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Moving the heat around - what about moving the cold out?

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by oconnor, Nov 23, 2005.

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  1. oconnor

    oconnor Minister of Fire

    Joined:
    Nov 20, 2005
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    1,051
    Loc:
    Nova Scotia
    I own a 1100 Sq Ft bungalow where my stove is in the basement rec room. I
    have read much discussion on the problems (and code violations) associated
    with using the house HVAC system to move heat from the stove to the rest of
    the house. For those who aren't familiar, they include

    risk of depressurising the room the stove is in and bringing smoke and CO
    into the house
    increase risk during a fire

    I am curious about what code and experience say concerning moving the cold
    air from the floor above into the room the stove is in. Here is my situation

    My home has a vent in the floor at the far end of the hallway that looks
    into the rec room where my stove is. Under normal ops the heat from the
    stove rises up the stair way, and cold air falls down the vent. (Despite
    what most who visit think, heat doesn't rise up it).

    Given the problem of the open vent (fire spread) I am looking to duct it in
    and use a ducted fan to move the cold air from the floor of the hall to the
    floor of the basement. I hope this will help move heat down the hall to the
    bedrooms, as well as help fight some of the stack effect I get when my flu
    is cold (I have on old oil/wood stainless flu outside the house envelope) In
    the end, you can't get hot air in if the cold air can't get out, so I hope
    to move it thru the "cold air return".

    Any thoughts?

    Brent

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  2. elkimmeg

    elkimmeg Guest

    Most returns in the first floor use what is called pan joist the cavity between joist becomes the return route. The joist are combustiable and most pan bays leak air. I wish they were never used but code allow it Even Ashre ( Heating and air condition hand book also recomends not using pan joist it is the poorest least efficient way to return air. Many times strapping spaces leave gaping holes to a the entire joist work structure. If your Hot air system has flexible ducts they too by code can not be used to distrubute air from a solid fuel burning appliance In fact any duct syetem can not be used to distrubute air from a soild flel burning system unless it was tested an and listed to do so. Ask your wife this question I want to get heat to the next floor. is it ok if cut floor ducts in. Should we have a fire your safe exit time could be reduced by 2/3 You will not mind I just increased the risk of aphixiatining to you and the kids. Right go ahead honey knock yourself dead
  3. oconnor

    oconnor Minister of Fire

    Joined:
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    1,051
    Loc:
    Nova Scotia
    elkimmeg

    The vent I am refering to is not a pan joist, but literaly a square hole in my floor (FYI, my floor / ceiling above my basement is concrete, hence not at all combustible, and cold air won't light anything on fire). What I am refering to is ducting the hole in with 5" round steel ductwork to allow the cold air that already falls thru the whole to get to the basement floor without having a gapping whole in the floor (And which I might add I also have fire concerns about, given it is a straight thru passage for fire/smoke if the pressure gradient ever changes, like in a house fire.)

    Note as well I am not attaching this to my hot air furnace, or any other HVAC system. It will be nothing more than a fan assisted cold air return from the main floor, at floor level, to the basement floor, at floor level.

    On your point on distributing air from a solid fuel appliance thru ductwork that isn't certified, if you reread my post, I am not moving any air from my stove thru ducts, I am moving air down to my basement, where my stove can heat it and physics can take over. (Hot air rises, pushing more lower cold air on the main floor down to basement, thru the duct, assisted by the duct fan)

    I don't intend to be arguing/persuing semantics, but is there a legitamate difference between moving hot air from my basement (Which I'm not doing, as the risk of decreasing pressure in the room the stove is in could kill us all) and moving cold air to my basement (which I intend, unless otherwise convinced, which as I see it increases pressure in my basement from its norm, reduces stack effect, and allows the heat to follow it's natural circulation path around my house) from the eyes of the building codes as some of you see them.

    I emphasise, I am not using my HVAC to move hot air from my stove, but a small duct and fan to move cold air to my stove.
  4. Todd

    Todd Minister of Fire

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    Loc:
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    Try sticking a fan in that vent blowing down to your basement. It will help circulate more air. The heat will be forced to rise from the cold air pushing down.
  5. oconnor

    oconnor Minister of Fire

    Joined:
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    Loc:
    Nova Scotia
    Quote - " It will be nothing more than a fan assisted cold air return from the main floor, at floor level, to the basement floor, at floor level. "

    That's what I said.
  6. elkimmeg

    elkimmeg Guest

    The purpose of the post is to make one factor all the ramifications of what they are planning to do. There are hidden dangers to factor in. It seems to have alerted you good. A closed secondary system moving cooler air is the best approach I might add that protection is as simple as ceiling dampers that can be used in the floors as well. They have spring loaded fusiable links that melt should a temp of a fire create heenough heat to melt and close them. Closed that would reduce the spread of fire and restore containment. My one suggestion to increase safety to your plan and I do agree it is best to move heavier colder air to make room for warmer stove heated air. So how is it in god's country NS great trout fishing and I have even panned gold there swam in the north Nunberland straights
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