VC Encore 2040-CAT-C, Overnight Burn Day Trial

[Pastachio619]

Hoping for some help from this community, been lurking for a few weeks now and reading as much as possible. I bought a new home a month or two ago with a 1 year old VC Encore 2040-C. The previous owner left me 2-3 cords of split wood that is covered and seasoned so I figured I would burn instead of using the furnace since it is on a tee for me. I started the first couple weeks of burning by keeping the damper open and not engaging the cat just to get the hang of things, plus it was not that cold out so we kept warm enough over the night by just loading the stove up and closing the primary air as much as possible but not closing the damper.

Around Thanksgiving the temps dropped so I started engaging the cat thinking I was ready. The first three nights went well and I even got it to where I had coals left over in the am to start up the next day. On the fourth night I loaded up the stove to the max, let it burn hot to about 600F (stove top temp) then closed the damper. I waited 5-10 minutes then closed the primary all the way.

I was then shocked that smoke was coming out the back/top of the stove since at the time I had not heard of back puffing, although the previous owner did warn me about back draft. I had thought back draft was an issue when starting your first fire of the day. After reading I now think the issue was that I closed the primary to quickly and not in increments. I also had a massive amount of ash in the bottom to the point it was coming out when I opened the door which I think was restricting air flow even more.

Since the back puffing I have been too nervous to close the damper on overnight burns since I have three young kids and am nervous they will be breathing in smoke. The short night burns are causing the house to be cold in the morning (around 60F) and leaving me with massive amounts of condensation on my windows in the AM. So I either need to figure this VC out to the point I am confident it wont back puff on the family overnight or say to heck with it and turn the furnace on. $200 extra a month to run the furnace seems like a steal once you see smoke coming from the fire place and the fan distributing it across the house.

My questions are:

1. What indicators should I see once the damper is closed to know that back puffing will 100% not be an issue while I am sleeping.
2. What should the flames look like? Is rolling flames around the top of the stove ok as long as I have consistent flames elsewhere and the CAT is engaged?
3. Are there any other indicators that back puffing is about to occur other than the slow flame that billows around the entire stove followed by no flame.
4. Is it possible for a stove to back puff tiny amounts that I wont notice? Or if back puffing is occurring is it always visible? I just dont want the family breathing it in when we have other options just cause I am enjoying playing with fire.

Earlier today I did a trial run like it was an overnight burn and below is my process and the results.

- started with 2 red oak logs to burn through so I had good coals
- then placed 4 logs, 1 red oak 5" in diameter, 2 beech around 3", and a small 1" round at the bottom
- let it burn for 10 min till stove top was 680F and stack temp. read 450F then closed the damper
- waited 5 minutes then did a 1/4 turn on the primary
- waited 15 minutes after the first turn and did another 1/4" turn

it has been 2.5 hours and now its all coals, stove top temp is 385F, stack temp is 175F.

I have attached two videos. The first is after my first 1/4 turn on the primary air, flame was coming from the log bottoms, the cat was engaged, but I did have rolling flames around the top which made me thinking it was about to back puff. Is the first video normal or was being concerned warranted? Second video is where the fire settled to, small consistent flames spitting out.

My burn time seems way to short like I have to much draft but the flames in the first video make me think it was about to back puff on me. Crazy.

 

[Burnin Since 1991]

Welcome to the forum and to the world of wood burning.

A back puff and back draft are two different things. A back draft is when the chimney isn't drawing well and when you open the door you get a blast of smoke. Usually if you open up the bypass and then open the air intake and crack the door for a moment, the draft should be fine. Their are other back drafting issues but I think your issue is back puffing.

Back puffing is when wood in your stove is smoldering and the intake is restricted and the cat is engaged and the wood ignites, causing a mini explosion inside the stove. Or sometimes multiples. Open the intake, open the bypass and let the wood burn a little more before engaging the cat and cutting back on the air. Wood that isn't seasoned enough can lead to this too.

Do you have your manual?

 

[Turbo89]

That’s not back-puffing, that looks like secondary ignition (burning the smoke), and is an indication you’re burning good!

These stoves are finicky to run, and I recommend you get a catalyst temp sensor if the OEM isn’t installed (back of the stove, aligned with the stove pipe but low). There’s a series of post troubleshooting the encore, which are probably worth reading (I’d post links, but that’s hard in a phone).

Generally speaking, this is how I run my encore (I have a temp sensor):

1. Light it, leave the door cracked and air wide open until I get a good flame. Close the door and let it burn in high until I see a stove top temp (STT) of about 500,
2. I close the bypass to engage the cat (left back handle), and make sure the catalyst takes off (reaches temp above 600).
3. Leave it burning high until I see the cat reach 8-900+ degrees, and then back the air down to where I want it.

On a reload, i follow the manual and open the bypass, then rake coals to the rear, and then stack in wood. I again burn on high to catch everything, then close back in the CAT. If it’s a hot reload (above say 600 degree CAT), you can close in faster.

