If you've installed a ceiling fan in your shop (or home), DON'T follow the standard industry advice about "clockwise" or "counterclockwise".  Fan blades are designed in both tilt directions, and thus some fans should turn one way, others the opposite.  The proper selection/sensing is "down flow", with the air coming toward you as you stand under the fan.  This direction works both summer AND winter.  Summer:  obviously, the air motion cools exposed skin and this cools the body.  Winter:  if you want heat drawn from the top of a room and distributed down and around, run the fan so the air goes DOWN.  If you reverse it to "upflow", the air will circulate up against the ceiling, but then moves horizontally to the inlet of the fan, which means air circulation occurs only between the ceiling and the space about 6~12" below the fan blades.  Winter "downflow" will capture the heat off the celling and mix it into the room.  It still cools exposed skin, so the winter choice becomes long sleeved shirts or simply turning off the fan.  You will find this advice is not shared by the fan manufacturers.  But they gave up their engineering departments decades ago, so it's the marketing people drawing up those pretty--but erroneous--diagrams.  [CV:  I started my career in 1972 working for a fan manufacturer.]

Dang, great advice and topic Pete! Thanks for the info!

Thanks Pete. Does this apply south of the equator too?

7 hours ago, Grandpadave52 said:

Thanks Pete. Does this apply south of the equator too?

Yes, because down there they walk on the ceiling.   

 

I think.

Sorry Pete but I have to, respectively, disagree with you. I have checked the ceiling fan in my BR just now and I can feel the air currents coming down the walls ( even to the floor ) when the fan is in the updraft mode, even on the lowest speed. The room is 9 x 12' the fan is 8" off the 9'ceiling.

At the shop where I worked before retirement, my main work area was in a 40 x 60' room with a 14' ceiling. we had two wall mounted 20 x 20" box fans, 8'off the floor, that could be adjusted 360* on two axis. During the summer the fans would be aimed at the work areas for direct cooling, during the winter I would adjust them so the airflow was straight up, on all but the coldest days we could run the heater, ceiling mounted, gas fired, forced air, once in the morning to take the chill off the room, after the first run the heater would not kick on again the the room's temperature was comfortable. The workers body heat along with the lights would provide enough heat.  

In the winter, airflow should be directed UP. Since ceiling fans do not suck air, they only push it, directing the flow UP, forces the hotter air to circulate down which allows you to use the warmer air you paid to create instead of just heating the ceiling. It also reduces or eliminates the amount of airflow you feel against your body which cools you. With the open blade design, there is almost NO AIR FLOW behind the blades

On 6/27/2025 at 8:57 AM, PeteM said:

If you've installed a ceiling fan in your shop (or home), DON'T follow the standard industry advice about "clockwise" or "counterclockwise".  Fan blades are designed in both tilt directions, and thus some fans should turn one way, others the opposite.  The proper selection/sensing is "down flow", with the air coming toward you as you stand under the fan.  This direction works both summer AND winter.  Summer:  obviously, the air motion cools exposed skin and this cools the body.  Winter:  if you want heat drawn from the top of a room and distributed down and around, run the fan so the air goes DOWN.  If you reverse it to "upflow", the air will circulate up against the ceiling, but then moves horizontally to the inlet of the fan, which means air circulation occurs only between the ceiling and the space about 6~12" below the fan blades.  Winter "downflow" will capture the heat off the celling and mix it into the room.  It still cools exposed skin, so the winter choice becomes long sleeved shirts or simply turning off the fan.  You will find this advice is not shared by the fan manufacturers.  But they gave up their engineering departments decades ago, so it's the marketing people drawing up those pretty--but erroneous--diagrams.  [CV:  I started my career in 1972 working for a fan manufacturer.]

Here in South Texas, during the heat of the day hours, in rooms on the Sun side of the house, I switch it to up flow so it the cooler air can push the hotter air up at least till dark then I switch it back to down flow. But by 11 am it just feels like the warmer air is getting pushed down (and warmer air attracts mosquitoes) so I switch it back so it'll suck the warmer air up.

Seems like it pushes the humid air up as well.

In the

Much of this topic has to do with perceived comfort, and that can be very individualistic. I will note that hot air naturally rises in any structure, so running the fan upward to keep the heat on the ceiling shouldn't be necessary. Underlying all this: we feel more comfortable when there is air motion: up, down, sideways, don't matter, we just like the breeze. I'm just surprised that commercial buildings have not taken this into consideration (there are a few, but not many). I really expected by now that ceiling fans would be standard in office buildings. Ah well.

9 hours ago, PeteM said:

Much of this topic has to do with perceived comfort, and that can be very individualistic. I will note that hot air naturally rises in any structure, so running the fan upward to keep the heat on the ceiling shouldn't be necessary. Underlying all this: we feel more comfortable when there is air motion: up, down, sideways, don't matter, we just like the breeze. I'm just surprised that commercial buildings have not taken this into consideration (there are a few, but not many). I really expected by now that ceiling fans would be standard in office buildings. Ah well.

By forcing air up, the air above has to go somewhere and gets pushed outward and displaced downward. Since there is no containment, there can't be any vacuum or compression. Moving air has to come from somewhere and has to go somewhere.. As for the commercial applications, I worked on a 750,000 sq ft warehouse a while back. They had ceiling fans that I think are 24 ft dia. The building is in the Nevada desert and energy use was a big factor. They also have dozens of 6 or 8 ft dia fans at the top of the full length of the building on one wall and vents on the opposite wall being used as air exchangers. Airflow, static pressure, and air exchanging is interesting and if used properly a lot of money can be saved.. Cheap anemometers are available (some less than $15) and can give a lot of info..

