What safety measure should be taken when performing maintenance on combustion appliances?

When performing maintenance on combustion appliances, turning off the appliance and disconnecting power if possible is a critical safety measure. This action helps prevent accidental ignition of the appliance during maintenance and protects the technician from potential electrical hazards. By ensuring the appliance is powered off, you eliminate risks associated with both combustion and electrical malfunctions, creating a safer working environment.

In addition to protecting the technician, this step also ensures that no gas, fuel, or other combustible substances are inadvertently ignited while maintenance activities, such as cleaning or part replacement, are being conducted. Maintaining a safe working environment is essential to prevent accidents that could lead to injuries or property damage.

Other options, such as closing windows or only checking fuel levels, do not address the primary risks involved in maintenance activities. Moreover, suggesting that no safety measures are needed is a misunderstanding of best practices in working with combustion appliances, where the potential for hazardous situations exists. Thus, ensuring the appliance is turned off and power is disconnected provides the necessary precautions to safeguard against these risks.