Fire intensity in your stove

How crazy are the flames in your stove with a settled in normal burn? Do they stay in the box, or does a lot of flame shoot up and out the top with the draft? Does all fire stay within the firebox? A lot on the burn tubes/little bit sneaks away? I don't think there's a right or wrong, just curious.

 

With a tube stove on a fresh new load it's common for some fire to make it past the baffle and up the pipe. ... that's why its good to have the chimney thermometer on the stove pipe.

 

Most heat comes from the stove top so flames running around your baffle and into that top chamber are good.

 

That's the thing I'm wondering about my stove, you can run it hard so the flames are blasting up between the baffles, and the stove top won't go above 375-400 F, with 300-325 probably being more normal. When I adjust the air so it stays mostly in the box, the stove temp measured above the door is slightly less, but the wood lasts longer.

 

That's my experience as well with the noncat. It goes through a lot of wood to get that last 100 degrees of stt.

 

The closer the flames are to the flue, the less opportunity they have to heat the exchanger (the body of the stove, especially the top) and the more energy escapes. But, that doesn't mean you should cut the air back early to keep the flames in the box, because doing that before the baffles are hot enough to ignite secondaries can cause smoky, incomplete combustion and contribute to creosote problems and pollution. Waste in the form of unburnt smoke is even more problematic than energy that escapes as unabsorbed heat.

A more practical ideal to shoot for is to get the baffles hot enough to ignite secondaries before the bulk of the fuel gets hot enough to start giving off smoke. That's the reason top-down fires are such a good idea for cold-stove starts. Regardless of how the fuel is arranged, managing the air early in the cycle is a balancing act. Too little air, and you get smoky, incomplete combustion. Too much, and more heat than necessary is lost up the chimney.

Fortunately flame typically changes color depending on its temperature, and air moving rapidly through the stove causes turbulence that makes flames wiggle around a lot. I have a non-cat stove so I aim for flames that are bright, pale yellow all the way to their tips, indicating fairly complete combustion, but moving slowly and gracefully, indicating the heat has plenty of time to be absorbed by the stove and make it into the room rather than being whisked up the chimney. I leave the air open wide until the flames are bright and clean, and then start closing it down. If the tops of the flames start to darken, I regard that as a decent indicator that I've restricted the air too much, too soon. If the flames are bright and very active, that's my cue to cut the air back a little more. Bright and slow is ideal, but when a cool stove forces me to choose I prefer bright and fast over dark and slow.

 

I shoot for a rolling flame in front of the door glass to keep it clean. When settled in I make sure the flames from the wood are dancing above it but not "attached" so to speak. Obviouy flames from lower splits are going to dance around the upper splits and touch but I'm talking just about the flame from the split its actually coming from. Secondaries will be all over the board from just flickering along the top to gas furnace like. I don't pay too much attention to them as long as there are some. I try to adjust the air down if secondaries get real crazy but don't get super worried if they stay that way.

 

Let's not forget in this conversation that the stove pipe ALSO represents a huge heating surface area, so some extra heat there isn't terrible. We just don't want some much heat that the chimney system suffers damage, hence the stove pipe thermometer.

 

Sadly I have an insert, so no exposed stovepipe.

 

That's how it seems for me as well. Like the good old 4 barrel carbs, use a lot more gas for a bit more performance.

 

I try for the best efficiency I can get using a wood stove which to me means the lowest setting that will provide enough heat for the conditions or the minimum needed to burn cleanly. My stove usually runs with no visible flame in the firebox although as I have a cat. type stove, the temp. above the cat. can be quite high with a black firebox below and the wood just smoldering. My specific stove has an 'S' shaped exhaust gas path, even with the bypass open, so getting flames up into the stove pipe is tough to impossible without badly overfiring the stove.

At any temps. above around 20 or 25F or so, my stove runs with little to no visible flame but the splits are red and producing a fair amount of heat. Exhaust temps. are in the 300 to 400F range so the stove is running very efficiently. As the temps. drop below 20F, I have to run the stove a bit harder and then there are visible flames, usually blue, in the top of the firebox and the glass gets scrubbed clean. Exhaust temps. go up and the stove needs filling more often while efficiency goes down somewhat.

All of the above applies to a damped- down stove that has been running for a while. When starting a fire, it is normal to have the firebox full of yellow flame and a fair amount of the flame spilling out of the firebox into the chamber above it but not as far as the flue coupling on the top / back of the stove.

Brian

 

I guess each stove has its own personality as far as initial flames and secondary burn flames are concerned. Our Napoleon 1400 which is in the workshop now has always produced the rolling and slow swirling secondary gas flames mentioned. We normally run it hot with 2 splits for a while with full air draft then add a split and go to about half draft. As long as it is fed enough to keep it in this mode it just goes and goes. Once going well we normally just add 2 splits at a time every 2 to 3 hours. The fire brick enclosed fire box and baffles seem to be the key with this design. Initially it used a double row of offset firebricks for the baffle and it seemed to]work even better than the new one piece fibre baffles (2) that they have used the last 8 or 10 years. The design precludes any chance of flames going into the flue itself so that is a non issue with the design used. When we heated the house with it I used to make square hard maple splits that would just go into the opening to the firebox. They were seasoned 2 years and on a cold night 2 of them n/s and half draft would go all or most of the night.

 

What he said....

 

I hear ya! We too use a hybrid cat in the house now. It is a little more sensitive to draft and requires more adjustment to keep it in the happy spot. I am not concerned with using the minimal amount of wood as much as I like to keep the glass as clean as possible so we can see the flames and amount of coals left. I get the impression hybrids are like this. It is mainly a matter of familiarity with our stoves and discovering the optimal way to operate them.

 

I might have a little flame peeking up past the baffle to the top, but I never had a pipe too hot. I'm running wide open with decently seasoned wood. I'd rather burn a little hot and make sure that I have no creosote in the pipe. They say you should run at least one hot fire a day. I try to burn hot at least 12 hours a day. It's pretty hard to overfire my stove with ash. I haven't had any hedge or anything that nuclear.

 

I burn mostly seasoned white poplar....I know everyone hates it, but it throws some decent heat, and sure can gallop.

 

I find a lot of this odd. I run my stove pretty much the same way every load. When the glue temp gets to x shut the air some. When it hits y shut it to the sweet spot. The numbers are a little different with a cold start than a reload, but not much. If I'm needing more heat I'll open the air when the flaming is done to burn down the coals. My hottest fire was also my longest burning. And it was a load of ash.

As far as how crazy the flames are. I like them just a hair faster than a slow roll. If it's jumping around like crazy my flue temps will be 900+ on a full load.

 

You have 3 cubic feet. There's a big difference there. I should have opted for the Mansfield.

 

I'm glad I went big, makes life a lot easier.

 

There's always a next time.