Heating oil filter at the oil burner (C) Daniel Friedman How to Change the Oil Filter Cartridge on an Oil Burner

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Heating oil filter change:

Step by Step Oil Filter Change Procedure. This article series describes the installation, use, maintenance, and repair of oil filters used on oil-fired boilers, furnaces, and water heaters.

We discuss tracking down air and oil leaks at or near the oil filter canister and we describe proper oil filter location and problems to check for during oil filter cartridge changes.

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How to Change a Heating Oil Filter: Step by Step Procedure for Servicing the Oil Burner Oil Filter Cartridge

Oil filter cartridgeThe oil filter cartridge should be changed during oil heating equipment annual cleaning, service, and tune-up

. You should not have to change oil filter cartridges more often. If the cartridge clogs and leads to service calls or heat loss between annual service calls then we suspect the oil tank is contaminated with water or sludge - problems that need to be corrected at the oil tank.

[Click to enlarge any image]

The procedure for changing the oil filter cartridge is simple, but if it's performed improperly you could be left with no heat.

  1. Turn off electrical power to the heating appliance (boiler, furnace, water heater) whose oil filter is to be serviced
  2. Place a catch pan or basin below the canister to catch any oil spills or drips
  3. Turn off oil supply to the system by closing the fire safety valve that should be located between the oil filter and the oil feeder supply line from the oil tank. If the valve is a fire-safety-valve it includes a spring-loaded fusible link that closes the valve in case of fire. These valves work in the opposite direction from conventional plumbing valves. Screwing the valve top out or counter-clockwise closes the valve.
  4. Remove the oil filter canister base: For oil canisters with a center bolt such as the unit shown just above, loosen the bolt found in the center of the canister top and remove it. Take care not to lose the fiber washer that seals the canister bolt and take care not to lose or damage the O-ring that seals the canister base to the canister lid.

    Watch out: for oil filter canisters that are supported only by oil piping you'll be wise to support the canister lid or assembly whenever loosening parts. Otherwise you may twist, bend, and cause leaks in the oil supply piping. Use two wrenches to loosen or tighten the canister bolt: one on the bolt itself and one on the rectangular projection at the canister lid inlet or outlet side. Leaks here cause oil burner startup bang, puffbacks, loss of heat. Details are

    Watch out: the canister bottom may simply fall off at this point - you will want to catch it to avoid unnecessary oil spillage. Other oil filter canisters may lack the bolt and may have to be opened by un-screwing the canister base from the top.
  5. Remove dirty oil filter cartridge and place it in a plastic bag for suitable disposal along with any waste oil and sludge collected during this process.
  6. Clean the oil filter canister: remove any oil sludge, dirt, debris from the bottom of the oil filter canister base.

    Check for water contamination in the oil tank when changing the oil filter cartridge. Water contamination in oil tanks can be detected by examining the bottom of the oil filter canister. If you see actual water, or more likely rusty red sludge, that may be good evidence that water from the oil storage tank has been trapped in and rested in the bottom of the oil filter canister. For details
  7. Heating oil filter cartridge & gaskets (C) D Friedman
  8. Insert the new oil filter cartridge into the canister base. If your oil filter replacement package included a new O-ring for the canister base-to-lid seal, use it to replace the old O-ring that we told you to save in step 4.

    Our photo (left) shows a typical heating oil canister filter and the gaskets that are packaged with it. The filter shown at the left of our photo is in most canisters inserted with the screen up where it fits into a recess in the canister lid.

    That large round gasket is used to seal between the oil filter canister top and the base.

    Inside the large gasket we show two smaller ones. The smallest red gasket is used under the air bleed screw found on the top of the oil canister, and the larger red gasket is used under the mounting bolt that secures the oil filter canister base to its top.
  9. Heating oil filter canister reassembly: Carefully, keeping the filter cartridge centered in the canister base, place the canister base up under the canister lid in proper position.
  10. Replace the heating oil filter canister mounting bolt (and a new fiber washer if one was provided in your oil filter cartridge kit) to secure the canister base to the lid, tightening the bolt securely but not so tight as to damage threads. If your canister does not use a center bolt the base usually assembles by screwing in in place into the lid.

