Jotul f45 thermometer question

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tjb5492

New Member
Nov 20, 2021
6
Pa
In the picture, what is the correct area to place the thermometer?

The manual says in a corner of the top grate.
It’s not specific As to what the top grate is.

Blue, red, or white mark in the photo ?
Trying to get my stove top temps dialed into the stove. When I load it up with 5 or so cuts set the air to control to closed, I see temps around 700 after all the wood catches on fire. This is using when the thermometer is on the blue mark. Wondering if I am getting a false reading if I should be moving it to another color.

Thoughts please! First time sold burner and absolutely loving keeping my uninsulated 1860s natural stone house with zero insulation warm!!!!!

58D0ED91-19E5-41C6-8960-1C2F489D24EC.jpeg
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
30,260
central pa
In the picture, what is the correct area to place the thermometer?

The manual says in a corner of the top grate.
It’s not specific As to what the top grate is.

Blue, red, or white mark in the photo ?
Trying to get my stove top temps dialed into the stove. When I load it up with 5 or so cuts set the air to control to closed, I see temps around 700 after all the wood catches on fire. This is using when the thermometer is on the blue mark. Wondering if I am getting a false reading if I should be moving it to another color.

Thoughts please! First time sold burner and absolutely loving keeping my uninsulated 1860s natural stone house with zero insulation warm!!!!!

View attachment 285852
The best place is in or on the pipe.
 
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MEngineer24

Member
Dec 6, 2020
194
WV
I have the F50 and have mine on placed on the red area. I understand and agree the manual is not specific but like you I took “either back corner of the griddle/top load door” to me the red area. Using the IR gun, the red area is very consistent on either side while the middle of course is always around 100 degrees higher.
 
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clancey

Minister of Fire
Feb 26, 2021
2,392
Colorado
I have questions about the thermometer too for I just do not understand it (new wood burner) and sometimes it scares me when I see 700 degrees or so and I put mine in the oven when I made bread and it was a hundred degrees off the temperature( higher) of the oven which is pretty exact and good..My thermometer is a chimgard and my installer placed it flat on one of my cooking plates (have two) on the left side on the top of the stove and I just wonder if there is a better one out there and you mention something about a ir gun and what is this about...is it better? I ask the installer about a stove pipe one but he did not want to drill a hole in the piping and would this be better. Sorry for all the stupid questions but just want to know if there is a better thermometer out there to judge the hotness of the stove...I have a different stove then you just wondering about the thermometer? old clancey
 

EbS-P

Minister of Fire
Jan 19, 2019
3,556
SE North Carolina
Personally I wouldn’t measure on the griddle/cook top. Get one of these.


I have two. One is wireless version it’s slick.
Edit….

I don’t think it matters where. It’s nice to have some temps to calibrate why you are seeing in the the firebox. Actual temps aren’t super important.
 
Last edited:

begreen

Mooderator
Staff member
Nov 18, 2005
96,422
South Puget Sound, WA
Either the red or blue location will work, be sure it is a stovetop and not a flue thermometer. Condar makes a decent one.
Or if you want better, Tel-Tru makes good industrial thermometers with a glass dial cover, oorder the 750º version.
Or use an IR thermometer.

As bholler noted, a flue thermometer is going to provide more meaningful information on the status of the burn. This thread illustrates the value of tracking flue temp vs stove top.
 

tjb5492

New Member
Nov 20, 2021
6
Pa
Hey everyone just wanted to say thank you for replying! I feel a bit better. I picked up a mid level IR gun, and I measured the temps out of the box with it and I saw a 100 degree difference between the Ir (read lower) and the cheap 10 dollar stovetop I got for it. I should have spent a few more dollars on a better one the first time around but got a 30 dollar flue thermometer the other day that is awaiting shipment.

Moral of the story is, my flu temps on my single walled pipe, about 18 inches from my chimney read 300-400 when I have a nice hot fire. Out of curiosity put the stovetop on the pipe at 18 inches and it read around 80-120 higher than the IR gun.

I feel much better as the cheapo stovetop seems to just read pretty high. I thought I was going to have to get a keyhole damper because I have a decent amount of pipe. I’ll monitor it and see how it goes but feeling MUCH better.
 

begreen

Mooderator
Staff member
Nov 18, 2005
96,422
South Puget Sound, WA
Yes, I really dislike the cheap stove thermometers. They can be quite misleading. Seems like only a few are reasonably accurate. Is the 300-400º reading with the thermometer or the IR gun? If the flue system is >25' then a key damper could still be warranted.
 

clancey

Minister of Fire
Feb 26, 2021
2,392
Colorado
I feel much better too and the information really settled my nerves down being new at this stuff.. Wrote the name down of all the different thermometers and now it seems like common sense with the video explaining it--lol--now i understand the different temperatures--somewhat and can't wait for the weather to get cold again so that I can light my stove...Yes...learning here little by little but picking up good information and much more than my wonderful stove installer knows--should tell him to join in on here....what really bothered me was he did not seem to care about my wood not being able to be tested for humidity because i could not get the probe in and he just felt it and put it to his cheek and said it was dry enough--lol...All my new gadgets and he did not care---cry cry....lol lol ...thanks everyone...Now I have a electric Ryobi drill and a 1/16 Dewalt drill bit to play with so that I can test for moisture on my splits..Drill the two small holes and put the gadget in and see what I have--more gadgets...thanks everyone...clancey
 

tjb5492

New Member
Nov 20, 2021
6
Pa
Yes, I really dislike the cheap stove thermometers. They can be quite misleading. Seems like only a few are reasonably accurate. Is the 300-400º reading with the thermometer or the IR gun? If the flue system is >25' then a key damper could still be warranted.
Yes with the IR, but that was more of a peak when the air control was almost wide open during the first 30 or so minutes. Once I shut it down, it dropped more to 300 and into the burn it was 250-300 range with only a few splits in.

