Cold air intake

[ilovecob]

Hi All,
I've been planning my new rocket. On my old on I liked sitting right by the fire. Cold air was always moving over my body. The fire was sucking the air from the room. I'm wondering if anyone has built in a cold air intake in their rocket stove?

Has it worked? Any ideas of how that might effect the system ?
I'm thinking about a 4" pipe run near the stove body to pre-heat the air from out doors and bringing it in at the top of the feed tube.

Thanks,

Michael

[Donkey]

I have messed about a little bit with intake configurations.
So far I haven't found a configuration that I REALLY like.

My difficulty is that if air is drawn from somewhere other than the wood-feed, (so far in my 2 tries) it creates the need for a cap over the wood feed.. Otherwise smoke tends to be blown out the feed opening and into the room. Also, the capped wood feed space creates a doldrum, where smoke will roil around before burning. This can cause creosote to build up in the feed tube, and puff smoke into the room when the cap is opened to put in more wood.

Ive thought of some kind of pivoting door/flapper valve, to select between air streams.. Flipped one way air comes down through the top of the wood feed, with the mouth open, ready for lighting/loading. Flipped the other closes the feed door and opens to pull air in from outside the building. Course, with the feed closed you loose the fire-in-the-floor look.. Which is pretty cool.

[Donkey]

Come ta think of it...
It would also remove the reason to sit right beside the stove.. As it would block the view of the fire entirely, unless it were made of stove-glass.
Which reminds me.. One of the drawbacks of rocket stoves is that the fire is mainly hidden from view. Total shame, something needs to be done about that...

[ilovecob]

Thanks for your thoughts and experience Donkey. Ya the intake would need a flapper for sure.
I can see how introducing a secondary intake would create a pull and maybe reduce the pull through the mouth making a place for smoke to rise from. I've had smoke rise a here and there with it's full of wood or something gets in the way. I suppose one can build in the intake and never use it...

[ernie]

one way to do it is to take a clod air feed in thrugh the cob bench and have the out let directly above the fire box. all of the other configs i have tried have not been happy.

[ilovecob]

I've installed cold air supply in the stove.
So far so good. I haven't found that I need a cap, but it definitely burns well when the cap is on.
I do need the valve to control the flow... and to pretty it up.

[Donkey]

Yeah, man.. That's cool.
There may be some barometric conditions that will make your air inlet not work on some days.. But, so what?? Most of the time it will be just fine, and when it's not, no harm..
Let us know how it goes.. Does colder, denser air from outside provide more oxy for burning, or does it tend to cool things down? Can you feel a definate draft coming through? What conditions change burn/draft characteristics?? Etc, etc, etc..

Oh, by the way.. I had to edit your image tags. For some reason the board didn't recognize your html code.. Better to use board code.. It's simpler anyway.

[ElfN]

I'm planning to solve this issue by having the feed tube outside in an enclosed porch. I am using an extra tall riser (55") to compensate for the slightly lengthened burn chamber.

Having the feed tube outside our living quarters will provide two other benefits. The addition of a small amount of reflected heat will help take the bitter off the air in the sun room and will save us a little room in our small living space.

ElfN

[Donkey]

Hello elfnori and welcome to the board.
One practical piece of advise..
With the nature of firewood, being what it is, the pieces tend to be somewhat nobbly and uneven. Sometimes the wood will hang up in the feed and will no longer drop naturally into the box as the bottom burns away. When this happens, the remaining wood can get top heavy and fall out of the feed onto your floor.
If the feed is in the space where you are, you will most likely notice it before things get dangerous. Usually, a little smoke will back out into the room first to warn you that something is wrong. At that point it's a simple thing to give the wood a wiggle to set everything right.
If you locate the feed outside, these warning signs may slip past.

Just make sure that you site your feed in a good spot, preferably where it's visible from the inside but CRITICALLY where there is nothing flammable around to cause a disaster.

Also.. With an extra long burn tunnel, it may be helpful to insulate it doubly. I would choose the lightest weight material available (and practical) to contact the flame and surround it with insulation. Best to keep the heat in the fire and out of the mass of the works, until that is, after the heat riser, where you want to soak it up.

Thanks for joining us and please, keep us updated on your progress.

[ElfN]

The stove isn't where I can see it from where I spend most of my time and the sun porch floor is brick.

Your comment is well taken, however. I will ensure to load careful.

ElfN