Blaze King Ashford 30.2 Questions

[Andrew S]

Hello everyone. First time posting on here and new to burning in wood stoves so bear with me on some of these. Looking for insights from other Blaze King owners. I had my Blaze King Ashford 30.2 installed in June of this year and have burned in it about 4 or 5 times since then.

My current setup has 6 inch black double wall stove pipe coming out of the stove 2 feet, then 2, 45 degree elbows transitioning into about a 2 foot horizontal run through the wall, into a tee, then going straight up about 13 or 14 feet. All pipe after it goes through the wall is Class A stainless insulated chimney pipe. Most of the vertical pipe runs inside of a chase on the outside of the house. I will include pictures for reference.

All my wood is at max, 21% moisture content. Mostly white ash. No softwoods.

All the burns I have done were during mild weather. Upper 50s during the day, low 40s/upper 30s at night.

My first question has to do with creosote on the glass and inside of the stove. I am seeing pretty heavy deposits of black, tar looking creosote on the walls and glass. Its also very difficult to remove from the glass. Almost like a baked on enamel. Granted this is after burning on low/medium for about 12 hours. Even so, running the stove on high for an hour doesn't seem to do much in the way of removing it. Is this something normal with these stoves since they run so low? Is this a low draft problem?

My next question would be smoke coming from the chimney while the catalyst is active. While running on low/medium, I noticed white smoke coming from the chimney cap. This was not immediately after reloading but about 6 or 7 hours later. Whenever I reload, I make sure to let the wood burn on high for at least a half hour before turning the thermostat down. Is this normal or is this a sign that the stove is running too low and I need to turn the thermostat up?

I suspect both of these problems may have something to do with my chimney. Inadequate draft?

Thanks in advance for your help.

 

[ratsrepus]

21% is high as far as Im concerned. If your running low and slow like the outside temperatures dictate you are that why the glass is getting sooted up. I'm north of you and I burn sawdust blocks this time of year. your wood moisture content might be ok in the dead of winter but not in October. Crank it up until the wood is good and chared or
get drier wood

by the way I have the same chimney set up as you and I have good draft

same set up

 

[stoveliker]

I think your chimney is borderline or not tall enough (despite examples where it does work). They recommend 15'. And for each 45 and each ft of horizontal run, one ought to add length to that 15'. Check the manual, they have explicit recommendations for flue length w/ elbows and horizontal runs.

That said, yes, running low does put tarry creosote in the box and on the window. Running a few hours high (as in fully open) should take care of that. If not, I think your draft is (indeed) insufficient. I think at 21% running high should get hot enough to burn off the creosote from the window.

Second, white smoke that comes out when running low but not when running high may be just water (same as breathing out in winter). When you run high, flue temps are higher, and it comes out as vapor (invisible). Running lower, it may precipitate out into visible "steam". It is hard to distinguish smoke from water vapor, but my experience (...) is that if it completely dissolves in a couple of feet, it is likely steam. Smoke is bluer, and does not dissolve, but dilutes. It still exists farther away from your flue.

In the end, you seeing creosote in the box is not surprising at 21%, running low, and (possibly) with borderline draft.

 

[Andrew S]

I think your chimney is borderline or not tall enough (despite examples where it does work). They recommend 15'. And for each 45 and each ft of horizontal run, one ought to add length to that 15'. Check the manual, they have explicit recommendations for flue length w/ elbows and horizontal runs.

That said, yes, running low does put tarry creosote in the box and on the window. Running a few hours high (as in fully open) should take care of that. If not, I think your draft is (indeed) insufficient. I think at 21% running high should get hot enough to burn off the creosote from the window.

Second, white smoke that comes out when running low but not when running high may be just water (same as breathing out in winter). When you run high, flue temps are higher, and it comes out as vapor (invisible). Running lower, it may precipitate out into visible "steam". It is hard to distinguish smoke from water vapor, but my experience (...) is that if it completely dissolves in a couple of feet, it is likely steam. Smoke is bluer, and does not dissolve, but dilutes. It still exists farther away from your flue.

In the end, you seeing creosote in the box is not surprising at 21%, running low, and (possibly) with borderline draft.

