Questions regarding running in cat mode overnight

[Charles1981]

I have multiple questions (I have a 2011 vermont casting encore two in one):

I reload before bed ~11pm most nights. I usually fill the firebox as full as reasonably possible. I wait until the stove top on the steel griddle is 500 degrees and top split in the fire box is mostly charred and then close the damper (typically this takes 5-10 minutes). Usually in about 5-10 minutes the cat appears engaged (see the flames back behind the shell design, although i can't always tell based on how I stacked in the box). I will typically wake at 6-7am the next morning and the stove is anywhere between 150-300 degrees depending on what wood type I have loaded.

Shoulder season it is usually 3/4 cotton wood, 1/4 ash and in winter 1/4 cotton wood and 3/4 ash. With the shoulder seasons and cotton heavy loads the stove is more 150 and just barely enough coals to stroke up a fire with small cuts, and with the ash heavy loads in the colder months it is usually more closer to 200-300 when I wake up and with a really nice coal bed to get things going with ease.

Typically after engaging the cat I will see the stove top go up to ~600 shortly and then it usually cruises around 500-400 for 5-6 hours after I have the air control closed down or almost completely closed down over a 30 minute period after reload.

I inspect my cat frequently (every few weeks) I see very little damage (a few squares 3-4 have some mild "buckling") but there is never a severe accumulation of ash and what is there can be blown out gently just by breathing through it.

1) I am just wondering what is happening after the stove top cools down in the 350-300-250 range? The cat in the back only glows for about 2 hours after it ignites. Then, even though the stove is easily cruising at 400-500 and very little if any smoke is coming out the chimney, I rarely see more than the occasional flame in the cat box. I know the manual says the cat is still working even if you don't see a secondary glow, but I am just curious if I am causing damage to the cat when the stove drops below 350-300 for those 2-3 hours before i wake up? It is a rutland burn indicator (black and orange).

Probably the best answer is get a cat probe and I will know more, but I just don't think I am ready to do that yet. I don't feel I am willing to start messing around with drilling holes in my stove at this point....

2) It seems most stoves don't have a steel griddle top. Is there a difference with a stove top thermometer's reading on the steel griddle top versus placing it on the cast iron portions? I haven't tried that yet but I am so used to managing this stove based on the rutland indicator on the steel griddle.

With indicator on the steel griddle can i still safely assume the internal stove temp is still roughly 2x the reading on the indicator?

3) What is the best way to reload the stove? I've read the "downdraft stove operation". I haven't really been raking coals to the front of the stove...Is this something I should do with this stove being it down draft? (I don't really know where the smoke enters the secondary chamber in the stove...and the wiki posted shows an example of the smoke entering from the bottom in the back of the stove...but I wasn't quite sure this is the case with this particular stove?

Any other suggestions? Thanks everyone, you all are always a big help!

 

[mellow]

Once your fire gets down the the coaling stage there is not much gas for the cat to work off of so it cools down, most of the particulates are gone and pure heat travels through the cat and up the chimney.

It does not hurt the cat, just part of the burn cycle.

A cat probe will help a lot, you will get a better feel for how your cat functions.

 

[jharkin]

1) I am just wondering what is happening after the stove top cools down in the 350-300-250 range? The cat in the back only glows for about 2 hours after it ignites. Then, even though the stove is easily cruising at 400-500 and very little if any smoke is coming out the chimney, I rarely see more than the occasional flame in the cat box. I know the manual says the cat is still working even if you don't see a secondary glow, but I am just curious if I am causing damage to the cat when the stove drops below 350-300 for those 2-3 hours before i wake up? It is a rutland burn indicator (black and orange).

Probably the best answer is get a cat probe and I will know more, but I just don't think I am ready to do that yet. I don't feel I am willing to start messing around with drilling holes in my stove at this point....

I agree with mellow. Once the cat is lit off no need to worry. You can leave it engaged and let the stove completely burn out without any problem at all. Once the fire is down to coals the flue gasses are just passing though the catalyst without burning there and there is no significant particulate matter at that point to cause any buildup. Any small ash that does get trapped just burns off the next time the cat lights off. I only check my cat 1-2 times a year and Ive never seen any buildup to be worried about.

