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gcrank1
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# Posted: 17 Nov 2021 20:55 - Edited by: gcrank1
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Last year, first winter with our 'new' 16x24 cabin, the bad stack/poor draft left us cold. Re-doing the stack properly (and safely) was going to be expensive and labor intensive; and our insurance co still wouldnt insure us. So we put in an LP furnace. Bingo, works for us!
I couldnt bear to give up my old (rebuilt by me in '83) antique upright wood stove, its been sitting in the north end. Ive been working out this idea for a long time and finally put it all together today.
The stove needs no clearances, there is no fire, but it is kicking out heat. Heat from the visually wonderful cath ceiling; you know, the place the furnace heat goes to and stacks downward over time.
I ran black stovepipe up to about 2' shy the ridge, put on a 'bell' top (ductwork fittings) and a fan pointed down into the bell. The warm air up top is pumped back down into the stove, heating the metalwork to radiate and with the door open Heat Comes Out!
Waayyy cool....ummm warm, well, you know what I mean.
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darz5150
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# Posted: 17 Nov 2021 21:01
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Great idea.
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Nobadays
Member
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# Posted: 17 Nov 2021 21:15
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Pictures!
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Brettny
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# Posted: 18 Nov 2021 05:57
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Move the cold air to the hot air. Trying to blow all the hot air through a fan dosnt work as well.
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WILL1E
Moderator
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# Posted: 18 Nov 2021 08:04
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Way to fight physics and make use of your relic!
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Nate R
Member
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# Posted: 18 Nov 2021 08:09
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Better than not using it! Cool idea! 
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paulz
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# Posted: 18 Nov 2021 08:30
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Yeah, pictures. A wood stove with no fire, how does that work?
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gcrank1
Member
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# Posted: 18 Nov 2021 10:27
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Sorry, I am pics challenged....among other things.....but ideas I got and I 'make up stuff' from bits and bobs.
Think a vintage upright wood stove (like a simple cheaper Round Oak).
With a black stovepipe going straight up within 18" of the ridge peak of the cath ceiling and kind of a 'bell' top like an old steam locomotive.
Like a static display
All the heat that rises up into that cath ceiling from out LP furnace sits up there unless it is kicked around to mix with the room air (yer feet can get mighty cold while the room warms up). We were using the ceiling fan or a small box fan to mix air; that works ok, and as said blowing from the 'cold' side of the room is a good way to do it.
But all that warm air way up top....I go up the ladder on the wall and It Is Cozy Up There!
So a round fan in the stovepipe 'bell' pushes that warm air down the 6" pipe and 'out thru the stove' into the room.
Works a treat And all on solar too.
I got the idea from a post/link a few yrs ago? here? about a Heat Tube, or something like that. Really just a vertical channel with a computer fan inside to pull warm topside air back down and discharge at foot level. Well, I have this stove and pipe......
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Aklogcabin
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# Posted: 18 Nov 2021 11:48
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I'm starting to understand this. You are blowing the recirculated harm air down into the heat plenum surrounding the fire box in the LP furnace. And it is redistributed with the heat blower fan . I think, Yeah good idea
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gcrank1
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# Posted: 18 Nov 2021 12:40
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No, nothing to do with the LP furnace.
My old wood stove is JUST a big 'pipe' with a fan forcing the cath ceiling warm risen air (orig made by the LP) back down to the 'floor'.
Because I dont like all that warm air sitting way up there where Im not at.
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snobdds
Member
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# Posted: 18 Nov 2021 13:41
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I still think the benefits of a woodstove far outweigh the cost of the pipe to install a woodstove. It's a one and done expense.
Just the option it creates for back up or supplemental heat should outpace the costs.
What am I missing here?
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gcrank1
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# Posted: 18 Nov 2021 16:11 - Edited by: gcrank1
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That this isnt about a woodstove or not, it is Only about getting the heat At The Top Of The Cath Ceiling Back Down To Knee Level.
And what I did will work for topside warm air from any heat source.
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ICC
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# Posted: 18 Nov 2021 17:28 - Edited by: ICC
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Quoting: gcrank1 That this isnt about a woodstove or not, it is Only about getting the heat At The Top Of The Cath Ceiling Back Down To Knee Level.
= the main reason I don't like cathedral ceilings. They can look wonderful but have drawbacks in practice.
A friend has a home with a truly magnificent great room. It is a full two stories in height. Upper floor balcony for the bedrooms overlooks the main floor. There is a very nice saltillo tile floor on the main level with radiant heat. Your feet are warm when on the main floor but the heat shoots right up to the upper areas.
But to each their own...
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snobdds
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# Posted: 18 Nov 2021 18:46
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Correct me if I'm wrong, but in floor heat is radiant heat and not convective heat. It heats the objects in the room, not the air. So there can be no way for a floor to be colder than the ceiling. I was always under the impression that radiant heat in a cathedral ceiling room is preferred for the reason I just mentioned. 95% of cabins use a wood stove which is radiant heat and for the most part, is the best way to minimize the convective properties of the heat rising.
