Ceramic or metal

[Mooch]

Hello, I know this subject has been discussed in the past but couldn't find anything new. Pros and cons on a metal vs ceramic cat? Real person experiences is metal worth the extra money? Does metal heat up quicker and or hotter? TIA

 

[Eman85]

Some in the Vermont Castings section have tried metal cats. @Woodsplitter67 and @arnermd have used both.

 

[stoveliker]

I have a metal cat. I had a ceramic cat in my previous crappy old 1982 DutchWest FA stove.
Very different systems, so hard to compare.

If you have a lot of draft, a metal one may be worse as its channels are smaller diameter, so they can clog more easily with fly ash (that a high draft stirs up).
I have a metal one now, and my chimney is about 27' tall (rather than the 15' the manual suggests is the minimum) - though with two 90s, and a long (nearly 4 ft...) horizontal run.
I have not measured my draft, but I don't have smoke roll out and can control the fire nicely (easily to extinguish all flame when dialing it down). So I don't know if I am in the "suck fly ash into the cat" regime - but I don't have issues with that.
Once every month or so I see 2-3 flakes of ash on the face. The next time I shut the stove down I take a hand held vacuum and it's done.

Both cats don't do well with flame impingement. Ceramic ones can crumble, metal ones can deform.

I think the metal ones might heat up slightly faster (I think they have less mass - but I'm not sure about that; I do know that the heat capacity of many ceramics is high, and that of steel is not so high, so it takes a lot more energy to heat up ceramics - I do not have specific knowledge of the ceramic substrates for wood stove cats).
(@Tron ?)

I believe that if you buy the same cat but on a different substrate, the active layer will be the same, so chemically there's not much difference.

I believe @Ashful has used both. Maybe @Highbeam too. This is all (mine, and the three folks I mentioned) in BKs. Your brand and therefore mileage w.r.t. the advice here, may therefore vary.

 

[FPX Dude]

My last ceramic cracked after 1 yr., so I went metal and just replace and that was now ~12,000hrs of use like 8 yrs. ago on my last one, I just replace this year with another metal and expect the same. I only clean once a year with compressed air and a new gasket and seems good to go.

 

[Mooch]

I have a metal cat. I had a ceramic cat in my previous crappy old 1982 DutchWest FA stove.
Very different systems, so hard to compare.

If you have a lot of draft, a metal one may be worse as its channels are smaller diameter, so they can clog more easily with fly ash (that a high draft stirs up).
I have a metal one now, and my chimney is about 27' tall (rather than the 15' the manual suggests is the minimum) - though with two 90s, and a long (nearly 4 ft...) horizontal run.
I have not measured my draft, but I don't have smoke roll out and can control the fire nicely (easily to extinguish all flame when dialing it down). So I don't know if I am in the "suck fly ash into the cat" regime - but I don't have issues with that.
Once every month or so I see 2-3 flakes of ash on the face. The next time I shut the stove down I take a hand held vacuum and it's done.

Both cats don't do well with flame impingement. Ceramic ones can crumble, metal ones can deform.

I think the metal ones might heat up slightly faster (I think they have less mass - but I'm not sure about that; I do know that the heat capacity of many ceramics is high, and that of steel is not so high, so it takes a lot more energy to heat up ceramics - I do not have specific knowledge of the ceramic substrates for wood stove cats).
(@Tron ?)

I believe that if you buy the same cat but on a different substrate, the active layer will be the same, so chemically there's not much difference.

I believe @Ashful has used both. Maybe @Highbeam too. This is all (mine, and the three folks I mentioned) in BKs. Your brand and therefore mileage w.r.t. the advice here, may therefore vary.

Thanks for your info. I do feel I have an optimal draft as I can close the air all the way down and snuff the fire and yet still open the bypass and never get smoke roll in. Just not sure what cat to buy.

My last ceramic cracked after 1 yr., so I went metal and just replace and that was now ~12,000hrs of use like 8 yrs. ago on my last one, I just replace this year with another metal and expect the same. I only clean once a year with compressed air and a new gasket and seems good to go.

Yeah mine is cracked in several spots also. I'm gonna try the metal cat. I'm assuming the cracks hinder it's performance? My cat temp won't get above 800° with 18-20mc black walnut. Hopefully it's because I need a new cat. And I need to work more on my mc to get it closer to 15%

 

[stoveliker]

Cracked doesn't necessarily indicate decreased performance. It does not mean it is not working; if channels are still there and the coating is intact, it may be working fine.

It could indicate you've shocked it by letting cold air (or wet wood) get to a hot cat.

Crumbled is another story.

800 deg may be fine or it may be the temp from the fire itself.
Do you see the cat temp go up if you decrease the air?

You can always get a new cat and keep this one on a shelf. (New cats tend to be hyperactive tho, so comparing to see if the old one behaves normally for its age is hard.)

How many hours did you use the old one?

And what stove is this?

 

[Mooch]

Cracked doesn't necessarily indicate decreased performance. It does not mean it is not working; if channels are still there and the coating is intact, it may be working fine.

It could indicate you've shocked it by letting cold air (or wet wood) get to a hot cat.

Crumbled is another story.

800 deg may be fine or it may be the temp from the fire itself.
Do you see the cat temp go up if you decrease the air?

You can always get a new cat and keep this one on a shelf. (New cats tend to be hyperactive tho, so comparing to see if the old one behaves normally for its age is hard.)

