Blaze King thermostat not working...help!

[moresnow]

@Highbeam and any others who may be wondering about my comment on flipping up the rear plate for inspection/cleaning. Zero idea if the unit in question has the flip up plate. Worth a peek.

From BKVP this AM.
"Yes. That plate was welded in early models, then hinged in other models."

 

[lsucet]

Whatever came with the stove...ceramic I guess?

I asked cause some here has problems with plugged steel cat. I will check for sure the cat. That's the only thing come to my mind.

 

[Ryan723]

Your symptoms sound just like when i plugged my OEM steel cat (due to 'user error' while learning to operate my stove).

If your cat was plugged, it may help to determine whether the problem is from flyash or from creosote, because the solutions are different.

As others have said, if you can get a good look at the front and back faces of the cat, it should give some good idea of what is happening. Also, if you can remember any particularly odd burns of late where something might have gone off the rails and lead to this problem.

Here are my observations from similar experiences from my BK Ashford. Not 100% familiar with the King, but I assume the theory of operation is similar enough to be a good reference.

Plugged from fly ash:

--You'll often see the buildup obscuring the openings on the front of the cells. As you've turned up the controls to compensate, you increase the velocity through the adjacent areas not blocked, often leading to more fly ash being sucked into the cat.
--BK manual suggest lightly brushing the face of the cat and a vacuum 'near the face' of the cat.
--I believe that at least once i've made this situation worse by vigorously vacuuming the face of the cat clean only to suck fly ash from the flue (and bits of creo flakes that fell down the stack and incinerated in the cat exhaust stream) from behind the cat against the back face of it due to vacuuming the front.
--(If you have a new cat gasket), you could pull the cat, give the cells a good inspection and gently tap it while you vacuum both sides to loosen. DO NOT stick anything into the cat cells to clean them. You will do more damage than good!
​

Plugged from creosote:

--I once had a burn during an oddly warm day (low draft) and with a load that had a few pieces that must have been MUCH wetter than I realized. I turned it down too low for that quality of wood and left for a few hours. The fire died on me, but not before drawing a LOT of damp, sticky smoke through the cat. The firebox had a coating of gross, sticky creo, which is not entirely unusual for a low burn. But the face of the cat and the internals of the cells were also gummed up.
--When i closed the bypass, the cat was gummed up enough it would stall the fire, just as you're seeing, regardless of thermostat air position.
--when I opened the bypass back up, the fire would come back vigorously.
--I don't know if i read this or came up with it out of desperation on the spot and would NOT recommend it as anything other than a 'what worked for me' scenario...but, what I did to burn the clogging creo deposits off the cat was the following:

--Got a fairly brisk fire burning with your best/driest wood in the front half of the stove with the bypass open. Not a huge load of fuel in case it didn't work, as I didn't want to have to burn a load with the bypass open nor smoldering through a full load with the bypass closed.
--when the flue is warm enough to have a good draft with the bypass open and the cat showing it is heated up (via the cat thermometer), i started to feather the bypass door shut.
--I varied the between holding the bypass partway closed for ~30-45 seconds and then back to fully open to let the fire regain some strength
--after a few attempts i was able to hold the bypass closed a little more and a little longer.
--after 5-10 minutes of this, i had burned enough of the junk out of the cat that it was able to flow enough to not snuff the fire. From there, burned it HOT to get the cat temp up and burn out more of the deposits.
--the idea is that you are feathering the bypass open and closed, alternating between the bypass open and the fire able to get enough draft to burn well with some times of partially or fully closed bypass to pull super-hot exhaust against the cat to burn out the creo built up in it.
--once you get it burned clean, be sure to vacuum it out when cool, as the burned out creo likely left some fine deposits within the cat cells
**this worked for me. I'm not advocating it as a best/easiest/safest solution. i knew i had creo in the cat and had checked and swept my stack and was sure I didn't have a dangerous accumulation of creosote in the flue before getting a hot fire going to try to burn out the cat. If you snuff it down too low, you could get some serious volatile smoke built up in the firebox that could backpuff when it gets enough air. I didn't know of a better way to clean the cat and didn't have a spare. The manual says "TIP: A nice hot fire will usually prove to be the best method of cleaning the combustor of deposits." so this seemed like a viable way to do that.
​

The fact this came on suddenly to you sounds like what happened to me with the creosoted-up cat. If you happen to know you had a burn that might have smoldered a lot with an inactive cat, i'd look into this.

Mods and those with more experience, I feel what I did above was done in a controlled and safe way (as i tried to emphasize above), but if you feel this is the wrong way to un-gum a cat, please let me know and i will edit or remove the post as I don't want to be spreading bad information.

