Restart a Furnace After Running out of Oil

Did you run out of oil? If you're lucky, the furnace or boiler will restart on its own after your oil tank is filled. But, if it doesn't, here's how to get it going again.

Steps

 * 1) Try pressing the 'reset button' (usually red), on the furnace itself. If there are two copper lines coming from your oil tank the pump should bleed itself.

If it still doesn't start, look inside the furnace when you try to run it. If there is no spray of oil, you need to bleed the fuel line as described below. If there is a spray of oil, you have other problems.
 * 1) Gather the right tools: See 'Things You'll Need' below.
 * 2) Shut off the furnace.There should be a toggle switch on the furnace for this. If the reset button is keeping the furnace off already (e.g. a red light "on" near reset button) turning the furnace off again is not necessary.
 * 3) Locate the bleeder valve. It is on the side of the fuel pump, maybe at 4 or 8 o'clock position. The fuel pump, which the fuel lines leads to, is probably on the left side of the burner unit. The bleeder looks sort of like a grease fitting with hex shoulder on it, like a nut, and a 3/8 inch wrench might fit it.
 * 4) Attach a short section of 1/4" nylon tubing to the bleeder. The tubing should be long enough to extend into the oil catch bucket/can. While the tubing is attached to the bleeder, prepare the bleeder by loosening it with a wrench (CCW turn loosens it, similar to typical nut or bolt), and then lightly re-tighten. During this process you might hear a light air gurgle from the tubing and that is okay.
 * 5) Now you're ready for the final step: Turn on the furnace and then loosen the bleeder promptly. The tubing should spit fuel and air, then a constant stream of fuel. Let the fuel stream run a few seconds to ensure all the air is out of the line. It may be necessary to manually trigger the start mechanism with the reset button.(See Tips.)
 * 6) Tighten the bleeder, and the burner (furnace) should start. If not, repeat Step 7. Sometimes it takes a couple of tries.
 * 7) Once you are sure it is running, tighten the bleeder firmly with a wrench.
 * 8) If multiple attempts at restarting the burner fail, the burner may "lock out" the reset button. To reset the reset button, press the button for 35 seconds, then release.
 * 9) If the furnace still doesn't start, the oil filter may need to be bled. It is usually a black cannister with a red top. Loosen the 1/4 inch bolt on the top (not the big one in the middle) until you hear air seeping out. Tighten it back up when oil starts bubbling out.

Tips

 * When bleeding the line, let the liquid fuel come out for a short time to make sure all the sludge and/or air is out of the line. The amount depends on how long your fuel line is. Filling a 16oz cup works for a 6 foot fuel line.
 * Consider contacting an oil burner service company to replace the filter and nozzle, since running out of oil probably caused sludge from the bottom of your oil tank to get into the works.
 * The bled out oil can be poured back into the tank that stores the fuel oil.
 * Consider using a paper filter before putting back in tank if necessary
 * If you use a plastic container to catch the bled out fuel, you should remove it as soon as possible. Oil dissolves plastic, and the container will lose its integrity in anywhere from a few hours to a few days.
 * When it's running, the typical furnace will 'roar.' When it's not running, you'll hear nothing, or just an electronic whine.
 * To ensure the furnace is operating you should be able to view an orange glow or fire through the inspection port, located on the front of the furnace.
 * Depending on your furnace, #2 diesel fuel can work in a pinch if you need oil now and can't get a delivery. Depending on your usage about 5 gallons of diesel fuel will give you 5 running hours (about 1 day of use).
 * In some states heating oil is dyed red. No cause for alarm.
 * The process may seem daunting, but it can proceed relatively smoothly and without fuss.
 * Gloves recommended.
 * Diesel fuel sold at the gas station can substitute for heating oil until your delivery is made. They are nearly identical, but fuel exempt from road taxes is dyed red to identify it for legal purposes. You can also use off-road diesel, which is usually dyed red.  If you use automotive diesel for home heating, the fuel tax can be listed on federal and state taxes as an itemized deduction.

Warnings

 * You are playing with fire and fuel here, so be careful.
 * Not all furnaces are alike. This process only relates to single oil line applications. If you are at all unsure please call a qualified Burner Service Technician.
 * Make sure the wrench fits the bleeder properly. Don't use excessive force when loosening or tightening the bleeder. If you strip the bleeder, it could be quite expensive to have it drilled out!
 * If you aren't careful, it is possible to make a BIG mess. At a minimum, you WILL get oil on your hands.
 * Don't go wild on the reset button. Try it once or twice. If the furnace doesn't start, it probably won't start until you bleed the line. By resetting the furnace multiple times you run the risk of flooding the combustion chamber with fuel.
 * If you decide to temporarily use diesel fuel be aware that some grades of diesel are more easily ignitable than standard #2 heating oil/#2 diesel and could create a fire hazard.
 * If you decide to temporarily use diesel fuel be sure you put in enough to hold you over until the heating oil can be delivered. Repeatedly running out of fuel will pull more sludge into the burner and increase the possibility of the filters and nozzles to be replaced and/or cleaned.

Things You'll Need

 * A wide-mouth container to catch some waste oil in. A metal coffee can with some sand or cat litter in the bottom to prevent splashing works well. (if you plan on putting the bled oil back in the tank make sure you do not use sand or kitty litter in the can.)
 * 1/4" flexible tubing fit over the bleeder valve to direct smelly fuel to catch container. This will make the process tidy and keep fuel from splattering all around the furnace. Strongly recommended but fuel line can be bled without it.
 * A wrench of the appropriate size, usually 3/8ths. A short handled fixed size wrench is best. You may be able to use an adjustable, but often there isn't enough room around the bleeder for all the excess metal.
 * Something to wipe your hands and tools with when you are done (you WILL get oil on your hands IF you don't use tubing on the bleeder valve).
 * A small bag of clay cat litter (not the clumping stuff). This is optional, but can be used to absorb any oil that may spill on the floor.

Related Tips and Steps

 * How to Remove a Stuck GE Washer Agitator
 * How to Flush a Water Heater
 * How to Replace Shut off Valves
 * How to Prevent Frozen Water Pipes
 * How to Repair a Clogged Ice Maker