Sirocco Insert Smoking

[ajzzara]

Hello,
We had our first fire this weekend as the temperatures at night dipped into the mid-30s. I threw a small load in when I woke up in the morning. Once the cat was active, I closed the bypass and eventually lowered the thermostat to around the 3:15 position. When I did this, I noticed considerable smoke coming from the chimney. If I raised the thermostat and got the fire going, the smoke would dissipate, and I would only see a bit of steam coming from the chimney. When I lowered it again, it went back to a lot of white smoke. This is only our 4th winter with the insert, and it is not used much as this is a weekend cabin. Is this an issue I should concern myself with? What would cause it, and how can I remediate it? I appreciate the help as always.

 

[stoveliker]

If you wait half an hour after decreasing the thermostat, is there still smoke?

Also, did you decrease in steps (from fully open to 3.15 in three steps or so of 10 mins each)?

 

[ajzzara]

Thanks for the fast response. It had to have been well over half an hour before I noticed smoke. So I would say yes to that.

I usually go from WOT to half and then to 3.15, with some time in between each step. I will be back up this weekend, so I can give it another more precise try with the three-step method you described . Do you think I am stalling the cat?

 

[Wisco Shepherd]

Thanks for the fast response. It had to have been well over half an hour before I noticed smoke. So I would say yes to that.

I usually go from WOT to half and then to 3.15, with some time in between each step. I will be back up this weekend, so I can give it another more precise try with the three-step method you described . Do you think I am stalling the cat?

Not a bad idea to give your cat a gentle brush and hit it with an air duster. Clean catalysts work better! Also I second the sequential air turn down it helped me with a different stove.

 

[stoveliker]

Stalling the cat is easily seen by looking at the cat temp gauge.

How tall is your flue? Cat effectiveness is a function of residence time of the gases in the cat. A tall flue might suck the gases through too fast leading to incomplete combustion

 

[ajzzara]

@stoveliker just around 15 ft

 

[Tron]

Stalling the cat is easily seen by looking at the cat temp gauge.

True, but that takes time to show up on the cat gauge. It's not instant.

 

[Highbeam]

Since this is year four can we assume that the first three years were problem free? This is a new thing? If so, that rules out your installation.

I propose that what you think is steam is not steam. It's smoke. The cats don't last forever. I only get 2 years out of mine, sometimes part of a third year. Smoke, white smoke, can be caused by a failed catalyst. Do what you can to confirm that your cat is working properly.

 

[stoveliker]

True, but that takes time to show up on the cat gauge. It's not instant.

Correct. So after you dial down the Tstat, you should see the cat gauge go up within the same half hour it takes to stabilize things. Go up or at least stay the same.
If it drops after decreasing the air (while burning less fuel in the primary fire, so giving more fuel to the cat), you're on the way to stall the cat.

Did you only burn "natural" (not lumber, treated, nailed, etc.) wood? Cord wood.

15 ft is not too much (it's barely the minimum). Is all of that straight up?

Given this (and assuming the cat is in good shape, which it should be if it only saw cordwood), it might be your draft is borderline. Not enough draft can also lead to stalling the cat.

 

[stoveliker]

Since this is year four can we assume that the first three years were problem free? This is a new thing? If so, that rules out your installation.

I propose that what you think is steam is not steam. It's smoke. The cats don't last forever. I only get 2 years out of mine, sometimes part of a third year. Smoke, white smoke, can be caused by a failed catalyst. Do what you can to confirm that your cat is working properly.

4th winter for only a weekend cabin - I think the cat should be fine if it's not abused.

I agree verifying the cat is working properly (see my temp change direction remarks) is needed (too).

 

[ajzzara]

Correct. So after you dial down the Tstat, you should see the cat gauge go up within the same half hour it takes to stabilize things. Go up or at least stay the same.
If it drops after decreasing the air (while burning less fuel in the primary fire, so giving more fuel to the cat), you're on the way to stall the cat.

Did you only burn "natural" (not lumber, treated, nailed, etc.) wood? Cord wood.

15 ft is not too much (it's barely the minimum). Is all of that straight up?

Given this (and assuming the cat is in good shape, which it should be if it only saw cordwood), it might be your draft is borderline. Not enough draft can also lead to stalling the cat.

I only burn cordwood.

It is all straight except for the slight angle where the liner exits the stove.

So basically I have to babysit the cat indicator? I thought the indicator or the sirocco insert was just to let you know if the cat is active or not. This info is from people on this forum, as well as the manual. The princess inserts and the regular stoves have more of a gauge-type cat, where as mine is lined with an idiot light. If I am

 

[stoveliker]

Ah, yes, the insert gauge that only shows "enough or not".
Evidently not meant to babysit.

