What type of appliance requires a mechanical draft system?

A mechanical draft system is typically required for oil-fired appliances due to the unique combustion characteristics and requirements of oil as a fuel source. Oil-fired appliances produce combustion gases that need to be effectively vented to the outside environment to ensure safety and efficiency. The mechanical draft system aids in this process by using fans or blowers to control the flow of air and exhaust gases, which is essential for maintaining proper combustion and preventing the build-up of harmful gases.

In contrast, gas-fired appliances also utilize draft systems but may operate with natural draft or venturi effects in some designs, which can work efficiently without a mechanical draft. Electric appliances do not produce combustion gases, so they do not require any type of draft system. Steam boilers, while they may involve some exhaust, often utilize natural draft due to their design and operating principles. Thus, the specific need for a mechanical draft system aligns closely with the operation of oil-fired appliances.