I just THOUGHT I knew how to burn my TL300

[razerface]

Well, I bought and installed the digital probe in my tl300. I put it 18 inches above the stove in the double wall pipe.
I bought a 4 and a 2 inch probe, installed the 4.

I started a fire. I was shocked! According to the mag temp gage we were always in the safe zone. With the digital, it got to 900 and set the alarm off before the magnetic gage even moved. I always burned wide open to get coals, but had to move the air all the way down and open the top,, and once in a while shut the damper to maintain temps under 900 in the flue. The mag temp was worthless on the double wall,,

I played around until I got coals. I loaded up a half full load and again, could not keep it under 1000 while getting the wood started. Once I closed the damper, the temps on stovetop came up to 600 as usual. The problem was, the flue burns at 900 to 940 .

Why would the flue stay that hot? Is that normal? We figured out we must have been sending 1400 + temps up the chimney the way we were burning before.

It was a scary thing to realize.

Right this minute, we are on the lowest notch,,running 550 stovetop, with 723 on the digital flue.

Isn't this a lot of heat up the pipe?

 

[shoot-straight]

I know nothing about your particular stove but many things seem off to me. Overall sounds like you have way to much air getting in there.

Thermometer on double pipe? I wouldn't expect that to work.

 

[razerface]

Filled it to the top. Stovetop got to 425, flue alarm went off at 900 deg. I know the full load keeps the heat from getting to the top where the mag temp is in middle of loading door until the load burns down a little. The afterburner was burning. Damper locked closed

 

[1kzwoman]

Have you thought of ash door gasket leaking? Or some internal gasketing failure..my reference is TL200 design stove

 

[razerface]

I just checked the gaskets on a cold stove yesterday. The only one that was suspect at all was one corner on the top lid,,and it had decent drag on the paper.

Moved from 3rd notch to second for overnight, temp on flue dropped to 863, stovetop still under 500

 

[1kzwoman]

My stove has gaskets between internal pieces in front of afterburner. There is also gaskets on damper assembly I believe.
How old is stove? How is it burned 24/7 or less?

 

[1kzwoman]

I found member recommended kindling splits to 550 stove top temps and good coal bed prior to adding larger splits helpful. You might search TL200, or Harman Exception or downdraft stoves
What is your moisture in wood like?

 

[BrotherBart]

900 on startup and 700 cruising ain't an alarm bell on a stove. Especially a downdraft stove where the secondary combustion is happening in that chamber in the back just before it heads up the pipe.

Unless it is the snap together crap from the hardware store the pipe is rated for 1,000 degrees continuous temp.

 

[1kzwoman]

Thank you for signing in BrotherBart

 

[BrotherBart]

I have never had a non-cat that didn't tag close to a thousand degrees connector pipe temp 18" or so above the stove top on a reload. But it drops fast the farther up the pipe that you measure it. Must be the reason UL testing requires the chimneys to endure close to 2,000 for a chimney fire and 1,000 continuous.

 

[fossil]

Magnetic thermometers are pretty much useless on double wall stove pipe. So, you were accustomed to seeing a thermometer that wasn't really telling anyone anything meaningful, then you installed a probe thermometer which displays the temperature of the flue gases inside the stovepipe. I don't understand why you say you were shocked. Rick

 

[fossil]

Right this minute, we are on the lowest notch,,running 550 stovetop, with 723 on the digital flue.

Sounds like yer cruisin'...enjoy. Rick

 

[razerface]

I just loaded. I had to turn the air down to the lowest notch. I tried it like we did before, burning on 3rd notch to get load burning, and temp was at 1350 within less then 2minutes.

1kz, stove is less then 1year old, burned it 2 weeks straight is our longest run. Usually burn from Thursday evening to Sunday night. Wood is 20% or less oak/walnut/ash

So when stove is 600 on top, it is ok for flue to hit 950-1000 when cruising? That is what it takes to heat the place when it is cold(teens)

 

[Seasoned Oak]

My single wall stovepipe measures about 250-400
while cruising on minimum air setting with a magnetic rutland gauge.
.But im measuring temps from the outside of the pipe.An IR gun measures about the same. I also dont let the damper open any longer than necessary. About 30 minutes from a cold stove. The stove can easily overheat with the damper open and yes your stovepipe will get very hot with that damper door open. But the stove produces way more usable heat into the space with the damper closed and the AB active. This stove is designed to spend most of its time with the damper door closed and the afterburner active IMO. One exception is if your using the optional fireplace screen with the front door open in which case you do after the fire is down to coals.

 

[razerface]

But it drops fast the farther up the pipe that you measure it. Must be the reason UL testing requires the chimneys to endure close to 2,000 for a chimney fire and 1,000 continuous.

Maybe I have not got my facts straight yet. I am trying to keep temps under 900 since I installed my new digital probe. I assumed 1200 would turn the pipe red, and when I read the tag on my stainless farther up the chimney, it says "650*C factory built chimneys". It is marked model excel.

That means I could run 1200(650C) constantly?

You say it will take 2000 on a fire, so the 1350 I get for a short time is ok?

 

[razerface]

My single wall stovepipe measures about 250-400
while cruising on minimum air setting with a magnetic rutland gauge.

What does that make your stovetop?

My flue will fluctuate and hit over 900 setting off my alarms with damper closed.

 

[Seasoned Oak]

What does that make your stovetop?
My flue will fluctuate and hit over 900 setting off my alarms with damper closed.

