thomas rubino

Only the horizontal portion.
As soon as it turns vertical, it no longer counts.

Hi John, interesting question.
Living in a 100  year old house, this is not a problem for us..
I suspect that in a tight house that has someone home, air would be exchanged simply by walking in and out the door a few times.
How the home is heated would affect that, too.
We heat with a masonry stove; we might light it twice a day.
600 clay bricks at 200+F, will convince you that a partially open window all night at 10F is a nice thing...

Of course, not everyone is able to heat with wood.
In a city, you might not go outside often enough to bring in fresh air.
Opening a window is the most efficient way to quickly add fresh air; no power required.

Fluffy has had enough!

Ok. I am looking more closely at your photos.
It appears that the flap on the feed tube could be an air channel. Is that so?
Why is it closed?
Was the bottom "air intake" originally closed and then cut open?

To run a thick metal stove, start with nothing but kindling, then slowly add larger wood as the metal heats up.
The hunk of wood you show in the feed tube is way too large for a hot stove; it is completely inappropriate in a cold one.

Well, as Austin stated, the metal is going to deteriorate quickly.
The design is faulty.
The hunk of wood you have in the feed tube is way too large for a cold stove.
What you have there is a K-tube.  Known to be a poor performer. (They like to burn backward up the K-feed tube)
The extra air intake at the bottom is allowing too much air.
Why should it pull air down through your feed tube when it has a convenient alternative?
If you want this to work for a while, I see two options. Seal up the bottom air intake and let the air flow over your wood, not under it.
Or close off the angled intake and run this like an L-Tube.

If you plan to build a masonry stove in the future, start by assembling a proper brick J-Tube.
That metal K-L Tube is going to burn you unexpectedly, and it will not last.
Oh, and close off the extra holes you made; they really are not helping.


 

Are there any 90-degree bends in your pipes?
Each one adds 5' to the total length, you are allowed 30' with a 6" J-Tube

Do you have a way to check the outlet chimney gas temperature?
It should be 60 C or higher.
We need more info on your system (sizes).

Mine did that.
It's condensation; the exit chimney temps are not hot enough, or your wood is not dry.

Hi Kara
I went 100% of grid back in 1983; so far, I have had no problems of this nature.
The solar flares, if bad enough, could affect things, they say.
Backwoods Solar is only 60 miles from here; they have been my supplier since 1985 or so.
They are very knowledgeable and way more up on the new electronics than I am.

In the 1980s and 90s an intentional EMP from a foreign power was the big "concern" for some folks.
Now in 2026, I suspect there are much better ways to interrupt the power grid, vehicles, and other infrastructure.
The CME threat sounds much more likely.

Would it affect even stand-alone, off-grid systems?  
Maybe, but despite Backwoods selling this. I suspect it is not very likely.
Would it affect you if connected to the electric grid?   I suspect that it would.

These are just my opinions; I have no real knowledge of how likely this scenario is.
For now, I will not be rushing over to buy this kit, although I do believe that it works as advertised.

Perhaps a professional off-grid installer will reply with more information.



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Hi John
You will be very happy once you get this built!
You're building a 6" J-Tube
Your specs will all work, but.
I would suggest increasing your feed tube depth to 40cm (apx 16")
The 45 cm (18") burn tunnel will  work fine, but personally I would lengthen it to 50cm (apx 20")
The riser height is good at 90 cm (36")
The 5cm (2") gap at the barrel top... in the original builds, it was believed that a tight gap increased flow to a piped system.
Over time, it became apparent that fly ash buildup on the top of the riser shrank the gap.
I suggest 7.5cm (3") minimum as your top gap.

Yes, a dry stack brick wall would protect your straw walls.
You can also cob up to 2/3rds of the barrel itself.  (more mass)
By placing your exit chimney next to the transition area, you can easily install a bypass valve to help you start smoke-free in shoulder seasons.