How many hours did you use the old one?

And what stove is this?

The cat temp goes down when I decrease the air. I'm a nights and weekends user. Owned the fireplace xtrordinair Apex 42 for 3 seasons now

 

[Megunticook]

I started with ceramic, after about 12 years I tried steel for 8 seasons, then went back to ceramic this year. Main reason was the steel cat got clogged with ash regularly, needed to be taken out and cleaned about every month or so. For some reason the ceramic doesn't have that issue. The steel cat also eventually started to "sag" down out of its metal enclosure.

Both function well.

 

[Mooch]

I started with ceramic, after about 12 years I tried steel for 8 seasons, then went back to ceramic this year. Main reason was the steel cat got clogged with ash regularly, needed to be taken out and cleaned about every month or so. For some reason the ceramic doesn't have that issue. The steel cat also eventually started to "sag" down out of its metal enclosure.

Both function well.

That's a good point to consider.

 

[stoveliker]

Cat temp going down suggests it's not functioning as it should.
Clogging does happen more with steel, but depends on the system, see my earlier remark about my cat.
It all depends on how much draft you have, and how that affects the airflow in your stove (whether it stirs up the ashes).

 

[Mooch]

Cat temp going down suggests it's not functioning as it should.
Clogging does happen more with steel, but depends on the system, see my earlier remark about my cat.
It all depends on how much draft you have, and how that affects the airflow in your stove (whether it stirs up the ashes).

So, really no reason to spend the extra money on a steel cat? No real benefits?

 

[stoveliker]

There are stories of people both ways. To me that suggests no significant operational benefit.

 

[Ashful]

Yep... I've used both. I went thru several of each in Jotul Firelight 12's, and now 3 of each in BK Ashford 30.1's. The steelcats used in the Jotuls were the older / cheaper diesel foil type, but those used in the BK's are all of the BK OEM Durafoil type.

First, diesel foil is junk. If you're looking at steelcats made of that garbage, don't even bother. It distorts at relatively low temperatures, and I think it may also have delamination problems. Just avoid it. If your cat looks like a roll of corrugated cardboard, it is probably diesel foil.

The Durafoil is good stuff, but as Stoveliker already aluded, I had troubles with those combustors clogging. It wasn't terrible on a 15 foot chimney, although ceramic was still better, but it was a real problem on my 30 foot chimney. Installation of a key damper helped, but I was still finding myself having to vacuum the cat clean at least once mid-season, to keep it flowing and working well enough. Running full cycles of hardwood on a high setting didn't help here, as that's a recipe for maximum fly ash, so your mileage may be better if you never run on higher settings.

My preference is ceramic, and it's all I'll be using in my BK's from now on. In fact, I just installed two new ceramic cats this fall, which I expect to last me the next 4-5 years. I have never had problems with them cracking... ever. Remember to open your bypass before going out to fetch your wood, so you're not opening a door to cold room air on a hot cat, and never burn wet wood. In a well-designed and properly operated stove, these things should last until the catalyst is completely flattened or depleted, before you see any apreciable mechanical failure or cracking.

 

[Mooch]

Yep... I've used both. I went thru several of each in Jotul Firelight 12's, and now 3 of each in BK Ashford 30.1's. The steelcats used in the Jotuls were the older / cheaper diesel foil type, but those used in the BK's are all of the BK OEM Durafoil type.

First, diesel foil is junk. If you're looking at steelcats made of that garbage, don't even bother. It distorts at relatively low temperatures, and I think it may also have delamination problems. Just avoid it. If your cat looks like a roll of corrugated cardboard, it is probably diesel foil.

The Durafoil is good stuff, but as Stoveliker already aluded, I had troubles with those combustors clogging. It wasn't terrible on a 15 foot chimney, although ceramic was still better, but it was a real problem on my 30 foot chimney. Installation of a key damper helped, but I was still finding myself having to vacuum the cat clean at least once mid-season, to keep it flowing and working well enough. Running full cycles of hardwood on a high setting didn't help here, as that's a recipe for maximum fly ash, so your mileage may be better if you never run on higher settings.

My preference is ceramic, and it's all I'll be using in my BK's from now on. In fact, I just installed two new ceramic cats this fall, which I expect to last me the next 4-5 years. I have never had problems with them cracking... ever. Remember to open your bypass before going out to fetch your wood, so you're not opening a door to cold room air on a hot cat, and never burn wet wood. In a well-designed and properly operated stove, these things should last until the catalyst is completely flattened or depleted, before you see any apreciable mechanical failure or cracking.

Thanks for the info. I'm gonna flip a coin 🪙

 

[Ashful]

Thanks for the info. I'm gonna flip a coin 🪙

Dude, they both work fine. If your chimney is real tall, favor ceramic to avoid the clogging issues. Otherwise, the durability of steel is pretty hard to beat, no worries with careless operators opening a door on a hot cat and thermally-shocking it.

I actually ran one of each the last five years, ceramic on my taller chimney with steel on the shorter pipe, to try to make some comparison. If there was a difference, it was too small to detect among the other larger factors that differentiated my two stove setups.

 

[Tron]

I do not have specific knowledge of the ceramic substrates for wood stove cats).
(@Tron ?)

Without any information on which substrate is being used for the cats, impossible to say. There are a literally thousands of suitable ceramic compounds out there.