Adventures running a cat stove with cordwood <12% MC

[Poindexter]

Poindexter, do you have metal clips on each side of the cat housing? If so, did you have them out when your bypass door popped out? I know on the Princess those things hold the bypass hinge pins into there slots.

Yup, this was part of the problem. The one time my bypass door came loose from its guide rails I had the cat and both of those metal clips out of the stove.

My BK dealer explained to me today how the edge of those clips is part of what keeps the hinge pins of the bypass door in the correct location. Live and learn.

I have been reading here but to taking time to post while my stove was down... Thanks in advance to all.

 

[Poindexter]

@BKVP it looks like @Ashful and @RAPhomme already have you covered on the 13% or less MC in the manual.

FWIW when I read that I doubled checked with Clint at my local BK dealer, I think he is the head bottle washer over there. He was a little surprised but has been banging the "16% or less" drum for many years. He said, "Well, if the manual says 13% I suppose you ought to get your wood down to 13% then."

So i did.

 

[Rearscreen]

The only brand of woodstove that malfunctioned for me was...ahh I'll just keep my mouth shut...

 

[Poindexter]

I am back in the saddle currently, many thanks to all.

I got away with using a wand brush vacuum on the cat to get it reactivated.

Along the way I learned the hard way that those two sheet metal stampings beside the cat are part of what keeps the bypass door from flapping in the breeze, apparently on both my Ashford, tarzan's Princess and who knows what other models.

It is fairly easy to get the bypass door off the operating rod without adjusting the bolt on the ramp. To get the bypass back on the operating rod you want to reach through the hole where the cat should be with one hand, operate the bypass lever on the side of the stove with one hand, and do it blind.

If you wring the head off the adjustment bolt on the ramp on the top side of the bypass door you are probably going to want to heat the bolt hole to dull red, hold it at dull red for 15-30 seconds and let it air cool overnight. That should soften the steel enough for you to tap threads into your freshly drilled hole without breaking the tap off in there. While you got it hot is a good time to use some pliers to get the broken off tip of the first tap out of the partially tapped hole.

My local BK dealer says Permatex copper high temp anti seize (Napa, rated to 1800dF) is better than "that grey stuff." "That grey stuff" comes off fairly easily with isopropyl soaked paper towel.

I used a Lowes-Depot Joe stainless steel 5/16 x1" 18tpi bolt as a replacement, with plenty of thread to also use Joe stainless 5/16 -18 nut as a mechanical lock. I was afraid I had broken a very expensive high grade bolt, but apparently not.

With everything back together I had an uneventful startup, the probe needle behaved like the cat was working rather than being passively heated by the fire in the box, once it was up to high active I turned the convection deck fans on to high, opened all the bedroom doors and was gaining 1dF every 5-7 minutes in 1200sqft, so yup, the cat is active, don't care if it is glowing. Outdoor ambient was +30 something dF when I lit the stove this morning.

I have been very careful about what I have and had not said to my local BK dealer. Kinda pushing the envelope here, and I know it. On the one hand my solar kilns exceeded my expectations. On the other hand the manual that came with my 30.0 says both "13% MC" and "don't burn construction scraps like 2x4s."

So I haven't been complaining to them about stuff that might be my fault.

You know that thing about "Price, quality or service, pick any two?"

I went to my local dealer again this afternoon to get a replacement combustor gasket cause I kinda wrinkled mine this morning and want to replace it before it becomes a problem. One of the guys had taken the bypass door, complete with ramp and intact bolt, out of the last Ashford 30.0 on the floor in case I needed it because they are following this thread.

I don't know what they are getting from me for Xmas, but they made my list this week.

I get to get back to the garage, finally. "My" side of the garage is taken up with shop tools, The side of the garage my wife needs to be parking in soon is taken up by this thing that's been on hold while I work on the stove.



It's a GlenL Tiny Titan, featured in the March 1965 Popular Mechanics as "Saucy Shingle."

