I need to move the heat !!

carlo said:

I have a new woodburning stove and thru peoples help on this forum I have been enjoying some greeat fires the last couple of weeks. Thank you.

Now that I understand the fundamentals to woodburning, my attention now turns to moving the heat that is in the room the stove is in, to other portions of the house. My stove sits in my livingroom. My livingroom measures 16'x13', but the big problem is that I have an 18' ceiling. I took a ladder and climbed up and no doubt the air above is very warm. I would like to move this air because what's happening is that the warm air rises and then seeps out thru 2 large windows I have in the room. I will be getting heavy curtains for those windows soon.

Obviously my first choice to move the warm air will be a ceiling fan. My big question is ...... How far should the ceiling fan be from the ceiling so that I'm able to move the warm air more effeciently thru the door (7' high) into other rooms.

My guess is the fan s/b 3' below the ceiling ..... that means the fan has to push the warm air down 8' to door level. ........ If I drop the ceiling fan 6' below the ceiling then the fan just has to push the warm air down 5' to door level. But if I'm at 5' below ceiling is the fan capturing all the warm air at ceiling level ?

I hope I'm describing this clearly. If anybody has any ideas on the best height I should hang the fan it would be most appreciated.

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Is the 18' throughout the ceiling, or is it a cathedral ceiling? The way ceiling fans work is to pull cool air up from the lower surfaces. As the cold air is rising, the warm air on the ceiling will be pushed towards the walls and move down the walls. I would suggest working with a lighting store to get their input on how big and how low to hang. In any case, it will move your heat down, I don't know about moving through a door. You may need a door fan in the upper corner pushing warm air into the other room.

If this opening is in direct line with the stove, put a small box fan on the floor in the other room and point it at the stove.

Good luck.

Hang two fans 6 feet down from the ceiling. Run them in opposite directions so one pulls and the other pushes.

Carlo - I agree on the ceiling fan posts so far. I try to heat a 2300 square foot, closed floor plan, 2 story colonial home with our woodstove. Once I finish figuring out the airflow and leaks I'll be able to do that easily with my stove. But in your case, you simply want to supplement your existing heating solution and enjoy the extra warmth that a fire can bring. No doubt just the ambience has a wonderful psychological feel that you are already enjoying. But getting that air to move into the adjacent room is the crux of your problem. You will definitely need to push warm air out of the room with door fans or push cold air into the room with a box fan. One question: how do you feel currently when sitting in the stove room?

Here's what the Casablanca Fan company has to say about hanging height:

http://www.casablancafanco.com/product/charts/hanging_system.html

Ceiling fans will go a long way toward destratifying the temperature of the air in the space where they're mounted, but will do little to move the air horizontally out of that room, unless the room is wide open to the adjacent space(s). Rick

carlo said:

What's a door fan ? Why a box fan ? Once my ceiling fan is in I will re-evaluate the room and adjacent rooms. Then I will start looking into other fans.

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A door fan is mounted in the upper corner of the door seeing the heat is near the ceiling. It moves warm air from one room into the other room. It's very small and tucks into the corner of the door frame.

The box fan sits in the room where there is cold air. The movement of cold air on the floor into the warm air room should cause the warm air to travel above the cold air in the opposite direction.

carlo said:

Like I said before .... a ceiling fan is going in for decor purposes, my wife wants one ...lol. I guess the ideal situation would be to have a ceiling fan pushing the warmer air that's 18' high down so a box fan can then throw cool air into the room and cause air flow between rooms. Does that make sense ?

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carlo, I'm not so sure you have grabbed ahold of the correct idea just yet.

After you install the ceiling fan, do not try to push that air down. Pull it up! As BeGreen stated, it sounds wrong, but it works. Suck the air up that is in the center of the room and that warm air will then flow down the cooler outside walls (like it would naturally). So don't start blowing the air down with that ceiling fan. Suck it up!

Also, the idea of sitting a fan in the doorway and instead of trying to blow warm air into the cooler rooms, do the opposite. Blow the cool air into the warmer room.

I had a hard time with both of these theories at first because they just sound all wrong. But, it works. In our case, we do blow some cool air towards the hallway (up high) while blowing cool air out of it (down low). It is amazing the difference in the even temperature of the home doing it this way. Also, with the ceiling fan, you won't feel so much draft on the floor this way.

Yes, the fan should be working with the natural convection, not against it. I propose two fans, the one closer to the stove pulling up, and the farthest one pushing down.

That will help bring some of the heat down but if you really want to heat the rest of the house, you need to bring cold air to the stove. I use a 635 cfm centrifugal blower to draw air from the opposite end of the house, under the floor and up into the base of my stove. The hearth room is still a few degrees warmer but the rest of the house is reasonably even. I made a box for my blower and have a 16x25 furnace filter inline.

We have high ceilings in our living room and I've tried to get the heat down by running the ceiling fan so that it blows upward. What we found is though the fan was definitely moving the hot air around we felt colder because of the evaporative effect as the air moved down the walls (where we sit). Our fan only has 2 speeds and the slowest is too fast for this application. I'd advise if you try a ceiling fan, get one that you can dial down to a very slow speed otherwise your mixing gains are offset by the evaporative cooling losses.

