The steps for replacing a boiler filter are to turn off the power source, protect the floor, remove the filter, and replace the filter. For people who require a visual aid, YouTube provides videos with instructions on how to replace broiler filters.
Before doing anything to replace the filter, turn off the power at the circuit breaker, and then turn it off at the cut-off switch. The cut-off switch is usually located near the entrance to the boiler room. Cut off the oil valve as well, and wait for the boiler to cool down. Next, lay down newspaper or old sheets on the floor to protect it from oil stains.
Wear protective gloves while handling the filter, and place a plastic bag under the filter to catch as much oil as possible while it is being removed. Use one hand to hold the bag in place and another to apply a wrench to the nut holding the filter in place. Once the nut is loosened, the old filter can be completely removed.
Insert the new filter in place of the old one, and put the new gasket on top. Use the wrench to close everything tightly, and then turn the power sources back on. Be on the lookout for any leaks that may indicate installation issues.