We have had a Blaze King that looks just like the current King 40 models ... since 2003. The occasional smell of smoke is something that puzzled us for a while. One night is was in the dark room and noted that there was a nice bed of coals but no flames visible. Then there was a mini flashover and a puff of smoke came out from any joint in the stack that was not sealed. A flame danced across inside the stove for a minute or two then disappeared. Several minutes later it repeat. We call it puffing. No flames ... Puff ... smoke leaks when it puffed, then a flame for a few minutes. After some experimenting we discovered that opening the draft just enough to get a constant flame, even just a small flame ... eliminated the puffing and the smoke smell in the house it created. Hope this helps
Blaze King King 40 New Cat Stove 2020 Smoke Smell
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Thank you for that information, I will keep it in mind if I get to the point of using the stove for a prolonged amount of time.
The smell issue, in my case, starts a few hours into the burn cycle when the thermostat closes to maintain the temperature setting, which is set to high (fully clockwise). I get the same results regardless of where the temperature control is adjusted to. I have been working with BK in an attempt to understand what is causing this however have not been able to understand it. I plan to ask BK to send a local expert to diagnose the problem and recommend what needs to be done to solve it. If there is a deficiency in the chimney system or installation I am more than happy to have it updated. Against my better judgment I made a considerable investment in a new 27' insulated liner with no positive results. I say against my better judgment because in my opinion the existing masonry chimney was performing properly. The chimney is completely exposed, internal to the house, and the draft values are constant between .05 and .08 inchH2O which seems to be accepted as good draft throughout the industry. Regarding the pic, I tried a different configuration of the piping with a straight run between the two 45's just to see if there was any difference; there was not. I test with 90, two 45's together, and one 45 at stove collar the other at thimble; all configurations yield the same results. BK assures me that there are 1000's of these stoves working properly in the field so I continue to look for a resolution.
![[Hearth.com] Blaze King King 40 New Cat Stove 2020 Smoke Smell](https://www.hearth.com/talk/data/attachments/287/287261-ada1f6835cce94075454e91579710aa4.jpg?hash=Ere6_G7oSM "[Hearth.com] Blaze King King 40 New Cat Stove 2020 Smoke Smell")
The smell issue, in my case, starts a few hours into the burn cycle when the thermostat closes to maintain the temperature setting, which is set to high (fully clockwise). I get the same results regardless of where the temperature control is adjusted to. I have been working with BK in an attempt to understand what is causing this however have not been able to understand it. I plan to ask BK to send a local expert to diagnose the problem and recommend what needs to be done to solve it. If there is a deficiency in the chimney system or installation I am more than happy to have it updated. Against my better judgment I made a considerable investment in a new 27' insulated liner with no positive results. I say against my better judgment because in my opinion the existing masonry chimney was performing properly. The chimney is completely exposed, internal to the house, and the draft values are constant between .05 and .08 inchH2O which seems to be accepted as good draft throughout the industry. Regarding the pic, I tried a different configuration of the piping with a straight run between the two 45's just to see if there was any difference; there was not. I test with 90, two 45's together, and one 45 at stove collar the other at thimble; all configurations yield the same results. BK assures me that there are 1000's of these stoves working properly in the field so I continue to look for a resolution.
Horizontal run is 23" and slopes up 1.5 inches from thimble to "T".
Piping = 2x45's, 2ft horizontal run, one base "T"
Height from stove top to horizontal = 29" - Requirement Min = 24" (I called BK and verified 29" was OK prior to purchasing stove)
Height from stove top to chimney top = 27' - Exceeds height requirement based on "Min recommended flue height" in manual
Chimney extends approximately 3 feet above ridgeline.
Piping = 2x45's, 2ft horizontal run, one base "T"
Height from stove top to horizontal = 29" - Requirement Min = 24" (I called BK and verified 29" was OK prior to purchasing stove)
Height from stove top to chimney top = 27' - Exceeds height requirement based on "Min recommended flue height" in manual
Chimney extends approximately 3 feet above ridgeline.
Dieselhead
Minister of Fire
I didn’t read all 5 pages but how airtight is the fireplace flue, any chance smoke is downdrafting through the fireplace?
Good question, I did rule it out, there is a closed damper at the bottom of the fireplace flue, the flue has a small hole that I put a lit candle flame to while the smell was coming from the stove, the flame was pulled into the hole verifying there is updraft in the fireplace chimney while the stove is operating. The house is older and not air tight, the fireplace burns with absolutely no smoke spillage even when the shower exhaust fan is running.
