BK Cat temps in relation to stove temps

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steve reynolds

New Member
Oct 27, 2012
43
ok i will try to get this answered... last time the thread got derailed because of safety concerns of my install, now that i got it fixed lets try again :)

this is kind of a tricky question so i will try to explain as best i can. first off i am going to post a pick of the stock thermometer i have on my stove. , i am assuming it is cat therm. because it is rite behind the cat on my stove but anyway here is the pic and when i refer to this particular thermometer i am going to refer to times because it doesnt have degrees on it. blaze king therm.jpg
so noon would be the mark rite before active at the top.
i am trying to decide how to burn it to reduce creosote, burn at an optimal temp. i also have a magnetic thermometer on my single wall stove pipe about 18 inches above stove.

ok here goes.
when my blaze king thermometer reaches say around 2:00 oclock in the active zone my stove pipe is near 325 to 350 degrees which is optimal burning temps from what i read. but! this stove has a thermostat which will cut the air down when it reaches a certain temp. and the fire will seem to completly go out for awhile and come back on when it cools down.. the way i have the thermostat set is it reaches 2:00 then goes out and lets air in and starts a burn again at noon.. but when the fire goes out the magnetic stove pipe temp goes down to 250 degrees and usually stays there and never really returns to optimal burn temp at 300 or above!
now with that info can i make any assumptions about these temps? does this tell me anything about cat? maybe cat isnt working? just kind of curious because i thought with the cat pipe temps should stay above the 300 degree temp? or am i wrong? just asking for some expertise!

now i know some are going to say my place is to small for stove, that may be, but., by what the cat thermometer is saying i cant burn it to much hotter than i am now.. i dont want to overburn it.. 2:00 seems like it would be a good burn point? correct me if i am wrong.
 
Hopefully some BK owners will help you out. Yes that is the Catalyst Thermometer as that's what it says right on the gauge;)
 
After burning for a awhile..less then a hour that cat probe should be way over towards that last marking..if not higher.
Are you closing the by-pass after the wood is charred?
Don't worry so much about the stack temps.
If you are operating your cat stove anywhere near right the cat will clean up the smoke no matter the flue temp.
That said check your chimney a few times a month.
Most cat owners do find crap on their cap screens..me included after a few months burning or even less.

I'm thinking you are just not charring the wood enough for the wood to out gas enough to keep the cat happy before you close the by-pass and turn the air down.

I'm amusing your wood is well seasoned.
 
HotCoals said:
After burning for a awhile..less then a hour that cat probe should be way over towards that last marking..if not higher.
Are you closing the by-pass after the wood is charred?
Don't worry so much about the stack temps.
If you are operating your cat stove anywhere near right the cat will clean up the smoke no matter the flue temp.
That said check your chimney a few times a month.
Most cat owners do find crap on their cap screens..me included after a few months burning or even less.

I'm thinking you are just not charring the wood enough for the wood to out gas enough to keep the cat happy before you close the by-pass and turn the air down.

I'm amusing your wood is well seasoned.
Click to expand...

i am closing the bypass somewhere around the 10 oclock on the cat thermometer on the initial start up no i dont think wood is getting charred before i close it..... maybe that is too soon? so you are saying i am burning the stove too cool? i have my thermostat set and it actually stops the burn about 2 oclock ... your saying i should let this thing go to at least 5 oclock position..
 
steve reynolds said:
i am closing the bypass somewhere around the 10 oclock on the cat thermometer on the initial start up no i dont think wood is getting charred before i close it..... maybe that is too soon? so you are saying i am burning the stove too cool? i have my thermostat set and it actually stops the burn about 2 oclock ... your saying i should let this thing go to at least 5 oclock position..
Click to expand...
Yep..nothing for it to go to the end of the scale.
 
steve reynolds said:
i have my thermostat set and it actually stops the burn about 2 oclock .
Click to expand...

I do not have a cat stove but I am very interested in how they work.

What point on the stove is being used as the temperature input to the thermostat?

MnDave
 
From a previous discussion with Hot Coals it sounded like an ambient room temperature and the sensor was under a cover. If that is the case then there seems to be a problem with coupling the temperature input to what the cat needs to perform efficiently.
 
I don't pay much attention to mine except on start up when the probe is below the active zone. I use it as a reference on when to close the bypass. As long as the stack is smoke free the cat is working as far as I'm concerned.

