Dialing in new BK Princess...

[slayer7]

Finally got my old Englander NC-13 insert replaced with a BlazeKing Princess a few weeks ago and have had about a half dozen good fires so far. After being used to the tube stove process and nuances for many years, there seems to be somewhat of a learning curve on this thing. While I think I have the overall basic process down, I believe some dialing in of my procedures is necessary and have some questions. For logistics, I’m using 3-4 yr old split/stacked/top-covered seasoned wood that raged in the old stove, and an insulated liner about 16’ with block off plate. So far, I've been burning about half loads in the firebox because of having to keep windows open and fans on because of the smell.

First, how long before this thing stops smelling while burning?? Have had several quite hot fires and every time, more fumes keep coming from the stove. I thought it would die down after the first fire or 2 but hasn’t slacked off that much over the last 3 or 4 fires…

What is the basic timing/settings everyone uses to engage the cat and cut back the thermostat? For instance, it seems on average that after 20 mins or so, the gauge suggests the cat is in the active range and it’s time to close the bypass. I’ve noticed if I close it while the gauge is in the first third of its range, say 9- 1:00 (around 300-400 degrees), the stove takes longer to get hotter/warm up than if I wait till it’s closer to the 3pm range (500*). What is the average reading on the cat gauge to close the bypass?

For the thermostat, I notice that if I cut the air back too quickly after closing the bypass or too quickly in general, the stove temp either starts to fall or takes quite a while to get hotter. Even after turning up the thermostat later, it seems really hard to get the stove top temp back up if it never reaches the 500+ degree range in the first place. I also haven’t been particularly successful in getting the stove to put out more heat/temp by turning up the air/thermostat later in the burn cycle. It seems to like to stay in the 300 to 400 degree range once throttled back. Not sure if these characteristics are by design or my procedures need tweaking.

Also, I see many folks talking about having an occasional “hot” fire to clean the glass, which mine has been getting increasingly dirty from the bottom corners up. What timing and temps does this entail exactly? I had the stove burning in the 625+ degree stove top temp range with visible fire in the box which I would consider “hot” and the glass did not clean up at all. What should be the maximum stove top temp of this unit in general?

So TLDR version, wondering on basic overall timing and temps to engage bypass and cut back air control and also how to keep/get glass clean…

Thanks.

 

[NHWS]

Nice looking installation.

It took my freestanding stove 3 or 4 progressively larger and hotter fires to before the obnoxious paint curing smell mostly stopped.

On a cold load, I close the bypass as soon as the cat gauge is in the active range. I then leave the air all the way open for 15 to 20 minutes (depending on the size of the load and how quickly the fire gets going) before starting to reduce the air. That 15-20 min helps to reduce the remaining MC of the wood, which reduces smoke. I then cut the air to 50%, wait for the temps on the flue probe to stabilize (2 to 5 minutes), and then cut it back further if needed. Hot reloads are similar, but I seldom wait more than 15 minutes before reducing the air to 50%. The cat gauge is slow to react, so I don't find it very useful on a hot reload.

Turning the air down from full to 50% often increases the cat temp, but reduces the flue temp. Turning it down much lower than 50% usually starts to slowly reduce both temps.

BK seems to recommend a hot fire (air full open) for 3+ hours once a week or so to clean the firebox, which will also help clean the glass. PNW weather is mild, so I mostly use the stove with the air fairly low, between 3:00 and 4:00. Burning low-and-slow most of the time, you either get used to the not-clean glass, burn hotter more often, or get practiced cleaning it with a razor blade. Once in a while the weather is colder and I run the stove with a full load and 50% air. 8+ hours of that is enough to help clean the glass.

If you are able to install it, an Auber AT100/AT200 flue thermometer is very helpful. I watch the flue temp more than any other measurement. I don't pay any attention to the stove top temps, but there are others here who are much more experienced with BK stoves than I am who might be able to provide more information.

 

[moresnow]

the gauge suggests the cat is in the active range and it’s time to close the bypass

When the gauge says you have reached the active zone... Close the bypass.
Follow the operator's manual from there. Good place to start.

