How To Bleed Your Oil Furnace
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How To Bleed Your Oil Furnace

You can save yourself $25 to $75 by bleeding your own oil burner lines. Even a first timer can do this in safely in 10 minutes or less.

The heating season is upon us up here on Walch's mountain. I still heat my beautiful old 2 and ½ story farm house with an old wood fired hot-air furnace, but most of my friends up here heat theirs with oil. Most of them have tanks that hold enough oil to see them through the heating season with their tanks running dry just as the warm weather returns. The two oil companies that deliver up here on my mountain will bleed the furnaces for their customers for a charge of $75. now that's a real racket, charging $75 for something that takes 10 minutes or less to accomplish. The dozen or so families that live up here with me have learned to call me instead who does it for free because they are my neighbors. Well, that the way of country folk. Last night the mercury plummeted down into the twenties and my telephone started ringing right after dinner. I had all of them up and running in less than two hours, but it gave me the idea for this article. Many of you may not have a friend who will come to your rescue and there's no need to pay through the nose for something you can do yourself.

Self bleeding furnaces

Modern oil furnaces are designed to bleed their own lines. If your furnaces has two oil lines running from the tank to pump, your furnace is designed to bleed it's own lines. Unfortunately, things don't always work in real life the way they are suppose to. Manually bleeding an oil furnace is easy, but we try the self bleeding approach first. Here's how.

  • Turn on the safety shut-off switch.
  • Press the furnace reset button. The reset button is usually a red button located on or near the pump.
  • The furnace should start. If it doesn't start and you don't see a spray of oil when looking through the inspection port, you will have to manually bleed the pump.

Safety should be your first concern.

If you follow the instructions I’m going to give you here, this is a safe operation. Never-the-less, you should have a fire extinguisher close at hand in case an accident should happen. You are working with combustible fuel oil and fire, so always be prepared for the unthinkable.

What you will need to bleed your furnace's pump.

  • ¼ inch diameter, 18 inch long piece of clear plastic tubing.
  • A large glass jar or metal can.
  • An open-end wrench. 3/8 inch is the most common size used.
  • Clay, non-clumping type, kitty litter.
  • Shop rags.

Bleeding the lines.

  • Put some sand or kitty litter in the bottom of the glass jar or can to make it less likely to tip over during the bleeding process.
  • Turn off the furnace's safety switch.
  • Place one end of the ¼ inch clear plastic tube in the container and work the other end on the bleeder fitting. The bleeder fitting looks a little like an old fashioned grease fitting. You can use any type of ¼ inch flexible tubing, but the clear plastic makes it easier to see when you have all the air out of the lines. This will be a tight fit.
  • Turn the room thermostat to 75 or 80 degrees.
  • Turn on the furnace safety switch.
  • Turn the bleeder ¼ turn counter clockwise to open it.
  • Press the reset button.
  • Watch the oil flowing through the plastic tubing. At first, the stream of oil will be broken by air bubbles. When all the air bubbles are gone, and a steady stream of oil is flowing through the tubing, close the bleeder fitting snugly. Depending on how much air is in the lines, it may take up to 16 ounces of oil for every six feet of oil line length to clear them.
  • Clean up any oil that may have spilled on the floor using the clay, non-clumping kitty litter.

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Comments (10)

Very useful Jerry, thank you.

Tweeted,digg & stumbled for reference.

This is another detailed instructional article, Jerry. Thanks for the share.

Great information on How To Bleed Your Oil Furnace. Keep up the great work. Darrell


Great info about how to blend oil furnace. Thank's a lot.

Oil Funace

Nice info and costless for blend oil furnace. Keep up the great work. Darrell


This is another detailed instructional article. Great information on How To Bleed Your Oil Furnace. Very useful Jerry, thank you.


What happens if you dont bleed your lines enough? Everythings seems to be working but the upstairs smells a little like oil??


If you don't bleed the lines enough the burner will cutin and out instead of remain on steadily until the thermostat shuts the furnace off. If you can smell oil in your home the burner is not burning all the oil completely and some of that unburned oil is getting blown into the heating ducts. Another possible cause is a problem with the furnace vent pipe. If there is a problem with the venting system, you have an even more dangerous situation on your hands because carbon monioxide will build up in your home because it will not be vented to outdoors. There could also be an oil leak in either the feed or return lines, which is fire hazard. You need to have this checked out without delay.

Thank you for the detailed information. I really appreciate you sharing your expertise.