2) It seems most stoves don't have a steel griddle top. Is there a difference with a stove top thermometer's reading on the steel griddle top versus placing it on the cast iron portions? I haven't tried that yet but I am so used to managing this stove based on the rutland indicator on the steel griddle.

With indicator on the steel griddle can i still safely assume the internal stove temp is still roughly 2x the reading on the indicator?

Minor nitpick but the griddle is cast iron just like the rest of the stove, it just has a machined finish. VC suggests putting the thermo there because the griddle is the thinnest part of the stovetop and gives you the hottest reading.

Dump the rutland, they are garbage. Get a Condar thermometer, the "Inferno" model is a good cheap one to use on the griddle. I also like Condars digital cat probe to monitor catalyst temps.

3) What is the best way to reload the stove? I've read the "downdraft stove operation". I haven't really been raking coals to the front of the stove...Is this something I should do with this stove being it down draft? (I don't really know where the smoke enters the secondary chamber in the stove...and the wiki posted shows an example of the smoke entering from the bottom in the back of the stove...but I wasn't quite sure this is the case with this particular stove?

Raking coals forward is not critical in these stoves. I sometimes do it on really big loads so that I get more burn in the front away from the cat inlet but to be honest I dont think it makes much difference. Its more of an issue in front loading burn tube noncat's that burn from front to back.

You can stir the ash bed a bit to let the excess ash fall down into the ashpan then load away. I wrote up some notes on how I cycle my stove in my rebuild thread. I have the older 2550 model but operation technique should be similar for you when running with the catalyst installed.

http://www.hearth.com/talk/threads/encore-2550-rebuild-start-to-finish.112149/#post-1492817

 

[Backwoods Savage]

Welcome to the forum Charles.

Some good answers above and you also should do well with the wood mix. We burn lots of ash but it has been a long time since be burned any cottonwood. However, many burn it regularly. Doesn't last as long and doesn't coal well but still give heat and that is our goal. Also great that you keep track of the chimney on a regular basis. It sounds as if you do well when engaging the cat but you could wait just a tad longer with no harm done.

1. No harm will be done to the cat during the last stages of the burn.

2. As stated above, the stove top can vary depending upon where you take the temperature. You could also purchase a low cost IR gun and read the temperatures all over the stove and flue. You can use them also to find leaky spots in your home that you may want to tighten up. Or you can also just have some fun with it, like taking the temperature of the sidewalk or top of your car in the summer months.

3. On reloads, no matter the stove, I like to level the coals. But on most stoves if down to just a few coals, then raking them to the front works well. We will also rake ours mostly toward the front before the night fill up.

Other suggestions? Enjoy the heat.

 

[Charles1981]

Thanks for all the information. I didn't realize the griddle was machined cast iron...I'm surprised there are no machined cast iron stoves available as I kind of like the silver shiny look...Maybe only thin cast iron can be machined?

I didn't realize the rutland were considered so poor? My stove store sells them and that is all that is at home depot as well. Do you think my rutland is truly that far off in regards to temperature? I seem to be operating the stove ok right now with it and it does respond rather quickly during reloads but I guess I can't be sure without something to verify that the temperature it is reporting is accurate...That kind of stinks as my wife is going to look at me very funny when a 2nd thermometer shows up and is sitting next to the rutland. Shes going to know soon enough I was geeking out on this forum again. She rags on me all the time that I'm playing with my wood on the lumber jack forum enough as is....

And as far as the cat glowing for only ~3 hours or so do you still think the cat is active? I still don't see much if any smoke out the chimney but again I guess this is all coming down to I really should have a cat probe if i really want to know. Creosote hasn't been a huge ordeal, but there is always some present when I have the sweep come out (but this year was the first year he came out to clean the liner) but he has never mentioned a creosote problem, but i will be more investigative the next time he comes out.

Thanks again,

Charles

 

[jharkin]

Machining all the panels of the stove could be done but there isn't much reason to. It would be very expensive and unpainted machined iron would quickly rust.

A lot of the interior panels are machined at mating surfaces and where tight tolerances are needed, just like an engine block is cast and then the cylinder bores and head are machined.

For the thermometers... A few years ago somebody posted a test where Rutland thermometers seemed to have the most variation in readings. Condars are not perfect but appear to be more consistent.

The cat will keep working long after it stops glowing. As long as you don't see grey smoke you are good. A little white steam is fine.