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snobdds
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# Posted: 18 Nov 2021 18:49 - Edited by: snobdds
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Quoting: gcrank1 That this isnt about a woodstove or not, it is Only about getting the heat At The Top Of The Cath Ceiling Back Down To Knee Level.
I don't think you will be able to displace enough air from your furnace to effectively create convection in a 6 inch pipe to overcome the stacking effect via a small fan.
Could be wrong though...
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gcrank1
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# Posted: 18 Nov 2021 19:02 - Edited by: gcrank1
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All I know is that at our old 1st cabin with a full open loft and only a (radiant) wood stove that you could go up any time and it was warmer up there than down by a good bit. We never had a fan.
Maybe 'minimize the convective properties' works better in conversation than practice?
Examples:
Blue flame LP heaters heat the air which then heats the objects in the space. Air is a poor conductor of heat.
Infrared LP heaters heat the objects in the room which then heat the air. I like infrared! (radiant), feels like the sun or a wood fire.
Sit in front of each and you can feel the diff. If you are right in front of the infrared it is glorious.
Either way the air in the room ends up heated, and up topside, though. Not actively doing something to 'kick it back down' or 'mix it up' means waiting a good while to saturate the space with heat to a comfortable temp.
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ICC
Member
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# Posted: 18 Nov 2021 21:06
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Quoting: snobdds It heats the objects in the room, not the air.
The air in a room that is heated with a radiant in-floor or under-floor system is not cold.
The air in the room is in contact with the floor, assuming there is air in the room.  That air warms and then what happens? The warmed air rises just like any warm air does. Objects on the floor, like furniture, absorb heat from the floor. Those objects also warm the air that contacts the surface of the objects.
In my friend's house, there are also heating tubes in a couple of the walls as well.
The thermostats measure the air temperature in the rooms as well as the floor temperature. It is a zoned system. The sensors all work together to provide a comfortable space.
Nothing can prevent a warm object (floor) from warming anything that contacts the floor (including air). And nothing can really stop warm air from rising, although a ceiling at 8 to 10-foot height limits how much upper air space gets warmed. Given a great room with 20 to 28-foot ceilings the air up there is warmer than the air closer to floor level.
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ICC
Member
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# Posted: 18 Nov 2021 21:09 - Edited by: ICC
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Quoting: gcrank1 a (radiant) wood stove
A wood stove is a combination radiant heater and an air heater. One can feel the heat radiating from a wood stove and the warmed air can circulate from the area where the stove is located and warm the air and then the objects in the room 30 feet distant from the wood stove.
The simple explanation: the metal box of a wood stove is heated by conduction; flames touch and heat the metal. The hot metal box radiates heat waves across the room in a straight line. The hot metal box also heats the room air by convection.
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ICC
Member
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# Posted: 18 Nov 2021 21:26
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Quoting: gcrank1 Either way the air in the room ends up heated, and up topside, though.
Yes.
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Peewee86
Member
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# Posted: 19 Nov 2021 10:42
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While my setup does not have the cool factor of a re-purposed stove, it is a little more high tech approach to air recirculation. I have a 6 inch in-line duct fan mounted in the ceiling joists on the lower level with the duct running through the upper level subfloor and up inside a wall cavity to within a few inches of the highest ceiling in the upper level. The fan has 10 speed options and a 402 CFM rating on its highest setting. It uses a DC motor so it uses about half of the current of other fans that I considered. Since I plan to use solar power I look at the energy consumption of everything I’m going to be putting into the cabin. It also has a temperature probe at the duct inlet on the upper level which will automatically turn the fan on and off at a preset temperatures.
I have also installed an inline duct silencer to reduce the sound of rushing air on higher speed settings. The silencer makes a noticeable difference. While I have not purchased one yet, the fan manufacture also has an optional radio frequency remote control available for their fan controllers.
The picture is looking upward from the lower floor. The silver tube is the duct silencer. Once I have the ceiling finished I will have an access panel to the fan motor.
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snobdds
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# Posted: 19 Nov 2021 10:57 - Edited by: snobdds
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I don't agree on the radiant turning to convection heat Quoting: ICC The air in the room is in contact with the floor, assuming there is air in the room. That air warms and then what happens? The warmed air rises just like any warm air does. Objects on the floor, like furniture, absorb heat from the floor. Those objects also warm the air that contacts the surface of the objects.
This is defying the laws of physics and thermal dynamics. Radiant heat has no conversion to convective heat, there is a conversion to conduction heat though through objects in a room. They are two distinct and separate forms of heat. Radiant heat creates rays of energy that will only convert to heat once it hits and is absorbed by the body or object. A great example of this is the sun. On a cold day, when you stand in the sunshine, you still feel warmth on your face, but when you stand in the shade, you no longer feel the radiant heat it produces.
