Woodstock Stove: Survival Hybrid

RGrant, glad you're liking your stove. Can you please explain some things that I have read in various threads dealing with cat stoves?
Once the stove gets to a certain temp, folks say they engage the cat. Can you (or someone) explains to me what this means? Is it throwing a lever, flipping a switch...? I have been thinking i would like to get an Absolute Steel...do you know if its the same process on various stoves?
Also, someone in your thread talked about not being able to tend the fire with the cat engaged... what is the process for "disengaging the cat"? Do you have to go through certains steps? What if you need to add more wood to the stove cause you're leaving the house for a bit...can you just disengage the cat and add wood?
Thanks for any help answering these questions that I have after reading on these cat stoves...

 

Sure-
So picture a wood stove that has a normal exhaust port in the top, or in the back. The fire burns, and the smoke rises through the exhaust port through the "stove pipe" into the chimney and out of the house. When you "engage the catalyst" on my model you are literally moving a level which "flips a switch" or moves a piece of metal inside the stove- on mine very audibly- which cuts off the first exhaust port, and channels the smoke through a catalyst and the smoke takes a new route to the stove pipe and up the chimney and out of the house. It's a lot like diverting the smoke through a different channel or chamber.
When the stove is "running wide open" it encourages a faster burn. When the catalyst is engaged it allows for the fire to be slowed down and run at a lower rate of airflow and exhaust while still putting out steady heat, but usually with no or next to no visible smoke.
To disengage the catalyst all you have to do is turn the lever back the other way... It reopens the initial channel for exhaust and then you can add wood to keep the fire going. My model stove is such that when the catalyst is engaged, the lever is blocking the door to add wood so you have that extra reminder to disengage the catalyst to add wood.
The process in operating the Absolute Steel would be essentially identical.

 

So, if I'm understanding correctly...it's no big deal to go from cat mode to non cat mode if you need/want to for some reason...you can just throw the lever? You don't have to wait for temps to burn down to a certain number or anything like that?

 

Correct to a degree. You certainly can disengage the Catalyst if you need to add wood prior to bed time etc. to be sure it makes it to the AM. These stoves are not made to be run without the Cat engaged after getting up to operating temp. It's not a cat engaged or cat not engaged operating mode. Modern Cat stoves use the Cat. engaged every load.

 

From previous readings on threads, particularly on the Absolute Steel, I thought it had been said that you could run the stove with the cat engaged, or without...however you wanted to run it. Is this not the case?

I know it's more efficient burning and wood usage wise with the cat. But if you wanted to burn more with the secondaries, and to enjoy the flame show....

 

I still get secondary burn flames with the catalyst- but generally speaking if that’s what you were really after, I would go for a catalytic stove.

 

If you want flame, turn up the primary air until you are satisfied.

 

I think you have to be careful to make that assessment on a stove by stove basis.

 

Speaking as an IS owner, secondaries still do their thing in a hybrid stove with the cat engaged and the air adjusted high enough. The only time we really turn the air down enough for a "black box" for the duration of the burn is shoulder season or during a sunny, calm day when we don't need much heat. You'll still see fire with the air adjusted properly, and the cat will "use" the minimal exhaust from that secondary burn process to throw more heat.

 

I don't have a hybrid, but a straight-cat Keystone. I open the bypass for a couple minutes to cool the cat off before opening the door to reload, even if it's down to coals. It is probably more critical to do that if you are adding more wood, but the cat is still burning on wood that remains from the last load. I think it's better to minimize rapid temp changes to the cat whenever possible.
Even with a hybrid, I would have the cat engaged any time the stove was up to temp and the cat would light. If I'm not mistaken, that routes the exhaust through the stove differently, allowing the stove to extract more heat from the exhaust and getting the maximum amount of heat out of your wood. And as BigPapi said, the cat will also be burning anything left over from secondary combustion, giving you more heat. Even with the straight-cat Keystone, I can give it a little more air and have a bit of flame going in the box if I want to look at flames, or want a little more heat.
Also, the lower you have the air, the slower the exhaust moves through the stove. This allows for more heat extraction, and less heat wasted up the flue. If you need more heat, of course, you open the air a bit more. But even burning some flame in the box, my air might only be open 1/4 of the way.