    Watch out: as we warned above, for oil filter canisters that are supported only by oil piping you'll be wise to support the canister lid or assembly whenever tightening parts. Otherwise you may twist, bend, and cause leaks in the oil supply piping. Details are
    at OIL LINE LEAKS - Oil Line leaks found.
  11. Open the oil supply valve to allow oil to enter the oil filter canister and then
  12. Bleed air from the oil filter canister using the procedure we detail just below
    at OIL FILTER AIR BLEED STEPS. Use a new fiber washer for the air bleeder screw if one was provided in your heating oil filter kit. Remember to close the bleed screw at the end of this procedure.
  13. Turn on electrical power to the heating appliance and
  14. Allow the oil burner to run to assure that the system starts and runs properly.
  15. Leak check: Check the oil piping (OIL LINE PIPING LEAKS) and the oil filter canister top, center bolt and air bleeder bolt and any nearby fittings for evidence of oil leaks. Details of just where leaks occur at or around heating oil filters are
  16. Dispose of heating oil: if you collected heating oil in your drip pan and see that the oil is clean you can simply pour it into your oil tank through the filler pipe. Don't pour sludge, dirt, debris into the tank however.

Bleed Air from the Heating Oil Filter Canister after an Oil Filter Cartridge Change

Oil canister air bleed screw (C) D Friedman & E.S. Once you have installed the new oil filter cartridge inside the canister you will need to bleed air out of the canister and filter before restoring the system to service. If your heating oil tank is at a level higher than that of the filter itself this is an easy task as oil may flow from the tank through the filter without even having to run the oil burner.

But most heating service techs simply turn up the heat to cause the oil burner to turn on, bypassing the cad cell relay if necessary to keep the burner running even before actual flame ignition.

Watch out: do not try this burner-on method if you don't have the necessary training: pouring a dose of un-burned oil into the combustion chamber is dangerous and risks a puffback.

With your catch-basin below the oil filter canister, simply loosen or remove the air bleeder screw located on the canister top just before the canister outlet fitting (red arrow in our photo at left, courtesy of reader E.S.).

Then open the oil supply valve to permit oil to flow from the oil tank into the canister. You may hear or feel air escaping at the air bleeder opening.

Once you see a clear flow of heating oil at the bleeder opening you can replace the screw that closes that port.

Watch out: don't forget to include the fiber washer that seals the screw to the canister head or you may have oil or air leaks at the canister.

Tips for the Follow-Up Check for Oil Leaks After Oil Filter Cartridge Change

Heating oil filter at the oil burner (C) Daniel FriedmanAfter any service procedure that disturbs oil line, filter, or burner oil piping fittings we recommend checking for evidence of oil leaks again after the system has been in use for a day or so, because slow leaks and small leaks in the oil piping system may not show up immediately.

Clean the floor beneath and around the heating oil filter and oil piping. Check back in a day or two for fresh heating oil spots on the floor (below left).

If you leave a clean paper towel below the oil filter and connectors it can make spotting an oil drip easier.

Fix any oil leaks immediately. An air leak into the oil piping system leads to improper oil burner operation, risking a dangerous puff-back, or loss of heat in the building.

Reader Question: spin-on / off heating oil filter maintenance

10/30/2014 Anonymous said:

The furnace oil filter changing instructions are for canister and not the spin-on cartridge pictured.
Are there seperate instructions for removing and replacing a spin-on fuel filter cartridge (Gar-ber, Granby, etc)?


Thanks Anon for pointing out the need for this clarification. For a spin-on type oil filter cartridge the basic steps are the same: shut off the equipment, shut off the oil supply, place a pan to catch drips, remove and replace the filter. The central difference is that there is no center bolt to remove to drop the filter (as is the case with General Filters).

The mounting hardware for this filter is (as with other brands) specific to the filter brand, size, type. Gar-Ber filters,for example, include a die-cast metal head to which the oil lines are connected and to the under-side of which the Gar-Ber spin on heating oil filter screws on and off. The Gar-Ber filter head includes a port for a vacuum gauge and it also includes an air bleeder screw that serves the same function as we describe in the article above.

Gar-Ber spin-on / off oil filters are distributed by General Filters -

Granby spin-on / off oil filters (Granby EX200-999) are distributed by Granby Induystries - and also provide mounting hardware that connects to heating oil lines and that also includes an air bleeder plug. Granby also sells a traditional center-bolt oil filter as well. Granby notes that their 10 micron spin-on oil filter works with all spin-on filter heads of the same type and fit the CGF-10, Kerr K10, Purolator Per-103 and Nozzle Guard NG1500-M oil filter mounts.

Granby's instructions include this helpful note that gives some heating oil line vacuum reference points

"SERVICE: Replace the filter element at the beginning of each heating season, or when running vacuum exceeds 6’’ Hg on one-pipe systems or 15’’Hg on two-pipe systems."

Heating Oil Filter Articles


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