Encore (NC) burn time dilemma (long post)

[Diabel]

Hi everyone,

Another noobie here! First of all, a wonderful forum/site,
very informative & educational.

Here is a bit of info about me & my set up:

Stove: A two year old nc vc encore (1450) sitting at one end of a 19x35 room extending to other rooms via above average openings to a two story 3000 sq ft well insulated house with 9’ceillings.

Chimney: from the collar a 6” double wall pipe 5’ up then 45 degree elbow, then 1’ up at 45 degrees, then another 45 degree elbow, then at the ceiling a square box, then about 3’ of space between ceiling & deck top, then 11’ stainless steel insulated chimney.

Me: I am not new to wood burning. My friend has a vc encore cat at his cottage & our families often meet there on weekends. There, I am the designated stove man. The stove is a charm to work with. With couple of splits I can keep it going for hours. Room size 12x30 I can keep it around 75-77 with outside temp around 10..wives live it!! While back I read about the cats & surroundings needing replacing every 4-5 years & that the replacements were not cheap (around $400-500) labor incl. That was the deciding factor why I went with a nc encore.

Here is my situation:

I follow your advice, I load the stove (not always ) to the top! The procedure some of you have shared here works very well (most of the time). I do have to baby sit the stove during the initial couple of hrs. (keep an eye on it… would be a better description). I would open the damper, rake the coal to the mouth of the everburn, throw in 4 4-5” splits (one yr old maple – some of the pieces will hiss a bit but not all), air fully open, the outside flue temp will climb to 550 within about 10-15min.(if no hissing.. up to 30min if wood is hissing) the griddle at that point will read 500. At this point I will engage the damper (close it). 90% of the time the loud rumble will occur, the flue temp will rise the griddle temp will drop. This is when I baby sit the stove, I watch the flue temp & listen to the rumble, as the flue temp approaches 550-600 I cut back air to half open. If flue temp keeps going up I cut temp 75% & the rumble will quiet down, still very audible but not jet engine like (had I kept the air open 100% at this point the temp would keep climbing to 800 & the flue collar cast boot would glow dark red, hence the babysitting). This will continue for about 1.5 to 2hrs. Temps will stay around 500 flue & 550 griddle. The flames will be visible (dark yellow). At this point I consider it a good burn & will cut air back to about 95% closed. The rumble will still be audible but faintly (no smoke throughout the whole process I love it!). In the first 5-10 min. of that stage there will be no flames & the ambers will glow dark red & then I will start to see the red/blue dancing flames (yes). Temp reading at this point will be flue 400-450 & griddle 600-625. I can go to bed now!. On occasion I have stayed up & watched what happens next. The flames will change color to a pretty blue (much smaller & not dancing anymore), then about 1 hr. later they will disappear & all I will see is the dark red coals. Interestingly, if I was to cut air back 100% while the flames are in the dark yellow stage in such instance the flames will disappear for about 30secs. & then a wicked explosion will take place filling the firebox with blue flames & sometimes a puff of smoke will come through the flue connector & or the griddle. I do not like that therefore never cut air 100% at this stage. I also tried cutting air 100% at the next stage (dancing flames) & surprisingly the same explosions occur (about every 15secs. but no puffing smoke) either way I feel more comfortable going to bed with air 95% shut.

In terms of the burn times, I read conflicting descriptions. Some say from reload to when the stove top temp (griddle in my case) drops to around 400-450 they get 12hrs. Others say that when you stop feeling radiant heat from the stove & it is time to reload that is the cycle end again 10-12hrs. please tell me if this is how you measure it. In my case here is my burn time estimation:

I throw in say 5 splits (4-5”) at noon, go through the process I described & from the point that I can stop watching the stove (babysitting) it is 2pm at that point & temps are at 400-450 flue & 600-625 griddle. This will hold for about 2hrs. then gradually the temp will start to drop. By 6pm the flue temp will drop quite fast to around 200 & griddle 450 (hardly any heat coming from the stove at this point). There will be very little coals left & I will have difficulty starting the fire without kindling. Also, with 95% closed air I will get dark brown tint on the glass, if I close air only 50% the glass will be very clean but the actual burn time will be shortened by at least 1hr. So therefore my burn times can be pegged at 5.5 – 6hrs. I am not too impressed especially after reading some of the posts here & my success with the cat stove at the cottage. As per this forum I did the dollar bill test & the gaskets seem ok, there are couple of areas where with quite a bit of pressure applied I can pull the bill out (around the front door where the hinges are), but nowhere close to being an easy pull. Maybe overdraft….I thought about putting a rock behind the damper & see if that would help. One thing I did noticed, with a full ash pen & quite a bit of ashes in the box I will get a longer burn, but this would point to leaky gaskets (not the case). Couple days ago I got some nice splits from my neighbor (3yr old maple) I thoroughly cleaned the stove got the fire going, I put 3 6” splits & 1 4” split in. I got 5hrs from it. Before I had to reload the flue temp read 200 & griddle 375 with hardly any coals left. Again the glass was brown!!

