coals, cold chimney and smoke

[oldspark]

Put the front legs of the stove up on a couple of firebricks and see what it does to the angle of the pipe to the thimble. At this point straight into the thimble would be better than what ya got.

OK , wouldn't it be better to shorten the legs?

 

[Jotul118]

I have one of those type thankfully and the levels were not too alarming compared to what I have read. We haven't really had even the mild side of symptoms for exposure and the upstairs space where we sleep although insulated has deposits of draft. The space is not tight to a fault like most modern builds that one actually needs to go out and buy some sort of draft mechanism.

I noticed last night that when I stuffed the box for a longer burn there really wasn't an issue. It seems the issue presents itself when I do a smaller fire before retiring for the evening. The flue subsequently gets cold and combustion becomes detrimental.

 

[BrotherBart]

OK , wouldn't it be better to shorten the legs?

No.

 

[Jotul118]

Put the front legs of the stove up on a couple of firebricks and see what it does to the angle of the pipe to the thimble. At this point straight into the thimble would be better than what ya got.

Could I get away with that clearance wise, if I was to get closer to the thimble? I would only increase the pitch downward if I was to put the legs up on firebricks. That's why I was pondering chiseling into the marble slab. I am dyslexic at times though and I'll take a look.

 

[Jotul118]

OK , wouldn't it be better to shorten the legs?

I'll have to talk to a metal fabricator friend on mine about that, but good suggestion and thanks.

 

[Jotul118]

I know they say that you normally want the stove thermometer about 18 inches up from the stove outlet. Would it be any different with my set-up? I just want to make sure that my general readings are truly efficient.

 

[oconnor]

I wouldn't be worried about the thermometer to much. You've already mentioned a CO alarm that went off, you have a near level section of pipe in a location that would drastically effect draft, and the flue is barely as tall as your house. Those points are where my concerns would lie. Like BB said, CO will kill you.

 

[Isaac Carlson]

Don't cut the legs. If anything, have some shorter ones made up. You never know if you will regret cutting those legs.

 

[Cynnergy]

Can you reduce the height of the hearth somehow? Cut out some sub flooring and re-lay the stone?

I did have a quick peek at the manual for the 118 CB (the current model), and I'm pretty sure it says that rear clearance with a rear heatshield and double wall pipe is only 3"; single wall pipe, no rear heatshield and a protected wall is 8.5". I'm not an expert, and I don't know if your stove is the current model, but just logic would say that the less downward-sloping horizontal run the better?

 

[Jotul118]

When they talk of heat shields when referring to clearances, would the metal framing around the thimble assembly be considered such? I'm just thinking if I bring the stove closer to the wall would I have to install a larger footprint of heat shield? Please refer to photo above to see what I'm talking about.

The stove did just fine last night. I got in on the later side last night and filled the fire box, and there was a nice bed of glowing coals this morning. 0 PPM reading on the real time sensor as well as the stored history.

I want to thank all of you for your suggestions, patience and sage advice. It's both helpful and reassuring.

 

[Cynnergy]

No, the heatshield would be on your stove if you have one. I can't see one in your picture, but I'm not sure what it would look like on your stove. It might be in the exploded parts manual.

You don't have a protected wall either. A protected wall is a very specific construction, normally using sheet metal (you can make it look pretty with tiles and such) on non-combustile spacers on the wall behind the stove with a ventilated 1" air gap behind it.

That just about exhausts my knowledge so I hope some other members will help out with more ideas or details.

 

[oconnor]

Is this stove the newer Jotul 118CB, or the original 118? The manuals are different, and likely the clearances too. One is an EPA approved stove, the other isn't.

 

[Jotul118]

Is this stove the newer Jotul 118CB, or the original 118? The manuals are different, and likely the clearances too. One is an EPA approved stove, the other isn't.

This is the old pre-EPA model.

 

[Cynnergy]

OK with the old model it's a lot different - looks like 28" from the back of the stove. I think this is the manual here: (broken link removed to http://jotul.com/us/guides/_attachment/12830?_download=true&_ts=13e1d3b334b)

You should be able to reduce clearances by using a wall protector, see here for details on the options: http://woodheat.org/clearances.html. You reduce that 28" by 67% to 9 1/4" with the proper wall protector I believe.

 

[Sprinter]

I hate to add to your concerns, but I have to ask about your wood supply. The pics you posted show only unsplit rounds. What wood are you burning now and do you know how dry it is?

 

[Jotul118]

OK with the old model it's a lot different - looks like 28" from the back of the stove. I think this is the manual here: (broken link removed to http://jotul.com/us/guides/_attachment/12830?_download=true&_ts=13e1d3b334b)

You should be able to reduce clearances by using a wall protector, see here for details on the options: http://woodheat.org/clearances.html. You reduce that 28" by 67% to 9 1/4" with the proper wall protector I believe.

