Question About Insert Operating Temps & IR Thermometers

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Famer

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Hearth Supporter
Aug 18, 2008
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NJ
It's gotten pretty chilly here the past few nights (lows in the 30's) and I've been running my newly installed Kennebec C450 to avoid having to fire up the furnace. I've been doing OK with it - fires start up fast, no smoldering problems, it's been kicking out some good heat and I'm pretty sure I've had some secondary burns going.

Maybe I'm expecting too much too soon, but I haven't been able to sustain temps much higher than 450 degress. Mind you, this is the reading I get with an IR thermometer pointed at the top center of the box - a very small area that extends beyond the top of the fireplace - as I have the insert mounted as flush as possible.

Are the IR thermometers typically not very accurate? Or should I expect the temps measured at that location to be less than what the "real" temp is? Do I need to wait for it to get a little colder outside so I get more draft going and hotter fires?

I've been using good, dry wood (almost all of it under 15%, based on my moisture meter) and have been gradually reducing the air once it really gets going. From what I've read, it seems like 500-600 is a good operating range, but I've barely been able to get it to 500, and when I have, it hasn't lasted very long.

I know there are lots of variables to consider and I know this is a learning process…but am I doing something wrong?

Thanks!
 
Yep...the blower is on and the spot I try to hit with the IR thermometer is up behind the top opening of the doors. I try to point it back as far as I can get it. So, maybe I'm not too far off base with how I'm operating it so far. Phew. Being new to this I know it'll take some time to scale the learning curve, but at the same time I want to make sure I'm not overlooking anything.

Thanks for the reply!

Go Phillies!
 
I don`t have the IR thermomoter just the magnetic that sits on top of my insert. Rarely am I able to get the temp up over 500F. Usually it runs between 300 and 450. Really am doubtful as to it`s accruacy. But here is the thing-have never had glowing red steel, and also after burning 20/7 for the past 9 days the glass is still nice and clean. My advice is to just use the therm`s as a rough guide. If you are burning too hot, you will see it. Burning too cool--the glass will let you know. :)
 
Thanks guys for the replies!

My glass is pretty clean, no glowing metal and it's been keeping the family room and kitchen toasty warm. It's even been able to drop the temp on the second floor by a couple degrees the past few evenings. So, maybe I'm doing OK.

I guess I just had a number stuck in my head and was figuring I wasn't doing something right since I didn't seem to be getting too close to that mark. I'm relatively new to this, so I just wanted to make sure I wasn't missing anything.

Thanks again...and Go Phillies!
 
Famer said:
...I've been using good, dry wood (almost all of it under 15%, based on my moisture meter)...
Click to expand...

Measured where? I have a load I cut in May and split in June that measures 15% on the cut ends, and 17% on the sides. But if I split one of these quarter rounds in half, and measure the fresh interior surface, it reads 30%! A split from an older load reads 15% through and through. So one of these splits is probably 25%, and the other truly 15%, though they both read about the same on the "outside". I can sure tell the difference when I burn these. Just can't get off the ground with the wet one, while the dry one is engulfed in flames before I can even close the door.

My truly 15% wood has these features:
Bark is loose or pulling away from the wood.
Ends are really well checked.
Split feels not too heavy.
Sounds like a baseball bat when struck.
Bursts into flames when put on a bed of active coals.
 
I've split a number of pieces from the same load and have't seen anything over 25% on the inside of the split. The kids get a kick out of checking the splits before we put them on the fire and those measurements are usually below 15%. That, along with the fact that wood is lighting up right away and I'm not getting any hissing, crackling or popping would lead me to believe I'm using pretty good wood. It's be split for well over a year and stacked in my back yard.
 
You're doin fine. Wait until the outside temp really drops, that stove will draft better and you'll see some higher temps. I also hav the c450 and have a magnetic thermometer on the top of it, just behind the doors under the little round cross bar. Its a tight fit but I'd jam one in there if I were you. Nothing against the IR guns, just nice to have it there all the time. Even if it isn't dead accurate it still serves as a good reference.
 
Yeah...I'm thinking it'll really start cranking once the weather gets a bit colder. Hard to believe it, but I'm actually looking forward to the cold this year. It's supposed to go below freezing tonight and I can't wait to get home and get a fire going.