 

[Highbeam]

May need some clarification? When I vac. the backside of my cat area I can flip up the "curtain" to ascertain the condition/cleanliness of the backside of the cat area. Soot/pipe buildup can fall down and buildup in this area with use if not cleaned for extended periods. My model may be different. Guessing so? Ill have to look at the parts. Or maybe I am dreaming! Ive been in there many times cleaning.

Maybe you’re talking about the bypass plate?

On edit, cool, stove design was changed by bk! Another variation.

 

[Ashful]

Your symptoms sound just like when i plugged my OEM steel cat (due to 'user error' while learning to operate my stove).

If your cat was plugged, it may help to determine whether the problem is from flyash or from creosote, because the solutions are different.

As others have said, if you can get a good look at the front and back faces of the cat, it should give some good idea of what is happening. Also, if you can remember any particularly odd burns of late where something might have gone off the rails and lead to this problem.

Here are my observations from similar experiences from my BK Ashford. Not 100% familiar with the King, but I assume the theory of operation is similar enough to be a good reference.

Plugged from fly ash:

--You'll often see the buildup obscuring the openings on the front of the cells. As you've turned up the controls to compensate, you increase the velocity through the adjacent areas not blocked, often leading to more fly ash being sucked into the cat.
--BK manual suggest lightly brushing the face of the cat and a vacuum 'near the face' of the cat.
--I believe that at least once i've made this situation worse by vigorously vacuuming the face of the cat clean only to suck fly ash from the flue (and bits of creo flakes that fell down the stack and incinerated in the cat exhaust stream) from behind the cat against the back face of it due to vacuuming the front.
--(If you have a new cat gasket), you could pull the cat, give the cells a good inspection and gently tap it while you vacuum both sides to loosen. DO NOT stick anything into the cat cells to clean them. You will do more damage than good!
​

Plugged from creosote:

--I once had a burn during an oddly warm day (low draft) and with a load that had a few pieces that must have been MUCH wetter than I realized. I turned it down too low for that quality of wood and left for a few hours. The fire died on me, but not before drawing a LOT of damp, sticky smoke through the cat. The firebox had a coating of gross, sticky creo, which is not entirely unusual for a low burn. But the face of the cat and the internals of the cells were also gummed up.
--When i closed the bypass, the cat was gummed up enough it would stall the fire, just as you're seeing, regardless of thermostat air position.
--when I opened the bypass back up, the fire would come back vigorously.
--I don't know if i read this or came up with it out of desperation on the spot and would NOT recommend it as anything other than a 'what worked for me' scenario...but, what I did to burn the clogging creo deposits off the cat was the following:

--Got a fairly brisk fire burning with your best/driest wood in the front half of the stove with the bypass open. Not a huge load of fuel in case it didn't work, as I didn't want to have to burn a load with the bypass open nor smoldering through a full load with the bypass closed.
--when the flue is warm enough to have a good draft with the bypass open and the cat showing it is heated up (via the cat thermometer), i started to feather the bypass door shut.
--I varied the between holding the bypass partway closed for ~30-45 seconds and then back to fully open to let the fire regain some strength
--after a few attempts i was able to hold the bypass closed a little more and a little longer.
--after 5-10 minutes of this, i had burned enough of the junk out of the cat that it was able to flow enough to not snuff the fire. From there, burned it HOT to get the cat temp up and burn out more of the deposits.
--the idea is that you are feathering the bypass open and closed, alternating between the bypass open and the fire able to get enough draft to burn well with some times of partially or fully closed bypass to pull super-hot exhaust against the cat to burn out the creo built up in it.
--once you get it burned clean, be sure to vacuum it out when cool, as the burned out creo likely left some fine deposits within the cat cells
**this worked for me. I'm not advocating it as a best/easiest/safest solution. i knew i had creo in the cat and had checked and swept my stack and was sure I didn't have a dangerous accumulation of creosote in the flue before getting a hot fire going to try to burn out the cat. If you snuff it down too low, you could get some serious volatile smoke built up in the firebox that could backpuff when it gets enough air. I didn't know of a better way to clean the cat and didn't have a spare. The manual says "TIP: A nice hot fire will usually prove to be the best method of cleaning the combustor of deposits." so this seemed like a viable way to do that.
​

The fact this came on suddenly to you sounds like what happened to me with the creosoted-up cat. If you happen to know you had a burn that might have smoldered a lot with an inactive cat, i'd look into this.

Mods and those with more experience, I feel what I did above was done in a controlled and safe way (as i tried to emphasize above), but if you feel this is the wrong way to un-gum a cat, please let me know and i will edit or remove the post as I don't want to be spreading bad information.

