Which device delays the furnace blower startup to improve efficiency?

• A. Delay timer
• B. Pressure switch
• C. Time-delay relay
• D. Blower motor controller

Answer: (C)

The device that delays the furnace blower startup is the time-delay relay. It sits in the control circuit and, after the burner is energized, holds the blower off for a short, fixed interval. This pause gives the heat exchanger time to warm up and ensures proper heat transfer before air is pushed into the ducts, so the air that enters rooms is warm sooner and the system runs more efficiently. The pressure switch is there to verify adequate draft and safe venting and isn’t used to control when the blower starts. The blower motor controller handles the speed and operation of the blower once it’s running, not the timing of its start. A delay timer could create a similar pause in other contexts, but the time-delay relay is the specific component used to implement the blower startup delay in furnace control circuits.