Everyones says you need a ceiling fan in a catheral room with a wood stove. Sounds logical enough. And I know many many people have fans in rooms with wood stoves and THEREFORE will ASSUME rightly or wrongly that the fan is necessary. So … the question is, does anyone have EXPERIENCE with a wood stove with a BLOWER unit in a large catgheral room (20 x 28 and 20 ft at the ridge) without a ceiling fan?
ANd if air movement is “required” are there any other workable options which do not include a ceiling fan? Perhaps run a fan only on the central forced air heating system while the stove is in use? Perhaps lace more cold air returns in teh ceiling or upstairs rooms?
Thoughts.
Thanks everyone.
Replies
Stratification is your concern?
That will depend on the design of the rest of the house. No fan of ceiling fans, we have none. We have a woodstove in a 1200 sq ft room (with a 15' ceiling) that creates a wonderful convection current, no fan needed. No need for a blower on the stove either. Much nicer to need no active help preventing stratification. However, my place is probably a lot different from the design of your house.
A good alternative, if stratification is a problem, is to use some sort of duct to pull hot air off the ceiling and push it out on the floor. Can be far more effective than a ceiling fan, which is certainly not required. How is air moved around your house without the stove? That might be a better place to seek a solution.
I was careful in the design of my house to ensure we have good air movement. We achieve a .5 ACH (air changes per hour).
Thank you ...
Thank you very much VaTom. "I expected the conventional wisdom, "you gots to have one". Not that I would necessarily reject that if THAT IS THE ANSWER, but first would like to explore options.
I, like you, am no fan of fans. They are ugly utilitarian objects. I would love to add "jewelry" to the home in the form of a chandiler in place of a fan.
Can you be more specific as to how you designed a house in order to aviod teh issue of stratification problems? How did you design for "good air movement"?
As I said my room is 22 feet by 28 feet with a ridge beam running the 22 feet down the middle at about 21 feet high. Also attached to this space is a bump-out dining room with about 170 square feet, also wiith a 15 high ridge beam. The foyer and kitchen are relatively open spaces to the great room as well. A second story catwalk is also open directly above teh stove (really a zero clearance unit) and the foyer is also open to teh upstairs (not sure that is a good thing or a bad thing for stratification)
I will have forced air electirc and a heat pump, so I think it would be possible to run the fan on the furnace without actually using it for heat. How efficient that would be is unclear to me.. Perhaps I could also go heavy with cold air returns near the ceiling of the great room to circulate heated air.
I have also looked into building a separate duct and fan in the wall to pull air from teh ceiling down between rafters adn down the wall and blow it out at the floor (either in the great room or into a room on the other side of the wall).
Thanks for your input.
You're welcome Dudley (?),
Only a couple more years I've been around this forum than you have. Haven't been particularly active lately, if you're unfamiliar with me and my place.
I paid attention to air flow before I built, more than 20 yrs ago. Which would be part of your active heating/cooling system. I don't have one, but I do have an air system. Your furnace fan will likely be grossly over-sized to move a little air around the house. Any idea of how many cfm you'll have? My entire air system for 20,000 cu ft of house runs on 167 cfm of air flow. That's muffin fan sized, not squirrelcage.
But the principle is the same, moving air to where it's needed. My great room is shaped differently from yours, and has other features yours does not, which aid air movement. Your second story catwalk and stairs offer an interesting possibility, depending on what you're doing with air movement. Which you have not explained, or I didn't understand. The physical dimensions and ceilings have much to do with what you get, but not as much as where your ducts and vents are placed. You might want to peruse http://sustainabilityworkshop.autodesk.com/buildings/stack-ventilation-and-bernoullis-principle though much of it is for larger buildings.
I dug out that link for a French group concerned with earth tube effectiveness. Passive air movement is ideal, but there's nothing wrong with using a small active system. I do. My woodstove needs no active system, which was your question. Tonight will only be 25º, I didn't bother to light my woodstove. Today's sun provided the same thermosiphon the woodstove does. I hope your design with an active system works as well.
Examine your design with the basic premise: hot air rises, cold air falls. Rocket science this is not. That you were told ceiling fans were a requirement does not surprise me. Along the lines of ...you have to have roof gutters. Something else I don't have. Strikes me as a patch on poor design. Mike Smith was eloquent along those lines.
Pardon me for not being familiar with your house. The answer for "how you designed a house in order to aviod teh issue of stratification problems?" is to design for no stagnant air. I know, that's a "duh" answer, but it's that simple. If you need some active help to prevent stagnant air, choose your best option. Ceiling fans rarely are, in a large room.
