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Moving Woodstove Heat around the house

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by hotprinter, Jan 25, 2011.

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  1. hotprinter

    hotprinter Member

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    Here is an interesting article on moving heat.

    http://tinyurl.com/67s6smf

    According to this you should have the woodstove upstairs. Most of us in Alaska have them downstairs with the thought that hot air rises. Our stove is in the middle of the basement and we have a hard time getting the hot air upstairs. I like the idea in the article about moving the air through vents. I am going to put a vent right above the stove that will go right to the kitchen and living room. Then we will put a vent in each corner of the living room hoping that that will circulate the air coming up from the woodstove back down to the basement in a circular pattern like the illustration in the article. What is everyone else doing to move the air? Are there any fire codes or anything I need to be aware of? Also, do most feel it is necessary to use the fresh air kit to hook up to the blaze king? Ours is right in the middle of the room so it would take some work to get fresh air. Thanks for any info or discussion on this important topic.

    *** NEW BLAZE KING ULTRA TO BE INSTALLED THIS WEEK***

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  2. snowleopard

    snowleopard Minister of Fire

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    Hotprinter, I agree, this is a really important topic.

    I thought this article had some interesting points. When I read your post, I thought of `upstairs' to mean in the upper story of a house above the ground floor, but in the article, I'm reading that to mean `not in the basement, at ground floor level'. There are some people here successfully heating a house with stoves in the basement, but there are a couple of things they have to deal with. One is the subject of your post, which is heat circulation, and the other is the chimney effect--the idea (as I understand it) that when you bring in outside air, it's going to want to vent up at the height that it comes in from--that you're dealing with a pressure differential driven by differences in temperature. So your stove has to work against that to pull air down into a basement.

    I'm in a two-story house, with the downstairs story earth-sheltered across the back, and partially so on the east and west sides.. I was concerned about stack effect in this house, and wondered about putting in an OAK. The installer advised against it, saying that in extreme weather, he's seen them turn into ice-clogged nightmares, suggested that I at least wait and live with my stove to see if it was needed. I'm glad I did, because my system works really well, and I think it's due to something I haven't seen discussed much on here nor did I think about it before I installed the stove.

    To make a short story long and boring: the house has a stairway running along the center of the north wall; at the head of the stairs, parallel to the run of the stairs, is an slightly-leaky exterior door. The stairs run further than the dividing wall, with the last several steps open into the rooms below (landing, kitchen. dining room all fan off the base of the steps).

    There is a semi-open floor plan downstairs, with the kitchen to the east opening at the other end to a sunroom, which opens at its other end to the dining room, and the stove is located in the open diningroom/livingroom area--in other words, a large circle of rooms. A large pass-through window between kitchen and dining room contribute to this circulation as well. There is an exterior door in the sunroom at the opposite end from the dining room door, through which some outside air is pulled. Differing temperatures work as an engine to drive a slow circulation between these room, almost unnoticiable except in the results.

    I feel a definite flow of cool air down the stairs at ankle height when the stove is running, and it feeds the air flow. It's not a fridgid breeze, not chilling, just cool, even in very cold weather, so considerable air mixing must be taking place on the stairs. I can feel the flow in a pretty straight shot from the stairwell to the stove air intake. I assume that as the cool air comes downstairs, a significant (although probably not equivalent) amount of warmer air is displaced up the stairs.

    The stairwell ceiling is the same height as the upstairs ceiling, instead of having a ceiling that follows the dropping of the stairs, and I think this is a big part of what makes the house work in two ways: there is a considerable amount of headroom in which the hot air can pool on the upper-story level, so rather than exiting under the upstairs door, hot air can be driven up above the door height before it gets to the door--like a pool of hot air above the stairs; secondly, cool air entering under the upstairs door creates turbulence that drives warm air out of this pool, and gets it moving into the rest of the upstairs. Or so I assume.

    Upstairs, the bathrooms are located centrally, backed up against the stairwell wall. By leaving doors open to and between the bathroom, an adjoining bedroom, and the upstairs living room, another circle of air is created just off that reservoir. Temperature differences between these rooms create a constant, slow air flow--too slow to feel, but which carries the air back even into the far bedroom on the east side of the house--furthest away from the head of the stairs. When the stove has been running continuously for several hours with a moderate fire, we get a consistent temperature in the house, with the upstairs bedrooms only a degree or two cooler than the hearth room. I dont have cold drafts in the hearth room (although the sunroom and kitchen floors run cool, unless the boiler is running).