 

[OH_Varmntr]

Which gauge are you referring to when you are saying 9-1:00 being 300-400 degrees? The manual states the cat needs to be at least 500F prior to closing the bypass, which is indicated by the cat thermometer passing into the "Active" zone. The cat thermometer is reading the catalyst temp, not a stove top temp, and mine doesn't have temperatures on it. Does yours?

Are you familiar with the design and principles of a thermostatically regulated woodstove?

Keep in mind that your Princess is not like other stoves. The thermostatically controlled damper takes care of regulating the amount of air the firebox receives using your setpoint on the knob as a guide. This is why it is imperative that you size these types of stoves to the correct application. If it is too small of a stove, it will continually over-fire as the heat load is too great for the output capabilities of the stove. Too large of a stove for the application and it will continually be in a low-fire state as the heat-load isn't enough to pull the stove into a full-fire state.

There are a few older threads on this subject and it takes a bit of mindset change coming from a stove where you have direct control over the air entering the firebox.

I'm on season #3 with my Princess insert and have found it to be a pretty straight forward stove and following the manual is pretty spot on for use.

Page 20 of your manual shows a depiction of the cat thermometer with the needle just into the "Active" zone. I fire my stove with the bypass open until the needle just passes into the "Active" zone. I generally rake coals to the front of the firebox when the needle comes back down to the point depicted above and allow them to burn down for an hour or so with the bypass closed before reloading or I tend to find chunks of coals in the back corners of the firebox when I shovel ash. Allowing these coals to burn down gets me another hour or so of good useable heat without diminishing cat temps and allows me to reload with the cat temps still in the "Active" zone.

Another thing to keep in mind is the catalyst will tend to burn hot the first season or so and settle in as the surface area of the catalyst begins to "break-in".

As far as the smell, mine took a few hours into the first long-term burn to fully cure.

 

[Hard_Yakka]

The type of catalyst is also a variable. SSteel or Ceramic. Our BK King had the ceramic but the renters fouled it up before they departed to I replaced with a Condor SS. Way to efficient for this house, drove us out on the off shoulder heats so I went back to Ceramic.

We have two temp indicators, catalyst and about 18" up the stove pipe.
This was about 10-12 minutes after lighting with heat building up in Cat so usually flip the bypass. Fire box still had some red embers so this was not a cold start. I would agree that 15-20 minutes is a good average.

 

[Highbeam]

You’ll notice the owners manual does not mention anything about monitoring or reacting to the readings of a stove top thermometer. Take that stove top meter off and put it somewhere else, it’s not going to help you operate this cat stove.

Close the bypass when the cat meter crosses the active line. That’s why it is there. Then char the load for 10-20 minutes on high or when you feel it’s too ripping hot.

Then just find your setting and leave it there. The thermostat takes care of all the fiddling you’re used to with that noncat.

 

[Hard_Yakka]

What non cat the Jotul from '78?? This is a picture of a BK King that is in the barn-o-minium.
So I'm suppose to weld the OEM hole that is directly above the CAT for the CAT temp probe? Been using BK's King's since moving over to Spokane in '84 from B'ham before that a Jotul 'Elephant'. This BK King was bought in '04 and I don't need to RTxM.

 

[slayer7]

Thanks for everyone's replies.

I've been using the IR temp gun we used with the old stove to get the stovetop temps. The CAT probe gauge on top of the stove does not have any temps listed on it like everyone mentioned.

BK seems to recommend a hot fire (air full open) for 3+ hours once a week or so to clean the firebox, which will also help clean the glass.

I would agree with this, but what temp would be considered overfiring this stove? From what I've seen so far, if I leave the air totally open for too long, the stovetop temp is heading over 650 degrees. If I didn't cut it back, it looks like it would keep climbing.

 

[reaperman1]

I'm not sure how running for 3 hours is possible unless its in very small increments. One my stove, when I open the air up for too long the flu temps climb very fast. Within a couple of minutes I'd be way over 700 and climbing fast. Ive yet to find a way to run the stove hotter without exceeding what I'd call a safe stack temperature.

 

[Ashful]

I would agree with this, but what temp would be considered overfiring this stove?