I have some fairing left to do on the transom, one more piece of 1/8" okoume on the nose and it is ready for launch as tiller steer outboard. 3 cleats on the way from Amazon and it can spend the winter in the ceiling of the garage. Once I get to there I can see about load cells for the Arduino. Next spring before the ice goes out I'll be dragging a 15 horse OMC out of the shed for remote shift/steer/throttle setup. Looking for 35-40mph, with enough hickory on the front bumper to slice a jet ski clean in half.

 

[tarzan]

Good to hear your back in business.

 

[RAPhomme]

So is the moral of the story that it was all only fly ash?

Or is overfiring the cat at 1600+ a real thing?

 

[Poindexter]

So is the moral of the story that it was all only fly ash?

Or is overfiring the cat at 1600+ a real thing?

I dunno yet. Ive run at least 20 cords through this thing and never had this problem before.

Could be dryer wood makes more fly ash, dunno that either.

 

[begreen]

What a difference latitude makes. 20 cords would be 7 yrs burning for us in our mild region.

 

[Highbeam]

If his cat is shot because of repeatedly running it up off the dial, I would suggest that everyone ignore your advice to ignore the cat temp.

So looks like it's still okay to follow the owner's manual and my advice then?(I tried to add a smiley face like you did after a personal insult)

 

[baseroom]

LOVE the hydroplane! Ive got a 1956 electric start 18 horse Johnson OB I'd love to put on it!!

 

[Poindexter]

The only information of value from the cat temp meter is whether the cat is active or inactive. Otherwise ignore it.

Your wood is not too dry. Just load and burn per the manual.

Seems that your problems are self inflicted. Relax.

Ok. Yes I can do that, did a relatively instrumented burn today. What I haven't done effectively is communicate the 'problem' I am having with super dry wood. Please bear with me.

I loaded, oh 75% capacity, in a cold stove after early church. About the same amount of wood as I can plan to load on hot coals deeper into winter. It was +40 something dF outdoors when I lit the stove, +72dF in the house. Our forecast high today was +50dF (sounds about right), I am back down to +32dF right now at 1030pm.

First confound, I have learned to pile my wood in the back , light the front of the pile top to bottom and save as much VOCs as possible for later in the burn. The official BK video on youtube wants me to get every split charred on every surface while the loading door is still open. I can do that too, but I get better (longer) burn times if I heat the cat up to active just by burning the front face of the blob of cord wood stacked tightly in the stove.

Today I lit the front of the pile and had minimal to moderate charring going on the rest of the load when I got the cat hot enough to go active.

I have a magnetic thermometer on my flue pipe about a foot above the stove, but I am using double wall telescoping flue pipe. I have read several times that the actual temp of my flue gasses is "about" double that shown on my magnetic surface reading thermometer. I have no idea what the temp of my flue gasses is really is. Numbers subsequently reported are actual readings - of the magnetic probe on DW pipe.

In "winter" I use a box fan on the floor in the hall to push cold air out of the floors of the bedrooms towards the stove. I spend 5-6 months annually tripping over that fool thing and haven't trotted it out yet this year. The only fans i used today in 1200sqft is the fan kit on the convection deck.

My thermostat for "house temp" reading is 12 horizontal feet from the stove down the hall towards the bedrooms, and 5 feet off the floor. My perception of my wife's wardrobe is calibrated to this interior temp reading. She is out of town this w/e, but I have a pretty good idea of how much clothing she wears relative to that thermometer.

So I am happy with the whole stove, bypass door clamping force, clean pipe, freshly vacuumed combustor, blah blah blah.

Lit it up, got it hot.

At T=0 the cat probe was at the notch between active and inactive, the house was +72dF, flue temp was reading "400". I closed the bypass door to engage the cat.

At T +3 minutes the flue temp was "350" and the cat probe indicator was 1/4" above the notch between inactive and inactive. So clearly the combustor is working.

At T+5 minutes the the flue temp was "300" and the cat probe was 1/2" above the notch. So far so good. I don't need to get down on my knees (again) to see if the cat is glowing. I have adequate redundant data showing me the combustor is working, and I got arthritis.

