Took a road trip today. I stopped by Northern Tool and picked up a Vogelzang stovepipe thermometer, then went to Harbor Freight and picked up one of the cool laser non-contact thermometers and a moisture meter. Got back home, preheated the oven to 400 and placed the stovepipe thermometer on a cast iron skillet in the oven. I then went to check my wood moisture, and found that I got about 19-21% on the inside. When I got back the stovepipe thermometer was over 500, but the laser one and my meat thermometer both showed the skillet was within 10 degrees of 400. I think the one I got from Northern Tool is way off. I would return it tomorrow, but it's over an hour away.
Thermometers: accurate?
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Highbeam
Minister of Fire
In checking your stove thermometers against the oven I would caution folks to use the 350-400 oven setting since the oven's thermostat was optimized for baking which is not usually done above 450. 400 is a great check temp.
Brian VT
Minister of Fire
I've notice many posts saying that many (all?) of these thermometers are reading 100 deg. high when put in an oven.
I wonder if the air surrounding the them in the oven is the reason. Do they still read high when mounted to a surface that's been checked by an IR thermometer ?
Just curious. I realize these magnetic types are not precision instruments.
I wonder if the air surrounding the them in the oven is the reason. Do they still read high when mounted to a surface that's been checked by an IR thermometer ?
Just curious. I realize these magnetic types are not precision instruments.
Highbeam said:
I also checked mine on the 300 degree setting. It was not off as much, but still reading about 75 degrees high.
Mine was on a black cast iron skillet I use to fry eggs. It does not have the big sides like most skillets, but just a little lip. I left everything on for about a half hour to make sure the temps were stable. I put my meat thermometer on the skillet as well. The meat thermometer and the laser one were real close, but the magnetic one was way off
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I check my magnetic stove thermometer with an ISO 17025 calibrated thermocouple and Fluke gage. It's probably a bit overkill.
Of course, not that bad when you consider one of the technicians I work with uses one on his grill when he barbeques. And everyone wonders why you can never find a Fluke at work here when you need one.
Of course, not that bad when you consider one of the technicians I work with uses one on his grill when he barbeques. And everyone wonders why you can never find a Fluke at work here when you need one.
uh I wouldn't be trusting your oven temps. Read an interesting article awhile back saying that oven temps can easily be off +- 50f in popular name brand stoves including high end ones.
The article suggested you calibrate your oven with (drum roll) an oven proof thermometer.
My brand new dual fuel GE range's manual tells me how to calibrate the oven as it may not be accurate for baking. Nice to know that...
When I went to purchase a small thermometer for avy work, I noticed a +- 3C variation in around 20 identical mercury units. Temp is critical in avy science and this is just stupid variation. I think it is more the bad number placement and not the mercury. I guess you get what you pay for.
The article suggested you calibrate your oven with (drum roll) an oven proof thermometer.
My brand new dual fuel GE range's manual tells me how to calibrate the oven as it may not be accurate for baking. Nice to know that...
When I went to purchase a small thermometer for avy work, I noticed a +- 3C variation in around 20 identical mercury units. Temp is critical in avy science and this is just stupid variation. I think it is more the bad number placement and not the mercury. I guess you get what you pay for.
MotoBoyMatt
Member
ScottF said:
A friend of mine put a motorcycle crankshaft in the oven to aid in removing the bearings, he then used a deep fryer full of 10w30 to heat the new bearings prior to pressing them on. I'm not sure how he is still married.
Redox
Minister of Fire
Okay, I've read many posts about thermometers, for both stove top and for flue. As with many others I'm concerned that my thermometers aren't reading true. Here are some facts before I continue...
1. All the thermometers are bimetal.
2. The bimetal spring itself is not in contact with the heated surface.
3. The temperature being measured is at the point of contact.
4. There is transfer by conduction via contact, both metal and air, although not necessarily by the same amounts.
5. There is transfer by radiation through the air.
This post isn't concerned with probe thermometers, only surface mounted.
I suspect my thermometers aren't reading accurately. I've one made by Condar and two labeled Meeco Red Devil. The Condar is supposed to be for flue temps, and according to the company rep I spoke to, is not for stove top because high stove top temps may cause the thermometer decoration (letters, scale, etc.) to degrade/peel. The Meeco's I've used on both stove top and flue.
My oven, I believe, is accurate at 350F. I've acquired a well reputed oven thermometer (uses an alcohol filled glass tube), not once, but twice (nylon pad removed the scale on the first), and both say my oven is good at 350F. This may not be lab accurate, but for the purposes at hand I think it's good enough.
I put my thermometers in the oven, along with my oven thermometer, and set it at 350F. Once it reached 350F I let them sit there for 30 minutes, then checked the results.
Stove: 350F
Oven thermometer: 350F
Condar: 410F
Meeco: 480F-490F (both read the same)
Here is my question? Is the oven a reliable method of checking the reading of the thermometers? I believe it is.
Wood stove dealers and manufacturing reps have told me "Oh no, you can't do that.", and I wonder why not? They say the thermometers measure surface temperature, not air temperature. Well, that may be true in use on a stove top or flue with ambient air flowing around everything, but in an oven that is at temperature, temperature is temperature. If the inside of the oven is at 350F, then everything is; air, metal, porcelain, etc., including the thermometers. Therefore, to my thinking, the thermometers should all read the same, in this case, 350F.
