1. Welcome Hearth.com Guests and Visitors - Please enjoy our forums!
    Hearth.com GOLD Sponsors who help bring the site content to you:
    Hearthstone Soapstone and Cast-Iron stoves( Wood, Gas or Pellet Stoves and Inserts)
    Caluwe - Passion for Fire and Water ( Pellet and Wood Hydronic and Space Heating)

Moving the heat!

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by Squiner, Aug 29, 2009.

Thread Status:
Not open for further replies.
  1. Hurricane

    Hurricane Minister of Fire

    Joined:
    Feb 18, 2009
    Messages:
    565
    Loc:
    Central NJ

    I do not know what this test will prove. If you do not have a fire how do you test the chimney flow ? No one is going to have the fan running 15 minutes before starting the fire the fan is only used after the fire is good and hot with plenty of draft going on. I tested mine by having the stove running with coals and a fresh load of wood maybe 1/2 hour in so the air was lowered. After turning on the fan I checked the flame and fire performance for about 2 hours and did not notice any noticeable difference. I even tried opening a window in the stove room to see if the fire increased but it did not.

    On a new air tight house this may have a noticeable difference, and or if the stove was in the basement. In my house the return air has a wide open staircase to return up through. All I know is it worked for me. I would love to move the cold air instead, but moving cold air up from the basement would not be replaced by warm air downstairs without actually blowing the warm air down. In the colder months I will likely put a fan at the bottom of the stairs blowing up to increase air flow.

    Helpful Sponsor Ads!





  2. Lumber-Jack

    Lumber-Jack Minister of Fire

    Joined:
    Dec 29, 2008
    Messages:
    1,736
    Loc:
    Beautiful British Columbia
    It certainly wouldn't hurt to do that test, although I would add turning on any exhaust fans in the house as well. Any exhaust fan will have more effect on the pressure in the house than a fan that simply blows air from room to room. And of course much depends on how tight the house is. In an airtight house (if there was such a thing) the changing barometric pressure outside would have far more bearing on chimney draft than any exhaust or circulating fans could possibly have. As houses have got tighter and tighter over the years they have learned how important it is to add OAKs to appliances with chimneys and fresh air exchanges to furnaces.
    One point (which has already been mentioned in this thread) that Oconnor seems to miss, or avoid, is that crucial opening under the doors. He speaks of doors being closed as if that seals off , or restricts, any possible airflow. This simply is not the case, and heating contractors take that into consideration when designing flow pattern for forced air systems. Part of the "balance" they talk about is insuring air flows equally to all parts of the home (big rooms may need several ducts, while small rooms may only need one, adequate centralized return airflow, etc...), as long as there is an air gap of an inch or so under the door the air will flow freely, into the room and out of the room, with out any problems, the system remains balanced.. If this were not the case every time you closed a bathroom or bedroom door the system would be out of "balance".
  3. Squiner

    Squiner New Member

    Joined:
    Aug 22, 2008
    Messages:
    173
    Loc:
    Maryland
    Carbon_Liberator: Thanks for taking the time to understand/explain the issue , or lack there of, with respect to draft and circulating the air within a house.
  4. westkywood

    westkywood Feeling the Heat

    Joined:
    Oct 14, 2009
    Messages:
    366
    Loc:
    Kentucky
    I was just reading on the net about using duct work with duct fans ( in the attic etc )for a wood stove is against fire codes. It says that if there is a fire, the fire will be drawn up into the attic through the duct. Also if there is smoke, it can carry the smoke to the bedrooms ( or wherever the vents are ). I know this has been mentioned on here, but I havent heard it was against fire codes. Of course I have this system in my house and it works great. But if it is going to void my homeowners, I'll take it out. Anyone got info on this??
  5. EL DRIFTO

    EL DRIFTO New Member

    Joined:
    Oct 8, 2009
    Messages:
    65
    Loc:
    Independence MO
    considering the differences in danger/safety of having a stove, and having a stove with forced air:

    an ADDITIONAL co detector wherever it makes sense, just not near turbulant air
    considering the co may go directly into the fan

    shut the bedroom door, stuffed a pillow against the bottom & could of opened a window for all i know...
    instant vacuum on stove room. ex fans & some peoples houses aren't air tight
    if the air were flowing the other direction, the stove would get boost!
    so oak is NECCESSARY.

