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Oil furnace troubleshoot, no oil to burner
If your burner motor will start but not burn and there is no indication of a fog in the combustion chamber, we must look to the oil supply.
Is the tank empty? All oil tanks should have some way to gauge the amount of oil in the tank. Either a gauge mounted on the top of the tank if it is inside or above ground, or a graduated stick if the tank is in the ground.
If you have oil, did you run out of oil before you filled it? If so then you probably have air in the oil line. The unit must be bled. Note: if the system is a 2 pipe, the pump may not have a bleeder.
Is the tank empty? All oil tanks should have some way to gauge the amount of oil in the tank. Either a gauge mounted on the top of the tank if it is inside or above ground, or a graduated stick if the tank is in the ground.
If you have oil, did you run out of oil before you filled it? If so then you probably have air in the oil line. The unit must be bled. Note: if the system is a 2 pipe, the pump may not have a bleeder.
Bleeding the oil pump.
To the left is a close up of an oil pump showing the bleeder valve at the bottom of the pic.
Attach a 1/4" clear flexible hose to the end and run to a coffee can. Use a 3/8" end wrench on the valve. Reset the primary control. When the motor starts, open the valve about 1/3 turn. If clear oil comes out and the burner does not light, the problem is probably with the nozzle. If air and perhaps foamed oil comes out, leave the bleed open until the oil is clear. The burner should come on. If the primary control shuts off the burner, shut off the bleed valve (if you leave it open, air will enter the line) wait about 5 minutes and reset.
If no air or oil comes out after 2-3 resets, oil is not available.
This could be a plugged oil filter, plugged oil line, plugged pump screen, pump failure or coupling failure or an air leak in the oil line.
Lets start with the oil filter.
Attach a 1/4" clear flexible hose to the end and run to a coffee can. Use a 3/8" end wrench on the valve. Reset the primary control. When the motor starts, open the valve about 1/3 turn. If clear oil comes out and the burner does not light, the problem is probably with the nozzle. If air and perhaps foamed oil comes out, leave the bleed open until the oil is clear. The burner should come on. If the primary control shuts off the burner, shut off the bleed valve (if you leave it open, air will enter the line) wait about 5 minutes and reset.
If no air or oil comes out after 2-3 resets, oil is not available.
This could be a plugged oil filter, plugged oil line, plugged pump screen, pump failure or coupling failure or an air leak in the oil line.
Lets start with the oil filter.
The oil shut off valve
This valve is placed between the oil tank and the filter. The valve handle pulls up the shaft in the middle to open the valve. It is made of a low temperature solder that melts and closes the valve with spring pressure when there is a fire. When closed, the handle should be loose.
The oil filter element
This or something similar to it should be inside. If it has not been replaced for several years, it is probably plugged. The canister should be cleaned with strong detergent and hot water. Cleanliness is very important in all this work. Replace all gaskets with new ones from the filter element kit. When the filter is replaced, the canister should be bled. The small screw at the outlet side should be loosened with the valve open and bled until oil comes out. Wipe down the entire canister with a rag. Replace the newspaper with a clean one. The filter should be checked later for oil drips. This filter should be replaced every heating season.
Although this still seems to be the standard for the industry, this thing is from the dark ages. There are throw away spin on filters that are far superior like the one below.
Although this still seems to be the standard for the industry, this thing is from the dark ages. There are throw away spin on filters that are far superior like the one below.
Oil test kit
If oil is available through the filter you could have a plugged line or an air leak. Loosen the 3/8" line coming into the pump. If oil comes out, the line is clear, however there could be a suction leak.
A kit like the one on left, can be installed in the inlet line with a tee to see if it holds a vacuum. The vacuum test is a hard one to do effectively and any fittings installed to adapt to the gauge must be leak tight.
Yes, its starting to get complicated You can drop out at any time and call a professional.
If you believe you have oil, then the problem is in the pump or the drive.
A kit like the one on left, can be installed in the inlet line with a tee to see if it holds a vacuum. The vacuum test is a hard one to do effectively and any fittings installed to adapt to the gauge must be leak tight.
Yes, its starting to get complicated You can drop out at any time and call a professional.
If you believe you have oil, then the problem is in the pump or the drive.
A look at a pump and screen
If oil still is not available, check the pump screen. Remove the pump cover and check the screen. Not all pumps have a screen. Some have a chopper that is supposed to break up contaminants. The pump below has failed. The screen was not completely plugged however there was water in the oil and it locked up the pump. If the burner has not been recently serviced, pull the cover and check the screen.
These are drive couplers. They are mounted between the motor and the pump shaft. These can fail and not drive the pump. The pump must be removed to check the coupler.
While the pump is out, check the shaft of the pump. It should move with some resistance. Sometimes the pump will lock up and damage the coupler.
This problem is not obvious from looking at the burner run. The pump must be removed to check this.
Many pumps have been replaced when the coupler was at fault. This is a cheap fix compared to an expensive fix.
If all of these fail, the pump is at fault.
While the pump is out, check the shaft of the pump. It should move with some resistance. Sometimes the pump will lock up and damage the coupler.
This problem is not obvious from looking at the burner run. The pump must be removed to check this.
Many pumps have been replaced when the coupler was at fault. This is a cheap fix compared to an expensive fix.
If all of these fail, the pump is at fault.