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Moving Warm Air From 1st Floor to Basement???

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by BurnIt13, Mar 13, 2012.

  1. BurnIt13

    BurnIt13 Minister of Fire

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    I was reading through the following thread, and it got me thinking.
    http://www.hearth.com/econtent/index.php/forums/viewthread/91087/

    How can I move warm air to my basement? I've mastered moving warm air into adjacent rooms to the stove room and upstairs...but how on earth would I get warm air downstairs???

    My wood stove is centrally located on the first floor of my two story colonial. Coincidentally it points directly at the upstairs staircase, making it easy for hot air to travel upstairs. The door for the basement is right next to the staircase going upstairs...so there is a direct shot from the stove to the basement door.

    My basement gets quite cold in the winter when the boiler isn't running. Getting some heat down there would be a huge bonus.

    Any ideas???

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  2. Wade A.

    Wade A. Feeling the Heat

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    My $.02? You don't. Not with any degree of efficiency. Moving hot air up, by pushing cold air down is a natural convection loop, capitalizing on the the denser nature of cold air, and the less denser warm air's. Doing the opposite is that much harder.

    Unless you've got a very wide open stair well, and a pretty big fan, my prediction is that blowing cold air downstairs is not going to get you any great result. Could be wrong, and I'd be tickled if I was. Like I said, my $.02
  3. BurnIt13

    BurnIt13 Minister of Fire

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    Yeah....I was starting to get to get scientific and the only somewhat easy, attractive option is to install a "thru-room" fan in the floor and blow the warm air down through the floor. Even then, the warm air I'd be blowing down is the coolest air in the room near the floor. I'd have to rely on positive pressure for the displaced air to come back up through the basement stairwell.

    Even then....there is no going back. I'd have to cut a 8" hole in my floor and install a register with a fan in it. Looks like this:
    [​IMG]

    It takes 85 watts to run and I'd likely need two. That would run me about $20/month in electricity even if it worked well.
  4. Wade A.

    Wade A. Feeling the Heat

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    I actually wrote a paragraph about that option, but deleted it before posting. I didn't even want to go there. At most, I think you'd make both levels just tepid.
  5. BobUrban

    BobUrban Minister of Fire

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    What about using an OAK that draws from the basement instead of outside?? Someone may jump on here and explain why this is a really bad idea but I am throwing it out there and curious as to anyones results or downfalls that have tried this.

    Seems like the stove would eat cool air from the basement and create a bit of flow to replace the void pulling some of your warm air down the stairway???

    Am I totally off base here? Worst case is you could close off the OAK or re-route it back to the outside if you already have one hooked up.
  6. Wade A.

    Wade A. Feeling the Heat

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    A good thought Bob, and I dunno for sure, but I'm thinking you could not pull enough air to make an appreciable difference. Remember, that air upstairs has to be reached where it is hovering on top of cooler air. That takes some real air displacement. (The amount of which is specific to the volume of the rooms, the volume air that is drawn into the OAK, the size of the fire, the tightness of the house.....and on and on....)

    Which makes me reconsider and wonder if a floor fan with lots of CFM might indeed be worth considering. Until someone posts with some "ground-truth" on this though, I'm just guessing. But, as I said, the degree of performance is subject to a LOT of variables.

    Burn, have you tried pointing a floor fan downstairs to run a little test? If so, what....?
  7. dafattkidd

    dafattkidd Minister of Fire

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    How big is the basement? Is it finished? I think your best bet is a stove in the basement.
  8. Doing The Dixie Eyed Hustle

    Doing The Dixie Eyed Hustle Minister of Fire

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    I haven't been able to get heat down 5 steps in 4 years, I doubt getting it down to a basement is going to work.

    I'm open to thoughts, however :)
  9. stoveguy2esw

    stoveguy2esw Minister of Fire

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    simple version, aint happening

    long version. heat rises, cold descends, forcing heat down is like herding cats, as you shove it down it just blossoms back up around he air mover, you would literally have to pull a stronger vacuum in the lower space than the hot air can overcome by risingand "suck" it down there. this is not going to be accomplished with a residential air mover, and that basement air would have to be pumped out of the structure altogether, remember also that the upstairs air has volume and in order to evacuate air downward air must replace it upstairs, where is that air going to come from?

    its simply not somthing thats gonna happen, not bashing the OP, it was a great question and one ive had asked to me many times in the past, fighting to overcome physics generally is a losing battle though, time to find a heat source for the basement which will be located there, only way to heat that space
  10. jimbom

    jimbom Combustion Analyzer

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    Enclosed stairwell, 8" circular fan, midway down the steps, point down, open doors, move heat. I can raise the temperature of the basement ceiling ~4 °F. Experiment with the fan location. One particular step works best for me. Doesn't really help much if the basement floor is cold.
  11. madison

    madison Minister of Fire

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    I see two options, Zone the basement off your furnace or second stove... That heat will rise as well and the upstairs will be a bit warmer as a result.
  12. DanCorcoran

    DanCorcoran Minister of Fire

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    Whatever air leaves the basement (displaced by the air blown down from upstairs) will be the warmest air, at ceiling level. You sure you want to do that?
  13. BurnIt13

    BurnIt13 Minister of Fire

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    Nope....there was never really a need to warm the basement. I recently spruced it up and will be spending a little more time down there so this question popped in my head.

    The basement is about 675 square ft. It is unfinished. 1900 years old with a fieldstone foundation. Brick above grade. I have lined the brick with 2" foam board insulation (R11). I have framed a "clean room" down there that acts as an exercise room....would be nice to get it above 50 degrees in the winter.

