Non-catalytic stoves and optimal air input

[ElmBurner]

I tried to do some searches, but for what are probably obvious reasons, the searches tended to return results that didn't really answer my question.

So, I was thinking about how gasoline engines have an optimal air/fuel ratio that gets them to burn most efficiently. Fireplaces would seem to be similar...you want enough air to ensure that the fuel is completely burnt. The area where it tends to differ is that you also want to minimize airflow to ensure that you can extract the maximum amount of heat from the burnt fuel.

The issue here being that burning all the fuel means you are generating a lot of heat, which increases your draft, which increases your heat, which increases your draft... My guess is non-cat stoves do this by design, to prolong / encourage the secondary combustion.

Catalytic stoves seem to go to the other extreme, by shutting the air flow down so completely that the "fire" doesn't actually burn the fuel anymore...that's done in the cat.

To summarize, I think there are instances where I am getting more air than is necessary to keep my secondaries going. Does this make sense and/or has anyone modified their air intakes to further limit the air into the stove such that you are barely above the temperature needed for complete combustion?

Hopefully that made some sense...any thoughts?

 

[begreen]

There are stoves like the PE Super series and the Enviro Kodiak series that have the primary air linked secondary air that partially closed off the secondary when the primary is fully closed. And there a a couple reports here of folks that have added secondary air controls to their stoves for high draft situations.

 

[JA600L]

I tried to do some searches, but for what are probably obvious reasons, the searches tended to return results that didn't really answer my question.

So, I was thinking about how gasoline engines have an optimal air/fuel ratio that gets them to burn most efficiently. Fireplaces would seem to be similar...you want enough air to ensure that the fuel is completely burnt. The area where it tends to differ is that you also want to minimize airflow to ensure that you can extract the maximum amount of heat from the burnt fuel.

The issue here being that burning all the fuel means you are generating a lot of heat, which increases your draft, which increases your heat, which increases your draft... My guess is non-cat stoves do this by design, to prolong / encourage the secondary combustion.

Catalytic stoves seem to go to the other extreme, by shutting the air flow down so completely that the "fire" doesn't actually burn the fuel anymore...that's done in the cat.

To summarize, I think there are instances where I am getting more air than is necessary to keep my secondaries going. Does this make sense and/or has anyone modified their air intakes to further limit the air into the stove such that you are barely above the temperature needed for complete combustion?

Hopefully that made some sense...any thoughts?

Like adjusting the carburetor on a car, using a 5 gas analyzer in the exhaust stream would be ideal for fine tuning a Woodstoves air controls. Anything else is guess work.

 

[Squirrel]

No doubt you could build a wood stove with sensors and controllers that would be as efficient as possible in all conditions but the cost would be prohibitive.
I have added a secondary air control to my stove and, after much playing with it, decided on two settings, full open for above freezing and 2/3 shut down for below freezing.