Dry wood has been the key. We started last year with a VC Aspen in our sun / three-season room. We really struggled with it and as I've since learned it was due to wet wood. We're using the same "stock" this year and it's amazing what a year of drying time can do. It's working great in both the Aspen and the Kennebec.

Time to head home and get that fire started. :-)
 
Gauging stove temp depends on having an accurrate thermometer and putting it in the right spot. With wood at 15% and your draft all the way open you should be able to turn your stove cherry red....Could be a draft problem. Have you checked your spark arrestor screen on your chimney cap? My first guess would be a block in the draft at either end of your system. If you were a new burner I might suggest wet wood, but at 15%....thats tinder or almost. Maybe try a fire with just a lot of kindling and see if you can drive the temp up very fast to a temp of 600 degrees or so. If you are not successful with this mehod...I would say you have a draft problem at either end or even in the middle as Be Green suggests.
 
I think my draft is OK. I can get the fire to start up no problem and the area of the wood that's directly across from the air intake for the box seems get eaten away really fast. So I think I have decent air flow - even with it only being in the low 40's right now. But I'll see what happens and keep an eye on things as I get a better feel for the stove.
 
Just started my C450 Kennebec up again. Used all spruce, nothing bigger than my wrist. Criss crossed load. 2 sticks in a V pointing in at the bottom, East -west layer on top, then layers with all the way up until it almost touches the reburn plate. Add paper, and birch bark in front near the air inlet, light the paper and shut the door. 15 mins later - 750 degrees and the blower didn't even start up yet. Thermometer is as close to the outlet as I can get it (My Kennebec is fully extended into the room). When I moved the thermometer forward to the edge nearest the door, I get about a 100F temp drop.

All that, and I do have a draft problem, as mine is installed on a 5 inch flex - getting that changed in a couple weeks according to the installer who did it wrong the first time (but that is another thread....)

Next time I start it up, Ill move the thermometer closest to the front near the doors, and let you know what I see.
 
bokehman said:
JoeyJ said:
With wood at 15% and your draft all the way open you should be able to turn your stove cherry red.
Click to expand...
Cherry red <= 1500ºF. With most stoves having the draft all the way open keeps them from warming up.
Click to expand...

I don't what kind of stove you burn bokehman, but opening the draft heats up a stove...always
 
Re: IR temps on glass: I get the same temps generally as bokehman, but I have to say I go higher, over 900 at times.
I guess it's showing the temp on the glass, but it must not hold the heat much since it reacts pretty quickly when the flames go down.
 
Your IR gun should be in the neighborhood and give you an idea of the temp. More accurate (and expensive) guns allow you to change the emissivity to match the material you are trying to read the temp of. That'll get you closer to 1% of the actual.

I wouldn't use it from the couch, but within about 3 feet. Sounds like that's what you are doing, but if not keep in mind that the farther away you are the wider the surface area its measuring and you could be reading more than the temp of your insert.

One way to test how accurate your gun is - well at least at measuring the temp of water is to fill a bowl with ice water and try and measure the water surface temp. Should be real close to 32°. Then boil about 1/2" deep pot of water and measure the water surface. Should be darn close to 212° depending on your altitude.
 
JoeyJ,

I burn a Summit and I'm with Bokehman on this one. My stove heats up after I start shutting the air down and let the Secondaries kick in. I guess I could leave the door open a bit and get it to really heat up, and it might get hot with the primary open for a whole load of wood, but in normal use the temperature shoots up when I close the air down.
 
Just ran my Kennebec again, this time with thermometer all the way forward nearest the doors - temps read the same after about an hour (650-750) , but it doesn't have the same response time - moved the 'meter back next to the outlet, and it rose immediately to 750 F.

As for the draft heating or cooling, on my stove it depends on what phase of burn I'm in - more air early and the stove heats up, more air later (after moisture is evaperated and off gassing started), and it cools some.

It's all relative to the phase the burn is in.
 
Thought I'd pass along a quick update on this...It got pretty cold here last night and before my last re-load, I made a channel in the coal bed in front of the air input to the stove (pushed some coals to the right and some to the left) and loaded it up pretty good. I forget where I read that tip about making the "channel" for the air flow (on this forum somewhere), but it seemed to work really well with my stove.

It was the first time I've been able to get a secondary burn going with the air shut down all the way and it was holding steady around 500 degrees (with the blower on). It was almost time to hit the sack, but it was going so well that I stayed up a little longer just to watch it burn. Can't wait to try it again tonight!
 
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