Questions For Cat (Stove) Owners...

[Peter B.]

I'd still like to get a broader range of answers from cat stove owners...

(Though I've contributed to the subversion of this thread myself.)

Please refer to Post #1 to see poll questions.

Thanks.

Peter B.

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[mellow]

They can direct from the manufacture, as with anything.

But aftermarket then can cost much less:

http://catcombustor.mybisi.com/all-categories/Page1.html

 

[North of 60]

Doesn't seem like the answers could be accurate... cats need secondary air, and if you could close the air ALL the way, the fire would go out completely.

The fire does go completely out. There must be some fixed air to the Catalyst to sustain combustion though as Czar Car sayz
me thinx. 90% of the time on low burn my stove just smolders to create smoke to feed the CAT. The BK comes factory supplied with a CAT thermo. 500f is the initial lite off on a cold start and 250f on a reload. I just reload and close the bypass. Set the stat related to out door temps and walk away for the rest of the burn. I have no pipe damper but could have used it on my previous stove. I would never go back to a non CAT with my conditions. RE; cold climate and softwoods only to burn, in my experience.

N of 60

 

[karri0n]

N of 60, do you get that 500 deg. stove temp on the entire unit, or only directly above the cat? On low burn. Or is this a med/hi burn pic?

 

[North of 60]

N of 60, do you get that 500 deg. stove temp on the entire unit, or only directly above the cat? On low burn. Or is this a med/hi burn pic?

This is 2hrs into my low burn after the cat has settled down and not glowing anymore. It will settle down to 350-400 for the rest of it if my setting is at #1. Temps across the stove top away from the CAT will be 75-100 degrees lower. 0 smoke. Just heat waves.
Great for outside temps at -10C or above with the setup I have for insulation properties in my home. If its any warmer out I can turn it below the #1 setting and have a stove top temp above the cat at 250- 350F for many hours.

 

[mellow]

My sierra has about the same heat pattern as your BK. I can run about 400-500 degrees for atleast 5 hours with no visible flames.

If your board I have videos of it:

http://www.youtube.com/watch?v=nOh4iHULr44

 

[Todd]

Ha, that video looks like the stove is glaring at you with two red hot eyes!

 

[North of 60]

CATs are evil you know :lol:

 

[Green Energy]

My Ducthwest has 2nd air for the cat. I usually open it a half a turn to 3/4 and that helps the secondary combustion.

Talking about birds in the chimney, my brother-in-law, who does not have a wood stove, came home from a vacation to find his basement a mess. Black streaks on the walls, things out of place, and a turkey vulture staring at him. Both of the were quite shocked. After an awkward stand off, he was able to get the outside door open and danced the bird out the door. He is just glad that the bird did not come down the other flue that when into the living room. It is amazing the vulture could get through the chimney damper. He now is buying a chimney cap.

 

[Peter B.]

I am not exactly sold on secondary air tubes in a cat stove. From what I can see from mine is all the flammable gasses are being used by the cat, I see no smoke out of my chimney once I engage the cat, if there was something left unburnt I would think I could see it, but maybe not.

CO is clear ,odorless & a big source of energy. u can have clear smoke & inefficient burn!! more heat released from co+ o2-co2 than from WOODGAS+ inadequate o2 which results in CO because not enough O2 to complete combustion process.

mellow:

CZARCAR has a decent point I think... a surplus of O2 shouldn't hurt anything and may help... that is, unless it simply promotes a warmer fire than desired.

My secondary supply feeds to the firebox, and I assume most/all of the added air is used in combustion there, but any remainder still goes to the catalyst.

When I close my stove (manual) air intakes, the (fixed size) secondary remains open and is the only air source (but for leakage) for the fire or catalyst. I prefer closing the intakes fully... then there's never any guesswork about the 'ideal' intake opening/position. The secondary provides enough air alone to support steady combustion... but not enough to accelerate the fire.

Seems to work.

Peter B.

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[Peter B.]

Talking about birds in the chimney, my brother-in-law, who does not have a wood stove, came home from a vacation to find his basement a mess. Black streaks on the walls, things out of place, and a turkey vulture staring at him. Both of the were quite shocked. After an awkward stand off, he was able to get the outside door open and danced the bird out the door. He is just glad that the bird did not come down the other flue that when into the living room. It is amazing the vulture could get through the chimney damper. He now is buying a chimney cap.

sean:

This guy didn't come down the chimney, but he sure surprised me when he landed in the yard... and wandered all around the house... and stayed for two or three hours.

Once in a blue heron...

Peter B.

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[bwolfe1]

I guess I will now have to climb up on the roof and stick my CO detector by my cap and see if it reads anything with the cat lit.

strong canary with feeble brain might help the climb!did similar with my old clean burning sawdust burner but wondered about my good results having been affected by smoke dillution from other appliances plugged into same chiney
most modern gas analysis instrument for tuning oil & gas furnaces involve CO analysis of exhaust & though costlier theres a reason
SEDORE downdraft woodstove seems to burn clear smoke but mfr. resists testing for CO content of exhaust & kicked me off his YAHOO GROUP for insisting on answer
HI BRUCEW

Just to set the record straight, I am not resisting any testing of the Sedores. I don’t think any company would act upon the demands of one individual who won’t even identify credentials nor has ever had any experience with the product? I have offered to provide a Sedore for testing to CZARCAR if this issue is so important to him personally. When the CO testing was a re quest I was considering having it done, but when it became a demand, from someone who isn’t a customer, nor has made any effort to see one in action, I responded as most would. Now that CZARCAR has gone though the effort of creating two yahoo groups to press the issue I believe it shows this person will go to any lengths to get his interests served. Anybody else here respond to demands from unknown individuals? I feel that forming two yahoo groups exclusively for the Co analysis of one unit, is childish, which would answer why CZARCAR would think that we are all here to respond to his demands.