I'm inclined to think I'm short on flue as well. Will probably end up adding 8 to 10 feet. In regards to running the stove on high for a few hours to burn off the creosote, how do I keep the stove from getting too hot, as in the thermometer probe for the catalyst going all the way to the end of its range? I'd have to think that can't be good for the stove, correct?

 

[stoveliker]

The stove won't easily run too hot; that's what the Tstat is for. "All the way open" on the Tstat is not a setting where the bimetal coil won't close the air inlet a bit when it gets too hot. If you keep the door closed, overfiring is very, VERY unlikely with this stove.

Regarding the cat temp gauge: a new cat often is "hyper active", i.e. runs very high. Burn for a week or 2 every day, and it'll settle down.

 

[Poindexter]

I don't think I would add any chimney height until spring. Looks pretty normal overall to me, though mine is a 30.0.

Every once in a while I scrape the cresosote flakes off the inside of the box and give them a second chance to fly through the cat by letting them fall to the floor of the stove and lighting the stove back up; some folks scrape it out and take it to the dump. I pretty well stopped trying to clean the glass after about two seasons.

Two components to wood stove exhaust as someone above already mentioned. Cord wood is mostly a hydrocarbon just like oil. Long chains of carbon atoms with hydrogens stuck on everywhere they can go. Burn that, combine it with oxygen, burn it completely you should get CO2 and H2O. There are some minerals in there, a tree is a little more complex than that, but there is quite a bit of steam in your exhaust plume created by combining hydrogen with oxygen up around 600 degrees F. When it cools off, it will be white.

I am pretty sure BKVP has said a couple times here 22% is the absolute top end wettest wood that will work, but it also seems to me folks who can get a good quantity of fuel at 18% like it better than 20%. Don't be throwing kiln dried construction lumber in there trying to cocktail your total load MC down to 18%. 2x lumber just burns too fast. You don't want anything in the firebox under 13% MC or so, KD lumber is gonna be 6-8%.

If your stove is running pretty OK through the depth of winter I would leave the stack height alone and come back with fuel a little bit drier next year. You might try adding one (one only) of the bio-logs to an other wise full load of 21%. Like an enourmous wood pellet for pellet stoves, but the size of a salami. Try cocktailing your total load MC down with one of those if you want too.

 

[kennyp2339]

BK princess owner here and I can tell you its a night and day difference from 20% moisture content to 16% moisture content with my stove, hang tight and wait for more cold for improved draft before doing anything.

 

[Andrew S]

I don't think I would add any chimney height until spring. Looks pretty normal overall to me, though mine is a 30.0.

Every once in a while I scrape the cresosote flakes off the inside of the box and give them a second chance to fly through the cat by letting them fall to the floor of the stove and lighting the stove back up; some folks scrape it out and take it to the dump. I pretty well stopped trying to clean the glass after about two seasons.

Two components to wood stove exhaust as someone above already mentioned. Cord wood is mostly a hydrocarbon just like oil. Long chains of carbon atoms with hydrogens stuck on everywhere they can go. Burn that, combine it with oxygen, burn it completely you should get CO2 and H2O. There are some minerals in there, a tree is a little more complex than that, but there is quite a bit of steam in your exhaust plume created by combining hydrogen with oxygen up around 600 degrees F. When it cools off, it will be white.

I am pretty sure BKVP has said a couple times here 22% is the absolute top end wettest wood that will work, but it also seems to me folks who can get a good quantity of fuel at 18% like it better than 20%. Don't be throwing kiln dried construction lumber in there trying to cocktail your total load MC down to 18%. 2x lumber just burns too fast. You don't want anything in the firebox under 13% MC or so, KD lumber is gonna be 6-8%.

If your stove is running pretty OK through the depth of winter I would leave the stack height alone and come back with fuel a little bit drier next year. You might try adding one (one only) of the bio-logs to an other wise full load of 21%. Like an enourmous wood pellet for pellet stoves, but the size of a salami. Try cocktailing your total load MC down with one of those if you want too.

