How to Maintain a Furnace


Oil Furnaces: Oil Filters
Remember to close the oil shutoff valve between the fuel tank and the filter.
Remember to close the oil shutoff valve between the fuel tank and the filter.
Dorling Kindersley/Getty Images

The oil filter should be changed or cleaned at the start of the heating season and about midway through the season -- three or four times a year [source: NationalFurnace.com]. Here's how to clean or replace the filter:

Step 1: Close the oil shutoff valve between the fuel tank and the filter.

Step 2: Unscrew the bottom or cup of the filter housing and remove the filter.

Step 3: If the filter is disposable, insert a new one of the same size and type. If your furnace has a permanent filter, clean the filter according to the furnace manufacturer's recommendations.

Step 4: Replace all old filter gaskets with new ones.

Step 5: Screw in the bottom of the housing and open the oil shutoff valve.

Some oil furnaces have a pump strainer, which is located on the pump attached to the burner/ blower unit. Clean this strainer when you clean the oil filter. Here's how:

Step 1: Unbolt the cover of the pump housing (where the oil line enters the burner) and lift off the cover.

Step 2: Remove the thin gasket around the rim. Find and remove the strainer, which is a cylindrical or cup-shape wire mesh screen.

Step 3: Soak the strainer in kerosene for several minutes to loosen any built-up sludge. Carefully clean the strainer with an old, soft toothbrush.

Step 4: Inspect the strainer. If it's torn or badly bent, replace it with a new pump strainer of the same type.

Step 5: Set the strainer into place on the pump, place a new gasket on the rim and then bolt the cover of the pump housing back on.

Next, we'll take a look at the switches and stack control on the furnace.