Stovetop varies from 400-650 depending on what part of the burn and the air setting. I use single wall pipe so that extracts heat from the flue gas fast.Tall chimney so draft is strong. When the bypass is open ,you will have flames going right up the pipe so no wonder the flue pipe gets very hot.

 

[razerface]

Seasoned oak, I was considering single wall pipe last night, and I think that is an excellent option for this stove. More heat to the house and cool my flue. I have a 34ft chimney. I have very strong draft, and as you say, flames go right up inside the flue.

I am ordering another probe to install up higher so I can tell temp right before the stainless chimney. I will replace my double wall with single wall after I get done drilling a bunch of holes in the double to learn with the probes.

 

[mellow]

Which digital did you get?

 

[Jags]

Don't gloss over Fossil's post above. Using a magnetic thermo on a double wall pipe, your temp readings might as well be in M&M's. No correlation to real world temps.

 

[razerface]

Don't gloss over Fossil's post above. Using a magnetic thermo on a double wall pipe, your temp readings might as well be in M&M's. No correlation to real world temps.

I am questioning my real world temps taken with a digital probe. I want to find out what is a safe flue temp, as apparently I was wrong before. I do like m&m's,,,,,,




I will research what temps my pipe and chimney can handle, then use those numbers to run my flue. LOL,,It seems nobody wants to spit out any numbers on what is safe, so I'll make up my own. My stove dealer is the same way,,, just hem haws around and says it depends on your house, your stove, your dog, ect. It looks like I may be able to run higher temps then I thought. I am going to call some manufactures and see if they will say out loud how hot their pipe can safely go.

I have been searching threads for info, and see people constantly wanting to know "how hot is safe" in different threads. Most of us are new guys, but nobody ever really nails it down for us, so I am guessing nobody knows! LOL,,or it's a secret!

Mellow, i got the Auber. I just ordered another one to put high up in the pipe. I really like it so far. It has surprised me by what I've seen so far. The biggest thing is how fast the flue gets hot, showing me how short of time I have to get a fire going before I overheat the flue.(if I am overheating it)

 

[mellow]

When you mentioned the alarm I figured you had gotten the AT-100. Those thermocouples are dead on accurate.

 

[razerface]

Mine is AT200CHIM, which looks just like the AT100. I think they packaged the probes and buzzer with AT100 and gave it a new p/n

On edit: i see the AT200 has external buzzer and low temp(reload) alarm the TL100 does not have.

 

[branchburner]

I doubt you have any sort of air leak, but it possible. Fact is, downdraft stoves like Harman ( and Lopi Leyden and some VC models) will have higher flue temps than just about any other EPA stoves, whether bypass is open or shut, due to the burn technology. It's just the nature of the beast.

With bypass open to get a coal bed, there is no baffle to keep heat from shooting right up the flue. With bypass shut to get secondary burn, there is STILL really no baffle system to keep heat from shooting up the flue, other than the top of the AB package itself. The secondary combustion is at extremely high temps within the AB, giving great heat output from the back of the stove behind the firebox, right below the flue exit. So even with a blower/fan to help with heat transfer, a good deal of that heat will be drafted up the flue (more than with cat or tube stoves, and obviously more than enough to keep the flue clean).

Heat lost up the flue is at a minimum with a full load and AB engaged, with primary air shut or nearly shut... in other words, when cruising in low to mid gear. But not so much when starting with a cold stove, or doing a small fire. That why this is a great cold-weather stove but a lousy (IMHO) shoulder-season stove. You are also going to lose a bit more heat up the flue if pushing the stove really hard in super cold weather with lots of primary air.

Unless I'm mistaken, your internal probe temp numbers can be cut in half to be translated into single-wall exterior mag temps. (You are now measuring the gas temp directly rather than the metal temp.) So if your probe is at 700f when cruising, that equates to about 350f on an external thermometer. Sounds about right for that stove, lower if primary air is fully shut, but higher if primary is open. I think 800f is fine when trying blast the heat out in sub-zero temps, but to run continuously at 1000f is too high. You need to reduce the air/draft and accept that a stove will only heat so much house at so low an outdoor temp. I think these stoves are easily overfired when people push them too hard.

And as far as hitting 1400f internal = 700f external (for a very short time ONLY) when getting the fire to temp, also sounds about right for that stove. If you close the bypass and flue temps do not drop much, it probably means the AB did not engage (or you just have too much draft). My trick for getting to AB temp without excessive flue temps is to start the fire at full air, then shut it all the way back while the coal bed forms, then open it back up to full air right before closing the bypass. Then I will step the air down over a few intervals, to make sure I don't kill the secondary.

With a 34ft chimney and very strong draft, you might install a pipe damper as an extra element of draft control (while the other method is to try to adjust secondary air input with a modification, not recommended as it voids the warranty). Even if you rarely or never use it, it might be nice to have the option.

 

[razerface]

Branchburner, you know i did not relate the backwards temperature math. I was thinking my internal gas(air) temps were my markers, instead of dividing by 2 to get the pipe temp. (smack self in head) It is the pipe I am wanting to not overheat, not the air.Thank you!

Does that mean a surface pickup would be better then the probe if it was a fast thermocouple type? Then not worry about air temp,,,just pipe?

I think you may be correct on the pipe dampner needed. When I cleaned my chim a couple days ago, (from bottom)it was sucking the trash bag up the cold chimney.