Any input would be greatly appreciated! And my apologies for such a long post.

Cheers

D.

 

[swestall]

Your stove is operating as designed and you are lucky to get consistent secondary burns. You can only be sure of a complete secondary burn by looking at you chimney and making sure there is no smoke coming out of it. It sounds like you have a pretty good draft and that could account for it. If you cut the draft back, you might lose the reliability of the everburn working.
Go to the dealer and ask them to take this back and give you a CAT stove; that will solve the burn time problem. Otherwise, be happy that it is Everburning..

 

[Diabel]

Hey Swestall,

I have read your posts regarding the struggles with your Defiant, sorry to hear that. This everburn thing is like a marriage...you have to work at it every day, there are good days & there are the not so good ones! This thing is sure temperamental, there are so many factors involved in order to get a decent "smokeless" burn. On those bad days I wish I could (as per your comment) just bring the stove back to the dealer & replace it with a "cat" one, but that is not an option...Yet on those good smokeless days it sure makes you feel good...house is cozy warm, birds & neighbours are happy bla..bla..bla

These burn times though are just killing me Six hours....! I actually spoke with the dealer about that & he thinks that it is decent/realistic. At this point the good days by far exceed the bad ones in terms of establishing "everburn" but if that changes...then who knows! Hey can I swap the everburn refactory with cat refactory? The firebox in the same from looking at the two manuals.

Thanks
D.

 

[webbie]

4-6 hours is fine for typical burns in any stoves - BUT, a stove like that should be able to do 8+ hours easily when it it loaded and turned down......and you should not have to babysit it for 2 hours beforehand. In a marriage, we call that "high maintenance" . I would get 6-8 hours out of my acclaim which used similar technology, but the box was 30% or more smaller.

My guess is a bit of an overdraft. I would try installing a barometric damper in a TEE. If you don't want to do this, a turn damper might help as long as you fiddle with settings.

 

[Diabel]

Hello Craig,

This site is amazing....so much great information & so many knowledgeable & patient posters. It is slowly taking precedence over watching NHL Again thank you for setting it up!

Dealer believes that 21' set up is plain perfect for my stove. I read somewhere here that putting a rock behind the damper (in the flue) would test the overdraft possibility. What do you think?

Thanks

 

[webbie]

Well "plain perfect" might do for most stoves, but that sucker seems to only work with a chimney that is almost exactly what it was tested with....which is usually about 15 feet. Yeah, a rock will do the job.....maybe a few. You want to try closing off 1/4 of the flue or more. The neat thing about a barometric is that it constantly adjusts itself based on conditions...and the stove gets an even draft all the time.

 

[Diabel]

I could take a 4' section of the chimney off from the top & see what happens...

 

[webbie]

Just as well starting with the rocks.

 

[jpl1nh]

I think in your area you have lots of sugar maple but you probably have a good deal of red maple as well. Sugar maple is a very high BTU wood, red maple is far less. I'm always a bit skeptical when I hear people say they are burning maple since there is such a wide range of heat qualities depending on what type of maple. Also wanted to correct your understanding that the catalytic replacement necessary every 4-5 years costs around $400-$500. A new combustor for my stove is $125.00. I've read many threads about the (n)everburn system. I agree with Swestall, take it back and get the cat stove you enjoy operating so much at your friend's cottage.

 

[Diabel]

Yes, it is 95% maple around here. But I also will pick out cherry from my wood pile & load the stove with that...same result 5-6hrs burn!

Dealer told me that is is impossible to interchange the combustors i.e. non-cat with cat. I looked at the two manuals for encore 1450 nc & 2550 cat they look identical other than the combustor. He also told me that VC will stop selling cat stoves by 2010!

 

[jpl1nh]

Yes, it is 95% maple around here. But I also will pick out cherry from my wood pile & load the stove with that...same result 5-6hrs burn!

Dealer told me that is is impossible to interchange the combustors i.e. non-cat with cat. I looked at the two manuals for encore 1450 nc & 2550 cat they look identical other than the combustor. He also told me that VC will stop selling cat stoves by 2010!

You would have to exchange stoves to get a cat because you can't convert a non cat burn system to a cat. If VC stops selling cat stoves they lose one of their competative niches. If they are banking on their new "neverburn" technology inthe future then it won't be long before they stop selling stoves period!

