Too hot cat temp?

[griam01]

How hot is too hot on the cat temp? If it gets too hot what do you do?

I just reloaded with hot coals and had everything open. Less than 10 mins later the temp was at 1000 and then I closed everything down. It is now at 1500 so I was worried. When is it too hot? Thanks.


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[weatherguy]

I think 1800 is max, 1500 is fine

 

[davidmc]

My Buck 91 regularly gets 1800/2000. Buck Corporation guy told me not to worry about it they were under on the maximum so it's good for higher temps. I'm working on my 7th year if I remember correctly.
David

 

[begreen]

davidmc, that's good feedback and impressive cat performance.

 

[davidmc]

begreen, I think it has the steelcat in it. When I brushed my flue this fall I cleaned out the cells with a q-tip, they had a good bit of ash in them. I thought I might need to replace it but it's still lighting off real fast and getting high temps so I'll just go on with this one.
Dry wood all these years I imagine has helped with longevity.


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[heavy hammer]

That's great temps, I'm just wondering why the cat in my kuma is recommended to stay under 1400? Are there different varieties of cats out there?

 

[Woody Stover]

My Buck 91 regularly gets 1800/2000. Buck Corporation guy told me not to worry about it they were under on the maximum so it's good for higher temps. I'm working on my 7th year if I remember correctly.
David

Wow, I started getting nervous when my Buck went over 1600, after reading about catalyst peeling, and seeing a slight amount when I had the cat out last fall. That cat has about 4 yrs. on it and didn't push 1800 more than a handful of times, as far as I know. It's still working OK so I don't think a small amount of peeling is the end of 'em.
So you bought your stove used? As far as I could find, they don't make a steel cat for the 91. I guess you've never had the cat out of yours, or you would know for sure if it was steel or not? But I would think you must have had it out if you ran a q-tip through the cells; That would be kind of hard to do with the cat in the stove and the expanded-metal mixing screen in the way. I think with a steel cat, it would be hard to get a q-tip through.
Only the ceramic cat in the following pics is a cat for the 91.
Diesel-foil cat:

DuraFoil cat:

Ceramic cat:

 

[davidmc]

Good morning Woody Stover! I purchased my stove new in 2010. I got curious and pulled my paperwork on it to be sure.
I have no had my cat out and it was difficult cleaning the cells out thru the screen and lay on my back in front of my stove...lol.
It is a ceramic cat....fire cat.
I knew I had seen fire something or other, lol.

Thanks
David


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[redyute]

Manual says 1400° for my high valley, occasionally it may creep to 1500°. To get the temps down I close the air completely and turn the blower on high, that usually does the trick

 

[Woody Stover]

To get the temps down I close the air completely and turn the blower on high, that usually does the trick

For whatever reason, the Buck air controls are set up a little looser and you can't cut the air enough if you get too much wood gassing and cat temp goes high. Knowing what I do now, the first thing I would do on a Buck is tighten up the air shutoff plates if the cat wanted to go high. In the following pic, you can see that the plates are fastened to the slider rod with sheet metal screws. You can't see in this pic how large the gap actually is. I would put a thin spacer washer between each screw and the plate, which would raise the plates in relation to the air inlets, allowing the air to be cut more completely if needed. Some slightly longer screws might be needed with the washer in there.

 

[redyute]

Ah I see, that should help

 

[Woody Stover]

The last paragraph here is telling...

 

[rdust]

The last paragraph here is telling...

View attachment 189908

Here is what applied ceramics has to say.

 

[davidmc]

Woody, does your buck run @ high temps?
My controls were extremely tight when I got my stove so I had to loosen them up some.
David


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[Woody Stover]

Woody, does your buck run @ high temps?
My controls were extremely tight when I got my stove so I had to loosen them up some

Yeah, the cat went over 1800 several times early on. I got the stove used, and the ash pan gasket was frayed on the ends so excess air was getting in through the ash dump. I could tell because the coals were glowing more brightly over the ash dump. To replace the ash pan gasket, you have to make sure that the top run is glued on pretty high, where the steel starts to curve in, or the gasket won't catch the top of the ash pan housing very well. Once I got that taken care of, I made an attempt to tighten up the air plate gap I showed in post #10. I made a shim for the U-saddle that the slider rod rides in. That lifted the rod, which lifted the plates a little and closed the gap somewhat, but I still had to make sure I didn't get too much wood gassing when I loaded the stove, or the cat would "blaze orange." I pulled the coals to the middle so not as much wood got gassing on the reload. I didn't come up with the washer idea until later.

