How & Where to Measure Stove Temps

[Chuck the Canuck]

Howdy all. I had to take my stove door into the shop last week and have the bottom metal glass retainer replaced because it had buckled, and I was afraid that it was leaking air into the stove causing it to run hot. I also insisted on having the gasket replaced at that time because it seemed to have quite a bit of a gap where the 2 ends meet, and again I was worried about it leaking air. Both the gasket gap and the buckled retainer were located in the same general area at the bottom of the door, within a few inches of each other, and the fella seemed to insinuate that the stove was maybe being run a bit too hot, what with the polar vortex and extremely cold weather etc.... But he kindly did it all as a "one-off" thing since the stove was only 3 months old....

So now I'm a little bit worried about how to monitor the burn on my wood stove. The thing is, I get a little freaked out when it starts heading towards 800 degrees F, as read with an IR gun square in the middle of the stove top about 6" in from the flue collar, but at the same time the magnetic temp gauge on the flue barely reaches 400 degrees F during these times. So maybe I shouldn't be reading from the middle of the stove like that? Last night for instance, the middle of the stove is reading around 700F, but out towards the front it reads 620F. The left middle is like 585F, the right middle is 610F, and out towards the front of the stove its still another 20-
30 degrees or so cooler on each side, and the temps were only around 510-520F on the back corners of the stove top.

I wrote to Timberwolf Steel about where I'm supposed to be taking the stove top temp readings from. Here's what they had to say about it all:

The best place to take the temperature reading on your Timberwolf 2200 wood stove is actually on the stove pipe not the stove top.

There are stove pipe thermometers which attach to the upright stove pipe and they will register 150 degrees cooler than the internal combustion temperature of the firebox, which is the important temperature to monitor. As you say, measuring on the stove top is too open to mistake or variable temperatures to be reliable.

You want to run the stove so that the temp on the pipe never drops below 350 or exceeds 500 degrees. The best temp is actually 451 degrees F which gives the best complete burn. You do not want to run the unit to the point where it begins to glow since serious damage to the unit and venting can happen below that temperature point ( aprox 900-1000 degrees) and runs the high risk of causing a chimney fire. As the manual states you should never exceed 700 degrees.
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I've since moved the flue gauge down to 14" from the collar, as per the Timberwolf manual, but Id really appreciate any input regarding this issue as I don't want to be running the stove too hot and wearing it out after only 1 or 2 seasons of use......


Thanks,

 

[pen]

700-800 on the hottest spot of that stove top is about the max you want to see on a regular basis (IMO). Really, 700-750 as a redline would be better

Put the thermometers where you like them on the unit and they will measure temps for that location. I consider 750 the redline, but my thermometer shows 650 as the redline on it. To keep things simple, I just moved the thermometer to a spot that generally reads 100 degrees cooler than the hottest spot.

That way the "redline" on the thermometer is still reading what I consider the redline to be on the hottest spot of the stove,,,, and there wouldn't be any confusion if someone who doesn't run the stove often were to operate it.

I did the same with the stove pipe thermometer, just moved it around until it was in a location where the redline meant something. The problem with thermometers is that they are a one size fits all, it would be like every vehicle on the road getting the same tachometer.

 

[Backwoods Savage]

I would seriously question 150 degrees cooler. Not sure how they came up with that but on our stove, we can be, say, at 650 degree stove top and the flue (measured on horizontal single wall) will read around 300-350 maximum. Most modern stoves will run a lot cooler flue than stove top. The big concern is that the flue temperature not get too low as you do need some heat in there.

I too would be nervous getting a stovetop to 800 but many do that and even higher. But I would say that should be the highest anyone should aim at with a steel stove. Our soapstone says 700 tops but we do know many have had higher temperatures. No doubt there are tolerances built in but it is still best to follow manufacturers recommendations.

As for running the stove too hot, if so, thing will be warped and you may even see some white spots showing through the black. He no doubt was stating that as a cover because no doubt some have run their stoves super hot in order to keep the house warm. Did that cause the problem you had? I suppose it is possible but if he really thought you were over-firing the stove, I highly doubt he would be doing the work free of charge.

Rest in peace tonight Chuck.

 

[Chuck the Canuck]

700-800 on the hottest spot of that stove top is about the max you want to see on a regular basis (IMO). Really, 700-750 as a redline would be better

Up until now, if the stove went anywhere north of 750F in the hot spot I would simply turn on a fan that I have sitting in the basement and run it straight across the top of the stove. Usually takes about 10 minutes to get it back down to 680-690 and then I would switch the fan off (stove top slowly drops over time after the fan is turned off). But the thing is, the hot spot pretty much always heads up towards 700-750 when the secondaries kick in...... especially since I've started burning the smaller wood (stuff I usually make my bundles with) that was supposed to be for just in case I ran out of good wood....

 

[Chuck the Canuck]

He no doubt was stating that as a cover because no doubt some have run their stoves super hot in order to keep the house warm. Did that cause the problem you had?

To be honest, I don't really know how it happened. I don't even know when it happened. One evening I was sitting watching the fire and I thought there was a lot of flame down at the bottom of the door area, so before reloading I thought I'd look at the door gasket and see if it was deteriorating; that's when I noticed that the steel glass retainer had buckled. But hey, I'm sure it must have buckled because it got too hot, right? But why or when? I don't know. I'm a total newb with a wood stove. I've probably burned it too hot a time or two before I started watching out for that sort of thing. And then I wonder about that week or two when I thought it was a good idea to leave the door open just a crack for 10 or 15 minutes to get the fire going; it sure looked like a torch doing a sort of sling shot thing down the side of the stove and around the front side of the wood... maybe that was when the metal buckled???

But hey, I'm getting smarter now... I think.... maybe....

help

 

[Chuck the Canuck]

So here's how I relit the burn tonight. I loaded the stove, packed it in as tight as I could (not as full as I could, just as tight as I could) with smaller, less than ideal splits.
Sides caught immediately from the coals and the wood started burning, shut the door with the air open full, and let it get burning good.
I usually let it burn with the damper fully open until it reaches 350 on the flue thermometer, but tonight I started shutting it down (50%) at 300 F on the flue.
I had the damper fully closed in around 5 minutes, as the wood was fully engulfed and burning very well.

Here's the results:
The hotspot on the stove top seems to be holding at 675 degrees F.
The flue thermometer seems to be holding steady at 340 degrees F.
Lots of good secondary action, maybe a bit more than I'd like, but it seems to keep building once I've shut the damper down full.....

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As I watch the burn I can't help but wonder if the stove is still leaking air from somewhere? Any feedback?

 

[pen]

Sounds about perfect to me.

That black in the lower left corner happens to me occasionally if I have the air down pretty good on a good sized load, however it clears up later in the burn. This happens due to the air wash air being in a small amount with the air turned down low, and a full load of smaller splits outgassing pretty good just makes a recipe for a deposit there. If it that corner cleans up on its own later in the burn, then I see nothing to be concerned about. If it persists and is still black in the morning, then I'd be apt to think there was an air leak in that corner.

Well done.

 

[Chuck the Canuck]

Thanks Pen. I just checked the stove again.
The hotspot on the stove has climbed to 695 degrees F and
The flue thermometer has inched up to 350 degrees F.

Although overall, the burn doesn't have the appearance of going nuclear....

 

[Chuck the Canuck]

I'll keep my eye on the corner, although I'm pretty sure that the black spot is a regular occurrence and clears up over the course of the burn.

 

[Chuck the Canuck]

OK, all is good. The stove top is coming back down on it's own (it's at 680 F now). I guess I really am just learning how to operate this little stove.

Thanks for all the help.

Cheers,