I'm not sure what I'm doing wrong

Hi Shik
I have a Super 27 woodstove in the basement and Super 27 insert upstairs in the family room. First off, although I love these stoves for the simple design, I think they breath too easy and spent many a night watching my stack temp climb as quickly as my heart rate. My first step to better control was to install a flue damper in the basement stove. This helped a lot, but if I put in a full load for an overnight fire the stack temp would still climb into the scary zone so I would only fill the firebox about 1/2 full and pack it very tight. Not very practical for cold Canadian nights. After searching the net for suggestions I found a reference about slowing down the airflow by using steel wool, packed into the hole that is behind the metal plate just inside the door. After doing that, I now have 2 totally controllable stoves that will safely burn all night with full loads of wood. A simple hack, but a game changer for these Pacific Energy stoves. Hope this helps.

 

I really don't understand why most stove manufacturers don't give draft specs in the manual! It is such a vital part of the stove running properly...too low, that's no good, too high, that's almost worse! With wood and coal furnaces they almost always spec the draft and want it kept in a fairly narrow window, -0.04" to -0.06" is pretty common. I keep an inexpensive manometer hooked up to the stove pipe all the time...and check it after every re-load.

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I'm sure that works well...but just so that everybody reading this is aware...and it kinda counter-intuitive, but steel wool burns like dry tinder! I know the chances are low, but what if the stove backpuffed hard and spewed sparks out the intake into the steel wool...hopefully everything would be sucked into the stove, but if it burnt and then a flaming wad fell onto an unapproved hearth (not that anyone on FHC would have one of those!) could make for a bad day!
Not preaching, just a PSA for those unaware.
I think a pipe damper would be a better/safer fix for these stoves personally.
Simple Science: Burn Steel Wool

 

I guess anything is possible but the design of the plate covering the air inlet would make that scenario virtually impossible. I’m comfortable with the modifications and feel a whole lot better about going to bed with stack temperatures in the safe zone rather than sitting up all night watching the temperature climb towards 1200° and wondering when the chimney will ignite. 12 years of happy burning and a warm house so far, but I guess it’s up to each individual as to what they are comfortable with.

 

shik does your stove have a blower? Looks like there is an option for one at least on the current model. My buck 81 has a blower and the air outlets are on the front top of the stove. So there is an air space between the metal that serves as the top of the fire box and the actual top of the stove. This actually serves to somewhat insulate the top of the stove and reduces heat output of the stove if I’m running it without the blower.. so my stove top temp tends to be lower than my glass temp. if your stove will accept a blower and you don’t have one, that might be a worthwhile investment. Agree with the recommendations to install an inline flue damper... while a brand new stove may not need one, any gasket imperfections that develop as the stove is used can make it more difficult to control a burn. Good luck...

 

Not familiar with the stove, and I know it's brand new but, is the baffle (just above the secondary burn tubes) intact?

As others said, I'd probably add a damper in the pipe.

 

Those numbers do not look odd or excessive to me. Internal smoke pipe temps ~ 800F with a stove top temp of 460 sounds reasonable and that stack temp is certainly not excessive. Even 1200 F stack temp (internal, NOT external on the pipe itself) is not really excessively hot on a secondary tube burn stove running hard. That would make for a stove pipe temp. of around 600 F at the pipe surface, maybe a touch lower, which again is not excessive for a wood stove running hard.

As others have said, you can certainly put a key damper in the stove pipe and probably reduce the running, not starting temps but not by all that much.

I am not familiar with that stove but I believe it is a secondary burn type and that means the top of the firebox will be insulated; the stove will not put out the majority of its heat at the stove top above that insulation. The majority of the heat will probably come from the door glass and metal on the front of the stove, and in the ~700 F range, it should be producing a great deal of heat.

How long does it burn on a full load of hardwood at the settings that yield the numbers quoted below?

Brian

 

I have been following along, and this is a really good point about the insulation- I hadn't previously thought of that. Great suggestion.

Edit: I'm wrong.

 

There is no insulation on, or under the top of this stove. If you take the baffle out, you are looking at the bottom of the stovetop.
And I'd say half, or close to half of your heat is coming from the stove top...

 

I'll check that out. Sound a bit scary hahaha. Do you have a blower on your Super 27?

 

I don't have a blower on this. It's on my list. We actually really like the quiet and simplicity of a hot metal box with no sound but the creaks, snaps, pops etc. I have a couple of ecofans on top though. I know they move nowhere near the same amount of air. I'm definitely going to look at the damper. It seems to be the general consensus on here, so that's good!

 

Yeah, the temps last night seemed good, but all too often when I starting up, the pipe will get up to 1200 or so which is well into the "black" on my probe. Since I'm new to this, I feel like I need to stay within what the probe indicates as "safe" parameters. It could be that "blinking light" in an airplane problem. Perhaps I'm focussing too much on that one number on the probe. I notice many of you don't even run a probe. I don't know what a "good" fire that is not running too hot should even look like, or what an out of control fire would look like. Big learning curve I suppose.

 

Looking at the diagram that brenndatomu posted looks like theres just a gap where the air wash does it’s thing and likely puts some pretty hot temps. My inkling is your draft. Your stack is high. How well sealed is your house? I also wondered if the probe has some issues, calibration or “off” because unless your stove top is shielded underneath, those temperatures shouldn’t be too bad. Almost looks as if the probe is under a direct flame and not deflected by a baffle in the stove. I never ran a probe myself, others do but only out of precaution I suppose?
Using deductive reasoning to find a solution will help.
Your pipe is double walled yes? Most stove folks are cautious at temps within the first year, the trick is to find those comfortable spots to settle in at so you’re not blaming your stove for good operation that is designed to be hot. Problem is that those temps say the heat is going up your stack and not staying in the house.

