Differences in Oslo top temp.

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clr8ter

Feeling the Heat
Hearth Supporter
Oct 4, 2010
285
Southern NH
So recently, I got another Condar thermometer to replace/supplement the crappy Made-In-China Rutland one. I put the 2 Condars in the front corners, and the Rutland way on the back, within 3" of where the oslo stops, and the stainless pipe begins. I loaded it, and turned it down to below 1/2. A while later, the stove was running at around 550+, both sides, and the one in the back was reading around 700. Not sure if this is normal, as I never put a thermometer there. But that seems high. Granted, the stove was cooking…..What SHOULD the temp there be, given 550 at the front?

BTW, I know the Rutland one is in the ballpark, because I swapped it with the Condar, about the same. The Rutland's problem is mostly the needle sticking….
 
I can't really help but I will say the stove top temp varies greatly sometimes by a few hundred degrees depending if my fire is burning in one place more. I use the infer red thermometer to measure if I'm concerned about the temp, otherwise the stove top thermometer is a good ball park figure. I put mine at the back of the stove by the stove pipe. I tried it in the corners and can't tell you why I put it in the middle except that it seems to be more accurate as I never really have a fire burning in the corners. Someone who can help will come along soon :-)
 
There was a notable difference in temps when I took my Condar thermometer (and later my IR thermometer) and checked each of the four corners of the stove . . . I suspect it may be due to the path of the fire, how high the wood is stacked (since I side load the ash tends to build up on the right side and the wood often sits a bit higher there), etc.

I eventually put my thermometer in the right, rear corner as that seemed to be the most consistently hot corner for me . . . and then later when I put on the soapstone slab I just stuck the thermometer on the front top lip . . . as I realized at that point that I could get a pretty good idea as to when the fire is getting too hot or when it's not hot enough . . . I mean to say, I wouldn't trust my judgement about the temp to do a souffle or even bake some cookies, but I have reached the point where I can gauge it pretty well . . . and if in doubt I dig out my IR thermometer.
 
(since I side load the ash tends to build up on the right side and the wood often sits a bit higher there)

No kidding? My stove does that same thing. I was wondering if it was because the side door leaked and sucked a little extra air in, burning the wood more completely. So, what are you saying? That you wouldn't put much thought into the temp on the rearmost part of the stove outlet? (I don't know what that part is called. I want to call it a thimble, but I know that's the thing that passes a chimney thru a wall to the outside.)
 
No kidding? My stove does that same thing. I was wondering if it was because the side door leaked and sucked a little extra air in, burning the wood more completely. So, what are you saying? That you wouldn't put much thought into the temp on the rearmost part of the stove outlet? (I don't know what that part is called. I want to call it a thimble, but I know that's the thing that passes a chimney thru a wall to the outside.)

I guess what I am trying to say in my normally convoluted and garrulous way is that I would try moving the thermometer to each of the four corners . . . see which corner is the most hot the most often . . . and stick it there . . . and then realize that in time the difference of 50 or 100 degrees (or maybe even a bit more) may not make that much of a difference as you will learn how to keep the stove in the Goldilocks Zone (not too hot and not too cold -- just right) and will just use the stove top thermometer in time as a rough gauge as to the temp of the stove.
 
It is best to read your stove manual and see where they tell you to place a thermometer for accurate temperature readings. I believe the Oslo is the same as Jotul's F600, which we own where they say to place the thermometer on one of the corners of the top. When I shoot various spots on my stove with my IR thermometer the temperature in front of the flue collar on the top of the stove runs as much as 250 F higher than a reading on one of the corners. If you take readings from a place different from the manufacturers recommendation you won't have accurate information for how you are burning. For the F600 they call for running between 400 - 600 F on one of the corners. If you burned at these temperatures based on center of the top readings you would be burning too cool. And if you tried to reach temperatures up around 700F on one of the corners you would certainly be burning too hot.
 
Since I have a water pot on top, I have never even thought of measuring the temp in the middle of the top. Pretty much since day one, there has been a thermometer in both front corners. My question comes from the fact that I recently added one, and took the extra and put it on the flue collar way towards the back. I noticed it was running WAY hotter there, and wanted to know if it's normal. Looks like it may be…..
 