You cannot overfire a properly-installed BK, the caveat being that achieving a "proper" installation isn't all that trivial.

I've been running two BK Ashfords in my house, to the tune of 10 cords per year, for about 8 years now. So, something like 80 cords thru the pair of them. These comments come from that experience:

One of my BK30's is installed on about 30 feet of pipe with a pipe damper and a magnehelic, as it will most definitely over-fire without taming down the draft a bit on a pipe that tall. With the pipe damper adjusted to the optimum specified 0.05"WC, it is tame as a lamb, and I very routinely run full loads of wood through it at wide-open throttle (WOT), with no issues whatsoever.

My other BK30 is installed on something like only 15 - 18 feet of pipe, and you'd think that'd be the more tame of the pair, but it is not. Run at WOT, I don't dare leave it more than 10 - 15 minutes after closing the bypass, as it is becomes a true white-hot mouth of hell scenario every time. Before anyone asks, there is no air leak, and turning the thermostat down I can have it into "black box" mode in just a few seconds/minutes. The stove operates as it should but the trouble is that draft is climbing above the 0.06"WC specified maximum, even on a pipe that short.

I've brought this up before, but BK specifies an absolute minimum chimney of 15 feet, and an absolute maximum draft at WOT of 0.06"WC at steady-state. Without knowing the exact inlet cross-section of the stove, it's impossible for us to calculate whether or not these spec's are self-conflicting, but based on every measurement I've made, it appears they are nearly that. If 15 feet is "too short", but 18 feet over-drafts, it doesn't leave much margin for a proper setup without use of the forbidden key damper.

My advice, run it awhile on WOT and watch the fire, the cat temp, and the chimney temp. If you find them all heading hotter than you believe they should, then install a draft gauge, whether a magnehelic or one of the cheaper consumer-grade chimney draft gauges. If you find it heading anywhere over 0.06"WC after a long period at WOT, then it's time to install a key damper.

BK's are the best stove on earth, with regard to pushing the absolute maximum envelope of burn rates. I don't think there's anyone else achieving 10 hours per cubic foot of firebox, as BK's do every day. But as with any technology, "pushing the envelope" always means having to optimize the conditions around it. A Ferrari can't do "Ferrari things" on a dirt road, or while running poor fuel.

Give these stoves that optimum 0.05"WC, and feed them very dry wood, and they can do anything. But violate that, and your performance going to suffer at one end of the burn range, or the other.

 

[Ashful]

I'm not sure how running for 3 hours is possible unless its in very small increments. One my stove, when I open the air up for too long the flu temps climb very fast. Within a couple of minutes I'd be way over 700 and climbing fast. Ive yet to find a way to run the stove hotter without exceeding what I'd call a safe stack temperature.

You posted at the same time as me, so read my post above. What's your chimney height?

Many of us run full loads at wide-open throttle, on a very regular basis. It's possible, but proper draft is critical. Sounds to me like yours is too high, unless there's some other issue at play.

 

[reaperman1]

You posted at the same time as me, so read my post above. What's your chimney height?

Many of us run full loads at wide-open throttle, on a very regular basis. It's possible, but proper draft is critical. Sounds to me like yours is too high, unless there's some other issue at play.

My chimney is 5' of dual wall inside going strait up to 10' of Excel stainless. With approx 7' sticking above the roof.

 

[Ashful]

So, right at the 15 ft. minimum BK quotes for many of their stoves. My shortie also tends to run hot, as described above. It won't self-destruct, believe me I've tried, but I do agree the pipe runs pretty warm when left wide open.

I end up just throttling that one down a little, never leaving it wide open more than maybe 15-20 minutes after closing the bypass. Even just turning the knob from 6 o'clock (my WOT position) to 5:30 really tames it down a good bit.

I suppose you could measure draft and add a damper, but it seems like an awful lot of extra work and parts for what is likely only a very slightly over-nominal draft.

How's it behave when you turn down?