Even if that stove is oversized if the wood is good and the cat is healthy you should be able to dial it all the way down and burn clean.
 
Couple of thoguhts:

1) Your thermostat responds to stove body tempratures at the rear of the stove. It is not coupled to the cat temps. A hot cat will eventually heat up the whole stove body.

2) You don't need to worry about anything that the cat thermometer says except right at the beginning when it goes from inactive to active. After that there is no reason to even have a cat temp meter and many stoves don't. You don't have to worry about overheating the cat so long as you operate your stove with the stat in the normal ranges which BK defines as between 1 and 3 on a freestander.

3) Your flue temps are fine and even higher than most. A few of us use real probe meters to measure internal temps of our flues. The normal temps are 400-500 which corresponds with a surface temp of 200-250 on your single wall. You are actually warmer than most so your creo accumulation should be less.

4) Get the cat to active, lock the bypass, keep the stat between 1 and 3, and sweep the chimney as necessary.
 
Highbeam said:
Couple of thoguhts:

1) Your thermostat responds to stove body tempratures at the rear of the stove. It is not coupled to the cat temps. A hot cat will eventually heat up the whole stove body.

2) You don't need to worry about anything that the cat thermometer says except right at the beginning when it goes from inactive to active. After that there is no reason to even have a cat temp meter and many stoves don't. You don't have to worry about overheating the cat so long as you operate your stove with the stat in the normal ranges which BK defines as between 1 and 3 on a freestander.

3) Your flue temps are fine and even higher than most. A few of us use real probe meters to measure internal temps of our flues. The normal temps are 400-500 which corresponds with a surface temp of 200-250 on your single wall. You are actually warmer than most so your creo accumulation should be less.

4) Get the cat to active, lock the bypass, keep the stat between 1 and 3, and sweep the chimney as necessary.
Click to expand...

Agree with all this, no need to overthink things, as long as your house is warm and theres no smoke coming out of your stack just relax and enjoy the warmth.
 
One thing that the Bk can do is that after your load is going pretty good turn the t-stat to 2 and after awhile the thermostat will close the air down on it's own till it is shut and you end up with just a glow for the next 23.5 hours.
 
when you guys say lock the bypass, you just mean to close it right? i dont have any lock on my princess. its open or closed.

my stack temps with a good burn going after a hour or so are around 200* outside single wall. stove top 5-550*
 
not sure about the princess but my older royal heir does in fact lock. the procedure is shut door without turning latch handle, then close bypass, then turn door handle to latch and lock. there is a small tab that is supposed to actually lock the bypass from being opened until you release the door handle from latched position. the lock tab on mine is rite behind the latch handle where the handle meets the stove when closed..
in other words on mine, you are not supposed to be able to open bypass without unlocking the door first.
 
HotCoals said:
One thing that the Bk can do is that after your load is going pretty good turn the t-stat to 2 and after awhile the thermostat will close the air down on it's own till it is shut and you end up with just a glow for the next 23.5 hours.
Click to expand...
i wish mine had the number system or at least notches i could feel as i turn it.. mine just has an arrow pointing to hotter or cooler. i have to set mine by turning until i hear air damper close then back it off other way 1/4 inch at a time to get where i want it.. kind of a pain in butt but it works.. i know it is really touchy! 1/8 to 1/4 inch turns is all it takes fir coals to start changing colors from orange to red! :)
 
tobaccogrower said:
when you guys say lock the bypass, you just mean to close it right? i dont have any lock on my princess. its open or closed.
Click to expand...

The owner's manual does not tell you this very well if at all. You flop your bypass handle back to close the bypass, it stays there and you think it is closed. Well, if you keep turning the lever back beyond where you feel the door close then the lever will pop with an audible clunk. It will feel weird and it is apparently hard to describe in the owner's manual but you don't just turn the lever back to engage the cat, you keep pushing it back until it makes a loud clunk. That clunk is the "locking" that we speak of.

Steve, I would take out a pen, or some nail polish, or whatever and mark that dial.
 
ohlongarm said:
Are you saying let the cat probe go to 5 before closing the bypass?Thanks
Click to expand...
No..I close the by-pass right away or maybe 10 mins or so into the burn.
 