At t+30 minutes the flue temp was down to "225", my combustor was not over fired. In fact, it looked like this:



Notice the word "active" on the cat probe indicator, I didn't twist it today.

With the conditions above at T+30 I turned the Tstat down to medium, turned the convection fans on to medium, and opened all the bedroom doors on this level of the house. House temp was +73dF, up one degree already.

At T+65 minutes, 76 in the house, "150" flue temp, cat indicator about 3/4" above the active notch.

At T +136 minutes, 80dF in the house (my combustor is working just fine), "200" for the flue temp, cat probe indicator above the E in "active", higher thn it was at T+65.

At T +191 minutes, 83 in the house (very happy wife), "175" flue temp and the cat probe indicator at the A in "active".

At T +240 minutes (four lousy hours) I had 85 in the house, "175" for flue gas temp, and the cat probe 1/4" below the A in active.

At this point the wood in the firebox is burned down far enough to do a hot reload on a good bed of coals.

At T +300 minutes ( 5 hours) I had enough coals left to do a 'high maintenance' hot reload that would take 20 minutes instead of 5 minutes, but no matches or kindling required.

At T +10 hours (600 minutes) aka now, the cat has been inactive for hours. I probably wont need a match to get the cat hot again if I load it up right now, but I would need some paper under the kindling.

What i am seeing is if I fill the stove in the AM and go to work deeper into winter I am going to have a cooling cat already below the A in active when I start my lunch break. By the time I get home for a reload I am going to have an inactive cat.

At 12-16%MC this would have been a 10-12 hour burn with outdoor ambients in the neighborhood of -20dF, given my static insulation envelope.

So where did my burn time go? Dryer wood is suppose to waste fewer BTUs because there is less water to heat up, convert to steam and pump up the chimney.

I _think_ what I am up against this year is figuring out how soon I can turn the Tstat down to medium. Some number less than 30 minutes that increases my burn time (back to 'normal') without blowing the glass out of the door and setting my living room carpet on fire.

 

[Poindexter]

If you wonder why folks in Fairbanks freaking Alaska are building hydroplanes in the garage, check out http://yukon800.com/ . I esp appreciate "10 rounds of ammunition secured to" in the rules for the big show.

 

[Highbeam]

I have a magnetic thermometer on my flue pipe about a foot above the stove, but I am using double wall telescoping flue pipe. I have read several times that the actual temp of my flue gasses is "about" double that shown on my magnetic surface reading thermometer. I have no idea what the temp of my flue gasses is really is. Numbers subsequently reported are actual readings - of the magnetic probe on DW pipe.


At T=0 the cat probe was at the notch between active and inactive, the house was +72dF, flue temp was reading "400". I closed the bypass door to engage the cat.


So where did my burn time go? Dryer wood is suppose to waste fewer BTUs because there is less water to heat up, convert to steam and pump up the chimney.

I _think_ what I am up against this year is figuring out how soon I can turn the Tstat down to medium. Some number less than 30 minutes that increases my burn time (back to 'normal') without blowing the glass out of the door and setting my living room carpet on fire.

Whoa. You are reading temperatures on the outside wall of double wall pipe with a magnetic meter. Your internal flue gas temps are much more than double the readings you are getting. 400 is very high at this location. On single wall stove pipe, it is generally accepted that the inner temps are double the outer. I believe that you are getting things too hot at the beginning, possibly over the design temps for your flue and I would worry about melting the bypass frame in your stove. I would recommend a probe meter for your flue, mine has been a very helpful tool over the years. I char the load much as you do but I shut the door as soon as possible without snuffing the young fire. The closed loading door reduces the cat preheat time. Are you leaving the loading door open during this char?

The sooner you get your door closed, cat engaged, and bypass closed, the longer your burn time will be. Much fuel is being puked up the chimney during bypass. I do not attempt to get every surface charred. In fact, I could run the stove without a window. Just use the meter.

