Question about flue damper

[shawng111]

Good evening everyone, We are currently installing our 1st epa stove (Drolet Savannah) and the stove installer recomended we also install a flue damper which I agree since our flue is about 30 feet tall, so question is when we fire up the stove and it approches say 550 do we first turn down the air inlet and if it still is running too hot then start applying the damper? Hope that makes sense. Thanks everyone

 

[edthedawg]

There's a lot more that factors in other than just flue height, but if you're concerned about it, it can't hurt to install now. Just understand how its presence might impact your future cleanings, that's all.

Operationally, use it as a last resort. Use the stove controls as much as possible and get the flue hot (damper wide open) every day before damping down. If you keep it damped, you may not only get a lot of smoke backpuffing, but also risk a lot of creosote buildup.

My personal experience w/ the Heritage and 35ish (i can never remember the exact number) feet of 6"SS liner is to run wide open, and i kinda back the primary and the flue down together. Coldest days call for leaving both the primary and the flue cracked open just a bit. EPA stoves sometimes react a little odd w/ the primary controls. "Running Wide Open" ain't always what you might think it is. In our case, the damper was needed because the flue drew too much heat out of the box too quickly. So the stovetop temps stay much higher w/ the damper closed down

 

[northwinds]

I also have about 30 feet--straight up through the center of the house. I asked the installers to add a flue
damper, and they did, although they didn't think I needed it.

The stove ran fine last year, and there were no problems with build-up around the flue area. But I rarely
operated the flu damper because there was no overdraft problem.

I ended up taking the damper out this summer to see what difference it makes. I put a temp probe in
its place to get some data on chimney temps.

In answer to your question, that's how I used my flu damper--only when the stove started getting too hot.
Kind of a brake (primary air) plus another brake (flu damper). I don't think I ever needed to use the flue
damper after the primary air was closed off and the temp was still rising. It was more like, oh crap, it's
getting too hot, shut the primary air and close off the damper. Normally, my stove's primary air sweet spot
was a 2-3 inches inches to the left of being fully closed.

I'm thinking without the damper, I may be able to operate with the primary air more fully closed.

 

[shawng111]

Thanks everyone for your experience, I appreciate it. It's always nice to be ready when the time comes. Thanks again.

 

[edthedawg]

See what I've found is kinda similar (i think) to northwinds. Ignoring the flue damper, I can back the primary down very low, or even all the way closed, and I still:
- See the flames ripping in the box
- Get short, cold burns
- Hear the intake air rushing in quite noisily

And I DO run like that for the first 10-15 minutes of hard burning, because i want the flue to cook out any buildup. But I was unable to find any combination of loading or operating practices that would help this, until we put in the flue damper.

But when i close the damper, i finally get the burntime and stovetop temps up, the flames lick down nice and slow/rolling, and the pitch of the intake air rushing in knocks down considerably.

One caveat is the possibility of an intake damper. Some folks swear by 'em to slow down the aforementioned "always open" secondary. I'm not wild about this, since the flue is such an important aspect of the engine cycle. Big hot vertical tube of metal = draft machine. restricting its available feed seems to make more sense to me to happen on the "after the fire" side of things, as opposed to the "before the fire" side.

(I had started crafting a really poorly thought out analogy based on NASCAR throttle restrictor plates, but scrapped it in favor of sleep and/or ogling my hot wife.)