Most effective means of moving hot air?

December 16, 2009 1:24 PM

What is the best way to move hot air? Would it be blowing air across the heat source (ex: wood stove) or suck the air away from the heat source?

I use a wood stove to heat my home which works perfectly, but it occasionally gets too hot in the living room (where the wood stove is). I want to disperse some of this excess heat into the other rooms.

posted by ascetic to Science & Nature (11 answers total)

Blowing air across it is going to be easier. It's easy to direct a blown stream of air just where you want it, but the vacuum side of the fan will suck air from all directions, not in a neat stream over the heat source.
posted by jon1270 at 1:32 PM on December 16, 2009

Response by poster: Should the fan be level with the stove or above it?
posted by ascetic at 1:35 PM on December 16, 2009

On further thought, I wonder whether you wouldn't do better to blow air into or out of the room, rather than towards or away from the stove. Perhaps a fan near a doorway, blowing floor-level cool air into the warm room would encourage the desired circulation?
posted by jon1270 at 1:44 PM on December 16, 2009

We used a ceiling fan to do what you're wanting to do. We had the fan blowing gently down, which pushed the warm air outwards from the heated room into other rooms. An extra benefit is that the warm air normally collects in the upper part of the room (of course) so blowing it down meant we used less wood to keep cozy.

Fwiw it was not our house, so I wired the fan into a wall socket, with the wire secured by screw-eyes in the wall and ceiling from the socket up to the fan, instead of running the wiring in the ceiling. This may not be a great idea if the wires are loose, as they may get caught in the fan and cause havoc, but if you're neat it's a simple and quick solution.
posted by anadem at 1:52 PM on December 16, 2009

There are a number of ways to better distribute heat from your woodstove:

You can increase the airflow over the stove (a good way to do this is using an Ecofan).

You can use a ceiling fan to move air around (warm air rises, so if you have high ceilings, the fan can help mix the air).

You can use a fan that mounts in a doorway or install a fan in a wall (e.g. above a doorway).

You can install passive vents (openings in the wall) between rooms.

You can run a central heating fan to distribute warm air throughout the house.
posted by ssg at 2:39 PM on December 16, 2009

In general: blowing is a lot more efficient than sucking. Airflow will move faster based on the difference in pressure. With a suction source, the maximum possible difference in pressure is 1 atmosphere. With blowing, the maximum possible is... well, it's unlimited in the practical sense.

But for your case, you'll have to experiment. Room dynamics will matter more than physics of airflow.
posted by chairface at 2:51 PM on December 16, 2009 [1 favorite]

I put a small fan behind our wood stove and it does a good job of dispersing the heat.
posted by mearls at 3:23 PM on December 16, 2009

Those ecofans (or ones just like them anyway) are Stirling engine powered. I'd love to get a woodstove just so I had a place to put the fan...
posted by DU at 4:53 PM on December 16, 2009

Actually, the Ecofan generates electricity, which powers the fan, from a thin thermoelectric wafer. It is pretty cool to think about (and it works well), but it isn't very exciting to look at.
posted by ssg at 5:31 PM on December 16, 2009

You might visit this thread.
posted by the Real Dan at 10:57 PM on December 16, 2009

Depends on whether the fan in question was designed to blow or suck.
posted by gjc at 7:44 AM on December 17, 2009