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Make up air duct through mass

 
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I have found some allusion to people having done this but have not been able to come up with any actual examples.

Does anyone have any results from actually ducting outside air through a mass for combustion/house make up air in a well sealed structure?

Depending on climate (and other details) it seems like a well designed system could essentially function as an HRV/heat exchanger, pulling in and heating fresh air for multiple uses.

I have posed this question elsewhere on the inter webs, and peterberg has already referenced a simple explanation of the issues of building pressures, outside air and combustion appliances.
Here

There is ample discussion elsewhere already on the use of outdoor air for combustion whether direct to the fire or other, so I would rather focus energy on what it would take to successfully detail this in reality, and have you tried it? What were your conditions and results?

A very tight house is going to pull air in from somewhere, so I want to  try to control it in some form other than running around cracking and adjusting windows, or programming advanced balanced ventilation systems if there isn’t power to be supplied to them.

I will simplify my design goals here to be

An off grid structure with:
Minimal reliance on mechanical systems (i.e fans and pumps in this case)
Tight air-sealing
Lots of insulation
Wood heat
The consensus in the mainstream building world seems to be that these goals are incompatible.

My main goal in posting here is the “have you done it?”
What potential pitfalls do you see? (Besides the obvious backdraft risk, etc.)?
With thoughtful detailing and controls my brain thinks it will work.
I almost certainly will at least build it in the building I am currently working on as an experimental platform, results back in (insert random number here) years.
 
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mobile home wood stoves use a 2" round as makeup air.

It mostly works, due to the vacuum of the wood stove.

For a rocket I think one fifth area of the exhaust would be about right. Rockets have more thru put.
Are you going to split the incoming air to before the firebox, and heat riser?
You would need a shutter on intake air so after the burn the heat will stay in the mass.
 
Pete Arthur
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Oh yeah,  my makeup air is a doggy door 10 foot from the firebox. Works good, and the dogs like it.
 
gardener
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Chris McClellan ran the outside air through the mass in this install in Ohio.

https://permies.com/t/167229/Uncle-Mud-Basement-Cob-Rocket#1313191
 
pioneer
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I've pondered over this question myself as my build area sports not only a chimney, but some sort of vent that goes through the cinder block wall about 6 feet from the floor, back and around to the main chimney, of which there are two.  One for the upstairs, and one for the basement that I will use for my RMH.  Since this "vent" as I shall call it is to close to the build area I'm tempted to use it for make-up air but like you, I'm really not sure of it. I thought I read somewhere that moisture would be a problem as bringing in all that cold air will cause condensate to form and make things wet.  At any rate, you have to deal with the fact that you will be brining in very cold air and that will be a deduction against the temperatures you are trying to build in your stove.  I've considered building a bell that has a passthrough for the air to be warmed BEFORE it gets to the combustion chamber.  Anyway, that's my 2 cents.
 
M Stinwell
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Pete Arthur wrote:mobile home wood stoves use a 2" round as makeup air.

It mostly works, due to the vacuum of the wood stove.

For a rocket I think one fifth area of the exhaust would be about right. Rockets have more thru put.
Are you going to split the incoming air to before the firebox, and heat riser?
You would need a shutter on intake air so after the burn the heat will stay in the mass.



To be clear here I am not talking about ducting air directly to the stove for combustion. There is a lot out there about why this is a bad idea in the majority of cases. I am talking about using the rocket mass as a heat exchanger, providing warmed air to the building to be used however it needs to be.

Thomas I think your chimney as intake could possibly work, but you would need to tap into as an air supply low enough, i.e not up above the roof (needs to be below the neutral pressure plane of your house). It would also need to be protected as well as possible from draft/pressure changing wind gusts. The details of what this vent is and how it runs are not clear enough  here to give any real advice I would think.

I am operating entirely on intuition here so maybe someone with more air handling experience will chime in
 
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