Thermometer Choices

I just put a magnetic thermo that I was given on my stove.... just for grins and giggles.

I normally check my temps using an IR gun.

Magnetic = 200

IR Gun = 275

Any questions?

blrman07 wrote:I just put a magnetic thermo that I was given on my stove.... just for grins and giggles.

I normally check my temps using an IR gun.

Magnetic = 200

IR Gun = 275

Any questions?

Yes, Rev. Why not bend the needle on the magnetic 75 degrees more ? Then there'll be thermometer harmony in your house.

I lucked out with the Rutland magnetic I bought at the local hardware store eleven years ago. It very closely matches what the IR gun reads over the usual range of pipe operating temps. But I wouldn't be surprised if I need the assistance of needle nose pliers to do some fine tuning if I bought another one.

Paul

An IR gun still only reads flu pipe surface temperature and I do believe they at one time in our history made surface temp thermometers that read accurate enough . But I am covering a wide footprint of readings here I think with and IR thermometer, Mercury filled temp gauge, two thermo couples , and magnetic thermometers .

My point about the whole deal is reading the surface temps doesn't really relay good information about how the stove is accurately performing .

We are talking about a firepot pushing well over 1000° and flu gases reaching from 300-400° steady and that's after the MPD so the heat loss is greater than what I have been reading on this forum for a while now . Generally I read numbers like "stove is 600° and flu pipe is 100°" but that's not nearly accurate .

Do I "need" to know these numbers ? No I don't need them to survive and heat my house . Are they good to know? Why yes I think knowing the accurate numbers allows me to understand how the stove works a lot better .

On a side note: I'm not putting this information out there to argue with anyone or to say any of this is necessary . It's just information that someone can take or leave .

When I start burning with coal I will have more concrete firepot measurements and can actually crunch some numbers . I can give a little bit more light to the different anthracite numbers as well .

Josh,

In another thread , using my K-thermocouple and my IR gun, and making adjustments to dampers, I showed how the surface temp changes are proportional to flue gas temp changes. It stays very close to a 2:1 ratio over the usual range of stove operating temps. Simply double what the surface temps are and you'll be very close to what the flue gas temps are.

So yes, you can use stove and pipe surface temps to judge how well your stove settings are doing.

Plus, flue gas temps are meaningless as far as knowing stove heating efficiency because your only comparing them to different flue gas temps, not to the firebed temps to see how many BTU's the stove and pipes are removing from what the firebed is producing before that heat gets to the chimney.

Nothing wrong with knowing what's going on inside the stove and pipes. But, what really matters is the outside of the stove and pipes, because that's what is actually heating the house.

Paul

Sunny Boy wrote:Josh,

In another thread , using my K-thermocouple and my IR gun, and making adjustments to dampers, I showed how the surface temp changes are proportional to flue gas temp changes. It stays very close to a 2:1 ratio over the usual range of stove operating temps. Simply double what the surface temps are and you'll be very close to what the flue gas temps are.

So yes, you can use stove and pipe surface temps to judge how well your stove settings are doing.

Plus, flue gas temps are meaningless as far as knowing stove heating efficiency because your only comparing them to different flue gas temps, not to the firebed temps to see how many BTU's the stove and pipes are removing from what the firebed is producing before that heat gets to the chimney.

Nothing wrong with knowing what's going on inside the stove and pipes. But, what really matters is the outside of the stove and pipes, because that's what is actually heating the house.

Paul

have to agree, we know there is a spot in the firepot that is about 1800*, with in inches of it there are interior parts running 1000-800*. at the same time you may have anything from 150-650* exterior skin temp and possibly 98-300* smoke pipe skin temp.

while all these other readings ARE fun to think about, as far as heating goes only the stove body and smoke pipe skins matter. and the spread between THEM is much closer to the reality of efficiency than all the rest.

i do find it fascinating to be able to see all those readings at once just the same.

Sunny Boy wrote:Josh,

In another thread , using my K-thermocouple and my IR gun, and making adjustments to dampers, I showed how the surface temp changes are proportional to flue gas temp changes. It stays very close to a 2:1 ratio over the usual range of stove operating temps. Simply double what the surface temps are and you'll be very close to what the flue gas temps are.

So yes, you can use stove and pipe surface temps to judge how well your stove settings are doing.

Plus, flue gas temps are meaningless as far as knowing stove heating efficiency because your only comparing them to different flue gas temps, not to the firebed temps to see how many BTU's the stove and pipes are removing from what the firebed is producing before that heat gets to the chimney.

Nothing wrong with knowing what's going on inside the stove and pipes. But, what really matters is the outside of the stove and pipes, because that's what is actually heating the house.

Paul

Right... With thermometers that are accurate . I get it and understand that . I'm mainly preaching to myself here when I call these magnetic gauges worthless because I have trusted them for so long .

Like I said you don't even need any thermometer to know how to best work the stove . This is just all for fun if you will.

As far as the heat efficiency goes I feel it's good to know what the flu has temps are so you can figure on how to get those temps to radiate back into the room .

But as I said before I'm not trying to make this thread into a debate . I agree with what you said 100% .

What I'm really interested in is the heat that comes from the main belly of the stove and how it is transferred to the cast iron and then radiated to the room. I'm proving or disproving things to myself and this will be my journal if that's makes better sense . And if I'm the only one that's gets anything from it all even if it's just a smile on my face that's ok too

Gauges are working out awesome . It looks like this is going to be the scene every night for a while . I'm going to try to work off half a pallet of coal this winter and burn wood inbetween . Money is tight with a baby around the corner . Good thing I'm good with a axe and a maul . I've actually gotten really good with a Michigan axe . Hit the log a few times in different places and one good whack and it all splits at once . I'm using the maul less and less .

