Creosote question Blaze King

[jimehrhard]

I just purchased a BK Sirrocco 2.0 and love it. I've been burning wood since 1970s and had a number of non-cat stoves including a Vermont Castings Resolute (loved it!). The cat stove is different and I want to be sure I operating it correctly. When I start a fire, I get a really good burn until the thermostat is into the active zone (about 12:00) and then close the damper. Then I wait about 15 minutes until the thermostat is at about 6:00 to turn the thermostat to about 5:00 then wait a few more minutes to turn it to 4:00. I usually run it then for the duration. I want to be sure I am running the stove correctly and not creating creosote. Does everything sound right? Do I need to do anything differently?

I do love this stove. I not only get really long burns but, best of all, the temperature in the house stays pretty consistent the whole time.

 

[stoveliker]

You can close the bypass before the thermometer reaches 12:00 - close it when it is in the active regime.

Then keep burning on high until the wood has a good char (all wood is black) and dial down in steps as you do.

Do you have a flue probe thermometer?
How long has your wood been split and stacked off the ground?

 

[jimehrhard]

I do not have a flue probe thermometer. I cut and split my own wood. All of it is hardwood and has been off the ground and covered for over a year.

So I should shut the damper shortly after it enters the active zone? I was trying let it burn longer so I'd reduce creasote. Does it sound like the rest of my process is correct?

 

[stoveliker]

Hardwood or not is of no consequence (BKs are made in western softwood country...).
What matters is whether it's dry.
Oak can take up to three years to get sufficiently dry.

Yes, do close the bypass (it's not a damper) as soon as the cat gauge reaches the active range. That'll do more to avoid creosote in your flue than burning with the bypass open.

At a hot reload (cat was still active when reloading), open the bypass, wait a 2 minutes or so, open the door, load, close the door (wood starts burning before the reloading is done if it's sufficiently dry...), let it get going for a minute or so, close the bypass, let it run until the wood is charred before dialing down.

I do think the dialing down you do is the right way.

But a lot of the timings also depend on how dry wood is and how tall the flue is.
It's good d to add a flue probe 18" above the stove and use that to see how you are burning

 

[all night moe]

I cut and split my own wood. All of it is hardwood and has been off the ground and covered for over a year.

That's a good start. Not all wood seasons in a year. Some takes more than that....closer to 2.
Some, like oak, takes 3 yrs to fully season.

 

[jimehrhard]

Thanks for the answers. I didn't know that pine could be burned in these stoves. That's great news even though I think I'll still stick with hardwoods. I'll start shutting the bypass sooner and see how that works. In all, I'm really pleased with the way the stove burns. I'm mainly just worried about creasote when I see the wood just basically smoldering. I assume that is fine with the cat.

Is the flue cleaning still annually or do cat stoves create more creasote by low burning and therefore need to be cleaned more often?

 

[stoveliker]

As long as the cat is active, and your flue doesn't draft too hard, you should be fine in the flue (with dry wood).

If you clean by yourself (e.g. sooteater), I'd clean after every cord burned until you are confident (from seeing what you collect in the flue) that what you do is fine.

 

[Ashful]

You can close the bypass before the thermometer reaches 12:00 - close it when it is in the active regime.

Good advice for any beginner. But I'll go a step farther, and say to start closing it earlier and earlier as you gain some experience and familiarity, and watching how the stove reacts to it. I've found I can get very reliable cat light-off when the cat probe thermometer is still down in the middle of the inactive region, as long as at least half the load is charred and the fire looks healthy. I know it's going active, because the combustor begins to glow immediately... and those things don't glow much under 1000F.

Remember, the cat probe is not telling you the temperature of the cat right now, as it has a very long (like 5 - 10 minutes!) time constant. I believe BKVP once said "it's basically telling you what the temperature was 5 minutes ago", which is probably true after a reload when the temperature is rising relatively quickly.

Getting the combustor engaged and active sooner cuts down on how much creosote you're putting into that pipe over the course of a season, and maximizes the heat sent into the room, versus up the pipe!

I know that a few will respond with concerns about thermal shock to ceramic cats, using this early-engagement technique. But I've been running ceramic cats in my Ashfords since at least 2018, and never a problem with any fracturing or spalling. I'm running 6 - 11 cords per year, through a pair of Ashford 30.1's, so they're definitely getting a solid workout in this house.

 

[stoveliker]

Nothing glows under 900 or so (has not much to do with what the thing is and merely what temp it is...)

I agree with you, but hesitate to suggest deviating from instructions before they get a feeling of how the stove is supposed to behave.

 

[Dieselhead]

Good advice for any beginner. But I'll go a step farther, and say to start closing it earlier and earlier as you gain some experience and familiarity, and watching how the stove reacts to it. I've found I can get very reliable cat light-off when the cat probe thermometer is still down in the middle of the inactive region, as long as at least half the load is charred and the fire looks healthy. I know it's going active, because the combustor begins to glow immediately... and those things don't glow much under 1000F.

Remember, the cat probe is not telling you the temperature of the cat right now, as it has a very long (like 5 - 10 minutes!) time constant. I believe BKVP once said "it's basically telling you what the temperature was 5 minutes ago", which is probably true after a reload when the temperature is rising relatively quickly.