 

Agreed.

Certainly possible too...

 

The 'baffle' itself is the insulating member. The goal is to keep the firebox temps. high to maintain that secondary burn.

Per Pacific Energy's web page:
<begin quote>

Floating Firebox
It may be obvious that a firebox is subjected to wild extremes of temperature. In some stoves, those extremes, and the related expansion and contraction, can lead to premature fatigue, and even failure, of metal components. But not in a Pacific Energy, our floating firebox system is legendary in the industry. Solidly designed with 304 grade stainless steel brick-support rails, it allows key parts to freely expand and contract, which reduces metal fatigue and adds years of life to the entire stove. The stainless steel baffle (part of the clean-burning secondary combustion system) the flame shield (which protects the stove top from intense heat) are all part of the floating firebox system.

It costs more to build a stove this way, but we feel it’s well worth it. It’s one of the reasons we’re confident in offering a lifetime warranty on every one of our stoves and inserts. And why our products don’t click, tick and ping when they heat and cool.

FLAME SHIELD
Made from 304 grade stainless steel to protect the stove top from intense heat.

BAFFLE
High volume secondary air combustion system for maximum efficiency.

BRICK RAILS
Allow key parts to freely expand and contract, reducing metal fatigue and adding years of life to the stove.
<end quote>

Located at: Pacific Energy :: Floating Firebox

Again, unlike the olden' days when a stove was really nothing more than an iron or steel box that had the fire on the inside and the ambient room air on the outside, modern stoves, regardless of type, have mechanism(s) to keep the firebox temps. higher to result in a cleaner burn. Regardless of the particular method or materials, this serves to keep the outer layer of the stove cooler, relative to the internal firebox temps. than they would be given the older style 'box of fire' wood stoves. The result is more of the stove's heat comes from the front of these modern stoves than the older types, and the top is cooler, again compared to the older type stoves.

And again, I find the numbers quoted in the post I responded to initially in this thread to be reasonable and more- or- less expected. Certainly nothing dangerous IMO and IME.

Brian

 

I do not think so- I think you are right...... at least until you said you were wrong.



Brian

 

From the Duravent site:

"Designed for normal, continuous operation at 1000° F flue gas temperatures, DuraTech is subjected to rigorous and stringent HT requirements of the UL standard, including one hour at 1400° F, plus three ten minute chimney fire tests at 2100° F."

Running the flue temperatures constantly in excess of their rated maximums is a great way to burn your house down and/or ruin your stove pipe.

So yes, 1200 is excessive. I have seen it before on my noncat stone stove and was not happy at all. I don't want to see anything over 1000 on purpose. Ever. Usually my internal flue temperatures are at 400 on the cat stove, and on my noncat stove with a 19' all vertical chimney, the internal flue temperatures usually match the stove top temp.

I would recommend you verify the accuracy of both thermometers first. 1200 is really hot and according to the interwebs steel will be glowing dark red at 1200. A condar flue meter is better than that SBI one. You can use the same thermometer hole to insert a draft meter which will tell you if you need a damper to regulate draft strength.

 

Yes, carbon steel (is this pipe stainless for the inner wall?) starts to glow faintly at 950* ish...

 

Why would you have a stove on an unapproved hearth ?

KIds like to stab steel wool pads with a charged 9 volt battery - it's also a good way to show people why to be careful disposing of batteries.

 

1200 F is the flue gas inside the smoke pipe, not the smoke pipe walls. So the steel is no where near 1200 F.

He also mentions that he only reaches that temp at startup, not as a normal running temp. Again, look at the block of numbers he posted (and I quoted): stove top 460F with stove pipe probe (internal, not the stove pipe itself) temp at 780F.

Again, I believe these are normal, expected and acceptable temps. to operate a wood stove at. I personally would not let the flue gases get quite that high but certainly 1,000F is perfectly acceptable on start-up.

As to how hot the steel should be, it should never fluoresce (glow), which is about 900F for a very dull red- only visible in a dark room. By 1200 F, carbon steel will be orange and obviously visible in a well lit room and is much too hot to run at. But by the time the stove pipe is 1200 F, the internal flue gas would be well above 2,000 F and at that point I would say something has gone seriously wrong and needs to be corrected immediately.

I think what is important here is to think about all of this data in context rather than an abstract number and for an undefined amount of time. And again, I am going by the block of data he posted after the stove had been running a while, was stabilized and all those numbers look fine to me. A spike of 1000F at startup, for a matter of moments only, is not a deal- killer IMO. Of course I am not advocating running ANY stove at ANY specific temperatures but as reasonable people we should be able to expect a reasonable set of parameters for burning wood; 200F internal flue temps, at steady state (not passing 200F on startup but still climbing) is too low because the stove will be a smoldering mess. 1,200F is acceptable momentarily on startup as long as it is the stove pipe right above the stove and most certainly NOT the internal temp. of the chimney! We also have to remember that even with double- walled stove pipe, the temperatures inside drop rapidly as the flue gases approach the chimney, even if the smoke pipe run is only a few feet; my own flue gases lose about 200F from the stove top to the thimble and are just under 3' in total pipe length with one 90 degree bend on the way.

As to the other question of 'why will this stove not heat my house', I cannot even address that as I have no idea what the house heating requirements might be. Also, I think we can all agree that a lot more heat is required to recover a building's temperature than to maintain it.

Brian