 

[Highbeam]

What non cat the Jotul from '78?? This is a picture of a BK King that is in the barn-o-minium.
So I'm suppose to weld the OEM hole that is directly above the CAT for the CAT temp probe? Been using BK's King's since moving over to Spokane in '84 from B'ham before that a Jotul 'Elephant'. This BK King was bought in '04 and I don't need to RTxM.

I was talking to the OP of this thread and his noncat NC13.

Your cat meter is not a stove top temperature meter. It is important to keep using a cat meter. The owners manual even tells you how. Congratulations on getting out of bellingham!

 

[Highbeam]

I've brought this up before, but BK specifies an absolute minimum chimney of 15 feet, and an absolute maximum draft at WOT of 0.06"WC at steady-state. Without knowing the exact inlet cross-section of the stove, it's impossible for us to calculate whether or not these spec's are self-conflicting, but based on every measurement I've made, it appears they are nearly that. If 15 feet is "too short", but 18 feet over-drafts, it doesn't leave much margin for a proper setup without use of the forbidden key damper.

My advice, run it awhile on WOT and watch the fire, the cat temp, and the chimney temp. If you find them all heading hotter than you believe they should, then install a draft gauge, whether a magnehelic or one of the cheaper consumer-grade chimney draft gauges. If you find it heading anywhere over 0.06"WC after a long period at WOT, then it's time to install a key damper.

I agree. The princess model from 2012 (mine) only required 12' of chimney which is what I have and with dry softwoods can easily overtemp the flue during the high temp burn in of a new load. The way I resolve that is by shortening the char phase to a reasonable time period that doesn't overtemp the flue. About the time the flue temperatures are at 900, the cat is up into the teens of hundreds and it's time to close it down. I don't need or want to run a full load on high unless it is a partial load just to burn the firebox clean of tar. Then a smaller load of fuel seems to help keep flue temperatures in check better.

So I don't use a time for char but a flue temperature.

Some day it would be fun to measure my draft on top of a raging pile of softwoods. I predict that I'm over the 0.05" even with just a tall 12' flue.

 

[Ashful]

I agree. The princess model from 2012 (mine) only required 12' of chimney which is what I have and with dry softwoods can easily overtemp the flue during the high temp burn in of a new load. The way I resolve that is by shortening the char phase to a reasonable time period that doesn't overtemp the flue. About the time the flue temperatures are at 900, the cat is up into the teens of hundreds and it's time to close it down. I don't need or want to run a full load on high unless it is a partial load just to burn the firebox clean of tar. Then a smaller load of fuel seems to help keep flue temperatures in check better.

So I don't use a time for char but a flue temperature.

Some day it would be fun to measure my draft on top of a raging pile of softwoods. I predict that I'm over the 0.05" even with just a tall 12' flue.

I do the same on my BK30 with the short flue and no key damper. I usually run only 10 minutes, and never more than 15 minutes, on high after closing the damper. I actually gauge the time to turn down by the cat meter reaching a 12 o'clock position, which may not be the most scientific method in the world, but seems to work well at keeping the firebox reasonably clean and ensuring bake-out was sufficient to prevent a stall later in the burn.

The BK30 that's on the tall flue with the key damper is much better behaved, and gets a full 20 minutes on high, with each load. No concerns with that one ever going over-temp, it's as gentle as a lamb, with the key damper dialed in to .05"WC.

 

[Highbeam]

I do the same on my BK30 with the short flue and no key damper. I usually run only 10 minutes, and never more than 15 minutes, on high after closing the damper. I actually gauge the time to turn down by the cat meter reaching a 12 o'clock position, which may not be the most scientific method in the world, but seems to work well at keeping the firebox reasonably clean and ensuring bake-out was sufficient to prevent a stall later in the burn.

The BK30 that's on the tall flue with the key damper is much better behaved, and gets a full 20 minutes on high, with each load. No concerns with that one ever going over-temp, it's as gentle as a lamb, with the key damper dialed in to .05"WC.

Do you fiddle with it constantly to maintain 0.05” or do you only set it once for the burn. That 0.05” is supposed to be at high burn as I recall. A barometer damper would automate the fiddling.

Some smart guy ought to implement a simple device in the stove to automatically regulate draft pressure.

