Combustor: time to clean it?

[phatline]

I'm a couple months into my second year with a Blaze King Princess stove. Had a lot of fun last year getting it dialed in. We heated the entire winter in the Sierra Nevada mountains on 2.5 cords of wood. The gas furnace was back-up, and we never used more than 20 therms/month, so it was mostly wood heat for us.

Unfortunately my stove now seems to be having trouble getting the combustor up to temp / maintaining temp. It now takes about an hour on high in order to get the combustor up to max temp (3 o'clock on the BK cat gauge). In days past I would turn the stove down much earlier than that, maybe about 12 o'clock, but now if I were to do so the cat temp would immediately start a slow decline instead of lighting off.

And there's smoke. During that first hour it's smoking pretty bad out the chimney. In fact, even in days past this stove would always smoke quite a bit during the warm-up phase and until the flames died down to very low or completely extinguished. I am not happy with that since one of the reasons I got a cat stove was for lower emissions.

Curiosity got the better of me and I pulled the cat out this morning. Of course the gasket fell apart, so now I have a cold stove and time to think about whether to do a major cleaning on the cat (boiling water+vinegar procedure).

I took some photos before and after vacuuming the cat. It was definitely loaded with fly ash on the bottom of each cell. Some creosote deposits, which I believe (but can't prove) happen at the end of every burn and need to be burned off at the next cycle.

Also there seems to be deterioration of the coating/substrate at the front of most of the cells. Inside they seem intact, but the front edge has a "weathered" appearance. I've read that this could be due to flame impingement.

It is definitely the case that I get flame impingement at every start-up. I'm not sure how one would avoid that. My startup procedure (prior to the last two weeks) is to get the fire well established with the bypass open, then close the bypass and wait until the cat seems to be lightning off (temp is increasing on the cat gauge, generally up to 12 o'clock or more), and then aggressively turn the thermostatic control dial down until the flames settle down (but don't go out). Then 30 minutes later, when the cat is well and hot, turn the dial down again until the flames go out. So the flames would be impinging on the cat for up to 30 minutes. I'm not sure how I could avoid that...

So: photos attached! Please comment on whether you think I should do the vinegar wash or just reinstall this vacuumed cat. I'd also like to know if anyone thinks this cat looks to be in worse shape than you'd expect after 3-4 cords burned. First three are before vacuuming, next two are after.

FWIW most of my wood has been very well seasoned (I use a moisture meter and can tell dry from wet by weight, sound). Last year I did have some oak that was less than ideally seasoned--some pieces would make a hissing sound for a few minutes. I would wait for that to abate before closing the bypass.

Thanks everyone! Love this forum!

 

[weatherguy]

Its out might as well do the cleaning, have you tested the door to make sure its tight with the dollar bill test? Sounds like your doing everything I do so I hope you're doing it right. The cats do take longer after a little use but that time to get hot seems excessive, see what the cleaning does.
I hope Chris from BK reads this and gives us his opinion on both matters (cat cleaning and start up procedure).
Let us know how it turns out.

 

[phatline]

Well I'll be darned! I was going to say I'm sure the seal is good, because I can easily extinguish the flames by turning the thermostat down low enough. But I did the "$20 bill test" (no one's available!) and found a pretty significant gap in the top-right. I can even see through it if I look closely enough.

Went to tighten the latch and found that it can't be tightened... the bolt is bent and the nut is already turned as far as it can go. I'll have to ask BK for a replacement. Hard to see in the photo, but there is a slight curvature to the bolt past where the nut currently is.

 

[Todd]

I doubt you have to worry about flame impingement unless you flame guard shield was removed. Flame impingement looks like you took a scoop of a new bucket of ice cream. Looks like it needs a good cleaning, you have some creosote masking and fly ash accumulation. Also check the door gasket as stated above, they have been known to loose their seal over time and need adjustment.

 

[rdust]

Went to tighten the latch and found that it can't be tightened... the bolt is bent and the nut is already turned as far as it can go. I'll have to ask BK for a replacement. Hard to see in the photo, but there is a slight curvature to the bolt past where the nut currently is.

I'm not a fan of the latch system. If you want to get back up and going I would try to straighten the threaded part out(ie hammer) then run a die over the threaded piece to fix the threads. You can also buy a threaded bolt, bend it to match the latch then cut it to the proper length. Doing that would require some heat though.

I see you live in God's country, I love the Tahoe area!

 

[weatherguy]

Nothing will kill the cat quicker than a leaky door, don't ask me how I know this. That part is about $4.