 

[swestall]

Yes, it is 95% maple around here. But I also will pick out cherry from my wood pile & load the stove with that...same result 5-6hrs burn!

Dealer told me that is is impossible to interchange the combustors i.e. non-cat with cat. I looked at the two manuals for encore 1450 nc & 2550 cat they look identical other than the combustor. He also told me that VC will stop selling cat stoves by 2010!

You would have to exchange stoves to get a cat because you can't convert a non cat burn system to a cat. If VC stops selling cat stoves they lose one of their competative niches. If they are banking on their new "neverburn" technology inthe future then it won't be long before they stop selling stoves period!

YES, and that is exactly what I fear. The can't see it, the CAT stove is the best product that they have, the only one in fact. So when they stop selling it, the will be done.

Last night, I put 3 good sized splits in my Hearthstone at 10:30PM, I waited for about 10 minutes, came back to the stove, shut it down for secondary burn and went to bed. (no smoke) This morning I came down at 8AM and there was one split still in tact but when I hit it, it broke apart. The stove was still putting out heat and all I had to do was add two splits and off it went again.

So, don't let them tell you this is normal. Even if you have to call CFM customer service over and over, it is a possibility they will give you a CAT stove to replace the NC. If not, consider getting out while the getting is good. The dealers and CFM do have some interest in having people think its OK to have to manage the stove; but having to babysit a stove constantly is rediculous. The Englander at 1/2 the price is four times the stove; and others just get better from there.

I sincerely hope you are able to get this thing working for you; at least to the point that you can heat with it and it doesn't take too much of your time. BUT, you really have to keep an eye on the smoke coming out the stack because it equals creosote. I think that was the worst part for me, you could never trust that there was no smoke just because you had the secondary engaged. Good Luck with it.

As Craig emphasized, you need to get your draft as close to the factory design point to have this thing work optimally.

Regards,
SW

 

[tradergordo]

Diabel - there is a much simpler solution to your overdraft problem, you don't need to throw rocks down your flue, or install a barometric damper. Craig, after reading the Gulland article that YOU brought to my attention:
http://www.gulland.ca/florida_bungalow_syndrome.htm
I'm surprised you aren't adopting Gulland's advice on this subject.
All you need to do is take a piece of tin foil, stick it over your secondary air inlet (bottom rear of stove), fix it to the stove using the pre-drilled holes intended for the outdoor air connection, then poke a hole in the tin foil at the center. You can start with any size hole, and adjust as needed!

I had thoughts about this a while back, but didn't have confidence suggesting it to other people until reading Gulland's article about 5 minutes ago!! Read his article to understand why this is a better solution than alternatives such as a flue damper, cap restrictor, or barometric damper. If you want to get fancy, you can make something that is actually adjustable, this should not be much trouble really, I'm thinking of the things you normally see on the tops of charcoal grills, a simple metal, open/close slider.

Well "plain perfect" might do for most stoves, but that sucker seems to only work with a chimney that is almost exactly what it was tested with....which is usually about 15 feet. Yeah, a rock will do the job.....maybe a few. You want to try closing off 1/4 of the flue or more. The neat thing about a barometric is that it constantly adjusts itself based on conditions...and the stove gets an even draft all the time.

 

[Diabel]

Gordo,

Thanks for the reply! I saw the video, it is great. The tin foil is an excellent idea...why didn't I think of that. I will be trying that trick tomorrow! I wonder what would happen if I was to plug the inlet completely during these overfire episodes. I would feel much more comfortable letting the stove rip if I knew that I can control it. I even thought about taking the rear heat shield of & filming the glowing, it would be much more visible with it off.

Again, the video was a swell idea..thank you for putting it together.

 

[cmcramer]

Diabel -

I've had my VC Encore NC for just over a year. Your post reflects my experience exactly! Glad to hear someone else describe "the flue collar cast boot would glow dark red" issue. (...not sure that is the part's proper name...but I know what you mean) I, too, work to keep that from happening by managing the secondary air intake.

I agree that a standard, measureable definition of 'burn time' would be useful. If I can throw on some dry kindling, crack the ash door, and ignite a fire within a minute or two........is that the rightful end of a 'burn'? If so, I recently got 8.5 - 9.0 hours out of my stove by following Trader's recent advice: I take a moment to really pack the dang firebox as full as possible....(in a really hot stove with inches of coals) more than I normally would. I try to use all sizes of my best year old ash and pack the fire from left to right and top to bottom. Then I immediately cut the seconday air to 0%. Try it!

 

[Diabel]

Diabel -

I've had my VC Encore NC for just over a year. Your post reflects my experience exactly! Glad to hear someone else describe "the flue collar cast boot would glow dark red" issue. (...not sure that is the part's proper name...but I know what you mean) I, too, work to keep that from happening by managing the secondary air intake.