Your situation (and mine and many others) has often made me wonder if those building a house and planning to use wood heat wouldn't be smart to design in an air return at the highest point in rooms like this with some sort of air handler to distribute the heat back down to in-floor registers. In general I've wondered if having two returns for you central HVAC, one high for winter, and one low for summer wouldn't make sense. You'd block off the one you're not using dependent upon the weather.

Semipro said:

In general I've wondered if having two returns for you central HVAC, one high for winter, and one low for summer wouldn't make sense. You'd block off the one you're not using dependent upon the weather.

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HVAC system designed for AC and not just heat, will deploy "high returns" as that's the only way to get effective cooling. Those therefore don't need to be reversed for Winter wood stove heat redistribution.

LLigetfa said:

Semipro said:

In general I've wondered if having two returns for you central HVAC, one high for winter, and one low for summer wouldn't make sense. You'd block off the one you're not using dependent upon the weather.

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HVAC system designed for AC and not just heat, will deploy "high returns" as that's the only way to get effective cooling. Those therefore don't need to be reversed for Winter wood stove heat redistribution.

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Help me understand that. If cool air naturally stratifies so that cooler air is where the people are why would you want to pull hot air from a high return to refrigerate it and then return it to where the people are? I've had at least 6 houses with central HVAC and none have had a return near the ceiling or a high point. Four of those houses were in TX where AC is usually a higher priority than heating.

Maybe we're getting terminology wrong, by return I mean where the air is returned to the air handler before distribution to registers in each room. I understand ceiling mounted registers for cooling. That's what my houses in Texas had.

Semipro said:

Help me understand that. If cool air naturally stratifies so that cooler air is where the people are why would you want to pull hot air from a high return to refrigerate it and then return it to where the people are?

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First off, people aren't paper thin and laying on the floor. Given your a verage home has 8 foot ceilings and people's heads are closer to the ceiling than the floor, their sense of what is comfortable when it comes to AC is nearer their head than their ankle. Now heating is another story... cold ankles are sure to lodge a lot of complaints.

High returns generally are not at the top of an 18 foot ceiling. What I've seen are around 6 feet up off the floor. If a AC system is designed just for cooling, the outlets are most likely in the ceiling, in which case the returns would not be up high. Many of the newer systems use high velocity outlets which do a good job of mixing up the air like a ceiling fan would. Some homes now have two separate and distinct sytems in light of the fact the requirements are so different that a single system is a compromise.

IMHO there isn't a huge difference running a ceiling fan one way or the other. I believe it is turbulence in the room that makes the difference. I like Lligetfa's idea with the two fans - particularly with the high ceilings. I have a 24' peaked ceiling in my living room and know the huge temperature differential between the high and low. The crappy little ceiling fan at the peak does SFA (=very little) regardless of the dirrection.

I am planning a floor return in the adjacent (colder) room and flow through vents (holes in the wall basically) at the peak of the wall. Then I could shut the door to the room and the return would pull the air from the peak through the cold room. I don't know if something like this would be applicable for the op?

oh yeah - the question.

I think closer to the middle of the room would be more effective than the ceiling - less suction/pressure regardless of the direction.

BeGreen, LL,
After experiencing almost 30 years of the hottest most humid weather Texas had to offer I can tell you that in most all houses there, the returns were low, the registers were high (and unfortunately run through a hot attic) and ceiling fans were ubiquitous. Many newer houses there employed dual systems as LL mentioned but still had low returns.

The house we now live in also has dual ground-source HVAC systems, and numerous design features that take advantage of convective flow including a high cupola and central staircases. We use the AC in the upper level (if needed) to cool the whole house in summer and vice versa with the heat downstairs in winter (along with the wood stove). Our house would be a great study of convective heat flow. I'm not taking credit for it either, I didn't build it.

To get back to the orignial post, my opinion stands. A ceiling fan may be useful for destratifying air in higher rooms but only if the evaporative cooling it creates on human skin is more than offset by the amount of warmth the person gets from the redistributed heat. I also believe that HVAC systems should be designed to take into account heat stratification and to work with it if possible to provide the most comfort to occupants. That is, I'd be fine letting warm air hug my 18 ft. ceiling in summer as long as I'm not feeling it. That wouldn't happen though as I'd be using a ceiling fan to take advantage of evaporative skin cooling

A perfect air distribution setup to me would include upper and lower registers/returns in each room whose mode of operation (inlet/outlet) could be switched when heating/cooling modes were switched. I believe some of the high velocity systems LL mentioned have dedicated returns in each room but I don't think they reverse modes with changes in heating/cooling.

In general, I think we're all saying pretty much the same thing with some relatively minor disagreement. I just think our observations of past and current practices differ. Seeing that you both currently live in cooler climates I can see why that might be.

Cool. My motto is "bigger is better". More air for less RPM = quieter. Also a large fan fills out a large room better - visually.