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Why Do Ceiling Fans Have a Reverse Switch

I am so excited that I get to be the person telling you about the reverse switch on a ceiling fan. When I first heard of what they did, I was skeptical about how functional it would actually be, but I discovered that under the right conditions, this feature can make a big difference to the airflow and temperature distribution in a home.

In this article, I will explain what the reverse switch on a ceiling fan means to the operation and function of the fan.

Ceiling fans have a reverse switch to change the direction of the blade rotation and airflow. Counterclockwise rotation results in a down draft that helps to cool people via windchill. Clockwise rotation results in an updraft that pulls cold air out of occupied space and forces warmer air into this space.

Reverse Switch Changes Direction of Draft

The basic purpose of the ceiling fan reverse switch is to change the direction in which the blades spin. You get counterclockwise rotation (typically the default) and clockwise rotation (the one that only exists if you have a reverse switch).

The two directions correspond to two different draft directions, which serve different functions (although there is some overlap).

When the fan blades spin counterclockwise, it is in summer mode, and the air is being pushed down into the occupied space of a room.

When the fan blades spin clockwise, it is in winter mode, and air is pulled upward. This draws up cold air that would otherwise stay in the lower portions of the room and displaces warmer air from the region just below the ceiling, sending it down to the occupied space.

Ceiling fan in counterclockwise and clockwise

Downdraft Provides Cooling

As air is blown over your skin by the counterclockwise-turning fan blades, you are cooled via the wind chill effect.

The human body is always surrounded by a thin layer of warm air directly next to the skin. This happens as the warmth from our skin slowly escapes to the air around us over time and it is a form of insulation.

The wind chill effect is when air blowing over you results in this warm layer of air being pushed away from the surface of the body.

The skin is no longer insulated by this heat layer, and more body heat can be lost to the air just above the skin. It is blown away again, and, in this way, the body is cooled down despite the fact that the temperature of the air in the room remains unchanged.

On its own, a ceiling fan producing a down draft helps to create good air circulation in the room and cools you down. In addition to an AC unit, it will more evenly distribute the cooled air and enhance the cooling effects of the AC.

Updraft Redistributes Warm Air At Ceiling

Warm air naturally rises. Since no one sits on the ceiling of a room (unless they are in a Mary Poppins story), this warm air is no good to the occupants who are looking to be warmed up indoors.

Not only that, but cold air sinks. So, as the air separates according to temperature, you are denied the warm air and exposed to the coldest air.

In the reverse mode, ceiling fan blades pull the cold air upward. It forces the air sitting against the ceiling to move away and enter the “void” created below the fan when the cold air was drawn up. This means that the warmer air is entering the occupied zone of the room, where it can benefit people.

On its own, the heating benefits are marginal as the fan can only redistribute air as opposed to heating it, but it does help to circulate the air. However, if you use it in conjunction with an external heat source, then you are effectively distributing this heated air, making both the heater and the fan more effective.

The upward air movement here is gentler than the downward air movement in summer mode, so there is no wind chill by-product of displacing the warm air at the ceiling.

Is There Any Point to Reversing a Ceiling Fan?

Non-reversing fans only spin counterclockwise, so assessing the necessity of the reversing models means assessing the effectiveness of the winter mode.

As mentioned in the previous section, the effectiveness is limited without an external heat source because the amount of warmer air that is displaced is not likely to be enough to significantly raise the temperature of all the air in the room.

You may feel a slight increase in temperature when you first turn it on, but because the fan spins constantly when on, there is not enough time for enough heat to gather there again.

Furthermore, you may initially feel warmer but the perception of warmth is likely to diminish as you spend time in the room (because no actual heat is being added).

This mode is good at keeping the warmth evenly distributed, but the level of warmth will depend on the existing temperature of the room.

Let’s assume you don’t plan on adding a space heater or radiator to the room. Is there any point in getting a reversible fan?

Well, I’d actually say that it depends more on how large the price gap is. If the reversible fan is the same price or only a little more expensive, then go for it. You never know; the marginal warming effects may be just enough for you, or you may end up adding that space heater at a later stage.

Additional Benefits

There are also other benefits that can be gained through the reverse function depending on the location of the ceiling fan.

A ceiling fan set to winter mode at the top of the stairs can draw cold air up from the basement or lower levels into the main part of the house or the upstairs bedrooms.

Illustration of a Ceiling fan above the basement stairs

If your ceiling fan is right over a window and you want to encourage air to flow through the room from outside, then winter mode can pull air in through the window, possibly more effectively than the summer mode, since the fan is near the window.

Winter mode can also help to distribute humidified air without also cooling you down.


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