Barometric stove dampers

[bjorn773]

I've been looking for a replacement stove to enable some longer burns. I believe the Blaze King would be the best fit with it's thermostatic damper control. I'm wondering if a similar burning scenario could be accomplished by adding a barometric damper to my current stove setup. If I left my stove damper open, would the baro unit maintain the proper draft to accomplish longer burns?

 

[Slow1]

I believe the argument against a baro damper on the flue is that it will suck air (warm) from the home which will have to be made up from somewhere outside the home (cold) and thus will impact the efficiency of the system as a whole in a negative way. Now I don't understand fully why this argument doesn't equally apply to the oil burner in my basement but I suppose perhaps the burner is much more sensitive to the draft.

 

[LLigetfa]

Ja, like Slow1 said plus the baro will draw humid air that will condense and cool the chimney resulting in creosote buildup.

Draft varies with flue temps and controlling the burn rate in the stove by limiting combustion air is the way to go. Make sure there are no door gasket leaks and look for other uncontrolled sources for combustion air. My RSF has thermostatically controlled combustion air with the exception of the doghouse (zipper) air. I modified it to provide better control.

 

[mike1234]

There are a lot of baro haters in this forum!! I'm not sure if it would work in your situation, but, if you could install it for 50.00 or so, and test it out, you might be saving yourself the cost of a whole new stove. In my furnace, if I close off the baro, I have a draft of .08. They want me to run .03, and the baro accomplishes this, so I burn less wood. I do clean the stovepipe monthly, probably could get away less, but not that hard to do.

I've been looking for a replacement stove to enable some longer burns. I believe the Blaze King would be the best fit with it's thermostatic damper control. I'm wondering if a similar burning scenario could be accomplished by adding a barometric damper to my current stove setup. If I left my stove damper open, would the baro unit maintain the proper draft to accomplish longer burns?

 

[CrappieKeith]

A BDR will slow down the draft.
Since condensation does not occure until you get around 250 degrees a setting of .03 will make 400 degrees.
Here's the problem or in real life the issue.
When the call for heat is low you need less heat. When it's high you'll need more heat.
Building the correct sized fire with good dry wood should eliminate most build up.
This may require several small loads burning hot when it's mild outside vs...a large load when it's cold and the heat load is heavy.
Most build up comes in the mild part of the heating season when we load up our furnaces and stove for those all day burns.
Which is really all day smolders. Stack temps are too low ,but hey.....no fuel bills are pretty cool too.

It really all comes down to temperatures in the flue if the base line of 20% moisture content in the wood is constant or less.
Sure exterior brick flues or oversized flues can be a culprit in condensation ,but it all comes back to stack temps.

Maintaing a clean flue is a responsibility when solid fuel is being burned to stave off the thousands of dollars your not paying for in liquid fuel.

 

[Slow1]

Ok... here's a question that has bugged me. IF I have a stack temp at say 400* (internal, 200 measured on external single wall) just where the entry point to the classA pipe is and it is running steady for hours on end up an external classA chimney, how much heat is likely lost as it goes up? I realize this clearly is a function of both the height of the chimney and the external temp, but is the cooling generally rapid? Say it is around 20f outside with a 20ft run, does anyone have any guess what the temp would be at the top there? is it going to lose enough to hit 212f and start condensing?

 

[LLigetfa]

It really all comes down to temperatures in the flue if the base line of 20% moisture content in the wood is constant or less.

Humidity in the home is also a factor. There is anecdotal evidence that excess humidity near a stove being drawn in as combustion air can affect creosote buildup. That is one factor a OAK can mitigate. It stands to reason that humid air through a baro could have the same effect if stack temps are allowed to drop.

I'm not a baro hater and don't love/hate a OAK either. The effects/benefots of both must be carefully considered.

 

[LLigetfa]

Ok... here's a question that has bugged me. IF I have a stack temp at say 400* (internal, 200 measured on external single wall) just where the entry point to the classA pipe is and it is running steady for hours on end up an external classA chimney, how much heat is likely lost as it goes up? I realize this clearly is a function of both the height of the chimney and the external temp, but is the cooling generally rapid? Say it is around 20f outside with a 20ft run, does anyone have any guess what the temp would be at the top there? is it going to lose enough to hit 212f and start condensing?

There are other factors that need to be quantified. The diameter of the flue and flow rate. A smaller flue will move the gasses faster giving it less time to cool and condense.

 

[Slow1]

Ok... here's a question that has bugged me. IF I have a stack temp at say 400* (internal, 200 measured on external single wall) just where the entry point to the classA pipe is and it is running steady for hours on end up an external classA chimney, how much heat is likely lost as it goes up? I realize this clearly is a function of both the height of the chimney and the external temp, but is the cooling generally rapid? Say it is around 20f outside with a 20ft run, does anyone have any guess what the temp would be at the top there? is it going to lose enough to hit 212f and start condensing?

There are other factors that need to be quantified. The diameter of the flue and flow rate. A smaller flue will move the gasses faster giving it less time to cool and condense.

Fair enough - assume a 6" flue then in an EPA stove so air inbound is going to be low I would guess. Making it personal assume it is a Fireview if you want, but I suppose bottom line is I'm wondering where the "safe" low end temp is without getting condensation at the top. I don't particularly want to climb up there and stick a thermometer in, but given this group I'm betting that SOMEONE here has!

 

[Todd]

Ok... here's a question that has bugged me. IF I have a stack temp at say 400* (internal, 200 measured on external single wall) just where the entry point to the classA pipe is and it is running steady for hours on end up an external classA chimney, how much heat is likely lost as it goes up? I realize this clearly is a function of both the height of the chimney and the external temp, but is the cooling generally rapid? Say it is around 20f outside with a 20ft run, does anyone have any guess what the temp would be at the top there? is it going to lose enough to hit 212f and start condensing?

There are other factors that need to be quantified. The diameter of the flue and flow rate. A smaller flue will move the gasses faster giving it less time to cool and condense.

Fair enough - assume a 6" flue then in an EPA stove so air inbound is going to be low I would guess. Making it personal assume it is a Fireview if you want, but I suppose bottom line is I'm wondering where the "safe" low end temp is without getting condensation at the top. I don't particularly want to climb up there and stick a thermometer in, but given this group I'm betting that SOMEONE here has!

I think I remember Brother Bart taking a reading at his cap with his IR thermometer, can't remember what it was, maybe 300 and something?