A system comprising a furnace, an impeller, and a controller. The impeller directs air into an environment through the furnace. The controller receives calls to heat the environment or circulate air in the environment. In response to receiving a call to heat the environment, the controller activates the furnace and the impeller such that the impeller draws a first amount of power and turns in a first direction causing air to be impelled from the impeller through the furnace into the environment. In response to receiving a call to circulate air in the environment, the controller activates the impeller such that the impeller draws a second amount of power and turns in a second direction causing air to be impelled from the impeller into the environment, wherein the second amount of power is less than the first amount of power and the second direction is opposite the first direction.