Where to place stove thermometer?

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79bombi

New Member
Oct 13, 2009
6
Maryland
I bought a Rutland Stove Thermometer for my new woodstove. On the single wall flue I am getting creosote temperatures according to the gauge on the thermometer with the damper closed but on the stovetop the temperatures seem fine with the damper closed and air control turned down a little. There seems to be a large discrepancy between the temperatures using the two different placements. Which one is correct?

I am a little paranoid as I am trying to correct a glazed creosote problem my old enlander catalytic stove was producing. Wood is 20% or less.
 

bluefrier

Feeling the Heat
Jul 3, 2008
325
Maryland
What kind of stove? Put it in your signature. Personally, I don't measure pipe temps because my stove is tucked away in a fireplace. If you are running a steel stove 400 - 600* stove top should yeild clean burns. Also newer stoves will run at lower pipe temps. If the chimney is not smoking I would'nt worry about creosote.
 

79bombi

New Member
Oct 13, 2009
6
Maryland
It is a Harman TL300.
 

firefighterjake

Minister of Fire
Jul 22, 2008
19,407
Unity/Bangor, Maine
First off, as you may or may not know, chimney thermometers are notorious for not always being entirely accurate . . . some makes/models can be way off. I will give a plug to Condar's thermometers (I have the stove top and a probe for my double wall) . . . there is no real way for me to check the accuracy of the flue probe thermometer, but the IR gun confirms that the stove top thermometer is right in the ballpark.

Second, what temps are you seeing on the thermometers?

Third, what you're saying kind of makes sense. With my stove and set up when the air control (no damper in my flue) is all the way open I tend to get a lot of heat up the flue and some heat in the firebox . . . however, once my flue temp is high enough (400+ with the probe thermometer) I start to cut back the air and the stove top temp begins to rise, while the flue temp either stays the same or sometimes drops a bit.

Perhaps what you should try is to get the flue temp up to the mid-range (i.e. hot enough to reduce creosote production, but not hot enough to start a chimney fire) . . . and then use just the stove's air control and start shutting it gradually in 10-15 minute increments and see if this doesn't get the stove up to its optimum temp (whatever temp that the manufacturer says is good) while keeping the flue's temp in the "zone." To me it would make sense that your stove top temps would be fine with both the air control and damper shut down since you're "trapping" the heat and heated smoke in the firebox . . . but perhaps at the expense of allowing the flue to run too cool. Try just using the air control on the stove without the damper and see what happens. It's a fine balacing act with the temps -- getting the maximum BTUs from the stove to warm the house and not allow too many BTUs go up the chimney, but at the same time keeping the flue warm enough to prevent creosote production.

Let us know what you find out.

And by the way, welcome to the forum . . . but you do have to tell us the meaning of the name.
 

firefighterjake

Minister of Fire
Jul 22, 2008
19,407
Unity/Bangor, Maine
I just realized I didn't answer your first question. Where do you place the thermometers. Most folks follow the thermometer's recommendations (well the manufacturer, not the actual thermometer's recommendations) to place 18 inches up on the flue.

As to where to place a thermometer on the stove . . . easy advice is to say follow the stove manufacturer's suggestion since they vary from makes and models. On my Jotul for example, the company suggests any one of the four corners . . . but other stove manufacturers may have you place the thermometer in the center, on the front, etc. It is also worth noting, that while Jotul recommends any of the four corners on the stove top, I have personally found a significant temperture difference between in temps between these four corners with the rear, right corner consistently being hotter . . . my belief that this is due to the fact that ash tends to pile up there and the wood that I load is therefore closer to the firebox top and hence closer to the thermometer.
 

Drumaz

Member
Jul 23, 2008
108
NW CT
I was thinking about getting a flue probe and running it along with the stovetop. I too get inconsistent readings on the four corners of my Jotul. I'm always concerned about the stove temp and almost obsess over it when the stove is running. 2 readings is better than one. Any good flue thermometers out there? I imagine I'd need the kind with the probe as it's double wall pipe.
 

firefighterjake

Minister of Fire
Jul 22, 2008
19,407
Unity/Bangor, Maine
Drumaz said:
I was thinking about getting a flue probe and running it along with the stovetop. I too get inconsistent readings on the four corners of my Jotul. I'm always concerned about the stove temp and almost obsess over it when the stove is running. 2 readings is better than one. Any good flue thermometers out there? I imagine I'd need the kind with the probe as it's double wall pipe.

The obsession will pass eventually . . . eventually you will reach a point where you will check the temps just to keep an eye on things, but you will not obsess over the numbers. Don't worry too much about the temp difference in the four corners . . . just ball park the numbers and you'll be fine.

Flue thermometers . . . yeah, you guessed right . . . for accurate readings you will need a probe thermometer with double wall pipe. I've had good luck with my Condar . . . but then again I don't really have anything to compare it against.
 

spirilis

Minister of Fire
Sep 8, 2009
940
Baltimore, MD
Just adding, if you get a flue pipe probe thermometer, give it the oven test first... I bought two Condar flue probe thermometers for my 2 woodstoves, and both were WAY off (reading ~1600F in the kitchen oven when it was set to 450). Just sayin', test it beforehand.
 

79bombi

New Member
Oct 13, 2009
6
Maryland
When I first made my post I read the directions for the Rutland thermometer and it said you could use it on the flue pipe or on the stove top. I am thinking there should be two diffrent ranges - 1) for the stove top which is much hotter and 2) for the flue which on my stove is cooler. As I am worried about my glazed creosote the cooler readings I was getting on the flue pipe were bothering me. Bottom line after another week or two I will check the flue to see how it looks.

79bombi is the small snowcat I own which I restored.

m7.jpg
 

freeburn

Feeling the Heat
Jan 5, 2008
391
USA
I'm resurrecting an old post in an attempt to get an answer. I've got one of those cheapo Rutland flue thermometers. I stuck it in the oven and set it at 400. The flue didn't move. Do you have to let it sit in there for a while? The oven is done preheating, and still same place? Does that mean REplace, or what?

EDIT: It was stuck, as soon as I touched the temp arrow it shot up. It reads 50 degrees higher than actual temp. I guess I'll keep it.
 

Valhalla

Minister of Fire
I certify my stove thermometers at the beginning
of every season in my wife's electric oven. Set it at
450 F. Then place all on a scrap piece of 3/8 " steel plate in the oven.
You can also use a cast iron griddle or pan.
I verify it all with a Fluke IR thermometer to match the electronic
oven temp actual reading, not the oven set reading.

Any found more than 25 +/- degrees go in the trash.

I then place one each, on the stove machined griddle
surface, stovetop castiron surface and another 12" up the
flue from the stove.

The wife calls it wood stove Mission Control!
 
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