 

[Highbeam]

My startup procedure (prior to the last two weeks) is to get the fire well established with the bypass open, then close the bypass and wait until the cat seems to be lightning off (temp is increasing on the cat gauge, generally up to 12 o'clock or more), and then aggressively turn the thermostatic control dial down until the flames settle down (but don't go out).

I don't think you are running it right. Leave that bypass and stat open until the cat meter is in the active zone. Then shut the bypass and dial down the stat as needed. Don't look at the cat meter after flopping the bypass lever over, its usefulness is gone. Odd things happen in a cat stove such as more smoke being made to feed the cat at lower stat settings. Ignore the flames, these things didn't even have windows until recently.

You've only put what three cords through this new cat and you think it needs a vinegar bath? No. These things are warrantied for 10 years of regular use and your cat is just a baby.

With the bypass open, these stoves are smokers.

 

[weatherguy]

Phat, are you closing the bypass before the cat is in the active zone? I was assuming you did but HB's post got me thinking.

 

[phatline]

I started always doing it that way, but it takes a long time! Sometimes I do get impatient and close the bypass early if the fire is very well established and the thermostat is close to the activation temp. It would then light off immediately and the temp would climb up into active range.

Before this recent downturn, the stove smokes long after the bypass is closed and regardless of the cat temp. Sure it's quite a bit less smoke than with the bypass open, but far from "clean". It seems to just smoke until the wood load is "settled down" and burning less vigorously. And I do mean smoke, not steam.

Highbeam: so you don't think it's worth doing the bath now that I have the cat out and sitting on my hearth? And I have time to kill while I wait for the new gasket .

PS: Blaze King has already offered to send me a new latch bolt. My local dealer didn't even want to talk to me about it. Thanks BK!

Thanks for all the help!

Phat, are you closing the bypass before the cat is in the active zone? I was assuming you did but HB's post got me thinking.

 

[rdust]

Before this recent downturn, the stove smokes long after the bypass is closed and regardless of the cat temp. Sure it's quite a bit less smoke than with the bypass open, but far from "clean". It seems to just smoke until the wood load is "settled down" and burning less vigorously. And I do mean smoke, not steam.

Mine has smoked a little from day one until the flames are out or near out. It's not trailing smoke but maybe a couple feet off the chimney before it dissipates. Other Princess owners have reported similar behavior.

 

[weatherguy]

Until it settles in smoking is normal, we seem to think its emitting more smoke than the cat can eat for a while, at least that's the consensus. You still should be burning clean the other 23 hours so your not polluting much.
I would think that closing the bypass too early cant be good for the cat but I'm no expert, I just wouldn't do it. Once your rolling it shouldn't take long on reloads to get it back up to active.

 

[phatline]

OK, after the cat is cleaned (maybe) and reinstalled (definitely!) I will try being a stickler on the warmup procedure and see how that goes. I really don't like looking outside after a reload and seeing my neighborhood flooded with smoke (happens on cold days when the inversion layer is going). With my procedure there is smoke (gradually diminishing) for hours after I close bypass... so it would be great to get to clean burning more quickly.

 

[Highbeam]

OK, after the cat is cleaned (maybe) and reinstalled (definitely!) I will try being a stickler on the warmup procedure and see how that goes. I really don't like looking outside after a reload and seeing my neighborhood flooded with smoke (happens on cold days when the inversion layer is going). With my procedure there is smoke (gradually diminishing) for hours after I close bypass... so it would be great to get to clean burning more quickly.

Cleaning the cat using that acid procedure is a last resort to try and rescue a dead cat. I wouldn't do it unless you were told to by BK. You have a cat warranty to maintain and the regular cleaning by vacuum and light air should open any closed passages. A good, hot, cat burn should show all cells brightly burning to verify it's working. That cat is almost brand new. Most folks burn more than 4 cords per year and you're not even there yet.

A brand new cat is ultra sensitive and responsive, it will settle in to a normal reaction after that first 4-5 cords and be dependable but not as sensitive as when new.

The smoke you speak of is what I would consider normal. Smokes like a freight train for awhile and then occasional waves of blue smoke or steam if it's really cold out.

 

[phatline]

That makes a lot of sense, Highbeam. I will first try reinstalling the vacuumed cat. There is no blockage at all, just a few clinging ash deposits and the apparent substrate flaking at the front. I ordered extra gasket tape, so if I'm still having issues I can always pull and do the vinegar bath. I'll report back with results.

Thanks again, everyone!