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Vent RMH through Roof or Wall?  RSS feed

 
Posts: 6
Location: Solola, Guatemala
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I am in the process of building my place and trying to decide if I should vent my RMH through the roof or through the wall.  Since I am about to put the roof on, I kind of need to make a decision.  To be honest, I have no experience with RMH, but my understanding is that there is no smoke coming out of the vent.  Is this correct?  If so, then can I vent through a wall and not worry about leaving soot marks all over the place?  Or do I still need to run a tube above the roof line to avoid black marks?  If this is the case, then is it better to just vent through the roof and not worry about it?  Part of why I am asking these questions is because I have not decided how many and where I am going to be putting in the RMHs.  If I am going to vent through the roof, I really need to figure this out before I finish the roof.  If there is no problem venting through a wall, even if it is near foot traffic or outdoor seating, then I can wait to decide where and how many RMHs to install.  I'd appreciate it if anyone could help clarify this issue.  Thanks.
 
gardener
Posts: 2710
Location: Southern alps, on the French side of the french /italian border 5000ft high Southern alpine climate.
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There's always smoke at the begining of the burn.

But besides this, you should not vent through a wall. Except if you are absolutely sure that the wind will always come from the same direction, and will never, absolutely never change direction.

Don't know about the US. But in France, chimneys need to raise 70cm (approximately 3ft) above the peak of the roof. Would these be insulated pipe against a wall, sticking out 10 ft above the gutter. Or a proper masonry chimney going through the roof.

Where i live, with the heavy loads of snow. We have to cable the chimneys sometimes, like guy ropes on a boat.

Check stack effect and whole house stack effects for the reason behind.
 
Clark Harris
Posts: 6
Location: Solola, Guatemala
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Satamax Antone wrote:There's always smoke at the begining of the burn.

But besides this, you should not vent through a wall. Except if you are absolutely sure that the wind will always come from the same direction, and will never, absolutely never change direction.

Don't know about the US. But in France, chimneys need to raise 70cm (approximately 3ft) above the peak of the roof. Would these be insulated pipe against a wall, sticking out 10 ft above the gutter. Or a proper masonry chimney going through the roof.

Where i live, with the heavy loads of snow. We have to cable the chimneys sometimes, like guy ropes on a boat.

Check stack effect and whole house stack effects for the reason behind.



So my place is in Guatemala at 2300 meters above sea level.  The wind almost always comes from the south, we never get any snow, but the nighttime temps get down below 0 Celsius in January/Feb and are usually around 5-10 Celsius the rest of the year.  Daytime is usually around 20-25 Celsius all year long.  As you can imagine, heating is not a huge need but would be nice from time to time.  This is why I am trying to figure out how many holes to cut and what kind of heating.  For now, I am leaning towards one RMH in the 1st floor living/dining room.  I was trying to avoid running a pipe through the upstairs bedroom to get to the roof, but from what you say and other research, it looks like I have to.  Now I have to figure out whether I want heating in the guest rooms or just extra blankets on the beds.
 
gardener
Posts: 2581
Location: Upstate NY, zone 5
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With that climate, you would want less of a mass and more of a quick heater. A small RMH (around 6"/15cm) with minimal mass would give you heat overnight from a short fire in early evening.

How are the rooms arranged? Would it be possible to run the ducting in mass through more than one room before going up the chimney?
 
pollinator
Posts: 1114
Location: RRV of da Nort
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@Satamax A.: "But besides this, you should not vent through a wall."

I guess I don't really agree with this.  We've used the approach below on two wood-burning units where the wind can be from many directions even if most of the time from either the north or the south-east (location just south of the Canadian border on US central plains).  One is a traditional wood burning stove on a main floor of the house and the other is a rocket (no-mass) heater prototype in an out-building.  Both adhere to the design and considerations of the 3-2-10 rule. True, it is a higher expense in class A chimney sections to get the chimney stack up to an appropriate height and we use venturi-type wind deflecting caps, but venting out the wall was for us, and possibly for many, an expedient and successful option.
ThruWallExhaust.jpg
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Satamax Antone
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John, we kind of agree. That's not what i, and many rocketers would call venting through the wall. The venting through the wall, is found in Ianto Evans's book. And goes directly through the wall, without a chimney. It works, untill the first gust of reverse wind. Which fills the house with smoke.

Here you are picturing a chimney. I never heard of that 3-2-10 rule. I would raise the chimney more myself. But, i don't know for sure. Since i do roofing for a living. Going through a roof is no big deal for me.

Clark, you could do as John pictured. But no direct through pipe, and no outside chimney. If you put it on the gable end, it looks better imho. Doing it with rocks or bricks is even better for looks. But with an insulated pipe inside, for good draft.

