Keeping the cat clean

[Eric Johnson]

I've been using an 8-inch add-on catalytic combustor for the first time this season, and it's working out pretty well. I've got it hooked up to an indoor boiler. I noticed that one night when I forgot to engage the cat before going to bed, the fire was pretty well out the next morning. That never happens when the cat is engaged. And, I get zero creosote in my insulated ss chimney.

The only problem I have had is accumulation of ash dust on the cat element. It ran fine for 2 months before I had to take it out and clean it. Then it went another month. Then another week. Finally, I discovered that my conventional manual damper was out of position so that when I thought it was open it was partially closed, etc. This allowed the boiler's forced air draft blower to blow dust directly onto the cat element, plugging it up. I never have the cat engaged when the damper is open.

So having fixed that problem, I think I'm good to go.

However, I also noticed that most of the dust/ash that makes it past the damper winds up in the cleanout. Presumably most of it is heavy enough to fall to the bottom of the cleanout (diagram) and not be carried up into the cat honeycomb. I would like to find a way to make sure that all the dust ends up at the bottom of the cleanout, so that I never have to clean dust out of the cat again (wishful thinking).

Any of you engineering types or other wood-burning gurus have any ideas how to do that? A basic diagram of what I am talking about is attached.

Oh yes, I did fix the damper. Don't know why they make them the way they do (loose & wobbly), but I just drilled a couple of small holes through the cast iron damper and the steel rod that it hangs on and put a couple of cotter pins through it. Now it does what I tell it to do, which is the way I like things.

 

[Rob From Wisconsin]

Hey Eric...
Great to hear your combustor worked well.
What was the color of the element??
When I got mine, it was almost pure white:
no noticeble contrast, almost like their wasn't
any apparent coating on the element.
Mine didn't work very well at all, possibly never.

Rob

 

[Eric Johnson]

Rob,

Mine was kind of golden brown, as I recall. When I had it out last time I did the whole vinegar bath clense, just to know where I stood. It's a little darker now, but that's just a little soot that survived the cleaning, I think. No cracks or any other signs of wear, after about 6 cords burned.

At first I didn't think mine was working either, mainly because it never did anything dramatic. I half expected it to glow or something, but it just sits there and gets hot. It's subtle, but I've noticed less smoke and more heat for the amount of wood consumed so far this year. Of course, I've done a lot of other things to the installation like new grates, better insulation, a new boiler room, etc., so who knows? A lot warmer this year, too.

Another tip-off is the fact that the black pipe below the combustor is typically sooty with a little flakey creosote, while the couple of feet directly above the cat is completely clean.

Maybe somebody knows a good way to test whether a cat is working. I sure don't and I suppose it's possible that mine doesn't and never has, but all signs point to the thing doing the job I'm paying it to do.

I'd urge you to give it another try, Rob.

 

[begreen]

I know the cat is working when there's less mice in the corn crib . (Sorry couldn't resist.)

 

[Rob From Wisconsin]

Thanks for the input, Eric.
I believe my element was defective, from what you tell me.
Mine appeared to have no coating whatsoever.
That would explain its poor performance.
I'll have to get in contact w/ Woodsman to see if they are
willing to correct it (perhaps send back old element).
Unfortunately, it has been over a year since I purchased it...

Rob

 

[Eric Johnson]

I'm sure if you send it back to Woodman's and they find it has no coating they will give you a replacement or a refund. If you only used it for a short time and it has no cracks or abrasions, then it's obviously a defective product and they can get a refund from the Mfg. Good luck.

 

[dflone]

To determine if the cat is working couldn't you install thermometer with a small diameter probe just above the cat and keep track of the temp. when the cat is engaged or not? Also for what it's worth, or not, I'd think it would probably be near impossible to keep all particles from traveling up into the cat without reducing the draft to the least necessary for optimum performance and then it still may be too much for the lighter stuff. Is cat height determined or adjustable?