 

[Hoytman]

Nice looking installation.

It took my freestanding stove 3 or 4 progressively larger and hotter fires to before the obnoxious paint curing smell mostly stopped.

On a cold load, I close the bypass as soon as the cat gauge is in the active range. I then leave the air all the way open for 15 to 20 minutes (depending on the size of the load and how quickly the fire gets going) before starting to reduce the air. That 15-20 min helps to reduce the remaining MC of the wood, which reduces smoke. I then cut the air to 50%, wait for the temps on the flue probe to stabilize (2 to 5 minutes), and then cut it back further if needed. Hot reloads are similar, but I seldom wait more than 15 minutes before reducing the air to 50%. The cat gauge is slow to react, so I don't find it very useful on a hot reload.

Turning the air down from full to 50% often increases the cat temp, but reduces the flue temp. Turning it down much lower than 50% usually starts to slowly reduce both temps.

BK seems to recommend a hot fire (air full open) for 3+ hours once a week or so to clean the firebox, which will also help clean the glass. PNW weather is mild, so I mostly use the stove with the air fairly low, between 3:00 and 4:00. Burning low-and-slow most of the time, you either get used to the not-clean glass, burn hotter more often, or get practiced cleaning it with a razor blade. Once in a while the weather is colder and I run the stove with a full load and 50% air. 8+ hours of that is enough to help clean the glass.

If you are able to install it, an Auber AT100/AT200 flue thermometer is very helpful. I watch the flue temp more than any other measurement. I don't pay any attention to the stove top temps, but there are others here who are much more experienced with BK stoves than I am who might be able to provide more information.

Let it burn hot for 3+ hours???
I’d like to see that in writing. Not saying you’re wrong, rather, that it doesn’t sound right.

 

[Hoytman]

Do you fiddle with it constantly to maintain 0.05” or do you only set it once for the burn. That 0.05” is supposed to be at high burn as I recall. A barometer damper would automate the fiddling.

Some smart guy ought to implement a simple device in the stove to automatically regulate draft pressure.

Your thermostat has already automated the fiddling.

Being a coal burner and frequently posting to a coal burning forum, I can tell you at least one manufacturer of coal stoves (one I’m very familiar with…and by manufacturer I’m talking about a personal conversation with the owner) has said the bi-metal thermostat really acts like a barometric damper, but better. He even says the baro isn’t needed. Some will argue against that, but that’s what he said. He said the bi-metallic does regulate the draft pressure…and my experience with his stove confirms this. It regulates it at a given set rate. Might be higher or lower depending on the chimney.

I can increase temperature just by turning up the dial. That in turn reads higher on the manometer to a point, but then I can dial that back some too just by closing the pipe damper and still maintain stove temp…but heat output is more because of heat exchanger in top of stove…which could and likely does make if function a little different from the BK wood stove.

Point being…the device is already on your stove…well, at least my stove. I can’t see the fuel type making a difference…they do what they do…and they do it extremely well.

Coal stove users often use a baro to keep draft steady during high winds…when it opens…the byproduct of it opening is allowing cooler room air to enter the chimney as the wind pulls on the chimney and the room air, instead if the stove air intakes therefore slowing the burn.

I won’t agree with the manufacturer completely that a baro isn’t needed or isn’t necessary. I will say the bi-metallic thermostat does a fine job on it’s own…but I also understand how the barometric damper could save fuel…because it’s response is instantaneous where the bi-metal is reliant on a temperature change.

Now with the bi-metal I can also see what the manufacturer is saying too…even though the bi-metal thermostat is slow to respond (gusting winds) it also just as responsive in its own way (sustained winds) where as the stove temperature begins to climb the thermostat senses this, closes and remains closed for a longer time period (sometimes much longer) and waits until the next call to raise stove temperature. So in a way the manufacturer is still right…and it’s why bi-metal regulators are often used on hand fed and hopper fed modern coal stoves (modern being from 1930’s to today).

I’m sure the fuel type only matters a little, but add wood, then a catalyst to burn that wood and I’m sure that changes how things function between my coal stove and a BK…even if only by a little in the grand scheme of things…and I don’t think they’re all that far apart function wise.