The air flow diagrams are not quite correct. First, the green arrows show fan blade direction that is the most common, but isn't always the case. Some fans (maybe 20%?) have the opposite blade tilt. The second diagram seems logical, but the departure from actual air flow is when the (orange) air is going down the wall. The size of the fan as shown is exaggerated compared to the size of the room: the diagram fan blades are depicted as about half the dimension of the room. IOW, a 48" fan in that diagram would imply the room is 8'. But in most cases, a room dimension of 8' would only get a 24" fan. In actual practice, the orange arrows going down the wall have a lot more flow area, and the orange-air velocity down is very small. The reduced velocity means the air does not penetrate down very far before being drawn back into the fan. The blue-arrow flow coming up to the fan (in the diagram) is a pattern only about 12" deep. Most fans, as actually applied, if operating in "flow up" rotation, only create air motion about 12" below the blade entry level. In general, "updraft" circulation doesn't reach the room occupant, and thus doesn't contribute to comfort.

8 hours ago, PeteM said:

The air flow diagrams are not quite correct. First, the green arrows show fan blade direction that is the most common, but isn't always the case. Some fans (maybe 20%?) have the opposite blade tilt. The second diagram seems logical, but the departure from actual air flow is when the (orange) air is going down the wall. The size of the fan as shown is exaggerated compared to the size of the room: the diagram fan blades are depicted as about half the dimension of the room. IOW, a 48" fan in that diagram would imply the room is 8'. But in most cases, a room dimension of 8' would only get a 24" fan. In actual practice, the orange arrows going down the wall have a lot more flow area, and the orange-air velocity down is very small. The reduced velocity means the air does not penetrate down very far before being drawn back into the fan. The blue-arrow flow coming up to the fan (in the diagram) is a pattern only about 12" deep. Most fans, as actually applied, if operating in "flow up" rotation, only create air motion about 12" below the blade entry level. In general, "updraft" circulation doesn't reach the room occupant, and thus doesn't contribute to comfort.

Orange is warm air and blue is cool. The rotation direction is inconsequential.. The fan doesn't suck air it only blows air which displaces the air it contacts... Thus, in the winter, you blow the air UP, which circulates the warm air from the ceiling down the walls to a place where it does some good. In the summer, you blow the air down to get the direct cooling effect.. the percentage of fan diameter in relation to room size has almost nothing to do with anything. A very small fan can move an enormous amount of still air. The drawings are correct and the concept is proven by the laws of physics... I understand that you feel that you somehow get a different result than that which has been proven for hundreds of years. If you were to study displacement and get a solid understanding along with how different types of fans alter air flow, you might see what is really happening. Nevertheless, I am glad that you are getting some comfort, whichever way your wind blows..

I was a Scoutmaster for many years. Still am in many ways. There is a gap between "teach" and "learn". I'm confident you'll figure it out with time.

4 hours ago, PeteM said:

I was a Scoutmaster for many years. Still am in many ways. There is a gap between "teach" and "learn". I'm confident you'll figure it out with time.

HHMMMM I'm sure there's an insult in there somewhere. Me not being a Scoutofile, I just do not understand.. Bragging about "still being one in many ways" is just plain sick... All the facts and physics in the world will never override that... The Abuse Scandals and Bankruptcy

Beginning in 2019, numerous states extended their statutes of limitations for child sexual abuse, triggering a flood of lawsuits detailing decades of historical abuse by SCOUTMASTERS and volunteers. To handle tens of thousands of claims, the BSA filed for Chapter 11 bankruptcy in 2020. The organization exited bankruptcy by establishing a $2.4 billion settlement fund to compensate survivors, which required them to sell off significant real estate and assets. [1, 2, 3]

On 6/29/2025 at 6:29 PM, Wichman3 said:

I have checked the ceiling fan in my BR just now and I can feel the air currents coming down the walls ( even to the floor ) when the fan is in the updraft mode, even on the lowest speed. The room is 9 x 12' the fan is 8" off the 9'ceiling.

That's called the "coanda effect": moving air is at a lower (static) pressure than still air, so an air stream directed along a surface (usually wall or ceiling) is held in place by the still air. As the air moves, it mixes with the room's air, which makes for a more even temperature in the room, and helps avoid drafts. Cold drafts are particularly uncomfortable for most people. Good mixing also helps with overall comfort with some velocity across the skin. But a ceiling fan (in cooling use) will add higher velocity across the skin and thereby cool more, usually allowing a higher room temperature for the same degree of perceived comfort. Note that good air practice avoids drafts, but ceiling fans deliberately create drafts: the difference is that cold air (usually 55~60 degreesF) blowing directly on skin is too aggressive, whereas the ceiling fan is pumping room temperature air (75 or so), and skin evaporation due to velocity is the object. Often, people using ceiling fans can set their thermostat several degrees higher: each degree makes the system about 1~2% more efficient. But note that's cooling mode. I leave my ceiling fans off in winter. But now we're entering into personal preference. Please note the original start of this thread was about upflow/downflow not being the same as clockwise/counterclockwise.