Nealm66
Minister of Fire
Man that’s a really cool looking setup. Sorry to hear the big king is making smoke smells. I’ll get a smell from my princess sometimes when I reload especially if I wait too long . It does fine if I catch it still fairly hot. It doesn’t seem to have the problem once I’ve got everything set and on cruise control. I have 2 90’s and a 3’ through the wall so that’s what I figure causes it. I bet you’re low inside bend is causing you some issues especially on reloading and when it’s warmer out but I’m definitely no expert
You know, I read about users complaining of smoke spillage at cold starts and reloads which makes me think their setup draft is low. In my setup there is no spillage at cold starts or reload, when the door opens the smoke is pulled right up the chimney regardless of what the state of burn. Something just doesn't add up!
What do you have for a height difference for your stove chimney termination and fireplace chimney termination? I understand you have checked the fireplace for positive draw. But.... Curious. This may have been covered/discussed already?
Nealm66
Minister of Fire
Mine draws smoke as well. It’s in 10’ ceiling before it takes the 3’ horizontal and then climbs up past a 12/12 roof by 3’ so it seems to draft pretty good but I’m still pretty sure the 3’ horizontal is what gives me the reload smell. If you only get the smell while you’re in reload mode and no smell once it’s settled in and cruising, I’d bet money your having a draft issue . Curious about your stove placement. The big king would look pretty sweet sitting inside where the fireplace is with some cool brickwork and would eliminate the quick bend.Anyways, again, I’m not anywhere near as knowledgeable as lots of folks on here but feeling bad for ya and trying to help. Maybe my suggestions might stir up some more input
I only have smoke smell when it is "Cruising" not while starting or loading.
The flue height difference is noticeable, have not actually measured but will when possible.
No, we enjoy using the fireplace from time to time.
One point about horizontal run, from extensive research I believe the horizontal run negative effects are minimized by creating an upward pitch in the pipe at approximately 1/4 inch rise per linear foot run. If you don't have the pipe pitched up you might want to try it and see if there is any improvement, little details can make a big difference.
The flue height difference is noticeable, have not actually measured but will when possible.
No, we enjoy using the fireplace from time to time.
One point about horizontal run, from extensive research I believe the horizontal run negative effects are minimized by creating an upward pitch in the pipe at approximately 1/4 inch rise per linear foot run. If you don't have the pipe pitched up you might want to try it and see if there is any improvement, little details can make a big difference.
Nealm66
Minister of Fire
Ok, I thought you were having problems during reload. That’s really weird. So it’s when you have the stove shut down is when the smoke smell happens. Does it help to open the draft a bit? Will it stop if you open the bypass?
Minimized yes, but the impedance it adds (which decreases draft) does require added vertical height to reach the same draft values.
Smell during cruising could be due to backpuffing (didn't read above to see if this was already mentioned).
My description is: when the wood produces more gases than are being burned, the air-gas mixture in the firebox can reach (semi-)explosive properties. Under the right conditions, it may suddenly burn/erupt/explode. This creates smoke (as gas explosions rarely feature complete combustion). And a pressure wave. The latter will result in gases escaping into the flue but also can result in said smoke and gases escaping the firebox through the air inlet. I.e. you see a short puff of smoke escaping the air inlet.
Nealm66
Minister of Fire
I was wondering if it still has the issue bypass the cat. Maybe the cat has issues? Or open the draft a bit might solve the back puffing?
Obviously the "explosion" needs to be bigger to push smoke out of the inlet when the bypass is open. But it should not be impossible.
However, the conditions for backpuffing (dialing down the air too fast) should not exist if the bypass is open, if one follows the operation instructions in the manual.
However, the conditions for backpuffing (dialing down the air too fast) should not exist if the bypass is open, if one follows the operation instructions in the manual.
Nealm66
Minister of Fire
I would like to extend the definition of backpuffing to include those times when you have a big pile of smoldering fuel doing what a BK does best which is cruise along in black box made and then the thermostat opens up a little bit. Eventually enough smoke is generated to start a flame but it's not usually a nice little candle flame that starts. The smoke accumulates faster that the cat can munch it until poof the box is full of flame. That flame front can consume so much of the smoke that there is not enough left for a flame and the cycle repeats until the flames can be steady. This happens on the way up as well as on the way down.
Noncats usually only poof on the way down after you chop the air.
Noncats usually only poof on the way down after you chop the air.
Easy enough to eliminate smell coming from the fireplace simply by covering it with a sealed damper at the time...even if only for diagnostic purposes to try and prove to BK it is the fireplace causing the smell. Can’t smell if it’s sealed at the top.
I am truly impressed by BK’s stoves since a forum member here that is local to me bought a used one. I am super impressed. I am also not impressed with BK’s efforts solving the issue for the “few” that do complain of this smell issue.
Has BK sent any representatives to help figure this out?
I would be pissed to spend $4000 on a stove and have a boat anchor that stinks the house up. Even with the super impressive burn times I would not tolerate that creosote smell coming into the house.
I have not heard of a single complaint from other catalyst stove manufacturers.
I am truly impressed by BK’s stoves since a forum member here that is local to me bought a used one. I am super impressed. I am also not impressed with BK’s efforts solving the issue for the “few” that do complain of this smell issue.
