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You’re in the middle of a Frederick, Maryland, winter when your oil furnace runs out of fuel. If the oil furnace doesn’t kick back on after refilling the tank, you may need to bleed and restart the furnace manually. Before you spend a day freezing, you can try bleeding the furnace yourself.

Before You Begin: Be Careful and Take Precautions

The only type of furnace you can bleed and restart is an oil furnace. If you have a gas furnace, or you aren’t sure what kind of furnace you have, don’t try to bleed the furnace yourself. If at any point during the process you become unsure of what’s happening, stop, turn off the furnace, and call a professional.

You’re dealing with components that get extremely hot and that connect to electricity. It can be dangerous to work on a furnace by yourself. Bleeding the furnace shouldn’t put you in any danger, but it’s better to focus on your safety than to start a project you’re not sure about just because you want the furnace working again.

A homeowner can successfully learn to do a project such as bleeding and restarting an oil furnace, but you must be confident that you know what you’re doing. People who are experienced with such do-it-yourself projects will probably be able to bleed the furnace without too much of an issue. People who rarely do this kind of work around the house should let a professional handle it. You can always learn if you want to, but going at it alone the first time isn’t a good idea if you don’t know what’s going on.

Step 1: Fill the Fuel Tank

If you let your oil tank get too low, the furnace might shut off and stop producing heat. Your first step, of course, is to refill the fuel tank. Bleeding the furnace won’t help you at all if your tank is empty when you start the process.

Step 2: Hit the Reset Button

Once you’ve refilled your oil tank, your next step is to hit the reset button. The furnace should start working again on its own. Bleeding the fuel line isn’t necessary unless the furnace doesn’t restart once you’ve put more oil inside. Typically, the reason for bleeding the furnace has to do with fuel levels: If you let the oil completely run out, that’s when the furnace may need extra help starting up again. To prevent this problem, refill the tank before the oil gets extremely low. You’ll also keep yourself from freezing when the furnace shuts off.

Step 3: Turn off the Furnace

If hitting the reset button doesn’t work, you have to bleed the furnace to get it working again. Start by turning off the furnace. There should be a switch directly on your furnace for this. On many furnaces, the reset button automatically shuts them off, so you may not need to switch off your furnace manually. You’ll see a red light if your reset button has the furnace turned off already.

Step 4: Collect Your Tools

You’ll need an adjustable wrench or an Allen key to fit the bleeder valve. If you’re not sure which will fit your furnace, check your manual or bring both along and see which is appropriate. You also need flexible nylon tubing with a 1/4-inch diameter. A foot of tubing should do fine.

Finally, grab a container to catch the oil waste that is going to drain out of your furnace. An old bucket or coffee can will work. Put cat litter or sawdust in the container’s bottom if you don’t want oil to splash. Alternatively, grab an empty bottle, preferably at least 32 ounces. If you want to reuse the fuel you bleed into the container, make sure the container is clean and do not fill it with anything. You can then return the fuel to the furnace when you’re finished with the bleeding process, but only do so if the oil coming out is clean. If you end up with sludge, do not reuse it.

Don’t forget to bring an old towel with you for your hands. You may want to wear clothes you don’t mind getting dirty, since there’s a chance you’ll end up with oil somewhere on you.

Step 5: Find the Bleeder Valve

To find the bleeder valve, you’ll need to find the fuel pump. The fuel pump will have tubes going to it. The bleeder valve is going to be on one side of the fuel pump, and it’ll have a hex nut on it. The nut may be metal or it might be a rubber plug. Don’t panic if you don’t see it right away. It’s a little hidden on some furnaces.

Loosen the nut a little bit to ensure you can turn it at the proper moment. Then tighten it again, about a quarter turn, so oil doesn’t dribble out. Don’t unscrew the nut completely.

Step 6: Attach Nylon Tubing

Slide the tubing into the bleeder valve and position it so its other end rests inside your container. Not everyone puts tubing on his or her bleeder valve. Some individuals just let the fuel dribble straight out into a container. If you don’t have nylon tubing and you need your furnace to restart, go ahead and follow the rest of the steps without it. Just be aware that the oil may splash, and the process will be messier this way. Also, make sure your container is sitting directly beneath the valve so oil doesn’t get on the floor.

If you have a second person helping you, that person can hold the container directly beneath the valve to catch the oil and to lessen the chance it’ll splash.

Step 7: Turn on the Furnace and Unscrew the Valve

Next, turn on the furnace. Remember how you loosened the valve before, then tightened it just enough to be sure you could turn it again quickly? Now’s the time to loosen it. You’ll probably need less than one turn to get the oil flowing. Loosen the valve until oil and air start to come out. Let it drain until solid fuel comes out.

If nothing comes out of the valve, you may have to hit the reset button after you’ve flipped the on/off switch. If your furnace automatically shuts itself off with the reset button, you might have to give it a couple of tries. If the furnace doesn’t turn on, you’ll need to call in a professional technician to take a look. The problem might be a clog, a damaged fuel line, or a pump issue.

Step 8: Tighten the Valve

When the oil comes out in a steady stream, tighten the valve. At this point, the burner should turn on. You’ll know it when you hear it; this is the sound you associate with the furnace kicking on. If that happens, congratulations! You’ve successfully bled and restarted your furnace. Remove your tubing, clean up your container, and enjoy the warmth.

If the furnace’s burner doesn’t turn on after bleeding the oil the first time, try again. Start by loosening the bleeder valve and letting fuel come out. You can try this several times. However, if your furnace isn’t firing until you’ve done it numerous times, then you’ve got worn out parts and you need to call someone in to look at it. It shouldn’t take more than once or twice to bleed and restart your furnace when the furnace is in proper working order.

When All Else Fails: Call a Professional

Only a professional can accurately diagnose why your furnace isn’t starting. If at any point in the process of bleeding the furnace something seems strange or you lose confidence, it’s time to call a professional. Similarly, if the process doesn’t work, something else is wrong and you need a technician to examine the furnace. Even if bleeding the furnace does work, but you find you have to do it frequently, it’s probably time for a professional opinion.

Griffith Energy Services can repair your oil furnace and dispatch an emergency technician at any time. Call us at 888-474-3391 if you’re unable to bleed your furnace or if the bleeding process doesn’t solve your problems. We’re here to get your home warm and your family comfortable again.

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