What is a crucial step before changing an oil filter?

Turning off the burner and relieving system pressure is essential before changing an oil filter because it ensures safety and prevents potential hazards. When the burner is operational, there is typically pressurized fuel oil within the system, which could lead to spills, leaks, or even fire hazards if disrupted during service. By shutting off the burner, you eliminate ignition sources and allow the system to cool, reducing the risk of accidents.

Additionally, relieving system pressure is critical as it helps prevent fuel spray or oil overflow, which could pose safety and environmental concerns. This step is foundational in maintaining safe operational practices when servicing oil heating systems. Proper precautions also protect the technician and ensure that the system is safe to work on. This routine practice represents the safety-first ethos common in HVAC and oil heat services.