    After everyone's comments I'm thinking I have 3 real ways to heat the basement.

    My gas steam boiler vents through an old chimney with a 6"x6" flue that has a flexible aluminum liner (that barely fit). In the next couple of years I will be upgrading my heating system from a gas steam boiler to gas forced hot water baseboard.

    1. When I upgrade, create a zone for the "sorta finished" room in the basement. With the rest of the basement unfinished, and the interior walls of this room uninsulated I fear that the heat loss will be too great in the heated room and the thermostat will never keep up. I would be better off with a space heater and only turn it on when I am in the room.

    2. Upgrade to a wall hung direct vent boiler. This will open up the flue in the chimney. There isn't enough clearance for a wood stove chimney pipe but there is for a pellet stove or gas stove vent pipe. Probably not the most cost effective option though.

    3. Install a wood stove against a wall. This will involve installing a new chimney on the side of the house. Again, not very cost effective.

    So option 1 seems like the cheapest and easiest way to provide heat to the room I want "warmed".
  14. elwoodps

    elwoodps Member

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    Another possible option during your boiler/baseboard heat upgrade would be to add a zone of hot water radiant floor heat in the "sorta finished" basement room. When done right, the heat radiating from the floor can make the occupants of a space feel warm, without heating the room air to what would normally be considered a comfortable temperature. An example of this phenomenon that we're all probably familiar with is how comfortable it can feel when you're outdoors in the sun with air temperatures in the 40s.

    The best designed radiant heat setups aren't controlled by an indoor thermostat that switches the heat on and off, to maintain a set air temperature: They're controlled by an Outdoor Reset thermostat, Set Point control, or similar device that regulates the temperature of the water going to the radiation (cast iron radiators, radiant floor, radiant ceiling, etc..) in order to keep the occupants comfortable, more or less independent of the room air temperature.
  15. FGZ

    FGZ Member

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    An outside air kit has to be routed to outside air in order to function at all. It is intended to route the air your stove needs from outside directly to the stove, so that your stove isn't feeding off of inside air which is being drawn in from the outside via air leaks throughout the house. Your stove has to have a certain amount of air to operate, and it will get that air either through the OAK or through tiny cracks/leaks throughout the house. Letting the OAK draw from in the basement is almost exactly like not having an OAK at all and won't help you draw hot air down into the basement without a lot of work. And even after you do all that work, you're now cooling the rest of the house by not having a functioning OAK.
  16. Ehouse

    Ehouse Minister of Fire

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    If you have duct work from a previous forced air system you could disconnect the cold air return ducts and put a small (mine is 1/25 hp) constant duty fan in the plenum controlled by a vari-speed switch. The air dropping into the basement would be the coolest from up above but still warmer than the basement air itself. leave the returns intact (and insulate them) and you have a way to evenly distribute the wood stove heat throughout the house. Add a coil on a loop from your new boiler and you have a home made hydro-air system that can kick on for back up heat.

    Ehouse
  17. Jackfre

    Jackfre Member

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    It is generally not a good idea to mix basement and house air. You potentially have radon and humidity, musty air issues in a basement that can affect the upstairs living space. If you want to persue this you could look at the floor to floor Tjernlund Aire-share. Pushing down there would likely not be enough static capability to "really" circulate the air in that configuration. It is excellent going the other way. A better option would be to go with one of the Fantech fans that could handle several feet of duct work and introduce the warmer air in a lower position so the heat could then rise.

    Your statement that "Ina few years you will upgrade to a warm air system" is, imho, not a good idea. My current house had even "converted" to a central HVAC system. The problem you end up with is that you basically have to tear the house down to properly add ductwork. Then, in that type installation the sealing of that duct is problematic, meaning it leaks like crazy. A 90% efficient furnace with a 70% efficient duct system will give you a 63% eff "high efficiency" system, day one. As well, you will loose closets, etc. I have a DOE publication that says the typical duct system will leak from 18-42% of its energy

    Here is what I did. I pulled the entire 5yr old ducted system. In addition to my lovely VC Encore (whew, had to satisfy the nature of the place;) I installed Fujitsu mini-split heat pumps. They do the heating and ac (I'm assuming you want the ducted system for ac purposes) better and more efficiently than your ducted system, with a great reduction in labor expense when compared to installing a GOOD duct system. As well, I have a Rinnai Energysavers. For your equipment room, the EX11C is the correct model and will operate brilliantly in your space.

    I like my equipment to be "net to the space" with little to no distribution loss. I have that with my Encore, mini-splits and gas fired Direct vent wall furnaces. Until last summer I lived in C MA too, and represented the manuf I recommended, so my bias is noted, but this is worth a long look prior to doing your planned modification. Happy Heating!
  18. mywaynow

    mywaynow Minister of Fire

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    I second the OAK option. It is very easy to do and will move air. If you pickup the air at the floor level in the basement, it will have to be replaced by air drawn from the source with the least resistance. Think about how much air goes out the stove pipe. That is the volume of exchange you can benefit from in the basement. Do take from ground level to avoid cannibalizing your warm air. It may be slow to react. but all air heat by stove is.
  19. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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    I did a little experiment five years ago with this and succeeded. But it took my humongous CFM commercial fan that we used in the warehouse blowing down that staircase to the basement to do it. I figured out that the electricity that thing used could probably heat the upstairs just as well. And not sound like a DC-10 taking off in the house.

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