On the other hand, having a gauge (like freestanding stoves) does allow to diagnose more easily any problems. E.g. a "tired" cat ready to retire.

Though I think that's unlikely if you only have burnt in the weekends.

Is this new behavior?
Is the cap clean (or clogged)? When was the last chimney cleaning?

If it's new so, did previous years without this behavior happen *at the same outside temps* ?
Did you tighten up the cabin? Any new exhausting (fan) equipment?

Given that you're near the minimum flue height, I'm still a bit concerned that it might be a draft issue.

If it's a tired cat issue, I suggest to ensure you char the load a bit longer (how long is aways hard to desribe...), and dial down a bit slower.

Regardless, I do suggest to get a new cat. BK will provide the first one free of charge IIRC.
@BKVP
Always good to have it in stock in case the cat is good now but goes bad mid-winter.

 

[ajzzara]

I am trying to remember if it did this last year or not, though if I had noticed it, then I think I would have posted about it. I am anal to a fault and like things to work as they should.
I will try your suggestion of turning it down gradually and trying to take notice. I'll also give cleaning the cat a try.
The cap is clean, and the last cleaning was a month or so ago.

 

[Tron]

BK will provide the first one free of charge IIRC.

Is that like always under any circumstance?
I expect mine (first one) to be due for replacement maybe in a year or two, and so far I've seen the cat as a consumable...

 

[stoveliker]

Is that like always under any circumstance?
I expect mine (first one) to be due for replacement maybe in a year or two, and so far I've seen the cat as a consumable...

I believe that is the standard yes. Unless they changed it recently.
Indeed it's a consumable.
I guess that they want to emphasize that, AND give the user the experience what it is to get going with a new cat once the first one gets sloggy. I think that'll help with users that might postpone replacing the cat. So it's a one time cost (though it may simply be prepaid) to ensure proper operation of the stove for a long time (assuming that the one-time replacement makes folks willing to repeat that at their own dime).

But that's only my thinking - which is based on "first cat within 10 years" (which is what I think is their rule); almost all cats die before 10 years are over, so providing a first replacement within 10 years means they are counting on having to do this. The only reason to do so is to instill an attitude in customers, I think.
Contact. your BK dealer or BKVP when you're almost there. (Telling them "I need to replace the cat" even if you're a bit early; better to have the new one on the shelf (no expiration date) than being too late and being cold...)

 

[Tron]

Contact. your BK dealer or BKVP when you're almost there. (Telling them "I need to replace the cat" even if you're a bit early; better to have the new one on the shelf (no expiration date) than being too late and being cold...)

Good call. I'll see how the cat behaves this heating season. I think I've read somewhere that they last around 10k hours, on average.
Given that the stove only runs ~1k/a around our neck of the woods, if that, and that it was installed in 2019, that'll give me a few years.

 

[stoveliker]

Yes, but I'd make sure you don't contact them in year 11...

I'm not sure if they want the old cat back though (another incentive for them to have you replace the cat; so they can analyze how a used one looks), so having one on the shelf may be not be possible. If that's the case, a summer-time BK contact to replace it is best.

 

[Highbeam]

The industry talks about years because these stoves don’t have hour meters and it’s easier to cancel warranties based on calendar years.

Full time wood heaters are rare and my year of use might be 5x as many hours as tron’s.

Also, I believe that running a stove on low is harder on the catalyst than on higher settings since at higher settings more of the work is being done by the primary fire.

 

[ajzzara]

Ok, So I started a fire last night. This morning, I loaded the stove, and :

-let the cat get to active before closing the bypass
-I waited about 25 min before started turning the stove down
-turned the stove down in 3 10-15 min increments.

Still got some smoke.

I then turned the stove back up a bit, and the smoke disappeared. Should I assume this is the sweet spot for my particular install? Would extending the chimney a foot or so make much of a difference and enhance the stove's performance?

 

[stoveliker]

And does it still smoke 2 hrs after that?
And does the cat stay active for hours after that (assuming it was a full load)?

With low flow (15' chimney and dialed down), residence time of the gases in the cat is large. It should be effective.
If it keeps smoking two hours after this, it's not working well.

I would expect it to drop out of the active range sooner than normal too.

I suggest getting a new cat. Put that in, see if all is well. If so your current one may be dying.
If not, it's another issue and you just have a spare cat in the shelf for when one dies. (Not if, when.)