Thanks! I'll re-group with that option in the spring.

 

[Jotul118]

I hate to add to your concerns, but I have to ask about your wood supply. The pics you posted show only unsplit rounds. What wood are you burning now and do you know how dry it is?

lol! That "work in progress" is for next season. I want to stay at least a season ahead if I can. The stuff I am burning now has been seasoned for quite a while.

 

[Jotul118]

Put the front legs of the stove up on a couple of firebricks and see what it does to the angle of the pipe to the thimble. At this point straight into the thimble would be better than what ya got.

So, here I am getting ready for another burn season. I thought I would follow up on this thread and thank all of you with dispensing sage advice. After last winter, I was overall very pleased, but being that it was my first season with, not only the Jotul, but in the new space, I certainly learned quite a few things and I am sure the curve will continue this season and beyond.

I was having issues with:

*priming and smoke kick back on a cold start
*insufficient combustion at the end of a burn cycle (CO2 alarm)

There was an issue with the height of my chimney stack and I added one more 3' section to it which seemed to have helped things quite a bit with draw. We'll have to see what this season brings, because as it stands I can get to the top cap if I need to shake out the creosote build up on the mesh screen, which I might just be getting rid of anyway. I much rather clean from the bottom up, so If I were to go with yet another 3' section, I should be all set with the cleaning of the chimney.

There was an issue with my set up relating to my flue run actually slanting slightly downward as opposed to the necessary rise one needs. I am happy to say the run is, at least, evened out at this point. I had the stove sitting on top of some beautiful granite, but a practical solution of a low profile fire rated hearth mat remedied bringing the stove closer to the floor safely while leveling out the flue run.

I was also told the closer I can get the stove to the wall will also help with more efficient draw at start up. Although it's not cheap, I purchased a large sheet of heavy duty copper, cut it down to size and set it up as a heat shield with the necessary 1 inch air space all around. I was able to drop one whole 12 inch section of single wall pipe from my original setup.

Growing up I was always around my grandmother who would cook with her copper pots from France where they have always been revered for how they heat so evenly and so on. So, it was surprising to me when I stopped by a friends house, where he almost has his stove right up against the wood wall in his study. The only thing between it is this interesting fabricated free standing copper backsplash.

Counter intuitive in a way, but it was pretty cool to the touch and even cooler behind it. I'll keep you updated on that.

Because of limitations of ceiling height and not wanting to carve out most of an already small space to run a chimney from the top of the stove, I decided to vent the stove through the back. Effectively 1 90 degree run before heading straight up on the outside of the building. This is where I am sure ditching that 12" section of single wall will help me in cold starts and longer burns with poor combustion near the end of the burn no longer hopefully being a thing of the past.

I will update and post some photos of the new setup. I haven't found much out there on rear vented setups, so it has been a good learning process.

 

[Cynnergy]

Thanks for the update! We love pics (hint hint).

 

[ddahlgren]

The wall thimble is painfully too low. If splitting that wood as you need it, it will have way too much moisture in it as does not season until split. After split get it off the ground and cover the top and about 6 inches down the sides. Looks to me you are burning green wood with a chimney angled the wrong way. If that is a magnetic thermometer I see on top of the double wall it is useless. Personally I would get an install guy in there before the CO takes you out of the game as small amounts that don't kill you are not harmless either. Not trying to be harsh but hate to see someone get hurt or wreck a relationship over a wood stove.

 

[Jotul118]

Sorry about the great delay in response. Thanks to all for great insight and advice. The wood I am burning is split and has been for some time and is burning beautifully. I installed the heavy gauge copper sheet behind the stove, which allowed me to move it closer to the wall. On top of that, I bought a low profile fire rated hearth mat which really helped with the deficit of the section of stove pipe that was running a deficit against proper elevation going out through the wall.

The draw has greatly improved and, although it is not really cold out yet, there has been no smoke outs and starting her up.

I love the stove, but being that it is designed for a slow cigar like burn, on top of it's being a deep box, I have a hard time with the fire consuming from front to back. I plan on adding another 3 foot length of chimney this weekend which should help also. It is presently right on line with the crest of the roof so the smoke likes to hang out around the second floor under certain conditions.

Where the wall thimble is concerned, in hindsight, I would have done things differently. It's a very small space and I had no clue on the engineering behind it all. I'm thinking that is a major reason why the stove is not burning front to back like it is designed to?

I've been burning for the last few weeks without a hick up. Brand new CO detector and it's been at 0 from the time I put the batteries in it. I am hoping that the extra 3 feet of chimney will help things when it's time to burn longer into the night.

Hope all is well with everyone and thanks for your continued guidance!

 

[Jotul118]

I forgot to ask, ddahlgreen mentioned the magnetic thermostat being useless, what is the best way for me to ascertain when it's burning optimally (not too hot/not too cold)?

Cheers!