I agree that a standard, measureable definition of 'burn time' would be useful. If I can throw on some dry kindling, crack the ash door, and ignite a fire within a minute or two........is that the rightful end of a 'burn'? If so, I recently got 8.5 - 9.0 hours out of my stove by following Trader's recent advice: I take a moment to really pack the dang firebox as full as possible....(in a really hot stove with inches of coals) more than I normally would. I try to use all sizes of my best year old ash and pack the fire from left to right and top to bottom. Then I immediately cut the seconday air to 0%. Try it!

In my case it is not the actual collar, it is the part where the collar bolts to. Thanks to Trader's simple yet brilliant idea I will try the tin foil & see if I can control the fire, then I will film the glowing action.


Yeah, when I take my time & pack it tight with large & small splits then I can get 8hrs. burn time & this is from loading to reloading (when the griddle surface temp is around 275 & not much heat output at this point). I could most likely let it go for couple of more hrs. & still be able to restart the fire with kindling but I would not call the 24/7 burning.

 

[tradergordo]

At first I bought into Vermont Casting's bogus pat answer to the complaints about glowing stoves (note that I think only people with the Encore specifically reported this problem as far as I can remember). They also told us that the stoves were designed such that it was IMPOSSIBLE for them to draw too much air as long as there were no leaks. They also said (if I remember correctly) that no one, under any circumstances, should ever need an in line flue damper. Basically they said over firing was due to leaks or operator error.

I think it can definitively be said without a doubt that what they told us was nonsense. I didn't realize until reading Gulland's article, that it was basically a well established fact that in extremely cold climates or cases of extra long straight up chimneys, many non-cat stoves WILL pull too much air. Obviously the first thing you want to check in these cases is for leaks, but if there are none, then you need to modify your air intake (preferably someone that is qualified should do this for you but how are you going to get that help from people who deny the very existence of a problem). John specifically stated in his recent interview with Craig that he has had to modify the air intake on EVERY STOVE he has ever owned because he has a 30 foot straight up chimney and lives in an area (in Canada) that can get extreme low temps. He says there is no such thing as "over-draft" and I now agree - the problem isn't your kick butt chimney, the problem is your stove that is allowing too much air to be pulled through! The part I especially didn't know is that its the EPA regulations that basically prevent the stove companies from building stoves that have air controls that can accommodate these situations.

The good news is that it IS possible to solve this problem by making a minor adjustment. I have seen some people express concerns of the safety aspect of restricting the air intake - well you tell me, what is safer, a careful adjustment to make your stove work as its supposed to, or glowing cherry red stove parts? Just be sensible, if you restrict too much, you will know it based on poor performance (bad secondary combustion, smoke out your stack from unburned gasses, etc).

 

[ICY99]

Interesting. On my 1984 VC Resolute the secondary air intake IS adjustable! I will try to post a pic. It consists of a tear-drop shaped cast iron piece which can pivot and cover up to 100% of the secondary air intake.

From the old VC Manual (pg 14):

"It is possible (though it occurs rarely) that you have excessive draft. This usually occurs with a tall interior masonry chimney that is located so the prevailing breezes blow across the top, as in the case of a house located high on a hill or near the shore. Should this prove to be the case, first experiment with closing down the secondary air control slightly. Easy does it here. A 30% closing is probably all that it will require. In extreme cases, try installing a flue damper to partially restrict the draft."

 

[tradergordo]

That IS interesting. The old owner's manuals were so much better than the new ones. Its sad that they seemed to be so much more knowledgeable back then than they are today. They knew about this problem in '84 and even described it and provided a solution. Today they pretend like the problem doesn't exist and people like Gulland have to point out "Hey guys, the problem still exists, and you aren't doing anything about it".

I would like to see that pic of the part you described. I think quite a few people (maybe not a majority, but still a good number) need to add something like this to their stove. But really almost anyone could POTENTIALLY experience the problem given unusual conditions (like extreme low temps and high winds) so I think almost every stove should have such a device to use in case of emergency. Its a basic safety issue. Of course the person has to understand the purpose and not restrict secondary air for no reason, or that would defeat the purpose. That's why it should be something that is a bit of a pain to access and adjust.

 

[sullystull]

I agree...I would like to see a pic. I have the large DW everburn. Temps in these parts can be pretty low and we often see 50+ mph winds. I experienced a "thermonuclear" event just the other night. Thanks to Trader's suggestion of restricting the air intake, I believe I can solve the problem and prevent it from happening again.

 

[ICY99]

Here is a photo of the secondary air intake on my 1984 Resolute. I've never posted a photo before. Please let me know if its viewable.