 

Now that the OP has has some time with the Survival Hybrid how are you liking it? Is it able to reliably get you over night burn times? Any issues with the stove? I am looking at going the minimalist route and building a cabin of about 800sf and looking pretty hard at this stove. So would love the feedback.

 

Hey, more than happy to respond.
Bottom line: I love it.

During the coldest of the winter here in Southwestern Connecticut the stove didn't leave me wanting for more. Wood consumption was about half what it was compared to my previous stove, the heat in the home was noticeably even room to room which it previously had not been, and from time to time I'd go out of my way to let my furnace run just so it wasn't sitting unused and had its parts moving. I don't know if that's needed or not, because it is obviously not used through the summer. It burned through the night and in the morning I'd get the stove up and running often with no kindling.

Here's what some people probably would not like about the stove: The fire box is small. You can stuff it, but with a small burn chamber, you can only get so much. The manual says that the max length wood you can put in is 16", but I just had my tape measure out and you can get 19" sticks in front to back with room to spare. Anything more and you've gotta get it on an angle. I have not cooked on the stove, something I had previously done with my last stove, but I do make water for tea/coffee on it. Depending on what your minimalist aims are, its something to consider.

I have found 8 hour burn times to be normal.

 

RGrant, Thank you so much for the update. Sounds like exactly what I am looking for. It is very hard to find a stove for smaller spaces that have the ability to do an overnight burn. I am surprised more people have not discovered this stove yet in the tiny house community.

 

A little update to file under "who cares?" perhaps- but if anyone is ever in the market for one of these and wants some more info to consider- here's another little bit to read.

This is my second winter with the Survival. Same catalyst. I take it out every so often, brush it off, clean it with the vacuum and blow it out with the battery powered leaf blower. So far I don't notice any drop off in efficacy, but sometime later in the winter when we got a warm stretch, which I'm nearly certain will happen, I'll give it the distilled water/vinegar bath and see if that does refresh it a bit.
I'm thinking I'll purchase a replacement catalyst at the end of this season to have on hand and have on the ready just in case.

So far the burning has gone well. I've been building up my stockpile of wood chasing down that 3 year plan, but I fell short. I think I have a 2 year supply right now, so I'll try again this summer and hope for a little better of a turn out.
The wood I'm burning is good, but not great, so I know that is impacting me a little. I still am the guy who uses compressed wood bricks, I had about 5 or 6 bundles (40 pound bags) from the last time I ordered them. This year I bought another ton and split them with my in-laws. So I have 25 of the 40 pound bags. I put one or two of the bricks in each time I load the stove with the wood I have. There's 20 bricks in the bundle. I get good secondaries and unless I'm starting up the stove from nearly a cold start, I don't get any smoke to speak of.

When it was a bit warmer out, I'd really have the house quite warm. Too warm- 80+ downstairs with the stove and 75 or so upstairs.
This most recent snowfall (about 15 inches I think) and low temps in the teens the house was much more comfortable and pretty easy to run the stove. I didn't shut the air down quite as much and the burn got going good. I went to bed around 10 or something last night, didn't bother to refill the stove and slept in this morning because I didn't have work today. Was certainly cooler in the house, but still above 60. The bed of coals was really high, so I disengaged the cat, opened the air and cracked the door to the detente on the latch and let the coals burn down for a while as I made coffee. I loaded up the stove and got it going, but it was turning bright and sunny so I let the stove creep along rather than running it full out. Through the day the temp in the house crept up towards 70 and was pretty comfortable.
The sun is fading and the temps are on their way down to the mid teens again tonight, so I'm about to get it running pretty good again and tonight I'll make sure to load the stove before I go to bed with the intent on running it through the night and see what the temps are like in the morning tomorrow.
At present time for reference: it's 71 in the house and 28 outside. December 17 at 4:15 pm in Western CT.

 

An overnight on a cold night is a good experiment to make an assessment with.

 

I care. Lots of us reading your story.

 

Haven’t logged in in a few days and several weeks before that.

Came a hair from buying some of those blocks at TSC to try, but I backed out. Have never tried them.

I actually logged in tonight to specifically research the threads for block burners and your post was my first alert.
Sounds like the little stove of yours is doing more than it’s share of work for you. That is a great report.

 

The morning update-
First. Thanks for the kind words guys. It's nice to come across this kind of support/encouragement that you don't typically see on the internet.

