Wall- or Engine-mounted Block Heater Control


Electric block heaters are commonly used in cold climates to heat a vehicle engine block prior to driving. Heaters are connected to alternating current power and have a heating coil that goes into the engine block. For convenience, many people plug in the block heater at the end of the day. However, most engine block heaters use energy continuously once they are plugged in.

Typically, an engine block heater will be plugged in during the colder months and the heater will run continuously while connected. The engine block heater controls come in two varieties, engine mounted and wall mounted. A wall mounted heater has a two-hour delay when plugged in after vehicle use since the engine is already warm enough and will only turn on when the outside air temperature drops below a certain threshold. The engine mounted heater cycles on based on the engine temperature which means it operates similarly to the wall mounted option.

Timers or thematically controlled heaters are helpful for fleet vehicles, such as utility trucks or school buses. Energy is saved by reducing the number of operating hours the block heater is operating. Fleet vehicles use block heaters to reduce engine warm-up time, avoid starting difficulties and help defrost windows. Energy savings depend on location, ambient temperature and settings of the timer or thermostat.


Incentives of $100 per wall-mounted heater controls and $150 for engine-mounted controls are available for retrofits and new construction projects through Idaho Power’s Commercial and Industrial Energy Efficiency Program.


The cost of energy efficient engine block heater controls will vary based on size and type of the heater control. Simple payback on investment is often less than one year after incentive.