What's the purpose of a certain fan in my house?

August 26, 2006 5:29 PM

What is the purpose of the fan that is in my downstairs ceiling, connected with the upstairs hallway?

My house is a two-story "raised ranch" (meaning that the downstairs level is halfway below ground, half above) with a fireplace downstairs. The house is about 30 years old.

In just about the middle of the house, there is a fan/vent in the downstairs ceiling; it connects with a large vent at the bottom of the upstairs hallway wall. There's a rotating dimmer switch that turns it on/adjusts the speed.

(The dimmer switch, by the way, is upstairs - which to me seems to imply that its intended benefit is for people upstairs, not down.)

It's a rather loud fan, but we can't determine what its purpose is. My best guess is that it's an old-fashioned way of circulating heat from the fireplace to the upstairs during winter ... but I can't imagine why anyone would want to use it, given how loud it is.

We've started to wonder whether the loudness of the fan is due to the fact that it is damaged, and that it might become useful if it were repaired and ran quietly. But maybe not. Any idea what this thing is for?

posted by jbickers to Home & Garden (11 answers total)

How else would you blow hot air from the downstairs fireplace into the upper floor?
posted by Kickstart70 at 5:50 PM on August 26, 2006

If you have a point source for heat like a stove or fireplace, you need to create a circular flow of air to get that heat to go elsewhere in the house. The fan pulls heated air upstairs, and then it circulates back down the stairway into the living room. Without that kind of circulation you would have a very hot spot around the point source and no way of distributing that heat. This assumes the fireplace is efficient and is not just sucking heat up the chimney. You might want to consider a stove insert into the fireplace, and you can probably get the fan silenced with some lubrication or tightening of the mounting screws. If not, replacing it should not be very expensive. But it's probably also problematic to have the fan bring air into the upstairs hallway -- that won't guarantee much heat in the rooms off that hallway. But it's better than nothing.
posted by beagle at 6:14 PM on August 26, 2006

It could be that this fan is intended to do the opposite: circulate cooler air from the basement upstairs. In the summer your basement is usually 10-20 degrees cooler. Turning on this fan moves some of that cool air upstairs.
posted by cosmicbandito at 6:19 PM on August 26, 2006

I grew up in a raised ranch with a wood stove downstairs and a vent in the ceiling [or floor of the 2nd floor]. It's used to get some of the heat into the other upper areas of the house. W

We had a fan inside the vent that we'd plug in manually. It's pretty quiet, so I assume you fan isn't in top working order.
posted by yeti at 7:03 PM on August 26, 2006

You don't say where you live. I lived in Texas as a young kid, and our 1930sish ranch style house was equipped with a large (and loud) fan of the type you describe. Most houses in our neighborhood were. IT was called a "house fan".

The purpose was not heating, but cooling. The house fan was supposed to draw hot air upward and out of the second floor (attic in our case, really), thus pulling cooler air in from outside. To make this work properly, we only ran it at night. The recommended method.

This was all pre-A/C in houses, of course. The thing was : it worked surprisingly well. It kept the air moving, the house dry, and cool night air flowing on you as you slept. It was quite a large powerful fan.
posted by Miko at 9:49 PM on August 26, 2006

Hot air in our home pools at the top of the basement stairs. Maybe it's moving that air mass down into the basement.
posted by craniac at 10:00 PM on August 26, 2006

My father-in-law does this (in Western Washington), using his furnace fan system to draw cool air from the basement to the living area of the house in the summer. It works quite well.
posted by lhauser at 10:00 PM on August 26, 2006

Attic fans are common in the midwest, where I grew up. Usually they pull cool nightime air into the house and pull the hot air un into the attic, as mentioned earlier. Was your second floor once an attic? Are your bedrooms downstairs? If either of these are true, then it's probably what Miko said.
posted by chrisamiller at 11:23 PM on August 26, 2006

perhaps an old whole house fan?
posted by killy willy at 4:17 AM on August 27, 2006

Response by poster: Miko, I'm in Kentucky. And my puzzlement over this thing stems from the fact that the house was built in the late 70s - I'm not sure people around here were actually heating their homes via their fireplace at that time. (None of my neighbors have one of these fans, by the way.)
posted by jbickers at 6:35 AM on August 27, 2006

Plenty of folks used wood to supplement either forced air or electric baseboard heat (wood was quite a bit cheaper than oil in the 70s, especially if you chopped it yourself all summer).

Wasn't uncommon to see this when I was a kid growing up in a northern town (yep, in the 70s). Folks had a free standing Franklin stove in the basement and then opened up a vent so the hot air would travel up to the main floor. This overcame the problem of having a sooty stove and associated wood in the main floor.
posted by drmarcj at 8:27 AM on August 27, 2006