As Glenn stated, you could cope with less mass. In a house with this type of weather, i would go for a rocket cooking range with mass. It does double duty. Doesn't take much room. May be, if you go through that upstairs bedroom. Adding a little bell there could be interesting.

HTH.
 
Glenn Herbert
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Max's "you should not vent through a wall" referred to the idea of simply venting horizontally as the OP seemed to want. An exterior chimney designed properly can work, though still not as effective as a chimney that rises straight through the house and exits near the ridge.
 
Glenn Herbert
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Location: Upstate NY, zone 5
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There is one benefit to an external chimney as pictured, if you have a conventional woodstove. My beloved has heated with wood for decades, and has a chimney just like the picture. She threw out the catalytic element when it clogged, and runs the stove in what I think is typical fashion. She has to get out the chimney brush every few weeks in winter, and I would sincerely hate to have that mess getting inside the house. Just cleaning the elbow above the stove is bad enough.

(If she was planning on living in that house in the future, I would be building her an RMH.)
 
Clark Harris
Posts: 6
Location: Solola, Guatemala
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Satamax Antone wrote:
Since i do roofing for a living. Going through a roof is no big deal for me.
HTH.



Satamax,  Since the weather is so nice, our roof is only 1x6" planks on top of rafter with tar paper and metal roof on top.  How difficult would it be to cut the chimney holes after we live in the house for a while?  Would we have to pull up the metal roofing, or could we just cut a circle and install chimney?

And to clarify, when I said vent, I was planning to have a chimney outside the wall.  I am not used to talking about all of this stuff and I don't always choose my words correctly.  Thanks to everyone for explaining these things.

Glen,  The building is designed so that one guest room is above another, making it possible to heat both from one stove.  I have considered this option.

Another option I am considering is using gas heaters fueled with biogas.  These would not need a chimney, I think.  Then my only question would be, "how far can heaters be from biogas source?"
 
Satamax Antone
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Posts: 2710
Location: Southern alps, on the French side of the french /italian border 5000ft high Southern alpine climate.
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Clark, corrugated steel you mean? And a flat roof, or there is a slope?

If the roof is flat, that's a nightmare. I mean to rainproof a hole in it. I bet it rains heavily where you are?
 
Clark Harris
Posts: 6
Location: Solola, Guatemala
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The roof rises 1 meter for every 4 meters.  And the metal is the red corrugated metal with about 6 inches of flat between each rib.
 
Satamax Antone
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Location: Southern alps, on the French side of the french /italian border 5000ft high Southern alpine climate.
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Clark Harris wrote:The roof rises 1 meter for every 4 meters.  And the metal is the red corrugated metal with about 6 inches of flat between each rib.



What i call bac acier.   Easier then. The solution is to find a  roof passage if you want to use round pipe. Or you can even fabricate if you're using square chimney.

I use something like this for round tubes.


If you can weld or solder, you can do it too.

Or know how to hammer metal.  The trick is proper overlapping, working the  way water goes down. The problem arises when it's flood like rains, when water can rise back underneath the steel. But if needed, i can walk you through.
solin-poujoulat.gif
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John Weiland
pollinator
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Had to wait to get home from work to find a photo with the example from our home.....sorry, not the best photo.  Pitch of the roof is probably 45 degrees (12/12) which necessitated a pretty tall stack after going through the soffit for stability.  The stabilizing bars from the roof to the stack were a must as well.
ChimneyThruSoffit.JPG
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Posts: 13
Location: West Virginia
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Clark Harris wrote:

Satamax Antone wrote:
Since i do roofing for a living. Going through a roof is no big deal for me.
HTH.


Another option I am considering is using gas heaters fueled with biogas.  These would not need a chimney, I think.  Then my only question would be, "how far can heaters be from biogas source?"



  For example.... The most biogas you will get from a 1cubic meter (264 gallon) digester running near optimal output will be about enough gas to burn a cookstove for about 1.5 hours or a few mantle lamps. A electric generator could be ran if gas feed pressure is high enough for about 30 - 60 minutes per day on that too but pick 1 of the 3. Also, for IC engine electric generator, depending on your engine cylinder volume and power load, would require a gas scrubber setup to remove at least the Hydrogen sulfide from the gas before use in it, otherwise it could lead engine corrosion over the long run if what you're putting in your digester produces a lot of sulfides.

   It would be more labor intensive & waste of more space for less results to try to use biogas to heat a home on any scale unless you own a business scale farm with lots of waste & space for a massive digester. Better off sticking to a rocket stove mass heater or heat exchanging gassifier even with the need for chimney pipe.
 
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