Convection can not happen in a vacuum where radiant can. That is important distinction to keep in mind. A dried in cabin with all the windows closed and only a wood stove is a vacuum, in the sense there is no air flow in or out. Radiant is the only way to warm a vacuum. Now if there is a fan behind the wood stove blowing air across the stove, that turns it into convection and the displaced air needs to be made up through cracks for make up air.
Cabin with lofts feel warmer because of the thermal stacking effect. There is a pressure difference between the outside air and the air inside the building caused by the difference in temperature between the outside air and the inside air. There is always going to be outside air coming in through cracks that causes a separation of warmer less dense air to raise and cooler more dense air to sink.
https://youtu.be/7rlY5kP-7dw
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snobdds
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# Posted: 19 Nov 2021 11:20 - Edited by: snobdds
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Quoting: gcrank1 Either way the air in the room ends up heated, and up topside, though. Not actively doing something to 'kick it back down' or 'mix it up' means waiting a good while to saturate the space with heat to a comfortable temp.
Physics say if you move air through a fixed duct in one direction, you need to replace that air in the opposite direction. Put a fan on the floor and complete the convection cycle...
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gcrank1
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# Posted: 19 Nov 2021 12:39 - Edited by: gcrank1
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Ok, so you dont like my functional 'recirculation device'; ie, a fan would do as well.....
My 'device' is a fan, along with some 'tubing' AND I get to use my antique stove and pipe (and fan) that I already have; cost = -0-
Im happy with it 'completing the convection cycle' this way The air is gonna do what air does, fill the void and circulate.
Diff strokes for diff folks/more than one way to skin a cat.
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paulz
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# Posted: 19 Nov 2021 13:11
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You guys got me wondering, so I did a little testing last night. The wood stove had been going for about an hour. I checked the temp at the cabin floor and at the 15' ceiling peak, via the loft. About 12 degrees difference. Gave me a chance to try the ceiling fan I put in this summer, pulling the air upwards. Immediately felt the warm air coming down. I'll be using it this winter, glad this got brought up.
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gcrank1
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# Posted: 19 Nov 2021 14:04
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I did that before too, Paul; tried it both ways, summer setting for 'air down' and reversing for up. We didnt like the cooling effect the air down had on us even though it was warm air from up top. The air up feels like it 'pulls' the warmth from the furnace toward us and the fan 'kicks' the topside warm air down the cath ceiling sides and the walls.
My simple tests showed our cheapie ceiling fan draws about the same amps on low or med speed, growls and runs slow on msw inverter, fine on psw.
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Fanman
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# Posted: 19 Nov 2021 17:28
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Quoting: snobdds I don't agree on the radiant turning to convection heat... This is defying the laws of physics and thermal dynamics. Radiant heat has no conversion to convective heat, there is a conversion to conduction heat though through objects in a room. They are two distinct and separate forms of heat. Radiant heat creates rays of energy that will only convert to heat once it hits and is absorbed by the body or object...
Not quite. When we speak of "radiant heat" as in home heating, that heat is radiating from a large area warm surface like a floor or ceiling, as opposed to a small area surface like a heat exchanger designed to heat air flowing through it. Since the floor is warm, it will also heat the air in contact with it, so you get convective as well as radiant heat from it.
When radiant energy strikes a solid object, that object heats up, and if it's warmer than the air surrounding it, it in turn heats the air.
Strictly speaking, the warm object heats the cooler air via conduction; the reduced density of the warmed air causes the air to move via convection, and more heat is transferred to the incoming cooler air than would be if the air sat stagnant adjacent to the surface. If the air didn't move, it would quickly rise to the same temperature as the warm object and then there would be no more heat transfer since heat always, and only, moves from a warm mass to a colder one.
We have a hip roof cathedral ceiling and run the ceiling fan in reverse when the wood stove is burning, it makes a significant difference.
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snobdds
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# Posted: 19 Nov 2021 23:06 - Edited by: snobdds
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Quoting: Fanman Since the floor is warm, it will also heat the air in contact with it, so you get convective as well as radiant heat from it.
My understanding of the above is, this process is text book conductive heating, not convective. The air being in contact with a warm object is conduction heating.
If you agree then we agree on what's happening.
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Fanman
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# Posted: 20 Nov 2021 06:44
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Right, the warm surface heats the air by conduction at the interface, but the convection currents continuously bringing in cooler air means a higher temperature gradient and thus more heat transfer. Heat transfer calculations use "thermal conductivity"; there is one value for conduction, a larger value for free convection (air motion caused only by density differences), and a still larger value varying with airspeed for forced convection (i.e. a fan or blower).
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snobdds
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# Posted: 22 Nov 2021 12:16
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Not to beat a dead horse, but I don't think a floor or slab that is passively heated is going to create much convection heating. The floor would need a heat source, like in floor radiant heating, to make those radiant heat waves, cycle in closed space.
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