    if the stove door were left open & the flue ruptured...
    and my return air inlet were closer than 120",
    i'm thinking of using one of my furnaces LIMIT switches, through flexable metalic conduit,
    mounted @ the return air inlet edge, suspended off the surface a little, to shut the fan circut off in case it actually started inhaling fire there

    i can't think of any other differences
  6. kbrown

    kbrown Feeling the Heat

    Joined:
    Oct 19, 2008
    Messages:
    295
    Loc:
    SE, Michigan
    This is a very valid point. I am still on the fence about how I want to do ours and after reading through this entire post I am still not any closer to which method I want to take; hot to cold or cold to hot. I would say that I am leaning a bit more towards moving the cold air into the stove room since I want to always make sure there is higher pressure there to prevent any drafting problems. There is no OAK system here as we have never had a problem.
  7. Dune

    Dune Minister of Fire

    Joined:
    Jan 14, 2008
    Messages:
    2,768
    Loc:
    Commonwealth Of Massachussetts
    There is nothing to think about. Moving the hot air may work or may not. Moving the cold air will work, period. Moving the hot air is illegal and possibly unsafe. Moving the cold air is legal and safe. This has all been proven beyond a shadow of a doubt. If you need to prove it for yourself, gets some fans and thermometers. Position the fans to blow the hot air and note the temp increase. Now position the fans on the floor, facing the other way. Note the temp increase.

    I did these experiments for months. I can assure you that moving the cold air towards the stove uses less fans, easier to position(on the floor instead of hanging from the ceiling somehow) and raises the temps of the far rooms quicker and higher.
  8. EL DRIFTO

    EL DRIFTO New Member

    Joined:
    Oct 8, 2009
    Messages:
    65
    Loc:
    Independence MO
    ^that's good to know
    it seems like eff would be better throwing colder air @ the stove to heat

    although my hvac setup is working, i'm considering reconnecting the return air from upstairs
    & opening the A-coil, high pres, forced air side of the furnace up,
    to blow cold air @ stove & force hot up the stair way

    it won't be circulating any air in the bedrooms, but that may not matter
    unfortunately, flipping the gas furnace on again would result in the whole house being heated by the stairway, in my setup

    i would lean toward forcing cold air in any of the non-modified hvac systems here
    but i'm not thinking it would work as well with a modified hvac like mine
    & i haven't tried

    i wish it were simple & i could cut a 2'x2' hole in the floor above the stove & let gravity do it's trick
  9. Lumber-Jack

    Lumber-Jack Minister of Fire

    Joined:
    Dec 29, 2008
    Messages:
    1,736
    Loc:
    Beautiful British Columbia
    Might be more to think about than you think. LOL
    Ok I just did this experiment. I had a perfect set up, I just finished a porch room that sits right next to the room where I have the wood stove. The room is built on a cement slab (as is the stove room), and is approximately 7' x 14' x 8' high. I finished and insulated the room and removed the insulation between the wall separating the two rooms and cut a 14 x14" hole in the wall at about 7'. The hole will eventually be for a projector, but it also doubles as an air circulation channel, as well as the doorway.
    To do the experiment I set up an indoor/outdoor thermometer on a step ladder in the porch room with the outdoor probe sitting on the floor. I let the room temperature stabilize while I monitored and adjusted the stove temperature to keep it stabilized, so no fluxing would effect the porch room temperature. Then I put a fan in the doorway (kind of an awkward place to have a fan sitting) blowing the cold floor air out of the porch room and started checking and documenting the temperatures every 5 minutes. As expected the temps started rising. My thermometer reads in .10 of a degree increments. It took 30 minutes for the temps to reach a point where they stabilized. The temps at the top of the ladder went from 80.9 to 83.7 and the floor temp went from 66.3 to 67.9 .
    I then placed the fan in the projector hole blowing hot air into the porch room. Now at this point if it were always true that blowing cold air was more effective that blowing hot air one would expect that the temperature reading would start to drop. However, in only 15 minutes the top thermometer read 86.3 deg. and the bottom probe jumped to 73.1. At which point I felt I had proved beyond any doubt that moving the hot air (at least in this case), was much more effective. By this time it was 12:30 am so I went to bed and had a good nights sleep.


    I just hope the cops don't catch me for illegally moving hot air. LOL
  10. Lumber-Jack

    Lumber-Jack Minister of Fire

    Joined:
    Dec 29, 2008
    Messages:
    1,736
    Loc:
    Beautiful British Columbia
    Just so you don't think I'm making this stuff up, here is a couple pictures of the fan in the projector hole and the ladder and thermometer.
    [​IMG]
    [​IMG]
  11. EL DRIFTO