 

[jharkin]

Different manufacturers give different limits. Condar used to say anything over 1700 starts to damage the coating. They have since lowered that as you can see above.

I know from experience that around 1800 I see glowing iron inside my stove and it's at risk of a runaway.

I set my temp probe to alarm at 1650 and attempt to never let it go beyond 1700.

As I sit here typing it's 10F outside and the probe temp is 1611F with the air fully closed, I am watching it like a hawk.

 

[redyute]

I am watching it like a hawk.

Exactly how I do with mine I keep my eye on it. I stay at 1400°

 

[WranglerBowman]

For whatever reason, the Buck air controls are set up a little looser and you can't cut the air enough if you get too much wood gassing and cat temp goes high. Knowing what I do now, the first thing I would do on a Buck is tighten up the air shutoff plates if the cat wanted to go high. In the following pic, you can see that the plates are fastened to the slider rod with sheet metal screws. You can't see in this pic how large the gap actually is. I would put a thin spacer washer between each screw and the plate, which would raise the plates in relation to the air inlets, allowing the air to be cut more completely if needed. Some slightly longer screws might be needed with the washer in there.
View attachment 189907

Hey Woody Stover, to tighten up the air intake I just took those steel plates off, pulled the metal plate out and bent the rod they slide on with an upward bend so it holds the plates tight against the bottom of the stove. This will make it more difficult to slide but it keeps it pretty tight. I had an issue with some poor burning characteristics a couple years ago on my Buck 91 and the loose sliders proved to be the culprit.

 

[Woody Stover]

the Buck air controls are set up a little looser and you can't cut the air enough if you get too much wood gassing and cat temp goes high. Knowing what I do now, the first thing I would do on a Buck is tighten up the air shutoff plates if the cat wanted to go high.

Hey Woody Stover, to tighten up the air intake I just took those steel plates off, pulled the metal plate out and bent the rod they slide on with an upward bend so it holds the plates tight against the bottom of the stove....I had an issue with some poor burning characteristics a couple years ago on my Buck 91 and the loose sliders proved to be the culprit.

Sounds like it would work well...I hadn't looked as far as taking the rod out to bend it upward. The plates are probably the only thing holding the rod in, I guess?
What were the "poor burning characteristics" that you had...cat burning too hot? Why aren't you burning the 91 now...just because you got a good deal on the King mentioned in your other post, and wanted to try it out? BTW, just how good a deal did you get??

 

[WranglerBowman]

Sounds like it would work well...I hadn't looked as far as taking the rod out to bend it upward. The plates are probably the only thing holding the rod in, I guess?
What were the "poor burning characteristics" that you had...cat burning too hot? Why aren't you burning the 91 now...just because you got a good deal on the King mentioned in your other post, and wanted to try it out? BTW, just how good a deal did you get??

The rod slides on 2 guides at either end of the stove and metal plates slide and hit those guides at full open and fully shut so once you remove the metal plates over the are intake the rod can just slide out Then just slightly bend it till you have a slight upward bend, run it back through the guides and reattach the metal plates. It worked really well for me.

The poor burning characteristics were that I was getting a black build up on one side of the stove and noticed the flames, when their were visible flames, like to be on that same side so realized there was an air leak. After examining the plates there was actually a difference in the in air gap from side to side, e.g. left side would have an opening of 1/2" and right side was open 3/4" when they should be uniform, as well as the plate on the right wasn't making contact with the metal stove bottom any more. I guess that metal rod just starts to sag a little over time with repeated heating and cooling.