Other general things about running this stove: 1. Ideal CAT operating temps are 1,000-1,300 degrees. 2. Max CAT temp is about 1650 degrees. 3. Max STT is 650, but I wouldn’t be to worried if you see 700. 4. These stoves do not like wet wood, they off gas and can cause runaway stove temps if you really pack it. 5. You should be able to turn the air all the way down and it will sit there and burn really low all night (sometimes you don’t even see a flame).

 

[dmccoole]

Recommend the AT100 and 6" probe: https://www.auberins.com/index.php?main_page=product_info&cPath=17&products_id=1063 https://www.auberins.com/index.php?main_page=product_info&cPath=20_3&products_id=22

I ended up getting the wifi enabled thermometer so I can monitor the temp on my cell as I'm not usually in front of the woodstove: https://www.auberins.com/index.php?main_page=product_info&cPath=17&products_id=1064

 

[Pastachio619]

Thanks for the responses.

Burnin - I do have my manual and have read it a couple times. Also used it to get back to the CAT to confirm it is in good shape and clean which it was. So are you thinking when I had the back puffing issue I just didnt let the logs burn enough before closing? I know the stove top was hot and in the range where they say to close the damper but maybe I already had it hot from the load before and the fresh logs needed more time.


Turbo - Thanks for the information. So secondary ignition isnt a problem as long as I have a consistent flame going elsewhere in the fire or a large bed of coals? I am just trying to understand how to tell when its about to back puff cause when it did I had a secondary ignition followed by no flames in the stove and I saw very few coals. So now when I see what is shown in the first video (rolling flames at the top of the stove) I start to get nervous and then end up watching the fire and not going to sleep!

So I guess to feel comfortable I can sleep and not get smoke in the house I need a good bed of coals, at least a small consistent flame, and I need the cat probe to read 1,000 - 1,300.

I will start raking the coals to the back which I wasnt doing. Thanks for the info on the max stove top temp, I can regularly hit 650F but I find it dosent seem to go much higher unless I am reloading logs in the middle of its peak burn which I dont do.


Coole - Thanks for sending the links. The current CAT thermometer is the standard one that comes with the stove, I dont think it even has a probe on it since it never moves. No matter how hot I have got the stove or cat engaged or not it has never moved. I am going to buy the Auber set up you sent later tonight. Can the screen handle the heat do you know? How far away from the fire should I have it?



Question. Does back puffing ever occur later on in the burn? I am under the assumption that if the damper is closed and i slowly cut the air back and I do not see back puffing in the first 10-15 after closing the air then I am OK to go to bed worry free.

 

[VRB Farm]

Can you tell us about where your stove is installed (basement, 1st floor etc) and your pipe size and configuration (height, turns, etc) .

Low pipe temps and back puffing are all signs you don’t have enough draft, most likely this neeeds to be addressed.

I would not gauge how the stove is running based on the fire and flames in the box. I can have little to no flames and a cat temps in the 1100-1300. Knowing what your cat is doing is how you want to run this stove, it maintains stack temps for draft while STT can be low.

 

[Turbo89]

Turbo - Thanks for the information. So secondary ignition isnt a problem as long as I have a consistent flame going elsewhere in the fire or a large bed of coals? I am just trying to understand how to tell when its about to back puff cause when it did I had a secondary ignition followed by no flames in the stove and I saw very few coals. So now when I see what is shown in the first video (rolling flames at the top of the stove) I start to get nervous and then end up watching the fire and not going to sleep!

So I guess to feel comfortable I can sleep and not get smoke in the house I need a good bed of coals, at least a small consistent flame, and I need the cat probe to read 1,000 - 1,300.

What exactly is driving the concern of back puffing?

I watched that video again like 5 times, i just hear normal stove creaking sounds and see a really nice secondary ignition. Your stove should never back-puff, and I’ve never experienced once with my 18’ straight up flue.

If you close the air all the way down the flame front should basically go out (I’ve don’t this with a completely stuffed firebox, shortly after a reload and still didn’t get a back puff).

I agree with VRB - you really can’t gauge how well the stove is running by the firebox. I run this thing off the auber CAT temp probe, if I see good CAT ignition (above 600), I’m happy enough to leave it.

As VRB mentioned, it would be good to know your flue arrangement is. Maybe this is why you’re concerned?

 

[skb31]

I had written up a longer post but held off. You should get the digital meter and probe as step 1. You need cat chamber temps in real time to understand what is happening.

I monitor my meter remotely with a cheap little Wyze cam. I figured out a cool trick to place something white up close near the cam which forces the background where my meter is to be darker in night vision mode. I can share a pic if needed.

If you need help or tips installing the probe just ask here. I modified the bracket for the factory bimetal probe to hold the new probe. As soon as I got my stove working well I bought a back up cat chamber probe and will always have an extra on hand.

 

[Pastachio619]

Attached is my set up. 6" diameter pipe, one turn. I am not sure the height of my chimney, I went out and measured the best I could from the ground I would guess 20' tall.

I am going to buy the Auber equipment tonight.

Reason for the concern on the back puffing is because it happened to me a few nights ago. I was half passed out on the couch and my wife came down and said it smelled like something is on fire. Last time she said that at our old house an outlet was on fire so I jumped up and was extremely worried. I went to the wood burner but I didnt see any smoke, took me way to long to realize there was smoke puffing out the stove top any time the flames rolled around in the burner.