I too know that oven temps from the factory can differ by a significant amount. I bake, I cook, I like an oven that is what it says it is. Mine is calibrated very closely to 350F, close enough that I can rely on it for fairly fussy baking. I also know that positioning in the oven can make a difference, so in this case I put everything in the center, gathered all together so that the difference in degrees due to location was minimized.
Some have told me that thermometers are calibrated to measure a temperature other than what the actual contact temperature is, but if that is true, how can it be reliable. The differences are as many as there are stoves on the market, no longer on the market, made by DIY's, etc., not to mention all the different locations it is possible to put a thermometer. In other words, unless you are using a probe, which is not under discussion in my post here, you can't trust a surface thermometer as an indicator of interior temperature unless it is calibrated at manufacture for a specific location on a specific model of stove, unless you have measured it yourself, or unless through experience in operating your stove. With that in mind it seems to me that a surface thermometer needs to report the temperature of the surface at the spot it is mounted, nothing more. If that is true, then testing in an oven should be fairly reliable.
Comments please...
1. All the thermometers are bimetal.
2. The bimetal spring itself is not in contact with the heated surface.
3. The temperature being measured is at the point of contact.
4. There is transfer by conduction via contact, both metal and air, although not necessarily by the same amounts.
5. There is transfer by radiation through the air.
This post isn't concerned with probe thermometers, only surface mounted.
I suspect my thermometers aren't reading accurately. I've one made by Condar and two labeled Meeco Red Devil. The Condar is supposed to be for flue temps, and according to the company rep I spoke to, is not for stove top because high stove top temps may cause the thermometer decoration (letters, scale, etc.) to degrade/peel. The Meeco's I've used on both stove top and flue.
My oven, I believe, is accurate at 350F. I've acquired a well reputed oven thermometer (uses an alcohol filled glass tube), not once, but twice (nylon pad removed the scale on the first), and both say my oven is good at 350F. This may not be lab accurate, but for the purposes at hand I think it's good enough.
I put my thermometers in the oven, along with my oven thermometer, and set it at 350F. Once it reached 350F I let them sit there for 30 minutes, then checked the results.
Stove: 350F
Oven thermometer: 350F
Condar: 410F
Meeco: 480F-490F (both read the same)
Here is my question? Is the oven a reliable method of checking the reading of the thermometers? I believe it is.
Wood stove dealers and manufacturing reps have told me "Oh no, you can't do that.", and I wonder why not? They say the thermometers measure surface temperature, not air temperature. Well, that may be true in use on a stove top or flue with ambient air flowing around everything, but in an oven that is at temperature, temperature is temperature. If the inside of the oven is at 350F, then everything is; air, metal, porcelain, etc., including the thermometers. Therefore, to my thinking, the thermometers should all read the same, in this case, 350F.
I too know that oven temps from the factory can differ by a significant amount. I bake, I cook, I like an oven that is what it says it is. Mine is calibrated very closely to 350F, close enough that I can rely on it for fairly fussy baking. I also know that positioning in the oven can make a difference, so in this case I put everything in the center, gathered all together so that the difference in degrees due to location was minimized.
Some have told me that thermometers are calibrated to measure a temperature other than what the actual contact temperature is, but if that is true, how can it be reliable. The differences are as many as there are stoves on the market, no longer on the market, made by DIY's, etc., not to mention all the different locations it is possible to put a thermometer. In other words, unless you are using a probe, which is not under discussion in my post here, you can't trust a surface thermometer as an indicator of interior temperature unless it is calibrated at manufacture for a specific location on a specific model of stove, unless you have measured it yourself, or unless through experience in operating your stove. With that in mind it seems to me that a surface thermometer needs to report the temperature of the surface at the spot it is mounted, nothing more. If that is true, then testing in an oven should be fairly reliable.
Comments please...
Milton Findley
Feeling the Heat
I have a bimetallic contact thermometer on my flue pipe. It says that I am always in the creosote range. But it apparently lies about that given the chimney cleaners experience last spring. The IR thermometer is more accurate I think, and the laser entertains the puppy.
Scott2373
Member
woodmiser
Feeling the Heat
Picked up a PID temp controller with LED readout and a thermocouple for just over $50. Reads up to 2370F with a K probe. I'm calling Hearthstone tomorrow about drilling and tapping 1/4-20 for the TC. There already is a 5/16 tapped hole for teh draft meter and it doubles as the top grate support (with a set screw installed) on my Clydesdale. The controller will run on 120VAC so it will be hard wired into the fan power. All you will see when it's done is the LED down in the lower corner of the stove tucked under in the gap between the hearth, the insert and the surround.
That one only reads up to 572F
Scott2373 said:
That one only reads up to 572F
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Scott2373
Member
It's ok if it only reads to 572° because my stove top only needs to be around 385° when it's ready to roll. My stove has a large air space between the box and stove top plus the baffle in there as well. I won't be getting the 600°+ temps on top like many burners here due to the design of the stove.
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