Enviro M55 Insert "combustion intake flapper" safety question

[bostonfan49]

Some time ago I added an OAK which is a straight piece of 4" metal piping out through my chimney with a screened end piece. The stoves standard inlet piece (before I added my section of piping) has a metal flapper on it. When the stove is off, the flapper is closed. When the stove is on the flapper opens inward, the higher the fan speed the wider the flap opens. I know this because I can stand out side my chimney and look directly into the OAK ( with the screen cover removed) and see the flap either open or closed.....

So now I have a power failure, smoke question. Like most insert owners, I probably have abundant natural draft with my exhaust going up and out the chimney (forget my UPS for the moment).....but then I think about that FLAPPER.......and I wonder about other makes of stoves. Do they have flappers on their combustion inlet? I ask because of my perceived safety understanding of an OAK. Isn't an OAK an extra way to vent smoke out of a stove....besides the stoves exhaust venting? If yes, then my flapper should be removed because it only opens inward........yes? no?

If my power goes out, the natural draft of my chimney should draw out all the smoke.
If I remove the flapper does my OAK now also act as an escape route for the smoke? Or....
could the added venting actually help increase the natural draft in my chimney? Why even have the flapper?

Thanks, Bill

 

[womaus]

I ask because of my perceived safety understanding of an OAK. Isn't an OAK an extra way to vent smoke out of a stove....besides the stoves exhaust venting? If yes, then my flapper should be removed because it only opens inward........yes? no?

If my power goes out, the natural draft of my chimney should draw out all the smoke.
If I remove the flapper does my OAK now also act as an escape route for the smoke? Or....
could the added venting actually help increase the natural draft in my chimney? Why even have the flapper?

Thanks, Bill

There is a flapper on my Accentra-2 FS. As we know the main reason for the OAK is to provide a way to get outside air into the stove for combustion, then to heat the stove heat transfer areas, then to exhaust that heated outside air through the vent. With an OAK you are using minimal inside air for the combustion, minimal air getting blown out of the house through the exhaust. Using just the interior air for the distribution, re-cycling if you will the already heated air. Much more efficient than using a stove without an OAK where you would be using the already heated interior air for combustion and eventually pushing it out the vent to the outside, pulling replacement air in from outside, creating drafts within the house.

In my stove the vent is passive, there is no control over the action of it other than the draft created by the combustion of the fuel and the combustion fan. There is not spring to hold the flapper shut, nor any electrical or mechanical apparatus to operate it. Hangs on a hinge, gravity taking charge. When the stove calls for outside air it swings forward, towards the burn chamber.

While I was troubleshooting my control board I was experiencing random shutdowns of the stove. I have the stove vent running horizontally through the wall 2 feet to the cleanup T, then just 30" or so up to the exhaust outlet. At no times during the shutdowns did I have any smoke back up into the living area, even with that minimal vent rise. The air intake area (with flapper) provides the needed extra air for the stack effect to take place, even in a power outage situation. As long as the exhaust vent stays warm the air should follow that natural path.

As to the reason it is there, when the stove is off? In my house it keeps the rats and cockroaches from escaping...

 

[bostonfan49]

As to the reason it is there, when the stove is off? In my house it keeps the rats andcockroaches from escaping...
So they are you friends, nice!
Bill

 

[womaus]

As to the reason it is there, when the stove is off? In my house it keeps the rats andcockroaches from escaping...
So they are you friends, nice!
Bill

We get along quite nicely...and I don't like to share.