Lastly, on my princess, the blower drops the cat meter reading a good bit. If your stove is built the same way then your cat meter readings are even less useful since everything from fan speed to ambient temperature can effect where that meter needle is pointing.

I do love this time of year when stoves are starting up again and the forums come out of hibernation.

 

[tarzan]

Don't you have "some" wood that's in the 12 to 16% moisture range? If you suspect your shorter burn times are do to the lower moisture content wood then try a load of higher moisture content wood to see if it changes things.

I to just engage the cat once it is capable of being active. If I need the loading door open for a few minutes to get things going I will but most of the time I just turn the thermostat all the way up. Open the bypass. Load the stove. Shut the loading door. Wait till the cat is capable of being active and close the bypass. Once the cat probe thermometer gets well into the active range I set the thermostat where I want it. Done for the day!

Yeah I realize that is not how the manual states to do it but I think the directions in my manual were written under the assumption of sub-par wood.

 

[Stump shot]

Highbeam is correct on needing a probe thermometer for the flue. Just looking at the color of the black paint, it has been too hot.

 

[begreen]

How much wood was reloaded at T+300min? 5 hrs burn time on a reload is quite short for a 3 cu ft stove.

 

[Poindexter]

How much wood was reloaded at T+300min? 5 hrs burn time on a reload is quite short for a 3 cu ft stove.

None. I turned the convection deck fans off, lowered the tstat to low to finish out the burn and went outdoors to cool off.

 

[Poindexter]

Highbeam is correct on needing a probe thermometer for the flue. Just looking at the color of the black paint, it has been too hot.

Ok, good to know.

 

[Poindexter]

Don't you have "some" wood that's in the 12 to 16% moisture range? If you suspect your shorter burn times are do to the lower moisture content wood then try a load of higher moisture content wood to see if it changes things.

I thought I did, but I don't this year. Winter of 2014/15 I burnt 8 cords at 12-16% MC with this stove, same flue pipe, same temp probes. The first of my kilns that I opened was already seasoned one year sitting at about 22-26% MC when I bought it in Dec 2015. The summer of 2016 as load one in kiln modules 1 and 2. Comes in at or slightly under 7%MC.

The other six modules are loaded with spruce that was live standing trees in Feb 2016. I figured it wouldn't be quite as dry as the first load that was already under FSP. One summer in the kiln, and they are at or slightly under 7%MC as well. And it's uniform top to bottom, there is no drier stuff on the top rack or slightly damper stuff on the floors, just slight flickers of 7%MC here and there, mostly my meter doesn't light up at all.

I got eight cords of the stuff, and I am done sticking pins in it until the spring thaw.

 

[Poindexter]

Whoa. I would recommend a probe meter for your flue, mine has been a very helpful tool over the years.

Appreciate the input. I'll run it by my wife, sounds like a good idea, esp with stumpshot's confirmation.

I char the load much as you do but I shut the door as soon as possible without snuffing the young fire. The closed loading door reduces the cat preheat time. Are you leaving the loading door open during this char?

Are you a regulated burner inside the EPA's rectangle of death, or just outside? So many zones of overlapping jurisdiction in Washington State, I don't really try to keep up.

At my (regulated burner) address, with my wood blah blah, i have only been able to get to engaged cat and clean plume from a cold stove inside the legal 20 minute time limit by keeping both the loading door and the bypass door open until the combustor is hot enough to engage.

This year using the same process but drier wood I am getting some cold start to clean plume times in the 12-15 minute range.

I also have only 15'6" of stack, collar to cap, so in this warmer weather not nearly as much draft as i will have in colder weather later.

For whatever reason I can consistently get my combustor engaged fastest by keep the loading door cracked open until it is time to close both doors.