    I have thought a lot about this, because I didn't expect it to work so well. I've tried to visulize airflow as cool and warmer air flowing around the house, and am still figuring this out. I expected warmth downstairs, and a little `heat rises' effect upstairs. Instead, I am comfortably heating the whole house, and I wondered why (no complaints). I thought the fact that the upper story is somewhat labrynthian would work against my heating it, but I think that the temperature differences in this circular maze of rooms is actually driving circulation.

    I've been finding that everyone I spoke to who gets this same consistent warmth in their houses in this climate has something similar in their setup--either a series of horizontal-plane circles like mine, or ones on a vertical plane created by multiple grilles in rooms. I'm not an engineer, obviously--just a curious observer who got lucky with house configuration. But I wonder if it isn't something we should all be looking at a little harder in designing the house-stove-stack system. I think in a good situation, nothing needs to be done to move the air; the temperature differences between warmer rooms/cooler rooms drive circulation. It doesn't have to be a fast breeze--it can be imperceptibly slow, and still work. Look at how slowly the Great Current moves, yet it drives climate planet-wide.

    Consider making haste slowly on circulation changes until you get the BK up and running and see how things are flowing for you. Congrats!
  3. hotprinter

    hotprinter Member

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    Nice Post! Thanks. I am still trying to visualize your house layout. It sounds similar to mine, but I cannot seem to get the hot air upstairs, our house is pretty tight. Our house has a split level entry with the basement stairs going to the right and the upstairs going straight up from the landing halfway between. The woodstove is down the stairs, turn left and then it is sort of right in the middle of the living room (downstairs). It is right underneath the upstairs living room / dining room. I am planning on cutting a floor vent right above the stove with 2 additional vents near the outside wall hoping that will allow circulation, with the hot air coming up by the stove then going down the vents and maybe the stairs as in your house. Circulation will be the key. We are going to try it without a fan (we will have the upstairs ceiling fan going and maybe I will have it blow up instead of down. We have a vaulted ceiling and the fan is right in the middle so it should bring the warm air up and then move it down the ceiling. I hope I get as good of results as you have. Again, I appreciate your post, it was very insightful...
  4. VCBurner

    VCBurner Minister of Fire

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    Nice thread, always cool to hear about air circulation theories. I use small fans on the doorway floor, pointing out of the coldest rooms in the house. You can feel a rush of hot air going into the room as soon as you turn them on. Almost instantly the negative pressure starts sucking up the hot air. Just put your hand up and feel it. The cold air finds its way to the stove and gets a nice circulation going. They need to be small fans, though. And low to the ground. Anything big will cause the hot air to disperse and cool off before it reaches the cold room.
  5. sandie

    sandie Feeling the Heat

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    VC burner when you said "I use small fans on the doorway floor, pointing out of the coldest rooms in the house"
    I wonder if you are having the fan at the floor doorway pulling FROM the room heated by wood INTO colder room or FROM the coldest room into the room heated by the wood stove?
    I struggle with this. I have a 25x15 ft room that the stove is in and two open doorways leading to kitchen and to dining room and have a fan near the stove blowing from behind the stove out into the room. Works but would like to heat the rest of the house if possible at least on first floor but am not getting that from the VC Resolute lll. I get a room taht is now 59 degrees up to average about 66 degrees after a few hours of burning. This room has no other heat in it running(electric baseboard) but the rest of the house is heated by oil base board heat. So this room cools off the house so furnace runs a lot. When i run the wood stove the house stays pretty much at the temp I have on themostat and furnace runs a little less and this room warms to the 66 or 67 degrees. Not sure this stove is working at optimal of what it could, never cleared from inside out but I do keep teh holes inside clear and actually have vaccuumed them at begining of season and keep them clear of debris. Also have a secondary air on left side rear that I keep clear. Would love to heat more of the house with the wood.
    Ideas? Fans on floor should be pointed out from heated room or into heated room from colder one the theory being if you bring in cold air it will heat that colder air and displace warm air so it is pushed to next room. Thoughts?
  6. VCBurner

    VCBurner Minister of Fire

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    Make sure when you do the test, you're are burning good hard wood and get your stove at maximum BTU output (within normal temperature range of course,) It helps to have a stove top thermometer to see what's going on inside the stove. Looks are deceiving when it comes to fire. Sometimes it may look like the pits of hell in there but the temperatures are not good enough. Other times it may not look so bad but you're beyond recommended stove top temps. I think VC does not want them to be operated at more than 750 for long periods of time. Its Ok to get to 750 but sustaining that temperature for log periods will damage the stove.