 

[ajzzara]

@stoveliker, I just want to let you know I appreciate the attention you are giving this issue. At 8:30 eastern, we had the smoke when turned down. 3 hrs later it's still active albeit is getting close to dropping to inactive. Not much smoke at the 2 hr mark.
Also, the logs are pretty burnt down, I didn't pack the stove, so that's also why it could be dropping out of active? I have attached a pic.
Would adding a foot or so extension make a difference for me?
I really can't imagine the cat being dead. As stated its a weekend cabin, and we aren't here every weekend maybe every other week or every two weeks. I'm not putting that many hrs on it.

 

[stoveliker]

Sure, just trying to help. Not convinced I'm right ...

I have quite less coals left when my cat drops out of the active range. But you have a shorter flue.
And I think today (at least here East of you) it's not really "draft inducing weather"(it's relatively warm).

If at 2 hrs you didn't see much of anything,. maybe it's a draft issue. I agree that the cat age seems low for it to die (I noted that early on). Still cats have more or less infinite shelf life, so trying a new one is the best way to ensure it's not the cat.

So, given that the cat is not behaving far out of ordinary as you don't see consistent smoke throughout a no-flame burn, I revert back to the draft (flue height and weather combo).

Yes adding a foot or two might then help. You can do this temporarily by putting cheap single wall in the top. If that works, buy proper chimney pipe.

When changing cats don't forget every time you need a new gasket.

 

[ajzzara]

Sure, just trying to help. Not convinced I'm right ...

I have quite less coals left when my cat drops out of the active range. But you have a shorter flue.
And I think today (at least here East of you) it's not really "draft inducing weather"(it's relatively warm).

If at 2 hrs you didn't see much of anything,. maybe it's a draft issue. I agree that the cat age seems low for it to die (I noted that early on). Still cats have more or less infinite shelf life, so trying a new one is the best way to ensure it's not the cat.

So, given that the cat is not behaving far out of ordinary as you don't see consistent smoke throughout a no-flame burn, I revert back to the draft (flue height and weather combo).

Yes adding a foot or two might then help. You can do this temporarily by putting cheap single wall in the top. If that works, buy proper chimney pipe.

When changing cats don't forget every time you need a new gasket.

Sure, just trying to help. Not convinced I'm right ...

I have quite less coals left when my cat drops out of the active range. But you have a shorter flue.
And I think today (at least here East of you) it's not really "draft inducing weather"(it's relatively warm).

If at 2 hrs you didn't see much of anything,. maybe it's a draft issue. I agree that the cat age seems low for it to die (I noted that early on). Still cats have more or less infinite shelf life, so trying a new one is the best way to ensure it's not the cat.

So, given that the cat is not behaving far out of ordinary as you don't see consistent smoke throughout a no-flame burn, I revert back to the draft (flue height and weather combo).

Yes adding a foot or two might then help. You can do this temporarily by putting cheap single wall in the top. If that works, buy proper chimney pipe.

When changing cats don't forget every time you need a new gasket.

Sure, just trying to help. Not convinced I'm right ...

I have quite less coals left when my cat drops out of the active range. But you have a shorter flue.
And I think today (at least here East of you) it's not really "draft inducing weather"(it's relatively warm).

If at 2 hrs you didn't see much of anything,. maybe it's a draft issue. I agree that the cat age seems low for it to die (I noted that early on). Still cats have more or less infinite shelf life, so trying a new one is the best way to ensure it's not the cat.

So, given that the cat is not behaving far out of ordinary as you don't see consistent smoke throughout a no-flame burn, I revert back to the draft (flue height and weather combo).

Yes adding a foot or two might then help. You can do this temporarily by putting cheap single wall in the top. If that works, buy proper chimney pipe.

When changing cats don't forget every time you need a new gasket.

After I sent my last response I tuned the intake to about 4 ish. The cat is back in the active and humming along.
I was thinking that the weather is a factor. Its 57 ans sunny here currently. I think maybe ill fixate on something else till it gets colder and revisit.

 

[stoveliker]

Good. I agree; given the age of the cat, the temperature, the flue height, and most importantly that there was no smoke 2 hrs in (when 3 hrs in still has the amount of fuel seen in the pic) it's a good possibility that draft is the culprit.
Temperature outside and flue height will help with this.

When it's warm, one can't dial down as far as when it's cold because draft stalls, leading to insufficient fuel for the cat to keep itself hot, and therefore smoke out of the chimney.

As I said you can stuff a piece of leftover single wall pipe in the top to see if it helps. Or indeed wait for colder weather.
Generally below 45 things should work better.

Keep us updated.