On the one hand, our local ordinance is driven by neighbor complaints and I could probably get away with longer cold starts. On the other hand, if I do say so myself, it does take a reasonably skilled operator paying close attention to actually get from cold stove to clean plume in 20 minutes. I think it is a BS parameter on the books all over the country because the EPA wants it on the books. If any citizen ever gets a ticket for cold start over 20 minutes I hope to hear about, and i will be happy to explain to the jury - at no cost to the defendant if i can afford the plane ticket - what an unreasonable PITA the 20 minute cold start specification is.

The sooner you get your door closed, cat engaged, and bypass closed, the longer your burn time will be. Much fuel is being puked up the chimney during bypass.

I agree absolutely. Wouldn't it be ironic if our stoves would emit less grams per burn if we were allowed to heat the cat with a smaller longer fire instead of smoking like a coal fired locomotive for 18 minutes trying to meet the 20 minute limit?

Lastly, on my princess, the blower drops the cat meter reading a good bit. If your stove is built the same way then your cat meter readings are even less useful since everything from fan speed to ambient temperature can effect where that meter needle is pointing.

Yup. I am reliably informed the Ashford 30.1s have some kind of berm, like a V or semicircular shape on top of the firebox to partially shield the cat probe from the air flow of the convection deck fans. Mine's a 30.0, which is why I left the fans off for the first 30 minutes of yesterday's burn.

I do love this time of year when stoves are starting up again and the forums come out of hibernation.

Usually I do too, but a mixed blessing for me this year.

Thanks for your input.

 

[Highbeam]

Are you a regulated burner inside the EPA's rectangle of death, or just outside? So many zones of overlapping jurisdiction in Washington State, I don't really try to keep up.

Yes. EPA required, low gph units only, 20 minutes to 20% opacity.

At my (regulated burner) address, with my wood blah blah, i have only been able to get to engaged cat and clean plume from a cold stove inside the legal 20 minute time limit by keeping both the loading door and the bypass door open until the combustor is hot enough to engage.

This year using the same process but drier wood I am getting some cold start to clean plume times in the 12-15 minute range.

I can't get to 20% in 20 minutes in the BK. No problem doing it in my non-cat though.

I also have only 15'6" of stack, collar to cap, so in this warmer weather not nearly as much draft as i will have in colder weather later.

I only have 12' from collar to cap. No problem burning in temperatures up to about 60 degrees. That 12' meets spec for my princess according to the manual that shipped with it. They have since increased the requirement to 15'.

For whatever reason I can consistently get my combustor engaged fastest by keep the loading door cracked open until it is time to close both doors.

I am wondering if this is a problem. See, while your door is cracked and the cat is at active temps it is being assaulted by cold, non-preheated, non regulated air stream. This is not unlike a leaky door gasket which is supposed to be the cause of 95% of cat failures. I am fairly certain that BKVP recommended closing the door ASAP.

Yes, the 20 minute requirement is unreasonable for the BK. Barely possible with a non-cat. Honestly, at my latitude, when it is cold enough to burn it is also dark enough to start a fire without anybody seeing the smoke for most of the day. The BK allows once per day loading so I can avoid daylight freight trains.

.

 

[Woody Stover]

Bk has engineered these stoves so that the cats will not overheat. As such, you can ignore any aspect of cat temp other than keeping it hot enough to be active.

Removing the numbers from the dial of a well-known probe thermometer doesn't translate to an indestructible cat, when the needle goes soaring toward 2000'F. Yes, the stove is engineered to prevent this, but....

I have had the needle on the dial up past the end of the active zone and halfway to the "g" in BlazeKing once, in 15-20 burns so far this season

From what Poindexter said, with the cat probe needle buried, the cat has gotten too hot, regardless of the fact that the stove is "engineered so that the cats will not overheat." I guess the engineering failed. I wouldn't think that excessive cat temp for a short period, one time, would destroy the cat but I don't know.

So looks like it's still okay to follow the owner's manual and my advice then?

Yeah, get your wood below 13%, and then ask yourself, if the stove is "engineered so that the cats will not overheat," why is this included in your manual? (As an aside, BK should really think about proofreading the text before publication.) Also, I don't see any "closed or plugged" cells in the "severe" pic...

