Reverse fan for heat...what a difference

[vrinner]

So I have had my fans up for the last few months and had them mainly running in "cooling" mode, blowing air down. These are 10' HD fans so they don't spin very fast and basically just keep the air moving with a very slight breeze. The shop has always seem cold, especially at night, gotta wear long sleeves or a jacket. So the last week I ran them in "heating" mode, pushing the air up to the ceiling. Man...it is so much more comfortable now, short sleeves and all.

 

[kelpaso1]

Yep now the warm air is rising up the middle the garage and down the walls to the floor.

 

[FredWanaker]

the argument seems to change every few years*. The old argument 20 years ago was that in winter one wanted the warm air trapped aloft pushed down, and in summer one wanted the cooler air near the floor pulled up. Now the argument is the opposite, push the air down in summer so you feel the breeze, and pull it up in winter to circulate the warm air without it blowing directly on you. I always go with whatever feels best. The way you are doing it usually feels best to me too.

*I have for example both old Hunter and Hampton Bay guides that say do A when now they say do B.

 

[txvwnut]

I’ve got three of the harbor freight air blowers mounted in the ceiling for summer time air movement. The other day I put a speed control on them and flipped them on at the lowest setting to pull the heat down to the work area. Man what a difference it made, makes wish ida done it sooner.

 

[Gunfixr]

In the house, I have a 72" ceiling fan in the living room. In the winter, I run it slow when using the wood stove, to spread the heat further out into the house. Having tried both directions, pushing down works better. I generally only use one of the first three speeds.

 

[Steve W.]

Don't have room for fans in the shop, but have several in the house. 7' 6" ceilings, so they are "ceiling-hugger" fans. Because they are so close to the ceiling, there is not enough room to refill the area above them if they push down at anything faster than the slowest speed. So, I have them blowing UP, all year round. Doesn't really matter if the house is being heated or cooled, air is pushed up to the ceiling, where it spreads out to all the walls, then down. Good circulation regardless of thermostat setting.

.

 

[isb cornbinder]

The direction of the fan makes little difference. The most important thing is keeping the air circulating and not layering AKA stratifying.

These big fans are not positive displacement and the fan cannot compress air.

 

[gmcgeo]

I have had noticed a difference in heat when i reversed my fan also. When growing up was always told to push heat down and switch in the summer.... i keep in reverse at all times now

 

[isb cornbinder]

The only cooling a person might feel is from improved evaporation of body sweating. The motion of a fan disturbs the molecules in the air and the friction of the molecules against each other produces heat. One of the most extreme examples of friction and heat is the entry of a space shuttle becoming very hot from friction with the atmosphere. Every so often we might see some article from space enter our atmosphere and burn up, from friction.
The fan direction makes little of no difference. I reverse my ceiling shop fan only when I want to avoid a direct draft on myself.

 

[ycgoat]

We have always had fans blowing down in summer and up in winter; I keep my house cool except for a wood stove, so it is uncomfortable in winter with the fans blowing down. What I have always questioned was the power bill. Do I save any power running the fans? My wife and I argue about this on occasion. She swears our power bill would be higher with out the fans.

 

[gmcgeo]

We have always had fans blowing down in summer and up in winter; I keep my house cool except for a wood stove, so it is uncomfortable in winter with the fans blowing down. What I have always questioned was the power bill. Do I save any power running the fans? My wife and I argue about this on occasion. She swears our power bill would be higher with out the fans.

I would test this theory and get to the bottom of who is right ? lol

 

[vrinner]

The only cooling a person might feel is from improved evaporation of body sweating. The motion of a fan disturbs the molecules in the air and the friction of the molecules against each other produces heat. One of the most extreme examples of friction and heat is the entry of a space shuttle becoming very hot from friction with the atmosphere. Every so often we might see some article from space enter our atmosphere and burn up, from friction.
The fan direction makes little of no difference. I reverse my ceiling shop fan only when I want to avoid a direct draft on myself.

Leave it to GJ posts to add facts about the space shuttle and the atmosphere to a post about ceiling fans.

But I think that is probably the case, it feels warmer because the air isn't blowing down directly on me and is moving around the sides of the building instead. End result is that it feels warmer.

 

[dave*99]

The direction of the fan makes little difference. The most important thing is keeping the air circulating and layering AKA stratifying.

These big fans are not positive displacement and the fan cannot compress air.

Stratifying and circulating are opposites.

Destratification Fan Application Guide - Continental Fan

A destratification fan is a ventilation device, typically suspended from the ceiling of a commercial or industrial building.

continentalfan.com

 

[isb cornbinder]

Stratifying and circulating are opposites.

Destratification Fan Application Guide - Continental Fan

A destratification fan is a ventilation device, typically suspended from the ceiling of a commercial or industrial building.

continentalfan.com

You are correct, I have edited a correction into my post. Now, I will be watching you.