I’ll have a better idea after today because I plan to monitor it more and really play with the IR gun when it’s cranking heat for once it cools down.

Love this community already!!
 

begreen

Mooderator
Staff member
Nov 18, 2005
96,422
South Puget Sound, WA
OK, then that sounds pretty normal. Peak temps in that range during the startup phase are not uncommon.
 

EbS-P

Minister of Fire
Jan 19, 2019
3,556
SE North Carolina
Double check the temp range on your IR thermometer. My first one maxed out at 700. Not much good when you are trying to figure out how hot the the over fire is getting. I hit 900 once.
 
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tjb5492

New Member
Nov 20, 2021
6
Pa
I have the F50 and have mine on placed on the red area. I understand and agree the manual is not specific but like you I took “either back corner of the griddle/top load door” to me the red area. Using the IR gun, the red area is very consistent on either side while the middle of course is always around 100 degrees higher.
Ah a fellow engineer I see!
Double check the temp range on your IR thermometer. My first one maxed out at 700. Not much good when you are trying to figure out how hot the the over fire is getting. I hit 900 once.
hah it’s good for like 2000 degrees. I happened to measure the hot bed of embers and it read a bit over 1,000
 

Todd

Minister of Fire
Nov 19, 2005
9,791
NW Wisconsin
Nice stove! I’m not sure why Jotul recommends that thermometer placement off to the side, I just use an IR thermometer and check it dead center top because that’s where it’s hottest. Like most people here I mostly monitor the flue temps during startups and loading, its quicker to react than the stove top and helps you determine when to start turning down the air Sooner. I usually start shutting down around a 500 internal flue temp which would be 200-250 external for you.
 

tjb5492

New Member
Nov 20, 2021
6
Pa
Nice stove! I’m not sure why Jotul recommends that thermometer placement off to the side, I just use an IR thermometer and check it dead center top because that’s where it’s hottest. Like most people here I mostly monitor the flue temps during startups and loading, its quicker to react than the stove top and helps you determine when to start turning down the air Sooner. I usually start shutting down around a 500 internal flue temp which would be 200-250 external for you.
See I was under the impression that the middle spot was like you said 100 degrees hotter because of the burners. My flue temps go up to 350, during the peak of the burn when the flames are really going. I have just under 20 ft pipe I think it’s 17 , so I may have a slight draft issue bring that I have no neighbors or houses to shield the wind.

If I load the stove full with 5 or so small/med splits, 16 inches, the stove with combust have have a flame show eventually even with the air shut all the way.
 
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Todd

Minister of Fire
Nov 19, 2005
9,791
NW Wisconsin
See I was under the impression that the middle spot was like you said 100 degrees hotter because of the burners. My flue temps go up to 350, during the peak of the burn when the flames are really going. I have just under 20 ft pipe I think it’s 17 , so I may have a slight draft issue bring that I have no neighbors or houses to shield the wind.

If I load the stove full with 5 or so small/med splits, 16 inches, the stove with combust have have a flame show eventually even with the air shut all the way.
17’ should be ok, I have 22’ straight up and the stove liked to run hot with certain weather conditions so I did a little mod and closed the two unrestricted primary air holes that feed the dog house in the fire box. This slowed it down and gave me more control. Not saying you should do this, you need to learn your stove, it takes some trial and error.

Lately I’ve been doing a 12 hour reload schedule with a full load of Aspen about 8-10 splits. Takes about 15-20 min to get settled in at the lowest setting. After about an hour flue temps range from 400-600 internal and stove top temps 500-700. All this depends on split size, weather and if I pay attention and start turning the stove down at the right time. Probably go to an 8 hr loading schedule as the weather gets colder.

I’ve been really impressed with this non cat stoves performance. Nice even output, great control and long burn times. Kind a reminds me of my Woodstock cat stoves I used to burn.
 

tjb5492

New Member
Nov 20, 2021
6
Pa
17’ should be ok, I have 22’ straight up and the stove liked to run hot with certain weather conditions so I did a little mod and closed the two unrestricted primary air holes that feed the dog house in the fire box. This slowed it down and gave me more control. Not saying you should do this, you need to learn your stove, it takes some trial and error.

Lately I’ve been doing a 12 hour reload schedule with a full load of Aspen about 8-10 splits. Takes about 15-20 min to get settled in at the lowest setting. After about an hour flue temps range from 400-600 internal and stove top temps 500-700. All this depends on split size, weather and if I pay attention and start turning the stove down at the right time. Probably go to an 8 hr loading schedule as the weather gets colder.

I’ve been really impressed with this non cat stoves performance. Nice even output, great control and long burn times. Kind a reminds me of my Woodstock cat stoves I used to burn.
I feel like flue temps are a bit hotter. External, but I feel like 200 external is my absolute min. I just measured with this load right now and my readings are:
IR
377 stovetop from back left corner
280 flue 18’’ up external temp

IMO the fire is pretty much died down but here’s what it looks like

image.jpg
 

Todd

Minister of Fire
Nov 19, 2005
9,791
NW Wisconsin
Your probably ok with those temps at that stage. Looks like you still have some flame going on and a good pile of coals keeping that flue temp up there. Take your single wall pipe temps with a grain of salt, not every stove or install will read the same, it’s just a general guide. If your seeing consistent temps and good burn times you’ll be fine.