What you describe is consistent with the readings I get from those same spots on my F 600, so I think it probably is the norm. I think the reason they specify taking readings from one of the top corners on the Jotuls is because those areas produce more stable readings. The top in front of the flue collar takes all the heat surges when you are first starting a fire and flames are blasting pretty good across the top baffle. Once the fire settles a bit during the main burn cycle I believe the temperatures level out a bit more, but that top center spot is always going to be the hottest spot on the stove.
 
On my Jotul Oslo 500 the temperature varies from corner to corner and the center. I believe it is because the flames and intensity is hotter in different places in the stove depending on how the wood is stacked and where it is burning more intense than in other places in my view. I'm not that concerned about it because generally it radiates heat evenly without any noticeable irregularities.
 
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Oh yeah, mine can vary side to side, too. But that's obviously caused by where the fire is, and how wood is stacked. I notice if you burn long enough in one stretch, it tends to even out.
 
I agree with you "clr8ter". After the burn is well established with a hot bed of coals, the temperature evens closely everywhere until the fire burns down or when new splits are added, at least for a while.
 
On my Oslo, the temps vary quite a bit too, with the center always being the hotest. I check temps with magnetic and IR thermometers.
 
Think of it this way. You have a 16 inch by 28 inch stove top.(roughly) You are passing super heated air from the fire box under this surface. That air is being funneled down to a 6 inch opening on the back of the stove thus concentrating the heat in that area. It really is no different than starting an old engine and checking the block and head temp compared to the exhaust manifold temp. I can check my temps on the corners and all will be within 50° of each other but check the center plate and near the rear end it can be as much as 150° hotter. Cast iron heats up differently than steel.
 
True enough, the porous nature of cast iron vs the dense properties of plate steel are dynamically different in the way they hold and radiate heat. That alone presents the argument of cast iron stoves vs steel plate stoves, which gives you more heat, which holds the heat longer, which one radiates better, etc. Cast stoves are traditional and plate steel stoves have brought new innovation in wood stove manufacturing. It is my view that the younger group prefers the newer designs in steel plate stoves and old timers such as myself prefer the more traditional cast iron. I can't say which one is better when it comes to efficiency but I like my Jotul, that is all I can say!
 
Uhhh, at 40, which category do I fall in? 'Cause I prefer the cast iron stoves, so much nicer to look at……..
 
I did not intend to disparage anyone. My statement was of my own volition. Last year I heard many on this forum talking about the Lopi Liberty as if it were the answer to heating requirements, sort of a panacea. Admittedly it is a well rated stove with many attributes. So the question is do you prefer to go in that direction or the cast direction. My feeling was that younger folks like the quick response the steel plate stoves offer. Cast stoves take longer to heat up but stay warm longer. I can't explain that. As for the age of those who prefer which type, I take back my original statement about various generation factors. All of today's stoves are good. It depends on your choice.
 
LOL, if you're referring to me, I don't feel disparaged. I forgot to add the "LOL" to my last post. Though I will say that I feel that there is no PERFECT stove. There are good ones, and bad ones. The Oslo, IMHO, is a very good one. But for someone else, another might be better. Also, if I were looking for a stove for strictly heating, and nothing else, say to stick in a basement, I might go with a steel stove. If going more industrial and less aesthetic would save money in that case, I'd do that. I think fancy cast iron costs more, no? Any of that make sense?
 
Uhhh, at 40, which category do I fall in? 'Cause I prefer the cast iron stoves, so much nicer to look at……..

Hehheh . . . guess I'm over the hill at 43 with my cast iron stove. ;)

And Brother Bart and his well known love of steel stoves may in fact be a 24-year-old and not a retiree! :)
 
Well folks, to each their own. I agree that the fancy cast stoves carry a stiff price tag. But so do the fancy steel stoves tooting their new and higher technology. It still all comes down to the same thing...... heat! There is a lot of profit in stove manufacturing, don't you think? They only get you once every 20 years and I think some of the trending is moving towards cleaner pellet stoves, less work and less mess. Of course you have to buy the pellets. Nothing like cutting your own wood, at least for me. So gang, whatever stove you have, we're all in this together.
 
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We can't forget the hybrids like the Jotul F55 and PE Alderlea's. From what I've read these convection stoves provide great heat with the cast iron wrapper and the longevity of a steel box. Those who like these stoves would be middle age folk? :)
 
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