I went so far as to duct fresh (filtered and dehumidified, as necessary) air into all closets. A small, affordable, luxury. Which was part of my overall air system.
Good luck.
Dudley? Maybe
I do recall a Dudley Doright cartoon in the 1970's. Many here probably do not remember, apparantly you do. I don't think I was thinking about het cartoon when I slelected teh name, DoRight. I just think things should be DoneRight.
No, I am not familar with your house from reading any posts here. I did visit your personal site just now. I am not really interested in the PAHS design stuff. Well, I am interested in everything, but not so sold as to have designed a PAHS for myself. I think it sounded like a hobby for you and perhaps grow into a business for those interest in the super green stuff. For me, I am a nubmers guy and beleive there are cost benefits for stuff and most of the extereme approaches to stuff don't make economic sense. I don't think spray foam is at a point to make economic sense, for example.
Anyway, I am concerned that hot air from the stove will rise (duh?) and make it difficult to be comfortable at seating level. The particular stove I am looking at has a blower system, which most people in this area use to pull air in from the outside. This does not make much sense to me. Why do you want to bring cold air into the stove surround to be heated (NOT COMBUSED)? Why try to warm air from 10 degrees up to 90? You can also use the blower to pull air from the room to be heated (70 degrees up to 90 degrees - makes more sense). So I was thiniking about using the blower (388 cfm) to pull air from the distant kitchen (say 35 feet away( so as to create an air flow in that situation tending to pull replacement air from the great room area with the stove into the kitchen. This still does not address the hot air rising to the ceiling.
I think you would be correct that to use the furnace an to move air would be overkill and expensive. You said you have a small fan system (167 cfm), could you be more specific or point me in a direction to investigate. That was one idea I had was to add a separate air movement system to bring ceiling air back down to teh floor with some kind of a register in the great room ceiling.
Yup, no spring chicken here, memory goes back considerably more than 40 years. You're not the cartoon character... As I said, I've been enjoying the fruits of my efforts for 20 years already. That web page is woefully out of date, put up as a surprise to me. I have no access. But it brings in a steady trickle of interest from a surprisingly large area. European visits are annual. I enjoy the consulting. One mystery was how that page got linked here, somebody in management did that. Possibly because it's linked on the immense BuiltItSolar site.
BTW, construction like mine is almost always substantially cheaper than US stick built. Depends on the concrete design and labor obviously. One nearby, built like mine but sans the curves, appraised 50% higher than construction cost, a direct comparison to stick built here. Instant equity! And opportunity for the owner to get a new truck. He likes the house so much he's putting up with an 80 mile each way commute. Crazy, but he says the job's not forever, the house is.
The French group is almost entirely thinshell concrete, curvilinear. NOT domes, though based on the Maison Bulles movement. Their goal is a house costing no more than 10,000 €. The original PAHS there was shaped like a nautilus. Another, near the Pyrenees, has rammed earth walls. PAHS has nothing to do with architecture, it's a heating/cooling system. My architecture was copied from cheap US commercial construction.
I'm a little lost with you. Are you designing a house, or completing construction of one, or retrofitting?
If designing, just get your air system correct and you'll have no need of an additional fan. Had a long conversation yesterday with a Georgia PAHSer nearing completion. His air system was a primary topic. House similar to mine but with a full basement, atrium connecting the 2 floors. You wouldn't believe the crystal chandelier he found for the atrium. Well, maybe you would, but it wouldn't fit most houses. Georgia has intesting requirements for non-standard houses. To get a building permit, the applicant must first prove the house will maintain 68º in January. His will, no woodstove. We've also figured out how to deal with changes in barometric pressure, which are a major problem for his wife. His air system is considerably more complicated than mine.
Regarding your furnace blower to move air, you won't find much electric draw there. A better question would be how much maintenance/replacement cost.
https://www.surpluscenter.com/ is a place you want to check out. Inventory changes a lot, and I notice they are no longer generally using the term "muffin". 16-1367 will give you 198 cfm for 17 bucks, draws 38 W. Another moves 122 cfm, for $11. Lots of fans there, various voltages. I keep spares on hand, but running nonstop they tend to last 10 yrs or so.
Good luck Al (call me anything you want, just don't forget to call me for dinner).
Way beyond me
Your details and scinece and discussion are way beyond me and really beyond my desires for my house. However, your knowledge of heat and air movements could be useful if it could be brought down to a simple level to address ONLY teh issue of heat rising from a wood stove. I am not building a PAHS, I just want to be comfortable with a wood buring device in my great room.