I’m convinced it’s more to do with wood burning from the outside-in and the catalyst itself being the biggest contributing difference, where anthracite coal burns from the bottom up. Wood burns from air entering from any direction and anthracite needs air from the bottom…over-fire air can kill the anthracite coal fire if there’s enough of it because it then pulls less air from below which means a starved for air fire.

My comments were more to compliment your own.

 

[NHWS]

Let it burn hot for 3+ hours???
I’d like to see that in writing. Not saying you’re wrong, rather, that it doesn’t sound right.

It's been mentioned on this site. I don't recall seeing it in the BK manual, but it's been a few months since I last read that. @BKVP is the best one to address the issue.

AFAIK, 'burn hot' means air mostly or all the way open with the cat engaged.

 

[Ashful]

Do you fiddle with it constantly to maintain 0.05” or do you only set it once for the burn. That 0.05” is supposed to be at high burn as I recall. A barometer damper would automate the fiddling.

Some smart guy ought to implement a simple device in the stove to automatically regulate draft pressure.

I open it wide before loading the stove, and leave it there on a cold start. About 10 minutes after lighting, the flue is starting to warm enough that draft rises to around 0.10", and I'll turn the key about 45 degrees to knock draft down near .05"WC. I usually set a second 10 minute timer, by which time I'm ready to adjust the damper to final position (near full-closed) and close the bypass damper. So, two adjustments during a cold start, and then no more after that, unless I just want to get real picky with fiddling during the charring phase.

On a hot reload, I may go straight to the full-closed position or run 5 minutes at 45 degree clocking if I want to pull a bit more draft to get the new load lit more quickly. Again, just one or two adjustments during bypass phase, and nothing thereafter.

As the cat(s) become more clogged later in the season, I begin to notice that closing the bypass damper will cause draft to climb a few hundredths of an inch. Again, I can fiddle with it if I want to be picky.

What's interesting is that the soot that collects around the key damper in the stovepipe creates a sort of detent, such that you don't even have to look at the thing once you get more than a week or two past a fresh chimney cleaning. Sort of like how our thermostats just seem to naturally stop at the right clocking when we turn down, after hundreds of cycles of turning them to the same position. Of course, the key damper "detent" is lost for a week or two after each chimney cleaning, and works best toward the very end of the season.

edit: Oh, and you don't adjust to .05"WC any time after turning down. Draft should and will climb when you turn down. The .05"WC measurement target is only valid under steady-state conditions at WOT.

 

[Ashful]

Just so we don't give anyone the wrong impression, you don't need any of this to run a BK. Your BK will run just as well as any other stove on a totally-over drafted flue. It is totally safe and controllable. I ran one of mine at 0.21"WC on 30 feet of pipe for a year, before deciding to actually check the draft, and had absolutely no issues with safely and effectively operating the stove.

But the more you dial in your draft toward that nominal 0.05"WC target, the more you can allow that BK to do the things that make it uniquely BK. Things like burning full loads at wide-open throttle, or getting 10+ hours of active cat time out of every cubic foot of firebox.

 

[Hoytman]

Buy the manometer or magnehelic and find the target draft listed by the manufacturer. You could likely even be a little bit lower draft than the target (within reason) but anything over the target draft burns more wood.

Hey…burning a BK is already going to save you a lot of wood … and every -.005”wc counts.😂😂

 

[BKVP]

Operating temperatures during earliest stage of combustion critical to dealing with moisture.

Naturally, the amount of time needed to deal with the moisture at a elevated burn rate is dependent upon the amount of moisture in the load of fuel. I'm burning tamarack that was cut, split and stacked under cover 5 years ago. The Delmhorst says it is less than 12% (poking 3 locations, fresh split face with 1" pins.

I need to run my King at a higher burn rate for about 30-45 minutes. If my wood was 20%, it might take a bit more. At 25%, or more you may need 1+ hours.

BTW, Happy Belated New Year!
BKVP

 

[Highbeam]

High “er” burn rate? I thought the char phase was supposed to be at max burn rate using the max thermostat setting.