    EL DRIFTO New Member

    Joined:
    Oct 8, 2009
    Messages:
    65
    Loc:
    Independence MO
    thanks for posting real world results

    if i'm understanding your example sir,
    both scenarios have the air moving the same direction through the inlet & outlet, to the room
    that could mean more air is moving with the second fan location

    if your experiment involved switching air direction @ the same fan location,
    i'd guess moving the hot air, near the ceiling, out would be faster
    than moving the, not so cold air, near the ceiling air, in
    because of greater temp diff

    maybe you could post some more stuff b4 you finish the projector

    as far as vaporized laughing gas...
  12. Dune

    Dune Minister of Fire

    Joined:
    Jan 14, 2008
    Messages:
    2,768
    Loc:
    Commonwealth Of Massachussetts
    Gee, I guess you proved that alright.
  13. Dune

    Dune Minister of Fire

    Joined:
    Jan 14, 2008
    Messages:
    2,768
    Loc:
    Commonwealth Of Massachussetts
    Now try heating a room that is thirty feet away, and doesn't have a huge opening cut into the wall seven feet up, just a doorway. And try both methods on different days, not consecutively.
  14. Hurricane

    Hurricane Minister of Fire

    Joined:
    Feb 18, 2009
    Messages:
    565
    Loc:
    Central NJ
    Great Test Carbon Liberator.
    I did the experiment with my basement, I have an open staircase to the basement and tried putting a fan at the bottom of the stairs blowing the cold air up, that worked but was replaced by the cold air on the floor upstairs and never made it past the stairs at the bottom. I needed to get the heat from the ceiling upstairs to the basement. I put a register at the top of the wall down the hall from the fireplace and ducted through the bay to the basement, boxed out the bay with a 6" duct connector. I used a insulated 6" flex duct and a panasonic continuous use exhaust fan ( that has thermal cutoff in case of fire ), and ran the output to the opposite end of the basement. This was bringing hot air to the far end of the basement, forcing the cold air back up the open staircase. Ran the stove and fan all night and the basement was a comfortable 72 degrees in the morning. It was only like 32 outside but 72 was better than I ever had down there. I think if I put the fan at the bottom of the stairs blowing up while the fan is blowing hot air down at the far end I can improve circulation and increase temp downstairs.
    So it worked for me and I am happy. My township inspector told me he ever heard of any law against moving hot air from any heat source, my furnace moves hot air. If people think it is illegal because of fire hazard so is a fan on the floor going to spread or feed the fire. Blowing cold air at the base of a house fire will cause the fire to roll across the ceiling faster.

    I do not think this is a testimony that all will work but in most cases there are ways to balance the temp in the house ad every layout is different.
  15. littlesmokey

    littlesmokey Minister of Fire

    Joined:
    Jun 25, 2007
    Messages:
    801
    Loc:
    Mighty vistas of the Wasatch Mountains Below the s
    I'm not going to get into this again, so my questions are simple. All this ducting and diverting and power fans and such. Don't you have to heat all that stuff, before it moves any warm air? And I have read that ducting regardless of conventional insulation loses 40-60% of it's heat. Are you considering this?

    And last my constant bother, have you even talked with your insurance company and the local code folk? Hate to think you have a fire, even if caused by a candle on the bath tub and your insurance won't pay because of your air movement experiment, or worse, you get redtagged and no one will insure you at all.

    If you don't want the advise of those who have posted here about moving cold air, OK. The thread should end, because you will never convince me or many others your idea is right. But you may confuse the issue for others.
  16. Hurricane

    Hurricane Minister of Fire

    Joined:
    Feb 18, 2009
    Messages:
    565
    Loc:
    Central NJ
    Answers posted above,

    How would you get the heat from upstairs down to the basement without a fan ?
    My brothers new house has the furnace in the attic and the system pushes the heat down to all of the rooms. It works in some instances, most newer homes in my area are built that way.
  17. Dune

    Dune Minister of Fire

    Joined:
    Jan 14, 2008
    Messages:
    2,768
    Loc:
    Commonwealth Of Massachussetts
    Yuh. First of all, it is not a great test. It is not a test at all. It doe not take into account delta T or established convection, additionaly the heat had to move virtualy no distance at all, nor were the circumstances of the comparison remotely similar.

    As to your "experiment", yes, heated air rises, glad you were able to prove that.
  18. Hurricane

    Hurricane Minister of Fire

    Joined:
    Feb 18, 2009
    Messages:
    565
    Loc:
    Central NJ
    You are right I proved that heat can rise all the way down to my basement.
    Not going to argue here anymore, people can decide what they want.
  19. EL DRIFTO

    EL DRIFTO New Member

    Joined:
    Oct 8, 2009
    Messages:
    65
    Loc:
    Independence MO
    well just to weigh in with the underdog, cause code man doesn't need any help:
    pointing a fan @ the stove is a FAIL, according to the manufacturer's ul instructions
    & therefore goes against my local & insur co laws

    just in case someone lost track of info after all the quoting

    happy burning
  20. littlesmokey

    littlesmokey Minister of Fire

    Joined:
    Jun 25, 2007
    Messages:
    801
    Loc:
    Mighty vistas of the Wasatch Mountains Below the s
    Reading out the sarcasm, the direction of the fan is away from the cold and towards the stove. The fan itself should be at the cold area to generate the convection and boosted as necessary, no one here is suggesting you set a fan blasting on the stove. Take your filters off and be adult about this. None of us, as far as I can tell are HVAC engineers, but folk who have used these appliances and know what works for us.