But I won't lie . Wood burning sucks for overnight sleep. I gotta get up at least twice every 3 hours to keep a wood fire working as steady as coal. It's going to be a fun winter . I for see me breaking down and buying more coal.

I'm beginning to second guess the thermocouple in the flu .
The Budenberg is a precision calibrated Mercury filled gauge and the thermocouples are Chinese made with Chinese made digital K type readers . The IR readings seem fairly close to the thermocouple in the firepot but not 100% agreeabl (I took the reading by reading the thermowells surface temp which I would have that matches the thermocouple reading but it seemed to be rather close enough) . The Budenberg consistently reads less than the thermocouple in the flu . Now I know different locations can read differently in the pipe but it's too big of a difference to not talk about . So here is a example . The Mercury gauge reads 127°c (260.6°F) but the thermocouple reads 394°F . That's a huge difference ! And they aren't that far apart. The IR read out of the surface temp of the pipe seems more in line with the Budenberg . So thoughts? There is only one way to hook up the thermocouple leads correct ? Anyways I'm putting my trust more in the Mercury gauge but who knows maybe it's out of calibration . And who knows maybe the Chinese accidentally put a different type of thermocouple in with the bag and labeled it wrong ?

Here is the difference in spacing . The thermocouple is the smaller fitting.

Ok I have an answer to my own question. I left the stove burn out last night because today is 66F and there is no point in burning until tomorrow night . This morning the K-type thermocouples were reading 66F as well as the IR reader and as well as the house temp on the walls. So there is my answer . The Thermocouples are accurate and the Budenburg needs to be calibrated . I'll bet I can calibrate it fairly easy so I will investigate that .
I am very happy that the thermocouples turned out to be accurate !

Now you are back to relying on the Chinese thermocouple, for your calibration.
Anyway, the thermocouple any type that is,
will produce a millivolt signal which is then translated to a temperature reading taking into consideration the ambient measurement.
FYI, the K-type thermocouple will have one yellow and one red conductor, a type J will have one red concuctor and one white conductor.
Red always being the Negative terminal.
Thermocouples are very rock solid as far as accuracy.
CS

coal stoker wrote:Now you are back to relying on the Chinese thermocouple, for your calibration.
Anyway, the thermocouple any type that is,
will produce a millivolt signal which is then translated to a temperature reading taking into consideration the ambient measurement.
FYI, the K-type thermocouple will have one yellow and one red conductor, a type J will have one red concuctor and one white conductor.
Red always being the Negative terminal.
Thermocouples are very rock solid as far as accuracy.
CS

It is very hard to find something NOT made in china these days haha. The only way I truly could get a reading I trusted would be to purchases a certified temp gauge brand new from a company that would supply very high end measuring devices . Or find someone with the stuff already to come check it out. hmmm that gives me an idea ! But having so many devices read the same temperature at one time and the one (the budenburg mercury gauge) reading less leads me to believe it is the one that needs to be calibrated. I was watching a show on all the inventors and scientist leading up to Einstein over the years and getting to that point through the experiments they were doing is amazing

Thank you for the confidence boost in the thermocouples and the color coding .

SJ,
All instruments will DRIFT over time, typically the cheaper the instrument or maybe in your case the older the instrument you will see some drift in measurement in relation to accuracy.
Your analog gauge looks to be of good quality so maybe it is just in need of calibration.
Where I work we have a .05% calibration tolerance of the total span of the measuring range.
Lets face it none of us are splitting atoms with these beauties we are heating our homes with so our readings can be relative to the appliances operating conditions.
Basically sometimes a reference # against operating conditions can be just as helpful as the actual accurate measurement.
Hate to say it but 2 instruments reading the same temp. can be more frustrating and confusing than it is worth.
CS

As mentioned, gauges drift over time.

And with the cheaper ones, they are often not accurate over the entire reading range to begin with. Whatever accuracy they have it's only for part of the gauge's range.

Plus, testing and recalibrating some types of gauges requires specialized equipment.

All the above are the main reasons why "U" tube water and mercury type gauges have been around so long. Simple, reliable, and easy to adjust.

And why I like the Dwyer 25. Pull the tube off, turn the knob until it reads "0". Put the tube back on and it's right back to being more than accurate enough.

As an engineer friend says, if it was made any simpler,.... it wouldn't work !

Paul

I could not more SB
The rabbit hole of tolerance and calibration is a deep one.
CS

coal stoker wrote:SJ,
All instruments will DRIFT over time, typically the cheaper the instrument or maybe in your case the older the instrument you will see some drift in measurement in relation to accuracy.
Your analog gauge looks to be of good quality so maybe it is just in need of calibration.
Where I work we have a .05% calibration tolerance of the total span of the measuring range.
Lets face it none of us are splitting atoms with these beauties we are heating our homes with so our readings can be relative to the appliances operating conditions.
Basically sometimes a reference # against operating conditions can be just as helpful as the actual accurate measurement.
Hate to say it but 2 instruments reading the same temp. can be more frustrating and confusing than it is worth.
CS

What about 4 though. The IR gun which is brand new and not the cheepest of the bunch by any means read 66 and the two thermocouples read 66 and the thermometer that reads room temp was 66 . That was why I am lead to believe the thermocouples are accurate enough .

The Budenburg is a Mercury filled analog gauge that is very high qaulity . I even spoke with the manufacturer about it . It was made in Manchester England UK .

I know none of this is necessary . The only gauge I really care about now is the Magnehelic and like Paul had mentioned before you can use the magnetic to figure the best burn even if it is reading wrong .

But because I have these I do wish to seek out the closest possible accurate readings while staying without blowing anymore money .