Keystone Cat Going - Gone Bad

[Woody Stover]

Woody,
How soon after you engaged did you look at your stack? Sometimes for me it can take 5 minutes or more til the stack goes smokeless. I also pay more attention to my stack temp than stove top when looking to engage. I think the majority of the time I engage with a stove top of about 200 but the internal stack temps are well within lite off range.

I've looked at the stack right after engaging, and later as well. Last night, though, it kicked in after about 10 min. when the stove temp got a bit higher. I'm using a magnetic thermo, laid on the stainless tee snout right behind the flue collar and reducer. Last night it was a little over 400...probably needed a little more. I've been thinking about getting a flue probe thermo and putting it where the tee goes vertical. I'm also considering getting a cat thermo. I guess that would give me a better idea what the temp is right there at the cat, but I'd need a mirror to see it...

 

[Todd]

Woody,
How soon after you engaged did you look at your stack? Sometimes for me it can take 5 minutes or more til the stack goes smokeless. I also pay more attention to my stack temp than stove top when looking to engage. I think the majority of the time I engage with a stove top of about 200 but the internal stack temps are well within lite off range.

I've looked at the stack right after engaging, and later as well. Last night, though, it kicked in after about 10 min. when the stove temp got a bit higher. I'm using a magnetic thermo, laid on the stainless tee snout right behind the flue collar and reducer. Last night it was a little over 400...probably needed a little more. I've been thinking about getting a flue probe thermo and putting it where the tee goes vertical. I'm also considering getting a cat thermo. I guess that would give me a better idea what the temp is right there at the cat, but I'd need a mirror to see it...

An internal probe prolly wouldn't work for your setup, I think they are calibrated to read about 18-24" up. A thermocouple would be most accurate but you should be fine with a little trial and error using the external magnetic thermometer.

I forgot who it was but last Fall someone drilled a hole through the top center stone of their Keystone and inserted a cat probe right on top of the cat. I was tempted too but am just too chicked. Never heard how it worked out, I wonder how accurate that would be?

 

[leeave96]

I haven't installed the new cat yet, but when I had my old cat out, looking at it there was some hairline cracks and a touch of surface crumbling when I lightly brushed it. The literature Woodstock sent with the new cat showed pics of a cat that was fire impinged, which looked scooped-out and pics of thermal shock. My cat looks like potential thermal shock.

I am hopeful the new SS cat will eliminate this risk. My plan is to keep burning like I did previously and see how this SS cat does. The Keystone is such a pleasant stove to watch the flames and if that is what is burning out the cat, if the new one fails, I guess I'll just buy one every year!

Bill

 

[gogreenburnwood]

Your thermal shock comment is right on target. I was told that if you load new wood in with a cat that is up to temperature. the new wood is "cold"" enough (plus the cold air you let in to put the wood in) to thermally shock the cat if you engage it right away, causing the hairline cracks and eventual crumbling. I was told to let the wood come up to temperature and not engage for at least 5 minutes.

 

[leeave96]

Your thermal shock comment is right on target. I was told that if you load new wood in with a cat that is up to temperature. the new wood is "cold"" enough (plus the cold air you let in to put the wood in) to thermally shock the cat if you engage it right away, causing the hairline cracks and eventual crumbling. I was told to let the wood come up to temperature and not engage for at least 5 minutes.

Hopefully this thermal shock issue will be eliminated with the stainless steel structure - we'll see.

What I don't get is the thermal shock on reloading. Let's pick a worse case: Your stove is 500 degrees stove top. You load seasoned-dry wood to top off the firebox. You are in bypass mode for reloading. The wood instantly catches because the firebox is so hot. After a few minutes - lets say 5 minutes max, you close the bypass and you are in cat mode. I don't see how the smoke temp coming off the wood, coupled with the already 500 degree stove top temp is going to thermally shock the cat - after all, the cat is at the top of the stove, only a few inches from the bypass. To me, this is not a thermal shock situation because everything is already super hot.

On the other hand, if you take that same stove, running at 500 degrees, and top it off with seasoned, but dripping wet or snow covered wood, I could see how flashes of steam could make trouble.

I also wonder how hard it is on the cat when you are at 650-700 stove top, bright orange glowing cat with zero flame cruising along - how that wears on the cat ceramic vs 500 degree stove top. Also, if you are at, 500 degrees and decide to reload, throwing the stove into bypass diverting hot air away from the cat and snuffing out the cat burn - causing instant cooling may also be a source of thermal shock.

I think this SS cat holds great promise in terms of a sturdy cat for some hard burns.

