Does a Fan Produce More Heat or Just Blow the Air Around?

oliver power · Post by **oliver power** » Mon. Jan. 13, 2014 8:12 pm

lsayre wrote:I would think that thermal destratification via a ceiling fan would do a lot to make a home more comfortable by taking heat that would normally be at the ceiling level and dispersing it into the lower living area. It doesn't make a stove more efficient, but it makes the heat the stove emits more beneficial to us ground dwellers. Freetown Fred has the right idea here. As I recall he stopped using his stoves fan, and switched to using a ceiling fan. He turns in some of the absolutely lowest coal consumption figures of any of us each year, and he lives in a large old house in an area that gets downright cold. And he has a simple box stove to boot.

Yes, Fred is circulating the hot air which already left the stove.

Post by **franco b** » Mon. Jan. 13, 2014 8:50 pm

lsayre wrote: But then what about the special case for the non-fan crowd that is already getting maximum efficiency and the worlds best low stack temperatures as a consequence. How do they benefit from adding a fan if they have already achieved blissful efficiency nirvana without one?

The better quality base heaters and base burners have extended heat exchange area utilizing a greater percentage of the total stove area so have no need of a fan to increase efficiency of heat exchange. There is just more of it.
This is in addition to a fire pot that mixes air more evenly which also contributes by requiring less excess air.

BPatrick · Post by **BPatrick** » Tue. Jan. 14, 2014 4:10 pm

A stove isn't going to put more heat out because a fan is on it...it will actually cool it. You should jve a fan or ceiling fan circulating the radiated air around the room so you don't habe warm or cold spots. You don't need a fan on high to do this.

waldo lemieux · Post by **waldo lemieux** » Tue. Jan. 14, 2014 4:15 pm

:surrender: Mother, make it stop...

KLook · Post by **KLook** » Tue. Jan. 14, 2014 4:19 pm

I'm tapping out Waldo....bring in some new recruits. :surrender:

Kevin

freetown fred · Post by **freetown fred** » Tue. Jan. 14, 2014 4:32 pm

YOU GUY'S are killin me ya know!!

joeq · Post by **joeq** » Tue. Jan. 14, 2014 4:46 pm

Mother...make it stop!

Post by **Lightning** » Tue. Jan. 14, 2014 4:59 pm

A kind man that is a member here shed some light on how people perceive things.. Its interesting how we see things that aren't really able to be seen, but instead are able to be felt. Heat, as interpreted by our senses is somewhat misunderstood and we all have developed our own ideas about how it will react given different circumstances. I think member McGiever hinted at this earlier in this thread. Its the core of why this thread has gotten so long on something that should be so simple. Truth is, once it is boiled down to 1's and 0's, truths and rules of physics, there is only one right answer and that answer is black and white.

So for now, I likely won't post again to this thread since I've exhausted my personal resources of explanation. But, It's interesting to see how others perceive heat and how it behaves...

kstills · Post by **kstills** » Tue. Jan. 14, 2014 5:04 pm

tony17112acst wrote:OK, I have the final answer.

I have confirmed in a physics forum that it is absolutely true that heat will transfer faster through metal as the difference in temperature on either side of the metal is greater. So cooling the outside of the metal box (stove) with a fan WILL cause heat to transfer more quickly from inside the box (stove) to the outside. The closer the outside temp gets to the inside temp of the box, the slower the heat transfer - until the two temps are equal and heat transfer stops all together.

That's all the info that was needed. So a summary of this 90+ post thread is:

Q: Does a Fan Produce More Heat or Just Blow the Air Around?
A: It produces more heat because of the principle that heat transfers more quickly through a medium as the difference of temperatures on either side of that medium becomes greater.

I think not....

freetown fred · Post by **freetown fred** » Tue. Jan. 14, 2014 5:06 pm

Hell, that's all ya wanted????--I put coal in my stove, light it up for the season, somehow the heat radiates off the stove & it keeps me warm! I done good didn't I?

kstills · Post by **kstills** » Tue. Jan. 14, 2014 5:07 pm

Larry is correct on this one.

The only thing producing heat is the coal.

Unless you increase the amount of coal being burned, you aren't producing more heat.

You can change the rate at which you lose heat up the chimney, but if you cool the chimney you reduce draft so you're going to run into issues with combustion efficiency.

All you are doing is converting a radiator into a hot air delivery system, but the btuh calculation comes from the coal, and only the coal.

kstills · Post by **kstills** » Tue. Jan. 14, 2014 5:10 pm

Let's look at the motor analogy.

What happens when you blow air on it?

The motor gets cooler.

What happens to the subsequent air being blown across the motor?

It gets cooler.

Until you reach equilibrium of air flow/heat generation.

The motor isn't getting hotter because you're blowing air on it......

kstills · Post by **kstills** » Tue. Jan. 14, 2014 5:17 pm

lsayre wrote:I would think that thermal destratification via a ceiling fan would do a lot to make a home more comfortable by taking heat that would normally be at the ceiling level and dispersing it into the lower living area. It doesn't make a stove more efficient, but it makes the heat the stove emits more beneficial to us ground dwellers. Freetown Fred has the right idea here. As I recall he stopped using his stoves fan, and switched to using a ceiling fan. He turns in some of the absolutely lowest coal consumption figures of any of us each year, and he lives in a large old house in an area that gets downright cold. And he has a simple box stove to boot.

Ding!

kstills · Post by **kstills** » Tue. Jan. 14, 2014 5:20 pm

.

I'm the OP and franco is correct. My sole concern was: if I point a fan at my stove, will I get more heat in the room than if I did not have a fan at all.

Does blowing air onto a hot object (like a coal stove) give you MORE HEAT output from the object, or does the fan just spread that heat around the room?

ddahlgren · Post by **ddahlgren** » Tue. Jan. 14, 2014 5:22 pm

waldo lemieux wrote::surrender: Mother, make it stop...

Yep!