I am just trying to determine what I am suppose to be seeing when things are good or when things are bad after closing the damper so I can be preventive about the back puffing. Knowing what to look for would also help with confidence and sleeping at night.

It has only back puffed once so maybe I am over reacting. I had a good burn last night and had left over coals in the AM. I just dont want it back puffing at all so nobody is breathing in the smoke.

 

[Turbo89]

Sounds like a good reason the be concerned, hopefully others that have experienced it can chime in and help. With 20’+ of stove pipe, I’m shocked there’s not enough draft. Only thing that sticks out is the sharp 90 deg bend (the manual tells you how many are allowed). Is that single wall pipe too, others may chime in on issues relating to that with this stove (I run all double wall).

 

[Pastachio619]

Two other questions just came to mind.

- When I close my damper both the stove top temp and the stack temp drop, even on succsessful overnight burns. Is this normal? I figured the stove top would drop but my stack would increase.

- Sometimes after loading a log I can smell the fire in the room with the burner. I always load from the front and with the primary fully open. Even when I am watching for smoke and see none leave the stove I can smell burning wood in the room after I close up. Is that normal or is it an indication that smoke is entering the room when I add a log? Or maybe both is true.

 

[Turbo89]

It’s not uncommon to see the temps drop when you reload. When you open the doors you should have the cat disengaged and air wide open, then crack it slightly for a second to let the draft start pulling air in from the door you opened.

I almost always reload from the top, and only when I forget to do the above do I smell smoke.

 

[VRB Farm]

Good to hear it’s not a normal occurrence.

Few things I see: all too familiar of a setup since my setup is very similar.

- I second/third getting the digital probe ASAP. I held off 6+ months and all I got was creosote in the lower single wall interior pipe. I grew up on an old jotul - where you just throw wood in and close the dampener and walk away, needless to say that’s not how this stove operates. And the digital probe is how to run these.

-1 visible 90 + another 90 to turn up in to the chimney- this “deducts” from over all stack height calculations by 6’ - I mention this if puffing comes an issue. This stove wants a min of 16’ overall. My installer apparently wasn’t great at math.

- see if there is any correlation to the back puffing to bath vent fans or hvac units running, high winds can also cause some down draft issues. Houses that are tight (mine) will be more prone to lack of draft, I even have an outside air intake direct to the stove.

Good looking fire to me:
-Strong coal bed glowing, dark above
- little to no flames, maybe a wispy few in the back.
- cat temps 1200+ during the burn.
-dirty glass (means long slow burns in the box, it cleans itself upon relight in the morning)

 

[VRB Farm]

Two other questions just came to mind.

- When I close my damper both the stove top temp and the stack temp drop, even on succsessful overnight burns. Is this normal? I figured the stove top would drop but my stack would increase.

- Sometimes after loading a log I can smell the fire in the room with the burner. I always load from the front and with the primary fully open. Even when I am watching for smoke and see none leave the stove I can smell burning wood in the room after I close up. Is that normal or is it an indication that smoke is entering the room when I add a log? Or maybe both is true.

-Adding logs is equivalent of adding ice cubes, 70degee log if inside being dropped into a 400 degree.
- use the top load : open dampener, open air to increase stack draft, wait a few sends, open griddle slowly, load wood in, burn forearm, close lid. Depending on coal bed and cat temp (again digital probe) Close down - pour drink and relax, enjoy the “air freshener” cabin scent of burning wood.

 

[Pastachio619]

Glad you mentioned dirty glass VRB because this typically happens once I close the damper and from what I had read I thought it was not ideal.

So loading from the top is better than the front? I grew up with a front loader and I just assumed that if I opened from the top it would allow more smoke to enter the home then loading from the front.

 

[skb31]

It’s my understanding that a stove pipe meter should be about 18 inches above the flue collar. My owners manual for the encore 2040 cat c says the stove top meter should be in the middle of the griddle.

On second thought with your setup you may want the pipe meter closer to where it enters chimney. I’m not sure but get a second opinion

 

[stoveliker]

I don't know the stove. But having rolling secondaries is good, as they are continuous burning the gases produced by the wood below. If you don't have secondaries, those gases can suddenly ignite, i.e. an explosion that can push smoke into the room.
That is not always happening as it depends on the gases/air ratio, flow (draft) etc.
So after a back puff, you may see secondaries. But that's not bad as had they been there before, there would likely not have been a backpuff.

Now with a cat stove, don't get afraid when you don't have secondaries, as this is not guaranteed to lead to back puffs.

 

[Megunticook]

Hear you on the concern for family health/safety, presume you have a CO alarm installed? That's the biggest concern but of course chronic low-level stove exhaust in your living space is not ideal. A meter would be useful.

I prefer not to top load any more, seems to allow more exhaust into the room.

Have you checked your griddle gasket? Gets hard and doesn't seal as well. I replace annually.

Be aware of weather conditions outside and adjust your practices accordingly. For example, on a warmer low-pressure day, like a drizzle or fog, be careful not to close the damper too soon and don't restrict primary air as much to avoid smoke in the room.

May take some practice to get the hang of it.