Thanks for the comment. At least 95% of my firewood has a MC in the teens. I just listed the 21% as the worst case scenario. Most of the wood has been cut/split/stacked/covered for at least 3 or 4 years so the higher moisture content ones probably just had a little rain exposure. I did pick up a pack of the Ecobricks (just a brand name of the bio logs you described) just for experimenting but have not used any yet. I will give them a go next time I have the stove running. Its helpful to get some reassurance from people who have been running these stoves for years, as I'm starting to understand there's a decent learning curve to them. Thanks again.

 

[begreen]

Things will likely improve as outside temperatures drop. The height may be less of an issue than the long horizontal run. Long horizontal runs really slow down flue gases. I am wondering if this could be reduced enough to have the top elbow go right into the thimble. Is the stove at the minimum clearance from combustibles at the rear? This is measured from the studs or sheetrock behind the stone veneer and not from the face of the stone.

Also, make sure the tee cap is on snug and sealing well.

 

[stoveliker]

It makes sense to see what happens when the weather gets colder. Such data can point to the (main) cause. However, the OP had "problems" suggesting performance was less than expected. Moreover, if it works well in winter, but not now, then a major benefit of the stove (run low in shoulder season) is not accessible without noted "problems".

Given that the wood may be less severe as first thought (though not perfect), and the height seems insufficient as compared to the specs in the manual, why suffer through a winter of poor to fair performance when getting the system up to specs will help with the issues noted..?

At this stack height, additional height will only make it run better (not worse from overdraft).

 

[stoveliker]

Things will likely improve as outside temperatures drop. The height may be less of an issue than the long horizontal run. Long horizontal runs really slow down flue gases. I am wondering if this could be reduced enough to have the top elbow go right into the thimble. Is the stove at the minimum clearance from combustibles at the rear? This is measured from the studs or sheetrock behind the stone veneer and not from the face of the stone.

Also, make sure the tee cap is on snug and sealing well.

I have the same horizontal run, also 2' long and 2' (well, 21" or so...) above the stove. It works fantastic - with a flue that is tall enough.

 

[begreen]

Every install/house/location is different. If the clearance is there, this is a small place where things can improve. I would be hesitant to add chimney to this installation. It already looks like a rocket on top of the chase and bracing it could be challenging.

 

[Andrew S]

Things will likely improve as outside temperatures drop. The height may be less of an issue than the long horizontal run. Long horizontal runs really slow down flue gases. I am wondering if this could be reduced enough to have the top elbow go right into the thimble. Is the stove at the minimum clearance from combustibles at the rear? This is measured from the studs or sheetrock behind the stone veneer and not from the face of the stone.

Also, make sure the tee cap is on snug and sealing well.

The stove is currently at its minimum clearance to the wall. 6 inches.

 

[stoveliker]

Every install/house/location is different. If the clearance is there, this is a small place where things can improve. I would be hesitant to add chimney to this installation. It already looks like a rocket on top of the chase and bracing it could be challenging.

That's all fine. However, it is well-known that BKs that don't comply with the specifications (and this one at 14' <15', AND two 90 elbows AND a horizontal run, does not) often (not always) result in problems - problems very consistent with the observations of the OP. Hence my suggestion.

I'll bow out, as I've given my view and barring new data I don't have much else to say.

@Andrew S good luck! Keep us updated on what happened (weather/changes/wood) and how your observations change as a result of changed parameters.

 

[begreen]

Yes, I agree, but the practical side of me looks at that stack and sees other potential issues. Colder weather should improve function hopefully. If not, then bracing an extended chimney will be paramount.

 

[Andrew S]

That's all fine. However, it is well-known that BKs that don't comply with the specifications (and this one at 14' <15', AND two 90 elbows AND a horizontal run, does not) often (not always) result in problems - problems very consistent with the observations of the OP. Hence my suggestion.

I'll bow out, as I've given my view.

@Andrew S good luck! Keep us updated on what happened (weather/changes/wood) and how your observations change as a result of changed parameters.

Will do. Thanks for your help!

 

[begreen]

I forgot to ask. Does this stove have an OAK connected? If not, have you tried opening a nearby window 1/2" to see if that affects the burn?

 

[Andrew S]

I forgot to ask. Does this stove have an OAK connected? If not, have you tried opening a nearby window 1/2" to see if that affects the burn?