Getting the combustor engaged and active sooner cuts down on how much creosote you're putting into that pipe over the course of a season, and maximizes the heat sent into the room, versus up the pipe!

I know that a few will respond with concerns about thermal shock to ceramic cats, using this early-engagement technique. But I've been running ceramic cats in my Ashfords since at least 2018, and never a problem with any fracturing or spalling. I'm running 6 - 11 cords per year, through a pair of Ashford 30.1's, so they're definitely getting a solid workout in this house.

I find I can get it to light off early with the dense hardwoods (oak, hickory etc.) but the lower btu like spruce I’ve been using a lot of definitely does not kick it off as early. I reason that it’s a less powerful wood btu wise, even though the box is fully involved sooner it just does not pack the punch.

 

[jimehrhard]

Good advice. A related question about the cat - should I assume that, when the cat is active, that the stove is NOT producing (much) creasote even though the wood is basically smoldering? To me, as a cat newbie, a smoldering fire seems like a recipe for creasote but it seems like it is the opposite with a cat stoves. Is that correct?

 

[stoveliker]

Good advice. A related question about the cat - should I assume that, when the cat is active, that the stove is NOT producing (much) creasote even though the wood is basically smoldering? To me, as a cat newbie, a smoldering fire seems like a recipe for creasote but it seems like it is the opposite with a cat stoves. Is that correct?

That is correct. Many of us run without flame a significant part of the time. Our flues are good. Not squeaky clean but on par with other stoves that are well-run with good dry wood.

In the end the proof is in the pudding, hence the advice to clean after every cord or so initially.
Or to look at the chimney. Some smoke will happen at some times but overall the majority of the time my neighbors can't see that I'm even burning.

 

[Dieselhead]

I keep an old mirror around and when the stove goes cold (rare) I use a flashlight and the mirror to inspect the flue by aiming it up the bypass. Also you may start to notice some smoke start to back up into the house on hot reloads when the stack starts to get crusty.

 

[jimehrhard]

Another Cat question - After I fire the stove up and close the bypass, the cat glows nicely. But after I reduce the thermostat (after about 15-20 minutes), the cat stops glowing (the indicator is still active, all the way down to the 6:00 position). Is this normal? Is the Cat still working even if it is not glowing?

 

[stoveliker]

Yes, a cat is active from 500 F and up. Glowing only starts at 900-950 or so (depending on your eyes, experience,and darkness of the room and firebox).

The cat will be as hot as the fuel it is combusting allows it to be. It's all good.if it's active.

 

[jimehrhard]

Yes, a cat is active from 500 F and up. Glowing only starts at 900-950 or so (depending on your eyes, experience,and darkness of the room and firebox).

The cat will be as hot as the fuel it is combusting allows it to be. It's all good.if it's active.

 

[jimehrhard]

The thermostat is well into the active area but the cat does not glow. It glows when first starting up. Is it still working when it is not glowing if it stays in the active area.

 

[stoveliker]

Yes that is what I said. It's active when it above 500. You can't see 500 F. So it's acting it's not glowing IF the thermometer (cat gauge) says it's active. All you need to know is what the cat gauge indicates.

Note terminology:
The thermometer (cat gauge) is in the active range.
The thermostat is not visible and is controlled by the knob on the right back corner.

 

[jimehrhard]

Sorry about the terms. I'm still learning about the cat and the system.

 

[stoveliker]

Not a problem, just helping pointing out what is what so we all discuss based on the same understanding.

 

[Tron]

I find I can get it to light off early with the dense hardwoods (oak, hickory etc.) but the lower btu like spruce I’ve been using a lot of definitely does not kick it off as early. I reason that it’s a less powerful wood btu wise, even though the box is fully involved sooner it just does not pack the punch.

Really?
All I burn is southern pine harvested from dead trees, well dried, of course, and it lights off immediately during the reload. So does the cat.

I'm with @Ashful, if the cat's inactive when I reload, I don't wait until the gauge shows active, I know it's going to become active even below the active zone. As mentioned, looking at the cat is a good indication, if it's glowing (even only in places), all's good.

 

[all night moe]

All I burn is southern pine harvested from dead trees, well dried, of course, and it lights off immediately during the reload. So does the cat.

Pine and spruce are 2 different animals.
Spruce is low on the totem pole. Comparatively, pines are heaven sent.

 

[Tron]

Pine and spruce are 2 different animals.

No spruce around here, so I really woudn't know ;-)

 

[stoveliker]

I think it's not how many BTUs is in the wood that makes a cat light off early or late, I think it's how fast BTUs can be released from the wood.

In my experience wood that goes quicker (I have pine and spruce) light off the cat quicker than wood in which the fire spreads a bit slower (for me oak and locust). I thought that simply more/bigger flame (=more heat) heat the cat faster and there you go.
(Now my oak currently is 4.5 years old; I aim for 3 years old, but last years I burned a bit less than I had - and it takes off before reloading is done, yet it takes off slower than the pine or spruce where the whole firebox looks like the gates of hell within a minute after closing the door.)

But that's my experience with my system; ymmv

 

[Tron]

pine or spruce where the whole firebox looks like the gates of hell within a minute after closing the door

Yes, that's about right ;-)