IR "Gun" Thermometers

[Creek-Chub]

Ok, so I broke down and bought a cheap IR thermometer from Harbor Freight. $30. I've got the 30-NC running with a fresh load, and am getting wildly different temps when I take a reading. My Rutland stovetop thermometer seems to be fairly close to it when I shoot the IR right beside it, so I'm thinking I've just got a bit to learn. The Rutland, located near the center of the top of the stove, is showing 550. Shooting the IR beside it is pretty much the same temp, but when I move it to dead center of the stove I'm up around 900 degrees. Towards the outside of the stove it slowly goes down to 300 or so. Shooting inside the stove, through the glass, gives me 800 or so depending on where I shoot.

When you guys with IR's take a reading inside of the stove, what are you shooting at?

At the very least, this is making me question the temp readings I have come to sort of rely on, not to mention the posts we hear about "I run my stove at "X" temp", or "I get this beast to run at 650 degrees for hours on end". I'm starting to think that it's all relative, and that if you're too concerned about temps, and not how the stove is acting, that you're missing the real boat.

Thoughts?

 

[pen]

Agreed! It really is all relative unless you are running the exact same stove as another, with the exact same wood, the exact same chimney, with the exact same thermometer (as if they were accurate to start) in the exact same location, in the exact same universe.

Essentially, in my mind, there are way too many variables to control here. With that said, I use my thermometer on my stove top and on the chimney pipe as a "guide". It lets me know where I am at but I really don't pay much attention to the numbers. I just use it for consistency purposes. REally, the same setup with a Cold Warm and Hot setting with dashed lines in between would be just as effective. I tell how I burn by the heat given off, the look of the exhaust out the chimney, how long the burn lasts, and what is deposited in the chimney. Course, that takes some getting used to to have a baseline. I suppose common sense should reign in the meantime.

pen

 

[Corey]

Welcome to the wonderful world of stove temp measurement. Yes measuring different types of stoves, with different equipment, in different locations at different times - all give different readings - so it is a little bit of black art. (and we wonder why auto manufacturers started using gauges with 'C' at one end, 'H' at the other and EVERYTHING in the middle is 'Normal')

The 550F seems about normal. I have seen 900-950 on the top center of my insert, under a pretty hard burn, looking directly at the top sheet of the firebox where the fire curves around the baffle and hits the sheet on the inside. But it's almost too hot to hold your hand within 12 inches of it, so I'd consider that pretty HOTTT!

IR guns can be affected by quite a few things - the amount of surface in the 'field of view' which is generally averaged to give the temp reading - the emissivity of the surface or how it 'shines' in IR light. A flat black stove is ~.95 but shiny metal surfaces and glass can be all over the place. Of course the calibration of the gun and how close you are to it's top range and probably a few additional things I've left out.

Overall, I'd use it as a guide for what levels of burning you're at as opposed to an exact temperature measurement.

 

[fbelec]

use it on the spot that the stove manuf. tells you to put it. it should say in the manual, if not shoot the company a email.

 

[Ratman]

Ok, so I broke down and bought a cheap IR thermometer from Harbor Freight. $30. I've got the 30-NC running with a fresh load, and am getting wildly different temps when I take a reading. My Rutland stovetop thermometer seems to be fairly close to it when I shoot the IR right beside it, so I'm thinking I've just got a bit to learn. The Rutland, located near the center of the top of the stove, is showing 550. Shooting the IR beside it is pretty much the same temp, but when I move it to dead center of the stove I'm up around 900 degrees. Towards the outside of the stove it slowly goes down to 300 or so. Shooting inside the stove, through the glass, gives me 800 or so depending on where I shoot.

When you guys with IR's take a reading inside of the stove, what are you shooting at?

At the very least, this is making me question the temp readings I have come to sort of rely on, not to mention the posts we hear about "I run my stove at "X" temp", or "I get this beast to run at 650 degrees for hours on end". I'm starting to think that it's all relative, and that if you're too concerned about temps, and not how the stove is acting, that you're missing the real boat.

Thoughts?

Return the gun and take your wife out to lunch.
Problem solved.

 

[Creek-Chub]

I'll consider taking my wife to lunch, but there's no way I'm returning the gun. Do you have any idea how much fun this thing is? I'm constantly wandering around the house shooting things with it. Stove, doors, nostrils, my wife's butt (Honey! It's saying your butt is 270 degrees! Man, that's hot!) Take it back? Not a chance.

 

[BrotherBart]

My 30-NC always runs hotter on the upper step. Measured with a magnetic thermo or the IR gun. But only around a hundred degrees hotter. Make sure the baffle boards are pushed together in the center. If the exhaust is escaping between them instead of at the front if will get damned hot on the upper step. The normal temp difference I have always attributed to the flame arresting flange welded to the stove top right in front of the flue exit. The hot gases headed for the flue slam into it and then go around it.

 

[Creek-Chub]

Bart - that was the culprit. I end up having to slide them together once a week or so when she's going steady. You even thinking about sticking some kaowool or something on top to help out? On a side note, I happened to notice mine are pretty chewed up after one season. Mostly from operator error when loading, I'm sure, but they're starting to potato chip a little too. Yours still in good shape? Englander wants an arm and a leg for new ones...

 

[BrotherBart]

Bart - that was the culprit. I end up having to slide them together once a week or so when she's going steady. You even thinking about sticking some kaowool or something on top to help out? On a side note, I happened to notice mine are pretty chewed up after one season. Mostly from operator error when loading, I'm sure, but they're starting to potato chip a little too. Yours still in good shape? Englander wants an arm and a leg for new ones...

I had some kiln elements just the size of the extra space. I bought a stainless steel rod for a couple of bucks at the hardware store, slid it in the kiln element cut to length to hold it straight and lay it on the left side when I put the boards back in after cleaning. If you just want to hold them together just put a stainless hose clamp on the second or third burn tube far enough in to hold them together.

I dinged the boards up the first season before I tossed my poker in the basement and just went with using my homemade ash rake and tongs. That and since I quit stacking splits higher than the brick retainers has made it where I haven't dinged it since then. I have found the burn times the same as trying to pack it to the roof and leaving the room up top gives the gases a good place to burn.

Yeah the price they get for those things is nuts. Not to mention the shipping charge. Corie has looked at the performance hit from having the boards not wide enough to fill the space but never has said anything since. I would guess that the boss reminded him how much re-certifying the stove would cost after a component change.

 

[Creek-Chub]

Sounds pretty simple, but I'm not following the hose clamp idea. Help?

Edit:

I've got it now. The hose clamp shoves both boards to one side, and the kiln elements take up the extra space that would have been a void. Now I just have to find some high temp something or other to fill that void...