    Good luck Sandie, let me know how it works out.

    Chris
  7. Jutt77

    Jutt77 Feeling the Heat

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    A lot of folks place fans at the floor level. While this can assist natural convection, I think a fan is much more effective at moving hot air when mounted closer to the ceiling. Here's what I do to circulate heat which works WITH the physical properties of warm air. Most homes are designed with transoms. Transoms are basically the top of a doorway and act as a dam for hot air. The key to moving hot air from one space to another is to have fans reside where the hot air is thus the closer your fan is to the ceiling level the more effective it is at moving hot air. A lot of folks place fans at floor level and blow back towards the stove. While this is fine as it assists convection, it doesn't effectively move the hot air past the transom from one space into another. Imagine if you flipped your house upside down, the transoms would then be a floor level and it would then make sense to have the fans at floor level since you would then have to move cold air past the transom to another space.

    Since there are no obstacles like a transom at floor level, cold air is automatically pulled from a cold area (back of the house for example) to a warm area (stove room) via high pressure to low pressure movement without the need for a fan. However, due to transoms, moving heat at the ceiling level effectively requires fans.

    In my house (single level ranch 1300 sq ft), my stove is at one end of the house. My bedrooms are in the other end of the house. I mounted a 10" fan on the bottom of the transom from my stove room pointed to the rear of the house. Another 10" fan is pointed from the rear of the house into our bedroom. During a 20 degree night for example, the stove room stays at around 75-77, the rear of the house stays around 70-72 and the back bedroom stay around 66-68 degrees. Without the fans the back bedroom hover around 50 degrees.

    To test how well your moving the hot air, have someone stand in a room furtherest away from the stove while someone makes a very small bit of smoke come out of the stove into the room (blow really hard into one side of the stove and you should get a puff of smoke to come out of the other). Smoke rises the same as heat and both flow along the same path if you will. I can smell smoke in the back bedroom just a few seconds later so I know the air movement is working quite well. If it is taking a while to smell the smoke then you should redesign your air flow.

    Here's a good article about this: http://www.woodheat.org/index.php?option=com_content&view=article&id=52&Itemid=60

    I drew some cheesy graphics showing one my fans:

    [​IMG]
  8. Boozie

    Boozie Feeling the Heat

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    Where did you get your hanging fan? I had a small fan that I used to set on my computer. I attached it to a curtain rod extension. It's blowing OUT of the room. Now I just need to know where to set a fan blowing cold air INTO the room. I posted my floor plans on here previously.

    In case you didn't see my floor plan as you leave the family room, walk up 2 steps to landing, turn left and go up stairs. To the right is an open kitchen, to the left is hallway down to the bedrooms.

    The stove insert is at the end of the room in picture #2.

    Attached Files:

  9. Jutt77

    Jutt77 Feeling the Heat

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    Hey Barb,

    I just replaced the black fan with 2 of these: http://www.amazon.com/gp/product/B001R1Q2C6/ref=oss_product

    Cheap, very quiet and they have 2 screwhead slots on the bottom of the base to mount to a wall or in my case, the bottom of a transom. They are a 3 speed model but I never have to set them any higher than the lowest setting.

    As for a floor level fan, try placing one below your other fan pointed towards the stove. That should help in theory.
  10. VCBurner

    VCBurner Minister of Fire

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    Hello Jutt77,
    I agree with the things you said about moving hot air around the house! But there is only one problem with your theory:
    There are two parts to achieving a good HVAC system. Supply and return. Without return air, supply air will not be as effective. The best solution is to combine both and get the ideal air movement. The level of success achieved with only one of these theories depends on too many variables. So, the end result can't be measured on this thread. The proof is in the pudding. If one more works better than the other in a particular home then that's what should be used. I don't it's a matter of right or wrong here!
  11. Boozie

    Boozie Feeling the Heat

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  12. ironpony

    ironpony Minister of Fire

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    I have had the most success blowing the cold air, floor level, out of the cold room/area
    towards the stove area, my results have been all the areas are three degrees
    warmer respectively
  13. Jutt77

    Jutt77 Feeling the Heat

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    Thats a good point, my solution works well in my particular home, floorplan, amount of insulation (or lack of), etc. Adding another fan blowing cold air towards the stove would probably add good results as well but I've found that I dont need it at this point. I might try it though on a really cold night and compare the differences.
  14. Jutt77

    Jutt77 Feeling the Heat

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    No, the other is in the back of the house blowing the warm air into the bedroom.