Has BK sent any representatives to help figure this out?
I would be pissed to spend $4000 on a stove and have a boat anchor that stinks the house up. Even with the super impressive burn times I would not tolerate that creosote smell coming into the house.
I have not heard of a single complaint from other catalyst stove manufacturers.
I agree with this explanation. If you have the patients to sit ... we can watch the stove burn wood gas right at the top and it sort of curls around with the fresh air coming in by the glass. Then that flame goes out and there is nothing but hot coals and hot logs ... then suddenly there is enough oxygen and it ignites. That produces a big expansion of gasses inside and some puffs out around the stack and door. I think it is pretty much what a fireman would call a flash over when someone opens a door or window where a house fire has been smouldering.
Two other thoughts:
I suspect the drafting from the fireplace could be causing problems. I'd seal it off really well to see what happens.
Does the King have its own stack inside the brickwork. ???
Secondly, if you get the chimney swept by someone that does not know the Blaze King they may have done the job with the by-pass for the cat burner closed.
This can result in a lot of creosote landing in the the chamber that the the cat burner is in. It's not particularly easy to get that out with the cat burner in place.
If you try to remove the cat burner to clean out the chamber ... it will almost certain crumble into garbage so maybe have a new one standing by.
and a question .. after it has been up and running an after the door is closed for the cat burner, can you see actually doing its thing. In a dark room you you have to get down on your knees to look up at the roof to see ... it will be glowing bright orange/yellow if it is getting good air flow. It seems to take about 15 - 20 minutes to get it going like that.
I suspect the drafting from the fireplace could be causing problems. I'd seal it off really well to see what happens.
Does the King have its own stack inside the brickwork. ???
Secondly, if you get the chimney swept by someone that does not know the Blaze King they may have done the job with the by-pass for the cat burner closed.
This can result in a lot of creosote landing in the the chamber that the the cat burner is in. It's not particularly easy to get that out with the cat burner in place.
If you try to remove the cat burner to clean out the chamber ... it will almost certain crumble into garbage so maybe have a new one standing by.
and a question .. after it has been up and running an after the door is closed for the cat burner, can you see actually doing its thing. In a dark room you you have to get down on your knees to look up at the roof to see ... it will be glowing bright orange/yellow if it is getting good air flow. It seems to take about 15 - 20 minutes to get it going like that.
Maybe I should emphasize that with 15 or so years of experience with the Blaze King Classic ... the biggest one ... the only time we got puffing was
when we were trying to run it too low OR if I had just loaded it with wood ... especially cold wood ... and all that we really burning was the coals on the bottom. When running the maple syrup evaporator I learned the value of having wood that was at least near room temp. That quickly got applied to the BK in the house and the puffing and smell quickly disappeared.
So if you are running with the temp control wide open and you are getting the puffing ... you have another problem ... with not enough draft.
Maybe creosote. Maybe critters up in the stack. Maybe draft being scavenged by your fireplace.
Hope some of this helps
when we were trying to run it too low OR if I had just loaded it with wood ... especially cold wood ... and all that we really burning was the coals on the bottom. When running the maple syrup evaporator I learned the value of having wood that was at least near room temp. That quickly got applied to the BK in the house and the puffing and smell quickly disappeared.
So if you are running with the temp control wide open and you are getting the puffing ... you have another problem ... with not enough draft.
Maybe creosote. Maybe critters up in the stack. Maybe draft being scavenged by your fireplace.
Hope some of this helps
By definition above back puffing is not an issue in my case. The smell starts after the stove has reached full temperature and is being throttled by the thermostatic control and appears to be coming from the hinge side of the door. This happens regardless of the temperature setting. About the CAT, the CAT is always glowing bright when the smell is present.
One interesting point regarding Stoveliker comment "And a pressure wave. The latter will result in gases escaping into the flue but also can result in said smoke and gases escaping the firebox through the air inlet. ", that is the volume of the air inlet path is quite large in the King 40 and as a result absorbs the back puff preventing the escape of gases, that is unless the duration of the explosion is quite long. The air inlet path is filled with clean air, under normal operation, and when it back puffs that volume of clean air must be displaced before the burnt gases can escape.
Update on my install, 27' of 8" equivalent insulated liner installed, unfortunately it did not solve the problem of smoke smell.
One interesting point regarding Stoveliker comment "And a pressure wave. The latter will result in gases escaping into the flue but also can result in said smoke and gases escaping the firebox through the air inlet. ", that is the volume of the air inlet path is quite large in the King 40 and as a result absorbs the back puff preventing the escape of gases, that is unless the duration of the explosion is quite long. The air inlet path is filled with clean air, under normal operation, and when it back puffs that volume of clean air must be displaced before the burnt gases can escape.
Update on my install, 27' of 8" equivalent insulated liner installed, unfortunately it did not solve the problem of smoke smell.
