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?