HotCoals said:
No..I close the by-pass right away or maybe 10 mins or so into the burn.
Click to expand...
But only when the cat probe shows active correct,what about charring the wood and all that. Thanks
 
As long as the cat is active and your wood isn't snow covered or dripping wet, the "charring" isn't required in the owner's manual. It doesn't hurt to let the new load get rolling for awhile though. I like to see my flue temps rising and the cat meter well into the active zone before engagement. The cat thermometer is a pass/fail indicator according to the manual.

For funzies I have seen the cat thermometer run to the top of the active range and beyond. It is not important how high that meter gets if you believe what BK tells you.
 
ohlongarm said:
But only when the cat probe shows active correct,what about charring the wood and all that. Thanks
Click to expand...
I do it diff ways at times. Mostly depending on how warm the stove bed is and the amount of coals.
Of course if you don't char the wood enough there will not be enough out gassing to keep the cat happy and it could stall.
I like to see close to 10:00 at least on the probe before closing the by-pass.
Sometimes I will be on 3 till the probe hits noon or higher..then dial down to 2 and the t-stat will actually close the flopper after another 1/2 hour or so on it's own...then I just leave it there.
Anyways after awhile my probe always gets way over towards 5:00 for a hour or two...then slowly works its way back.
 
Hotcoals:

5 o'clock is pointing at the word "columbus" right? So you routinely bury the needle way past the top of the active range?

You say 10:00 is when you close the bypass. Where is that? Looks like that first tick above the active line, is that about right? I do that too.
 
Highbeam said:
Hotcoals:

5 o'clock is pointing at the word "columbus" right? So you routinely bury the needle way past the top of the active range?

You say 10:00 is when you close the bypass. Where is that? Looks like that first tick above the active line, is that about right? I do that too.
Click to expand...
Well I had to go look and I'm wrong..4:00 is more like it..but I reach that almost every load for awhile at least...like a hour or so.
Yep..10-11:00..I don't leave the by pass open very long anymore..not saying I'm doing things 100% right..just that's the way I do things..lol.

Of course the probe thermometer can be off..even if adjusted to the correct cold start I bet they can be off.
 
HotCoals said:
Well I had to go look and I'm wrong..4:00 is more like it..but I reach that almost every load for awhile at least...like a hour or so.
Yep..10-11:00..I don't leave the by pass open very long anymore..not saying I'm doing things 100% right..just that's the way I do things..lol.

Of course the probe thermometer can be off..even if adjusted to the correct cold start I bet they can be off.
Click to expand...
HC,my cat probe seldom goes beyond 3:00 is this indicative of improper burning or a problem,wood is as good as it gets etc,usually I'm at 1000 to 1200 for a short time then it settles in at 600 to 800,although when I first got the stove I would sometimes bury the cat needle.Cat is clean no plugged cells,have a new Condar cat probe the BK took a chit.Thanks
 
steve reynolds said:
ok here goes.
when my blaze king thermometer reaches say around 2:00 oclock in the active zone my stove pipe is near 325 to 350 degrees which is optimal burning temps from what i read. but! this stove has a thermostat which will cut the air down when it reaches a certain temp. and the fire will seem to completly go out for awhile and come back on when it cools down.. the way i have the thermostat set is it reaches 2:00 then goes out and lets air in and starts a burn again at noon.. but when the fire goes out the magnetic stove pipe temp goes down to 250 degrees and usually stays there and never really returns to optimal burn temp at 300 or above!
now with that info can i make any assumptions about these temps? does this tell me anything about cat? maybe cat isnt working? just kind of curious because i thought with the cat pipe temps should stay above the 300 degree temp? or am i wrong? just asking for some expertise!
Click to expand...

What is the timeline and what do your burn cycles look like? The BK cat/tstat combo may provide a longer and ,more even burn but it is still a wood fire in a batch burner. I don't think the stove works nearly as well with the traditional add a log burning style as other stoves do. I find for a typical winter (heating the house as opposed to making a warm spot) batch burn that the tstat does a good job of keeping the cat thermometer very consistent through the burn. If I leave the stove alone, it stays at the initial setting for about the first third of the burn then starts gradually decreasing until about 2/3 of the way through the burn where I make a decision about how much heat I want in the house. Options range from turn the tstat all the way off and cruise to open it all the way up with a few sticks of softwood on top to maximize heat output and get to the next reload as soon as possible. My guess is stack temps vary quite a bit through the cycle but the stack is clear and the stove temp is fairly even given that it is a wood batch burner.
 

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