Good post (but long!). The only thing I’d add here is that continuing to burn with a cat that’s been plugged with fly ash can lead it to fall out of active sooner than intended, and lead to creosote plugging. Sounds far-fetched, but I’ve personally done it twice, with a steelcat in an Ashford.

Running a Steelcat with a very tall flue seems to be a good recipe for ash plugging, in some stoves.

 

[Rangerbait]

Sounds like the consensus is I need to buy a new cat then? What is the life expectancy of these things?

 

[begreen]

Sounds like the consensus is I need to buy a new cat then? What is the life expectancy of these things?

Have you cleaned it thoroughly?

 

[jetsam]

Sounds like the consensus is I need to buy a new cat then? What is the life expectancy of these things?

No, I don't think anyone is at 'new cat' yet. After 1 year and 6 cords, utterly dead? Not likely.

Also, a dead cat wouldn't effect the fire when the bypass is flipped.

I would take the pipe off, clean behind the cat with a shopvac, brush the face of the cat with a paintbrush, then shopvac the face of the cat. If you still can't see through the cat with a flashlight, it's still plugged and you may need to take it out to unplug it. (This would be very uncommon.)

Go ahead and order a new cat gasket now, though. They are cheap and even if you don't use it now, you will need it in a couple years when you boil or replace the cat.

 

[Highbeam]

Go ahead and order a new cat gasket now, though. They are cheap and even if you don't use it now, you will need it in a couple years when you boil or replace the cat.

Every time I've replaced my cat, the new cat comes with a new gasket. Boiling the cat was a bad idea in my experience, only bought a couple months of life and the money/effort would have been better used on a new cat.

If Ranger can't clear the cat without removing it then yes, a new gasket is necessary.

 

[SuperJ]

Complete cowboy idea to a creosote clogged cat. I've never tried it and I'm not suggesting anyone else does, but what about hitting the cat with a plumbers torch just enough to get it glowing and burn the crap out?
I'm sure if you held it too close for too long you might degrade the cat.

 

[jetsam]

Every time I've replaced my cat, the new cat comes with a new gasket. Boiling the cat was a bad idea in my experience, only bought a couple months of life and the money/effort would have been better used on a new cat.

If Ranger can't clear the cat without removing it then yes, a new gasket is necessary.

My last one didn't. I bought 3 gaskets with the new cat in case I had to remove a cat for whatever reason.

 

[jetsam]

Complete cowboy idea to a creosote clogged cat. I've never tried it and I'm not suggesting anyone else does, but what about hitting the cat with a plumbers torch just enough to get it glowing and burn the crap out?
I'm sure if you held it too close for too long you might degrade the cat.

That could cause thermal shock and fracture a ceramic cat.

Beyond that, with ceramic or steel, if you soften the substrate you get greatly reduced surface area when the substrate settles. Also, MAPP gas burns at almost the melting point of palladium, so I would advise caution.

Not saying it wouldn't work, but I'd rather go without a gasket for a couple days because I pulled the cat, especially on a ceramic one.

 

[Ashful]

That could cause thermal shock and fracture a ceramic cat.

Beyond that, with ceramic or steel, if you soften the substrate you get greatly reduced surface area when the substrate settles. Also, MAPP gas burns at almost the melting point of palladium, so I would advise caution.

Not saying it wouldn't work, but I'd rather go without a gasket for a couple days because I pulled the cat, especially on a ceramic one.

Each time I plugged my cat, pipe cleaners and substantial swearing were required to get them cleaned. The shop vac just wasn’t enough, and experiments with compressed air got me scolded by the maid.

 

[jetsam]

I still say that we should spec out a reuseable gasket that will work for this. Next time I do some cat swapping I will spend some time digging through gasket manufacturers.

 

[Highbeam]

I still say that we should spec out a reuseable gasket that will work for this. Next time I do some cat swapping I will spend some time digging through gasket manufacturers.

It’s gotta be better than that one cat reseller that tells you to not use a gasket at all! Woodstock has us beat on this one with a gasket free cat, or at least reusable.

 

[jetsam]

It’s gotta be better than that one cat reseller that tells you to not use a gasket at all! Woodstock has us beat on this one with a gasket free cat, or at least reusable.

Honestly, it's like a 1/16" gap and it wouldn't be the end of the world if there was no gasket there. Even a poor gasket that only blocked 90% of the airflow in that little gap would be fine. I just want to get a shopvac back there once in a while.

 

[Ashful]

Honestly, it's like a 1/16" gap and it wouldn't be the end of the world if there was no gasket there. Even a poor gasket that only blocked 90% of the airflow in that little gap would be fine. I just want to get a shopvac back there once in a while.