I'm not burning the 91 any more because I was finally able to catch a Blaze King, they're rarer on the mid Atlantic east coast and go quick if one comes up for sale. I loved the 91 but my work days are sometimes 14 hours and it stinks coming home to a cool house and barely enough coals to get a fire going again so I needed something that put out more heat for a longer time period. The only way the 91 could keep up with the heat I needed was to reload every 6 hours. I picked up the BK Ultra for $2k and a 5 hr drive one way...well worth it considering I'd been looking/lusting for an BK Ultra for the last 2 years and had only seen one ever pop up for sale within 300 miles of me. The quotes I got from a couple woodstove dealers, that could get one, was $3600 for a new one and I had pick it up at their place...that's more than my last 2 vehicles cost...combined!

 

[Dobish]

the other day mine was really hot. Even with the air all the way shut down, it was still cranking pretty good (like around 1500). If it gets too hot, should I just open the bypass and try and cool it off?

 

[WranglerBowman]

the other day mine was really hot. Even with the air all the way shut down, it was still cranking pretty good (like around 1500). If it gets too hot, should I just open the bypass and try and cool it off?

That's exactly what I used to do. If the Buck 91 cat was getting too hot I would keep the fans on high, close the air intake almost completely, and open the bypass partially so a lot of the heat goes up the chimney but also keeps air flowing over the cat. I wouldn't think it would be good to block off an overheated cat as it may shock it for lack of a better word.

 

[Woody Stover]

The poor burning characteristics were that I was getting a black build up on one side of the stove and noticed the flames, when their were visible flames, like to be on that same side so realized there was an air leak. After examining the plates there was actually a difference in the in air gap from side to side, e.g. left side would have an opening of 1/2" and right side was open 3/4" when they should be uniform, as well as the plate on the right wasn't making contact with the metal stove bottom any more. I guess that metal rod just starts to sag a little over time with repeated heating and cooling.

There's not really many places where air can leak into the stove. Door gasket, ash pan gasket (evidenced by glowing coals over the ash dump,) bay window gaskets (not likely to be a major leak there, I wouldn't think,)...and the air intake plates, which are fixable. I don't see that 1/4" plate-steel rod sagging...there's not much heat there, under the air intake channel. There was a slight difference in the plates on the two sides, but only like 1/16", not the 1/4" you are talking about.

I picked up the BK Ultra for $2k....I loved the 91 but my work days are sometimes 14 hours and it stinks coming home to a cool house and barely enough coals to get a fire going again so I needed something that put out more heat for a longer time period. The only way the 91 could keep up with the heat I needed was to reload every 6 hours.

Nice deal on the King, even if you had to drive to get it.
Wow, your house must be big, or maybe it's like my MIL's...plaster walls with no insulation, stove at one end of the layout, 9.5' ceilings, three walls of glass in the stove room, etc. Still, I was able to keep the house in the mid 60s in the back, to the upper 60s in the front rooms with 12-hr. burns in the 91. Stove temp measured on the front was still around 250 when I came to re-load. This was with good hardwood like Oak and hard Maple. Hickory and BL would extend the useful burn a bit longer. What kind of wood are you burning? If you are having to burn a load in 6 hrs. to get the heat you need, an additional stove or a wood furnace may be the only answer. I don't think the King will throw the raw heat of the 91 on a per-hour basis but maybe the 4 cu.ft. box will help keep house temp up at the end of the burn...I measured the 91 at about 3 cu.ft. usable space. Sounds like your house loses heat fast once the stove output drops off. I guess there's no one that can stoke the stove when you are working those 14-hr. days?
I used to burn a few medium-small "sacrificial splits" to get the stove temp in the 91 back up, then load up. That way I could get the cat lit and the stove cruising pretty quickly without burning up too much of the main load.

the other day mine was really hot. Even with the air all the way shut down, it was still cranking pretty good (like around 1500). If it gets too hot, should I just open the bypass and try and cool it off?

That's what I had to do with the Buck early on, before I got better control of the air and got better at re-loading so that I didn't get too much wood gassing--I would just bypass the cat for a while until I got the load slowed down a bit.