    You don't have to take the advise, but you should seriously look at both sides and see the bad advise on one. If you can't pleasant burning, but this forum won't help you justify bad ideas.
  21. Dune

    Dune Minister of Fire

    Joined:
    Jan 14, 2008
    Messages:
    2,768
    Loc:
    Commonwealth Of Massachussetts
    See the thread; "Installing duct with inline fan" in the DIY forum. I an done here, but it is all covered in that thread, including the illegality of the duct inlets and the source of said info.
  22. EL DRIFTO

    EL DRIFTO New Member

    Joined:
    Oct 8, 2009
    Messages:
    65
    Loc:
    Independence MO
    what publication has this code ??
    i'm sure it's out there & i'm not smarter than the code by any means, but for the spirit of debate

    local code inspector said to install it by the ul instructions that came with the stove
    they're on the internet
    i asked about other codes, he didn't mention others
    my ins co said the same, needed access to rear panel of stove
    24" to combustibles.

    consider three concerns, co, draft & sucking in fire
    an LP furnace, as far as co concerns, could eventually rupture the exchanger
    this results in all of the co loss inside going through the air system, absolutely unmonitored by the furnace
    typical co detector locations do this now, like any basement detector going in the stairway ceiling, in detector instructions
    an hvac flue pipe rupture could enter the air return or not, in any ratio & in any other imaginable hvac example
    & the correct detector location is still the basement stairway ceiling
    imagining every possable hvac, co failure, with my air return, in the basement b4 my stove & how my co detector was working b4
    i have twice as many now

    my stove has a third, smaller hole, 3" near the air inlet that's certainly worth mentioning, if you think OAKs are air tight
    weak draft problems caused by small fires or ex fans would be handled the same way the current co detection system works
    any size co leak, all sucked in by the air handler, detected in the return air path
    all the co coming off the coals, all day long, long after the fire is out & my draft has reversed, hasn't set off my detectors yet
    (all that draft coming in the chimney & window is going out somewhere higher than the basement floor)

    considering hvac fires i've seen
    the fan fails, gas keeps going, burns through metal to ceiling above furnace
    limit switches not in design, bypassed or failed
    i haven't seen a house fire caused by the hvac system blowing fire into a room

    no furnace does anything if a fire is going through the air handler anywhere in the entire system, even if it's fanning a fire anywhere in the house, except maybe turn the fan on if it got hot enough inside the exchanger...hhahahahhahahaaahahh

    since the stove is literally bullet proof, that means the only breeches would be leaving the door open or cracked glass on the inlet side
    both would cause an over burn, but not like the flue pipe on the outlet side
    mine is down to the integrity of the flue pipe
    i can't get my flue pipe loose unless i move the stove so...
  23. Marsh

    Marsh New Member

    Joined:
    Nov 29, 2008
    Messages:
    18
    Loc:
    OH
    Squiner, how is the system working for you now that we have had some cold weather? Also, i am lloking to do the same and need a good QUIET blower. Any recommendations? Not looking to go budget but one that will last and run quietly. Plan to use insulated flex duct.
  24. Hurricane

    Hurricane Minister of Fire

    Joined:
    Feb 18, 2009
    Messages:
    565
    Loc:
    Central NJ
    Marsh, I went with this fan from Panasonic. because I wanted quiet over budget too. I am extremely happy and you cannot hear the fan from anywhere, rated for continuous use and low electricity usage. Search around the internet I found a difference of about $100 between sellers. I have the 240 cfm model and paid about $125 delivered.

    http://www2.panasonic.com/consumer-...ine-Fans.list.75114_11002_7000000000000005702

    Good luck.
  25. Squiner

    Squiner New Member

    Joined:
    Aug 22, 2008
    Messages:
    173
    Loc:
    Maryland
    Marsh,

    I'm afraid it's difficult to give an accurate update. Since I'm in the middle of a remodel I have 1/3 of the rear portion of my house with no insulation in the vaulted ceiling. The rooms get to about 60 with the outside temps around 30. This is with the room with the stove around 75.

    I do feel that once the back of the house is buttoned up it will be much better, but it's just my opinion.
Thread Status:
Not open for further replies.

Share This Page