BKVP recently relayed a story to me about customer who was seeing a little smoke out of his stack on a one year old AF30. He ended up finding the cat gasket was partially out of place and hanging down behind the combustor. They replaced the gasket, and smoke is completely gone. Stove also performs better, and has much better control. They figure it must have somehow slipped during shipping, but they don't know how, as they tape them on really well.

So, it seems like having a complete gasket seal can be pretty important.

 

[jetsam]

That's counterintuitive if you compare the surface area of the cat's openings with the surface area of the gap around the outside of the cat.

I guess maybe the space around the outside might have less drag and turbulance since its walls are smooth... but then it has a metal plate blocking a lot of it in the form of that little tab on the front of the cat, I think.

Still, if it caused visible smoke spillage, I guess a lot of air was going through the gap for some reason. (Was HIS cat plugged too?)

 

[tarzan]

That's counterintuitive if you compare the surface area of the cat's openings with the surface area of the gap around the outside of the cat.

I guess maybe the space around the outside might have less drag and turbulance since its walls are smooth... but then it has a metal plate blocking a lot of it in the form of that little tab on the front of the cat, I think.

Still, if it caused visible smoke spillage, I guess a lot of air was going through the gap for some reason. (Was HIS cat plugged too?)

Next time you have the cat out, put it back and run it without a gasket for a while to see how it performs.

In my case, the gap was close to 1/4”x10” and let allot of smoke slip by. That was with the a new steelcat.

 

[Ashful]

That's counterintuitive if you compare the surface area of the cat's openings with the surface area of the gap around the outside of the cat.

It seems to me there is a difference between steel at and ceramic, in this regard. When I switched from steel to ceramic, my draft dropped by almost half. With the ceramic, I could not get down to .05” WC on high burn, even with the key damper completely closed. With the ceramic cat, I can hold .05” WC on high all day long with damper at 30 degrees off closed position.

So, I’d assume gasket is much more important on steel cat than ceramic cat, but at only $6 for enough of it to reinstall my cat once per year, I’ll just run one either way.

 

[Highbeam]

It seems to me there is a difference between steel at and ceramic, in this regard. When I switched from steel to ceramic, my draft dropped by almost half. With the ceramic, I could not get down to .05” WC on high burn, even with the key damper completely closed. With the ceramic cat, I can hold .05” WC on high all day long with damper at 30 degrees off closed position.

So, I’d assume gasket is much more important on steel cat than ceramic cat, but at only $6 for enough of it to reinstall my cat once per year, I’ll just run one either way.

I think you need to edit something in there.

So the steel cat with its smaller cells is actually causing more restriction which makes more draft in the flue? Enough difference to mimic a pipe damper at 30 degrees open vs closed tight?

 

[Rangerbait]

Took the pipe off and inspected/vacuumed...lots of ash clogging up the cat



After the vacuum season



Noticed that a bit of the lower part of the cat is crumbling...how did that happen?



It lives!

 

[jetsam]

Holy yuck! Good to hear that you are back in action.

That cat has experienced a lot of trauma in 1 year. Make sure that everyone in the house knows that you need to open the bypass before opening the door. Also let the wood steam off before closing the bypass if it had surface moisture or snow. Drying the next load by the stove can help sort this problem out.

I'd also say consider a steel cat next time, but that will make your ash problem worse. I've actually added a cat vac to my regular chimney sweeping routine since I went steel. As you know, it only takes a minute to brush and vac it from the front.

 

[Rangerbait]

Holy yuck! Good to hear that you are back in action.

That cat has experienced a lot of trauma in 1 year. Make sure that everyone in the house knows that you need to open the bypass before opening the door. Also let the wood steam off before closing the bypass if it had surface moisture or snow. Drying the next load by the stove can help sort this problem out.

I'd also say consider a steel cat next time, but that will make your ash problem worse. I've actually added a cat vac to my regular chimney sweeping routine since I went steel. As you know, it only takes a minute to brush and vac it from the front.

We’ve definitely had a couple incidents of opening the door while the cat was still engaged...that’s the cause of the hammered cat?

 

[jetsam]

We’ve definitely had a couple incidents of opening the door while the cat was still engaged...that’s the cause of the hammered cat?

It can break due to mechanical shock (if something hits it) or thermal shock (rapid temperature change).

Hit a cold ceramic tile with a blowtorch, and it will pop into chunks, right? Same with the ceramic cat substrate.

Popping the door open draws a massive rush of room temperature air through the cat- even more so for you since you have an 8" flue. The cat might be at 1500 or 2000 degrees. Even if it's 100° in your stove room, that's a 1400-1900° differential. Snap crackle pop.

That does not happen to steel cats, but their smaller cells plug more easily.

My old ceramic cat got shocked at least a few times that way, but it looked a lot better than yours when I retired it. :/

I think yours will be ok until retirement age if you take care of it.