Bill

 

[leeave96]

Update: We've got a little cooler weather this evening - cold and rainy too. I'm going to swap out the cat and fire-up the stove and see how it goes. More later!

Bill

 

[leeave96]

Update: Installed the new cat. Fired the stove, engaged the new cat at 250 stove top - instant orange glow. Stove top temp is going up, no real flames in the firebox, nice shoulder season low cat burn going tonight.

Live is good!

Bill

 

[Todd]

I really think these new steel cats are the ticket. Woodstock is going to have a lot less headaches from crumbling cats.

Got my fire going low and slow tonight on this cold rainy evening and it feels good.

 

[leeave96]

I loaded the stove-up about 1/2 full, lit off a match. Let the stove warm-up to 250 degrees stove top. Flipped the cat lever, looked around front and the cat was instantly glowing bright orange. As the stove continued to burn, I dampered down to no flames and the cat continued bright orange and I had a nice shoulder season burn. Almost no heat from the front or sides, but the stove top was over 500 degrees. Knocked off the chill for the night and let it burn down and out over night.

My old cat would burn bright, but not like this one. Todd, I don't know if you can see any difference between the intensitity of your ceramic vs steel cat in your Keystones, but this cat is much - much brighter. It makes me think the cat I had wasn't so good from the start. If it cools off again this weekend, I'll fire thing-up again with a larger load and see how quickly the temps jump towards 700 degrees.

Bill

 

[Todd]

I really can't tell any difference between the two, they both seem to lite off and glow a bright red during a low burn. Heat output also seems to be the same, no problem getting either stove up over 600. It could be you just had a bad cat.

 

[VCBurner]

Update: Received my new cat combuster today

Bad News: It's to warm to burn

The new combuster's stainless steel structure is very thin, almost looks like corrigated carboard cross-section. I hope this sucker works!

If it get's colder between now and next fall, I'll give it a try. I gather that flame impingement and thermal shock damaged are pretty much minimized with this stainless steel vs the ceramic - we'll see.

Bill

Hey Bill,

Sorry to hear about your cat trouble. I haven't been on here much and just saw your thread. I sort of skimmed through the thread so forgive me if I sound redundant.

I believe you'll love the SS cat, our cat lights off within 15 minutes of a cold start, which is great for shoulder season burning. I realize the Keystone and DW are very different but I think you'll also benefit from the new cat! I still wish I could see the glowing cat without having to kneel down in front of the stove and looking up into the top of my firebox. My shoulder season light off procedure is as follows:

Rake away ashes in the center of the stove and place two 2-3 inch rounds in the raked area E/W;
Place two Rutland Safelite Firestarter Squares between the two small splits and light them;
Place more small splits or rounds next to the two original "sticks" so they don't roll and allow other logs to snuff the firestarters;
Continue to throw another layer of small logs up to 2 inch on top of the first layer, this allows the second layer to light up quickly. The size of the third layer depends on how long a fire I want, this time of year I only put 3-4 layers amounting to 50-75% capacity of mostly small stuff;
I leave the ash pan open for 5-10 minutes after lighting the fire to catch everything well untill my thermometer reads about 750 (important not to leave the room and forget the stove during this stage!)
then shut the ash pan and wait to see if the fire stabilizes, often turning on the blower after shutting the ash pan;
After about 5 minutes of observing a stabilized fire with the air wide open, damper down, shut air almost all the way, cat temp is often around 250 but within 5-10 minutes it will be glowing red and will coast for the rest of the burn cycle!

The whole process usually lasts 15-20 minutes from cold start to damper down procedure, I have the cat air completely shut untill the damper down procedure. This would probably be deadly for a ceramic cat, but the ss cat seems to handle the temperature change much better. I do this once or twice a day with a half load of usually small stuff often mixed with a lot of pine. This allows quick light offs and brought my house temp up from 58 to 70 on Friday morning! The load was topped off with a couple of 4" medium splits. It was a 3/4 full load of mostly sticks at 1-3 inch.

I try to keep the loads small and the splits small with a lot of pine so quick bursts of heat can be achieved without the long lasting hot fires you may get with big hard wood splits. The SS cat seems to light off so much quicker and handles the rapid temperature increase that is needed here at my house. Especially, since my wife is due to give birth in three weeks and is in no shape to start fires and tend to the stove. It is important for me to be able to start a fire quickly before leaving for work, I like to get up and go! Getting to work at 6:45 am and eating an egg sandwich on the go on the way is usually my way to start the day. For some people reading the paper, eating at home and hanging out for an hour or two is possible, but often times I have to leave the house by 5am!

Bill, good luck with the new cat, and keep us posted!
Take care,

Chris