Manual pipe dampers .. how, why, when

OKay...lot of good info here. Just so I understand this right I got to ask a dumb question.....where do I want my Baro-D in relation to the chimney-stove-manual-D?
IOW,, Do I want the Baro between my stove and Manual-D..? Or do I want the Baro after my manual-D..?

Thanx....hyway61

My MPD is the first from the stove. After that is the baro damper, before heading into the thimble.

Yep Dallas,,,,,that makes sense and what I figgered. That way the draft is regulated regardless of the manual-D position......hyway61

If you had the MPD after the baro it might leak smoke out the baro if you closed the MPD all the way.

Wouldn't the best place for the MPD be at the flue outlet of the stove? Otherwise the relatively thin flue pipe would be subject to the hot gas that you are trying to restrain.

I started out with a Franklin stove in 1977 and it had the MPD. It was the first winter and the house wasn't insulated or drywalled yet. At the same time, the "air tight" stoves were on the market. I had never burned wood before, so I figured that I could load up the Franklin and completely shut the damper and make it work like the modern "air tight".

We went to bed upstairs and I don't know why, but I turned on the light beside the bed and smoke was coming in the doorway. I ran down the steps and saw a completely glowing orange stove and fluepipe through the wall. I called down my wife and we threw buckets of water on the stove until we could open the door and throw water inside to outen the fire. The cast iron was cracked all over the place. Not wanting to waste money, we continued to use that stove for another 5 years until it was completely used up.

I ran down the steps and saw a completely glowing orange stove and fluepipe through the wall.

Best reason not to use a MPD.

Hello Guys-
I have a question for u guys, I have a vigilant (old style) coal stove, I had to put a manual damper on it because my draft
is way to strong, Before i could not get my stove above 300 degrees, my heat was going out of the chimney!!!!
Now i can heat the stove to 600-700 degrees with no problem, Is it possible that with my damper closed i still have
too much draft??? How do you know when its closed enough?? what will happen with the fire??? There are 2 big holes in the
center of my damper is that ok??
Thanks Ken
I

The correct damper should be sized to the pipe. This will be a damper smaller in diameter than the pipe. The holes are supposed to be there.

Now that you have the MPD, you'll probably have to play around with the under fire draft. Experiment with opening it a bit for a stronger burn. The MPD can be closed and the fire should be fine, due to the holes and space around the MPD.

Not to add any fuel to this fire, but as a former MPD user, I have to say a baro is REALLY nice. I don't think I'm any more efficient or anything like that, but it certainly makes life easier.

I don't use either a flue damper or a baro. Fact is I neck my 7" Hitzer flue down to the 6" liner I had installed six years ago for a 6" flue stove. Draws fine, hasn't over fired, and is idled back with the combustion air control flapper thing.

Sincerely,
Fire Marshall Bill

i could not get my harthmate to be consistant. one day fine next day burnout before 10 hours. someone at work who grew up around coalstoves in pinegrove said close the mpd . i said i thought it was for burning wood. he said close it. so i did. and now it is working like it should.can go now 12 to 18 hours all the time. worked for me.

Here is my latest on "dampers".

To bring you up to speed, I've got a hand fired Russo, on which I had installed a baro damper, initially. Afterward, I added an MPD, then a thermostatically controlled power damper for the under-fire draft. This set-up worked great through the whole winter season .... the thermostat would open the under-fire power damper, when it called for heat. The baro damper would keep the stove from over-firing.

Then we get to spring. A couple of mornings I woke up and my eyes were burning, slightly. There were no CO alarms from either of two detectors. I let the stove go out and had no problem with my eyes burning. (Side note: over the last couple of years, I have developed "sulfite sensitivity", so anything that has to do with sulfur, I have to have a close look at. I even wonder, if the stove hasn't been a "cause")

I decided, I wanted to eliminate the barometric damper, as a possible cause of my eye irritation. The problem being, the barometric damper was the device, which was keeping my stove from over-firing. What I ended up doing, after removing the baro damper, was installing an "adjustable limit switch" in the outlet hot air plenum, connected in series with the power damper circuit. Also, I adjusted the power damper to restrict the air input to allow only a reasonable burn. The purpose of the limit switch being, to close the power damper, if the hot air plenum was getting too hot.

This set-up won't help most of you, due to the fact that you don't have a power damper.

But, I want to look at the barometric damper situation. It has always been of prime importance to have good integrity in the chimney system. In my opinion, cutting a 6" hole in the stove pipe, is counter intuitive! While it might work reasonably well in the winter months, due to strong draft and high stove temps, in the spring and fall, when the stove is more at idle, and is sitting there with a load of unburned coal, is when the problems might arise. With the stove making little heat, the air can stratify and not allow for a good draft. There is no good reason to think, that none of the gases will escape through the barometric damper. If you were to hold the baro damper with the shutter closed and try to fill it with water, I think, you'd find that it leaked like a sieve. Also, if you look at a baro damper, which has been in use, you'll find it totally covered with as much ash and soot as the rest of the stove pipe. Is there any reason to believe that the gases which carried this to the shutter, would not leak into the room? Barometric dampers work well on any heating device, which more or less, are on or off, i.e. oil burner, stoker, etc..

That is just my opinion.

It all boils down to having a good draft or not.. If you have ANY draft, even .01" wc, the baro will 'leak' room air into the chimney, so nothing from inside the stove/firebox can leak 'out' into the room.. If you DON'T have any draft, then even the small gaps around the shaft of the MPD will leak combustion gasses, any unsealed flue pipe connections and of course the stove will leak at the air inlet as well..

When the weather warms up to the point that the chimney won't draw, the stove either needs to be run hotter to keep the chimney warm and drawing, or the stove needs to be shut down.. in warm, marginal weather, the house needs to have a window open or a dedicated outside air source so the weak-drawing chimney isn't trying to pull a vacuum on the house..

The easiest way to temporarily eliminate the Baro would be to cover it with aluminum foil. But low draft is low draft,, the combustion gasses will find a way out of the stove.

Greg L.

Amen. I'm so glad I installed a Class A SS insulated 6in. chimmey this time around. Much better getting the fire going when it's down and keeping a low quitefire going for the warm days this past spring.

I too have always had a MPD close to the stove and a Baro above it set for windy days. I find it makes it easier to control the fire with a MPD.

Will this tread ever die. You guys have said the same thing at least 10 times. Over two year no!!!! Give it a break.

Don