No OAK. I have not tried the window trick yet but my house is far from being very air tight. Built in 99 on a serious budget by the former owners. I forgot to mention that smoke spillage is an issue on reloading, even after preheating the flue prior to reloading.

 

[begreen]

One possibility is that the stove is in a negative pressure area. This could be because of air leakage on the second floor of the house. Things like leaky upstairs windows or an attic door or in the ceiling vent that is not well sealed off. If you open the window a little on a calm day and feel an inrush of cool air that could be an indicator of lower pressure in the room. Also, if there is an exhaust fan upstairs without a damper that can be a suspect.

 

[Andrew S]

One possibility is that the stove is in a negative pressure area. This could be because of air leakage on the second floor of the house. Things like leaky upstairs windows or an attic door or in the ceiling vent that is not well sealed off. If you open the window a little on a calm day and feel an inrush of cool air that could be an indicator of lower pressure in the room. Also, if there is an exhaust fan upstairs without a damper that can be a suspect.

Interesting. I will check it out the next time I have it running. Thanks!

 

[stoveliker]

One more remark. I got my manual and checked.
For each 90 deg elbow and for each foot of horizontal run, they recommend 2 feet of extra vertical height.
So, even if this was precisely 15', there is a need for 8 additional feet of height (two 90 degs and two feet horizontal). That amounts to 23' total, and leave (if this would be 15' now) a flue that is 1/3 too short (8/23 ~= 0.35).

If this would have been a straight shot up and be 0.653*15' = 9.8' tall, everybody would have "screamed": the flue is too short! [The physicist in me says that that is not truly fair as it is unlikely to be linearly scalable, but you get the point of the argument.]

Hence my insistence. A 1/3 too short flue just is asking for trouble. And the trouble expected for 1/3 too short a flue is precisely the trouble the OP sees.

This does not mean that there are no instance where this might work, and we know the recommendations have a safety margin so that BK does not end up with unsatisfied customers that (just) met specs (and see that the performance it is not all that bad here, a fact I attribute to the safety margin engineered into the stove) - we all know every install is different. But ...

I'll zip my lips again and invite the person who knows most about this: @BKVP

 

[BKVP]

Thanks for the comment. At least 95% of my firewood has a MC in the teens. I just listed the 21% as the worst case scenario. Most of the wood has been cut/split/stacked/covered for at least 3 or 4 years so the higher moisture content ones probably just had a little rain exposure. I did pick up a pack of the Ecobricks (just a brand name of the bio logs you described) just for experimenting but have not used any yet. I will give them a go next time I have the stove running. Its helpful to get some reassurance from people who have been running these stoves for years, as I'm starting to understand there's a decent learning curve to them. Thanks again.

Describe please how you measure the MC of your fuel....

 

[Andrew S]

Describe please how you measure the MC of your fuel....

Split a piece of firewood in half, then measure the moisture at the center and both ends. Then average those numbers. I have a basic two prong moisture meter. Prongs go with the grain of the wood

 

[BKVP]

Split a piece of firewood in half, then measure the moisture at the center and both ends. Then average those numbers. I have a basic two prong moisture meter. Prongs go with the grain of the wood

End readings are not of value. Bring a piece inside (not in same room as the stove) for 24 hours. Then split the wood and take a reading of the face of the fresh split. That reading is actually most predictable. If your MM has short pins, look for replacement pins that are 3/4 inch to 1 inch. You can drill 75% of the depth with a 1/64" drill bit and then jam the pins into the fuel. That is the best method for an accurate reading.

The white steam, buildup in firebox are both indicative of too low an operating burn rate given the MC/draft variables.

 

[Andrew S]

End readings are not of value. Bring a piece inside (not in same room as the stove) for 24 hours. Then split the wood and take a reading of the face of the fresh split. That reading is actually most predictable. If your MM has short pins, look for replacement pins that are 3/4 inch to 1 inch. You can drill 75% of the depth with a 1/64" drill bit and then jam the pins into the fuel. That is the best method for an accurate reading.

The white steam, buildup in firebox are both indicative of too low an operating burn rate given the MC/draft variables.

I will take a sample of a few pieces today. Given my current setup, would you recommend adding height to my chimney?