I have designed my house and I framed, roofed, and sided it. No electrical plumbing or HVAC yet, so I can still move a few things around if necessary. My plan for heating is forced air electric and heat pump and a large wood buring ZC unit. Originally I was not thinking of heating with wood, just the romance of it for the wife or only use it when it is really cold and the heat pump craps out in terms of efficiency. As I keep thining about it I think I might use the stove more than I originally thought. I don't like ceiling fans and like the idea of a chandiler in its place. So I am trying to think of ways of moving air IF THAT IS really necessary.
The line you apparently missed:
"If designing, just get your air system correct and you'll have no need of an additional fan."
This is what I did, from the get-go.
No, I got it
Design it right. Sure, great advice. Just design it right. Got it. Thanks.
Have a small (8" cage) blower
Have a small (8" cage) blower above the wood stove with ducting to the far side of the room.
Works well, controlled by it's own thermostat set at 90F on 85 off.
Easy to do if you are now building.
say hello to Nell for us <G>
Kind of my thoughts
That is the type of thing I am thinking about. It might be tough to get ducts to the other end of the room. I can easily run a duct between the rafters and then down between the studs in the wall, but that does not get me that far from the stove. Not sure if I could then extend that run (between rafters and studs = 30 ft) and then diagonally in the crawlspace another 30 feet. Do you think that run would be too long?
And what is the noise level of the type of fan you suggest?
Thanks
Ducts and Fans
double post
Ducts and Fans
Could you post a pic of your fireplace and great-room's ceiling beams?
If you have hollow zones on each side of your fireplace, you could run ducting or the flex ducting from a floor level wall register outlet to a smaller inlet air register at/near the ceiling.
Here's a start place for a quiet blower. I can't get the cut & paste option to work.... So at Amazon.com search for a duct booster blower. Hydrofarm ACFB8 8" duct booster fan to pull the warm air down to floor level.
Bill
Would love to post pics
I will see if I can take a couple of pics this week. then start the nightmare of figuring out how to post them here. We will see.
I hear you aboout using the fireplace surround and chase as an avenue for ducts. My fireplace framing is free standing, ie you can walk completely around it and is about 8 feet wide and 30 inches or so deep. the firebox itself is four feet wide. Therefore I should have a couple of feet to teh side of the firebox. Actually the chase narrows to six feet, but could still run ducts up/
Do you think a duct terminating so close to the fireplace would be helpful? I am sure it would be better to dump the air somewhere further away. And if so I suppose I coud still use hte chase.
Thanks.
I will check out the fans.
Any warm air at floor level is good...
With all the trapped warm air in the top of your great room, bringing it down to floor level is a good thing. Having a small snap switch thermostat in the top inlet would automatically start the blower(s) to prevent the blower from causing a chill factor.
With this new cold snap here in North Central Texas, I started our Lopi fireplace insert. Outside temps have been down to 21*. After a few days and nights, I placed a digitial thermometer on the hearth, about 3 ft. away from the start of the insert. Floor temp was 67*. At chest high in the same room of the fireplace, the same thermometer read 80*. So, in a reverse way, the Lopi's twin squirrel cage blowers take the colder air and the insert heats it to 220* as it leaves its top outlets. By the time the two temps mix, the room is warm and confortable. With a KillaWatt meter, those blower can run 24 hrs. on .18-cents, a very economical and cheap way to heat the house's cold air.
By bringing down the warm-hot air from the high ceiling, the temp differentical isn't as wide, but what you are trying to do is "use" the warmer air and de-stratify the air at the same time. It would be interesting to hear what your floor level air temp is and what it is at the top of the ceiling.
If you don't "use" that warm air, without pics, I'm guessing that possibly at the most, you have 8" of SIPS plywood/foam panels as your Great Room's roof decking. Even with the foam, all those BTU's in that level of stratified air are going to be wasted.
Personally, and without pics to see, going for a very high end "Oil Rubbed Bronze" bee-hive motif 52" ceiling fan, or two may be the better option, Those would look good and rivial the appearance and cost of a chandelier's crystals you'll have to take down and clean yearly. Plus, the slow speed fan(s) will do their job moving the air down from that high zone. I've seen some very interesting ceiling fan designs that would compliment your described architecture, tones, and textures.
Bill
Thanks Bill
After taking VaTom's step by step instructions to heart I am still interested in everyone else's thougts.
You you have a Lopi insert with a built in blower system and NO ADDITIONAL blower system or ceiling fans? Correct? How high is your ceiling? And you are statisfied with the heat stratification? Yes?
Not sure I agree with you on the asthetics of a fan vs a chandiler.....
However, you point about cleaning that chandiler is well taken.