electrode ends, you can follow these steps.
1. Turn the thermostat off.
2. Disconnect the yellow cord attached to the top of the burner.
3. Remove the nut that holds the burner shut. This can be done with a 9/16” wrench.
4. Swing the burner open slowly, careful not to hurt the oil line attached.
5. Once the burner is swung open, use a 5/8” socket to remove the nozzle.
6. Inspect the retention head and electrode ends to see if they will need to be cleaned.
7. Follow the nozzle cleaning instructions.
8. Install the clean nozzle.
9. Close the burner and tighten the nut back on.
10. Once the nut is on, reconnect the yellow cord.
11. Turn the thermostat back on and adjust the flame.
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Cleaning the nozzle
A waste oil furnace nozzle consists of three pieces. The head will unscrew from the stem, and the distributor sets inside the stem. Flush all three components out thoroughly with Brakleen or WD-40. Be sure that you can see clearly through the small orifice in the distributor. Reassemble the nozzle, but be sure to snug the stem and head back together, do not over tighten. Check the o-ring at the base of the stem for cuts or abrasions. Once everything is clean, check once again that you can clearly see through the nozzle. Sometimes the distributor will fall out of the stem as it is put back together, be careful this does not happen.
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