    Here's a Visio diagram. Please excuse the sloppiness, I'm an engineer at a telco and use Visio for network diagrams not building design.

    The diagram is labled. The arrows point in the direction that the fans are blowing. The fans are mounted on the bottom of transoms (top of a doorway). As I mentioned earlier, the cold air is pulled towards the stove quite effectively via convection so I haven't found a need to add a fan at floor level but your results may vary depending on a lot of different variables.
    This setup raises the ambient temp in the back bedroom almost 20 degrees compared to no fans and thats with the fans set on the lowest setting.
    [​IMG]
  15. DonNC

    DonNC Member

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    Great question and good answers guys. This thread is going to help me allot, starting now.
  16. VCBurner

    VCBurner Minister of Fire

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    I have thought about putting a corner door fan on my door header. The livingroom is quite a bit hotter than the rooms furthest from it, just like yours. I could see a corner header fan doing wonders at pushing all that heat that gets trapped above the cased opening. Maybe you can put the fan on the bedroom doorway on the floor pointing out and we can compare results! :)
    Thanks for the pics and blue print.

    Chris
  17. egclassic

    egclassic Feeling the Heat

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    I just bought one of these (http://www.suncourt.com/EntreeAir.html) from Lowes to send warm air down a hallway to our bedroom. Before, our room stayed at around 66-68*. With this fan installed in the doorway to the hall, our room now gets upto 72*. Well worth the $30.
  18. loon

    loon Minister of Fire

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    this is heading towards the bedrooms.

    the bottom of it is 7'2" so still lots of room..

    loon


    [​IMG]
  19. BrowningBAR

    BrowningBAR Minister of Fire

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    I have that exact same fan behind the Vigilant right now. Second season in use. I have it up on some red brick so the fan is level with the top of the stove. Seriously improved the movement of the heat.
  20. Jutt77

    Jutt77 Feeling the Heat

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    I think I'll try placing the fans at floor level blowing the opposite direction (towards the stove) then I'll record the temp results from various parts of the house every hour or so and get an average. Then I'll put the fans back up in the original location and record using the same method. I'll wait for back to back days of similar weather to help eliminate that variable and go from there and compare results.

    My initial guess is that blowing towards the stove will indeed facilitate convection but those *&%^ transoms will probably be a problem.
  21. shawneyboy

    shawneyboy New Member

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    I use 2 fans. To give you an idea of my setup I have an insulated basement stove room. Stairwell that leads up (20 feet from stove) to main level. I have a box fan at bottom of stairwell, pulling the cool air down the stairs, then pushing it in a circular pattern around stove room. At the top of the stairwell, in the doorway, I have one of those doorway fans, little 6 inch job, that takes captured warm air (transom) and "assists" it to get released to the main floor. On the main floor I have a few ceiling fans that I have always used, blowing up. Basically the 2 fans facilitate both the supply and the return.

    Shawn
  22. phatfarmerbob

    phatfarmerbob New Member

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    My stove is under a 2 part AC unit mounted just below the ceiling... i put that on FAN ONLY so it sucks air from about 3 inches from the ceiling and blows it at 45 degrees toward the hallway .. at the hall i have a fan on the floor blowing air back into the room... now i was wondering if a bathroom vent above the stove with a pipe leading up stairs throu the wall to about midway up the bedroom wall ( i dont want to cut a hole in the floor) would add heat to the bedroom any thoughts ?
  23. WoodpileOCD

    WoodpileOCD Minister of Fire

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    :cheese: great thread going here. I've thought about doing this and am going to try to find the corner fan at Lowes referenced here.
  24. Boozie

    Boozie Feeling the Heat

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    Where did you get this fan?
  25. BrowningBAR

    BrowningBAR Minister of Fire

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    It appears to be a window fan. I have two. They can either blow air in or out. Some allow one fan to blow in while the other fan blows out. During the spring/summer they work great as long as the temps aren't too hot and the humidity isn't too high.
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