Getting down to brass tax: I loaded the stove just before 10, from a bed of rolling coals that looked like lava- you know the thick bed of blazing hot coals. Once the temp was up to about 320 or so on the stove top I engaged the cat, brushed my teeth and when I came back I set the air controls back a little more than half way. If it was really rolling I'd have cut it back more, but it wasn't- so I didn't.
This morning I woke up at 6. The upstairs was 63, the downstairs was 63 and the temps outside was 17.

I don't have a system that is clear to me that I'm going to continue with or stick to. If its cold I'll load up the stove before bed, but if it isn't going to get down below 20 or so I don't know if I will. Landing somewhere near 60 in the house is fine with me, it doesn't take much of anything to get it blasting out heat.

A couple of observations that I'm making note of in my notepad here at home- when the stove is loaded, the catalyst engaged - the stove runs better with the air cut back, there doesn't seem to be any advantage to leaving the air open, rather having it cut back like 7/8 the way down seems to have a better burn. So I guess I'm finding this stove loves to be run efficiently. I need to do some more research to understand how that could be or why that makes sense. Has to be the nature of the catalytic firing, but a little more reading needs to be done before I can make a better guess.
One thing there's no doubt about is the length of the wood I'm using is too short. The paperwork on the stove says 16" is max, but I'm finding that 20" pieces fit. This is a long but a little narrow burn chamber with a fairly narrow opening in the front to load- so keep that in mind, but 20" splits go in no problem. I'm not going to cut wood any shorter than 18" any more, because I'm getting a 4 or so inch gap at the front of the stove where more wood could fit, but because I don't have pieces that small or to get the odd shaped or cutoff piece can sometimes be a little tricky since the opening isn't real wide. -- a long way to say I'm going to cut the wood to fit my stove.
It's supposed to get down to about 11F tonight, but after that its going to creep back up into the 30's overnight for the next week. Once we're forecasted to get into single digits or below zero I'll see what I have to do to manage that.

 

Good info RGrant. Couple of questions... When you loaded last night, what size load and what type of wood? What kind of coals this am? It sounds like you're saying the stove burnt the wood faster than you thought because you didnt get to turn the air down as much..is that correct?

 

I'll do my best to answer- I would estimate that there was a 1/4 full load of coals- about up to the opening at the door and ramping up in the back. With having a somewhat smaller burn chamber the coals tend to build up somewhat quickly, but the ash pan is really big. I only have to empty it once a week or so. If you rake the coals back and forth the grate in the middle lets the ash fall through pretty well. It can build up on the sides, but that's pretty easy to handle as well.

The wood I put in last night were 3 splits of maple that were short- about 12-14 inches long, the width was about the size of a 2 liter bottle and were a bit more triangular in shape rather than squared. I also put 1 of the compressed wood bricks in. One of these: Bio Bricks in CT - Delivery Available - Environmently Friendly Fuel

This AM the window of the stove showed a glow of red peering out from the dark chamber. When I opened the air controls and flipped the lever to take the catalyst out of engagement it pretty quickly brightened, and when I opened the door there was a slight blanket of grey/white ash on top of the coals, and they got brushed back by the air that was rushing in. They were all sorts of irregular shapes like most of us are used to and some were right around the size of golf balls. A good number were about the size of dice. In short order the coals that were a darker black began glowing red and within a few minutes the coal bed was dancing bright red / orange / yellow and there were sparkles of bright blue flames dancing in between the coals.

Last night I think I waited too long to load the stove before going to bed. I tried to load it with 10 or so minutes to go before I went to bed, but I should have given myself more like 40 minutes since I was already up, but winding down. I didn't allow the stove to fully get going last night- and that might have more to do with the quality of the wood I had. I also should have put in 2 or 3 of the bricks rather than just 1.

The stove was still hot to the touch and didn't need any kindling to get going. Since I'm working from home, there isn't any sort of expediency on my part to get the stove really rocking, so I'm ok with it taking its time to get cruising, and I'm enjoying tending the fire throughout the day. Soon I'll need to go back into the building so I'll practice a little here or there getting up at 5 and trying to get a quicker start.

Edit to add: I'm sure that the air controls being more open than usual burned the load of wood a little quicker, but I'm not sure how much quicker and the house wasn't really any colder than usual and the stove started back up per usual.