 

[jpl1nh]

1) Do you use a probe thermometer immediately over the cat for temp references?
In a Woodstock stove, the cat is in the stove. I have a thermometer directly over the cat on the soapstone and another on the stack about a foot up.

2) What temp (and where measured) do you typically use for reliable cat light off?
I light off my cat when my stack temps are 250 or above, or if I reload on with a temp of 425 or higher on the soapstone, generally I can just re-engage the cat.

3) Is there a noticeable temp surge on cat light off?
I can tell cat is working because there is a distinct temperature climb on the thermometer over the cat.

4) How long do you let the cat ‘warm up’ before closing stove air intake(s)?
see #2

5) Once the intakes are closed, does the burn temp remain relatively constant until the coal stage?
Depends on how much air I supply. When I need more heat, my air is more open and stove top may hit 600-even 700 for an hour or two then falls slowly back. At a slow burn, may hold 450 for several hours then very slow drop off.

6) Does the primary air control close fully (or is it - by design - always slightly open… like many EPA non-cats)?
I believe you can close primary air fully, but instructions say never to do that and I would suffocate my burn totally if I did so why would I want to?

7) Is there <any> secondary air supply?
Woodstock stoves do not have a secondary air supply. Primary air comes in as air wash. See #6

8) Do you use a flue damper?
That would depend completely on each unique chimney set-up. In my case it's not needed.

9) Finally, would you opt for another cat stove when it’s time to replace your current one? If not, why not?
Absolutely, though it will be a long, long, time before a Woodstock needed to be replaced. There is such a range of burn options with a cat stove that I would not want to be without.

 

[grommal]

Recently I replaced an old 1" thick catalyst with a fresh 2" model with a finer honeycomb. The stove's behavior has changed somewhat and I'm finding I need to change my fire tending habits a bit as well.

Since my stove is (obviously) not an EPA model, I'm curious about modern cat stove features and operation practices.

So, I guess this is sort of a "cat o' nine tails poll". Any/all answers appreciated.

Thanks.

Peter B.

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1) Do you use a probe thermometer immediately over the cat for temp references?

2) What temp (and where measured) do you typically use for reliable cat light off?

3) Is there a noticeable temp surge on cat light off?

4) How long do you let the cat 'warm up' before closing stove air intake(s)?

5) Once the intakes are closed, does the burn temp remain relatively constant until the coal stage?

6) Does the primary air control close fully (or is it - by design - always slightly open... like many EPA non-cats)?

7) Is there <any> secondary air supply?

8) Do you use a flue damper?

9) Finally, would you opt for another cat stove when it's time to replace your current one? If not, why not?

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I have a 1986 VC Defiant Encore cat (their first generation). This season was its last gasp, but it served us pretty well over the years. Here's my experience:

1. No. The manufacturer recommended a surface thermometer on the top-loading griddle door.
2. 450+ as measured on the top-door surface thermometer, plus good visible flames in the firebox.
3. Yes. I can definitely feel it get much hotter on the back of the stove where the catalytic element lives. This has no impact on the stove top temperature. Flue temperatures, judged by how hot the pipe feels, drops because the total airflow through the stove decreases markedly when the cat bypass is closed, so less heat rushing up the chimney.
4. See #2. No additional time beyond that.
5. Highly dependent on wood and draft conditions, as well as the setting for the primary air intake. Can continue to rise and peak 2-3 hours later, or hold quite steady, or drop off slowly almost right away. Most commonly, it rises slowly to 600+, requiring adjustment of primary air intake to avoid overfiring. Then, it holds above 500+ until coaling. Then slowly drops. A full load of good wood gets an 8hr burn with plenty of coals left.
6. No. It's adjusted so that it stays open a bit. If a stove has no leaks, and you let in no air, the fire will go out, right?
7. Yes. I believe all cat stoves have one, though they are often hidden and non-adjustable. Mine is on the rear of the stove below the cat chamber, and is not user-adjustable. It has a bimetallic element to adjust the flow automatically. This whole system has now failed this season (no secondary air flow at all), and with the other repairs the stove needs I'm in the market for a new stove for next season.
8. No.
9. No, but it's not primarily because of the cat itself, but because of the secondary burn chamber design. We have a somewhat finicky draft at times, and have had puffback problems over the years under certain conditions. This only happens when the cat bypass is closed, which restricts the total airflow through the stove greatly. We sometimes lose the flame in the firbox entirely while the wood is still giving off lots of gases. The gases build up in the firebox, and then they get ignited in the pathway leading to the cat. This causes them to burn very quickly in the stove, but all that expanding gas can't work its way through the secondary burn chamber where the cat lives fast enough, and we get back-puffing that actually burps the griddle top. So, this time around, I'm going to avoid any stove that uses a secondary burn chamber that looks like it will restrict the outflow in the same way, cat or no cat. This leaves stoves with secondary burn tubes in the firebox as my choice.