 

[dave*99]

I have a garage with the ceiling about 14' high at the peak. During heating season, I run the fan on low pulling the air up. That makes gentle warm air currents flow down the walls of the garage where the windows and doors make for cold spots. The temperature feels more even as I walk from the center to the walls.

I don't run the fan in the summer. The hot air stays up near the ceiling where I prefer it to stay.

In the house the fans blow down in the summer and are turned off in the winter. House ceilings are lower. etc.

YMMV

 

[dave*99]

(Delete)

 

[Gunfixr]

Well, after having tried both directions, at the same speeds, the rooms off the living room get warmer when the air pushes down than when pulled up. The stove keeps the living room hot, I don't need the fan for the living room.
Direction may not matter within the room, it does matter when trying to push to other rooms.
My fan has 6 speeds, the lowest one almost looks like it's coasting. The fastest is usually uncomfortable.
It's a DC motor fan, so it uses around 1/3 to 1/2 the energy of the same fan with a regular ac motor.

 

[mikedodge]

Fan direction does make a difference. You notice it most on extreme hot or cold days or when seasons are switching when it might be cold at night but hot during the day. You can change the direction and feel one way work better then the other.
It seems like there is a lot of contradiction which way to run them, some places say run it clockwise to pull the air up, other places say to blow the air down and it'll rise again along the walls. I dunno. You can feel one of our fans more then the other and it's direction and speed is always set at whatever seems to work the best. Its usuly off in the winter, I've never experimented to see if being on shortens the amount of furnace run time any.

 

[dave*99]

The effect you feel from the fan depends a lot on ceiling height.

 

[vrinner]

The effect you feel from the fan depends a lot on ceiling height.

So for my situation, it's a 20' ceiling height and I have 48" down rods. The fans are 120" diameter and at the max RPM is 60. For me, right now in "cooler" SoCal weather in a fully insulated garage, blowing up "feels" warmer than blowing down. I know that when it was warmer blowing down "feels" cooler.

 

[yeldogt]

With high ceilings and forced air heat -- having a fan move that stratified heat off the ceiling will make a difference. With 8' or 9' flat ceiling in a house the air movement with a typical system should move the air around enough. It really depends on the house -- older houses with less insulation and some leaks will benefit with some additional air movement.

Having lived in a NYC loft and rehabbed a fire house and now a church into a residence -- have some experience with high ceilings. Many here with garages do as well -- my current studio is two typical "A" frame building and both have cathedral ceilings. You will really notice the difference with a high "A" frame cathedral ..... I first noticed this in a cabin I built years ago. The key is to have the fan on a long enough down rod -- you want that fan to cycle the air up and into the "A" not just push it around. Same in the summer -- with a long down rod you are not pulling all the heat off the ceiling ..... hot air naturally wants to go up. It's important in the summer to keep it up there -- bigger fan moving slowing works better.

With radiant heat the ceiling should be colder than the rest of the building -- so no fan. My current project will be interesting if I can ever get it finished. It has 28' ceilings in one room that is about 1k sf and 38' in another room with about 400sf --- previous was all forced air ... We used two ceiling fans that ran 24/7 -- will be interesting to see how it works with all radiant in the winter. The kitchen is about 24' and lots of windows .... not sure how that going to work.

Personally -- I'm not a lover of fans. Don't like the look --- sort of a necessary evil.

 

[dave*99]

So for my situation, it's a 20' ceiling height and I have 48" down rods. The fans are 120" diameter and at the max RPM is 60. For me, right now in "cooler" SoCal weather in a fully insulated garage, blowing up "feels" warmer than blowing down. I know that when it was warmer blowing down "feels" cooler.

This makes perfect sense. In that configuration, you want to move the warm air that is stuck up at ceiling down to the floor. You do not want to "feel the breeze" from the fan as this can make you feel cooler. Without the fan, the air stratifies with the hot air stuck at the ceiling.

If one has a 7.5 foot ceiling and a ceiling hugger fan, you will "feel the breeze" no matter which way the fan spins. The stratification effect is minimal with or without the fan. Turn it on in the summer, enjoy the breeze. Winter? YMMV

 

[larry_g]

So for my situation, it's a 20' ceiling height and I have 48" down rods. The fans are 120" diameter and at the max RPM is 60. For me, right now in "cooler" SoCal weather in a fully insulated garage, blowing up "feels" warmer than blowing down. I know that when it was warmer blowing down "feels" cooler.

This is exactly what needs to happen. If it feels good to the people in the room then it is correct. There are so many variables in this equation that a blanket statement is impossible. Fan size, pitch, speed, room size, ceiling height, fan placement both height and position in the room. Each situation is going to have it's own best solution.

lg
no neat sig line

 

[yeldogt]

So for my situation, it's a 20' ceiling height and I have 48" down rods. The fans are 120" diameter and at the max RPM is 60. For me, right now in "cooler" SoCal weather in a fully insulated garage, blowing up "feels" warmer than blowing down. I know that when it was warmer blowing down "feels" cooler.

With 20' you could have gone longer with the down rod ..... I always use a 6' as they are common and give you a bit more head in the summer