At T +240 minutes (four lousy hours) I had 85 in the house, "175" for flue gas temp, and the cat probe 1/4" below the A in active. At this point the wood in the firebox is burned down far enough to do a hot reload on a good bed of coals.

If the cat is indeed toast, as you and the dealer think might be the case, maybe the cat only burns well when there is a very fuel-rich environment in the box, and drops out of the active zone relatively quickly. Would the thermo then sense dropping firebox temp and open up the air, resulting in quicker consumption of the rest of your fuel? Seems likely that a bad cat may be the problem, not too-dry wood. But if not, could you stack the wood outside of the kilns in open air now and allow it to re-absorb some moisture? Maybe even let it get rained on a couple times.

 

[Poindexter]

Yeah, get your wood below 13%, and then ask yourself, if the stove is "engineered so that the cats will not overheat," why is this included in your manual??

This I agree with. I am confident from experience it is "impossible" to overfire the Ashford 30 with wood at 12-16% MC, even with stacks and stacks of draft from outdoor ambients colder than -42 degrees.

If the cat is indeed toast, as you and the dealer think might be the case,

Neither of us think that. All I had to do was vacuum the fly ash off the cat, fix the stuff I broke and resume normal operation.

Seems likely that a bad cat may be the problem, not too-dry wood.

I don't think this at all. On yesterday's burn as posted above I turned the Tstat down to medium and the convection deck fans on to medium at T+30 minutes. The house was +73dF. At T+136 the house was up to 80dF, 83dF at T + 191 minutes and +85dF at T+240 minutes. On medium. I was picking up 1dF in the house every 11 minutes, on medium, between T+30 and T+65. Through the active burn from T+30 to T+240 the house went from +73dF to +85dF , 12 degree temp rise in 210 minutes. On medium. In 1200sqft. That's about 20 minutes of burn for each degree gained, average. The degree loss per hour for my insulation envelope with outdoor ambients between +30 and +50dF is something like 0.1 to 0.2 degrees per hour.

At -42 my envelope loses about 5 degrees per hour, so I will have to run the stove at higher throttle setting than medium at that time.

I think my cat is currently working just fine.

But if not, could you stack the wood outside of the kilns in open air now and allow it to re-absorb some moisture? Maybe even let it get rained on a couple times.

I don't get rain this time of year.

 

[Ashful]

Forgive if it has been asked, but why not just split some fresh wood, and mix green in with your 7% MC stuff, to average 15 - 20% MC?

My 30.1's don't have anything blocking the probe in the convection deck. While my stoves are marked 30.1, they seem to be missing most of the features later 30.1's have.


Sent from my iPhone using Tapatalk

 

[Poindexter]

The sooner you get your door closed, cat engaged, and bypass closed, the longer your burn time will be. Much fuel is being puked up the chimney during bypass. I do not attempt to get every surface charred. In fact, I could run the stove without a window. Just use the meter.

I suspect this will be a fertile field of inquiry, bold mine.

To that end i started with a cold stove this evening, built a log cabin in the stove of splits split down to nominal 2x2 inch size, filled the cabin with kindling and lit it off.

About 45 minutes later I had about a gallon of hot coals on the bottom of the stove, with the cat probe up by the E in active. Still haven't twisted my dial because of this thread and my OCD is killing me. I generally run with the cat probe indicator oriented so the active zone runs from 9 oclock to 3 oclock with high noon, the middle of the active range lined up with the nearby stove pipe.

Anyroad, I opened it back up, spread the coals around and loaded 12 splits onto my hot coals. First game of stove tetris this year, I think I could got 14 in there if I had planned better.

I let it char two minutes, closed the loading door, closed the bypass door.

At T=0, 1708 local, conditions were:

Tstat on high. Convection deck fans off. cat probe at E in active. House at +73 dF, all upstairs doors open. Stack temp reading as above, "200."

My plan is to run it on high for 30 minutes, drop the Tstat back to medium, turn the convection deck fans on and then monitor hourly until bedtime.