I have seen several references of "Stalling the CAT" What is stalling the CAT? To much smoke? Not enough smoke? Neither?
Engaging the cat too early. Before theres enough heat built up to fire the cat off it can stall and the stove temp will drop instead of climbing rapidly
When I wait until STT is 425 to engage the CAT I get CAT burn but not sub stain it. Doesn't seem to matter where the air adjustment is.
Sounds like your wood is a bit wet or the cat needs cleaned, Rog. You'll get similar conditions when the cat starts to wear out, but i wouldn't think thats the case yet. You should get 3 years out of that cat unless you're burning wet wood.
Would checking for smoke out of the chimney be a good check if the cat stalled or not? Sometimes on a smaller load my temps don’t jump a whole lot but there is no smoke coming out of the flue
Usually when the stove burns a long time the cat disengages, because there’s no more smoke for the cat to eat in the coaling stage. I consider stalling the cat much like stalling a standard vehicle. Usually happens when the cat is not up to the right temperature needs to be about 500°. When the cat is new, as it ages and ash diminishes reactive metals it stalls easier
In my experience, cat stall is usually referring to after you engage the cat and heat everything up but then, in an effort to achieve extremely long burn times, you set the intake control too low and that setting does not produce enough smoke to keep the cat hot enough to stay “active” so the cat stops doing its job and if the fuel keeps burning it pukes all of that icky smoke up the chimney. Super long burns are pretty awesome so many new users like to push the limits here and stall the cat a few times as they learn that low point minimum setting. Different for every install. I suppose engaging the catalyst before it’s ready could lead to a similar problem but if the intake setting is high enough, the cat will eventually get hot enough to go active.
Between a local guy who just bought a used King and installed a new CAT and many of Highbeam praises about BK stoves...ya’ both made a believer out of me.
Nope...not me. I keep saying the only thing better than a BK with a stat would be a WS with a stat. Why they haven’t put one on their stoves yet is beyond me. I know they are using them some for 2ndary air, but I’m talking about a simple dial to control the stove. They’re a great running device as well as a safety device and should be in all stoves IMO.
A catalytic combustor needs smoke, oxygen and a minimum temp to work. As they age, this minimum temp goes up. When new, a cat. will light (take off and gain temperature) just by showing it some newspaper and a match. But seriously, a small newspaper fire will light a new cat. Here is how I have been very successful stalling a cat. and making the biggest mess in the chimney and surrounding neighborhood: Load the stove full of fresh splits and start a fire under them. Leave the draft and flue damper wide open and wait until the firebox gets to, say, 700 degrees or so and close the bypass and reduce the draft opening. In other words, set it for the long- burn as someone already mentioned. The cat. will light and begin to climb in temp. But is a short amount of time, the firebox full of wood is still relatively cool with only a relatively small fire at the bottom, so the overall temp. in the firebox drops significantly. Because the cat. needs a minimum input temp. to stay lit, the cat. goes 'out' and stalls as the firebox cools down. But because there is still an active fire, the whole fuel load enters a smoldering phase which will last for the rest of the fire unless tended to and correctly. BTW, this is exactly why old- time smoke dragons (air tight stoves from before 1990 or so) burn so dirty and inefficiently. This unfortunately often happens when loading the entire firebox before going to work or bed. The way to avoid this, at least mostly, is to let the stove run longer to heat up the entire firebox of fuel before damping it down. Then the stove will continue to run with a bit of flame on the reduced draft, stay quite a bit hotter in the firebox and supply smoke and air at a much higher temp. to the cat.. All well and good but most of us do not want to spend an hour in front of the stove babysitting and nursing it along before going to work or bed. Or as Bart would say: 'Don't do what Donnie Don't does'. As others have said, a temperature sensitive draft control would go a long way to allow a catalytic stove (or hybrid) burn more reliably and efficiently regarding the cat.
. Woodtock stoves do have very good controls. Maybe they're like me and just don't think more than 12 hours is necessary.
The thermostat on BK is nice.. Changing a cat on 200 degrees Woodstock stove in under a minute is nice too
Sometimes, like if it’s really cold, 12 hours is all you get from a BK too. The thermostat isn’t just to help you get the ultra long burn times. It regulates heat output when you want higher outputs too. The IS with no thermostat can do 24 hours from what users report. You don’t need a thermostat for long burns. I hope more of the new 2020 cat models actually deliver on long burn time marketing claims. A wide range of output settings, whether thermostatic or not, is very good.
