When to reduce air, to burn "longer"

[Prometeo]

A thermocouple flue probe thermometer makes all the difference if you are really trying to run as low as possible. You can see in 60 seconds that you turned it down too far.

very helpful, but I would always be watching that temperature, I'll try to do without it for now!

 

[EbS-P]

very helpful, but I would always be watching that temperature, I'll try to do without it for now!

Only until you learn your stove. Then you rely on it less.

 

[bholler]

very helpful, but I would always be watching that temperature, I'll try to do without it for now!

But that is really what you need to run the stove properly

 

[Prometeo]

Only until you learn your stove. Then you rely on it less.

But that is really what you need to run the stove properly

Is there here any pics to show where to install?

 

[stoveliker]

18 inch above the stove

 

[Prometeo]

just received this, should work ?
( it go until 800 celsius )
made in china💥

 

[begreen]

The probe looks short and fat compared to the skinny 3" probe I am used to, but it might work ok as long as the probe doesn't get too dirty.

 

[stoveliker]

I assume you have single wall pipe? For double wall it might almost be too short?

Carefully measure the diameter to drill a nice and tight hole so you don't suck in too much air where you mount the probe.

 

[Prometeo]

I assume you have single wall pipe? For double wall it might almost be too short?

Carefully measure the diameter to drill a nice and tight hole so you don't suck in too much air where you mount the probe.

yes, single wall. Probe it's an M6 (6mm diameter) I think I'll try with a 5 or 5.5 tip first to see if the thread will be able to enter, when I have burning wood, what is the minimum temperature to avoid creosote? the chimney is 29 feet,
thanks

 

[stoveliker]

I'd try to stay above 135 C *at the top of the chimney*.
What that means for the temp where you measure near the stove is anyone's guess...

29 ft is a tall chimney, allowing for a lot of cooldown. Especially if there is no insulated liner, and it's an outside chimney.

So maybe stay above 250 C? Though that is not very efficient burning as a lot goes out the chimney...

 

[begreen]

Yes, it's just a guess unless some temporary instrumentation is placed at the top of the chimney. 200ºC is a decent target as long as the wood is <20% MC. Remember that this temp is for the active burn period. During the red coal stage when the volatiles are all burned off, it's ok if the flue temp goes lower.

 

[Prometeo]

Thanks very much both 👍
The flue passes inside the wall (first chimney) descends vertically, there is not much dispersion, because it is basically internal, also that chimney the piece that comes out of the roof is filled with foam ("fireproof") around the tube, to seal. Taking temperature up there is difficult. Until now I always read 200 C, or a little more, in the first piece of flue, 10 inches above the stove, with the laser thermometer (thanks for reasoning in celsius in this case). I'm curious to see internally, if there is, how much difference. Remains, the installation at this point!

 

[vatmark]

I have an Jotul F500 V2. I only use a stove top thermometer. I don't use the stove as the main source of heat and never pack the stove full. I wait until stove top is at around 400 degrees and then turn it down slowly and end up at about the halfway point where I leave it. If I put more wood in I wait until stove cools down to around 350, then add more wood and open air fully until wood starts burning well and then put air down to 50 % again.

 

[begreen]

Taking temperature up there is difficult. Until now I always read 200 C, or a little more, in the first piece of flue, 10 inches above the stove, with the laser thermometer

This reading sounds too hot. A 200ºC reading off of the surface of a single wall stove pipe should show about a 350-400ºC reading internally. If you find this correct with the probe, then too much heat is going up the flue. It is being wasted.

As far as I know, there is no such thing as fireproof foam. It should never be in contact with a single-wall chimney liner.

 

[stoveliker]

The temp inside the flue is about twice the external temp for a single wall pipe.

 

[Prometeo]

This reading sounds too hot. A 200ºC reading off of the surface of a single wall stove pipe should show about a 350-400ºC reading internally. If you find this correct with the probe, then too much heat is going up the flue. It is being wasted.

As far as I know, there is no such thing as fireproof foam. It should never be in contact with a single-wall chimney liner.

You are absolutely right, does not exist non-flammable foam, it simply resists up to 100 degrees, for two hours, if I remember correctly. However, the chimney is high, on the ground floor, where the stove is located, just before the flue enters the wall, I can read up to 100 degrees C but from that point there's still about 20 feet up to the point where it is sealed with foam, it should stay much cooler, I suppose.

 

[Prometeo]

The temp inside the flue is about twice the external temp for a single wall pipe.

however it is quite strange (in my opinion) that a single wall pipe does not reach flue gas temperature, I'll find out

 

[bholler]

however it is quite strange (in my opinion) that a single wall pipe does not reach flue gas temperature, I'll find out

It's basic physics. But with the length of your probe it will not be reading as high as it would if it was in the middle 1/3 as it should be

 

[bholler]

You are absolutely right, does not exist non-flammable foam, it simply resists up to 100 degrees, for two hours, if I remember correctly. However, the chimney is high, on the ground floor, where the stove is located, just before the flue enters the wall, I can read up to 100 degrees C but from that point there's still about 20 feet up to the point where it is sealed with foam, it should stay much cooler, I suppose.

A product that only stands up to 100c should absolutely not be very close and absolutely not in contact with chimney pipe. What would happen in the event of a chimney fire??

 

[stoveliker]

however it is quite strange (in my opinion) that a single wall pipe does not reach flue gas temperature, I'll find out

The pipe cools down from the max it sees due to its contact with cooler air in your room.
That even results in the gases in the pipe being a bit cooler near the wall than in the center of the pipe - depending a bit on how turbulent the flow is in the pipe.

The latter is the reason for the recommendation to have a longer temperature probe that reaches in the center. (on the other hand, you will be measuring the coldest section of the gas, and as you're interested in a minimum temperature to run safely, that's not alltogether bad - but do realize that comparing your numbers to other people's numbers may not work very well as you'll be measuring colder gases than the rest of us do).

 

[Prometeo]

A product that only stands up to 100c should absolutely not be very close and absolutely not in contact with chimney pipe. What would happen in the event of a chimney fire??

The flue is 29 feet, the foam is only at the end, I have a little more than 200 c at the start, just above the stove, at 9 feet I have a maximum of 100, at the point where the foam is it should be less than 50 "I suppose" that I have no risk, but in case of fire of the creosote, I don't know what exactly could happen, the flue column is made of square asbestos bricks, the single wall pipe passes inside, there is at least 2 inches of air around the single wall pipe. The last check, at the top chimney was clean, but something forms and detaches much earlier, near two curves 45

 

[bholler]

The flue is 29 feet, the foam is only at the end, I have a little more than 200 c at the start, just above the stove, at 9 feet I have a maximum of 100, at the point where the foam is it should be less than 50 "I suppose" that I have no risk, but in case of fire of the creosote, I don't know what exactly could happen, the flue column is made of square asbestos bricks, the single wall pipe passes inside, there is at least 2 inches of air around the single wall pipe. The last check, at the top chimney was clean, but something forms and detaches much earlier, near two curves 45

Creosote burns at roughly 1100 c. 200c foam will ignite and turn into burning goo running down the outside of your pipe. Does that sound like something you want?

 

[Prometeo]

Creosote burns at roughly 1100 c. 200c foam will ignite and turn into burning goo running down the outside of your pipe. Does that sound like something you want?

Thanks, I certainly don't want any problems caused by my negligence, how could i seal the single wall with in the chimney, cement ?

 

[bholler]

Thanks, I certainly don't want any problems caused by my negligence, how could i seal the single wall with in the chimney, cement ?

Usually with actual fireproof insulation and stainless steel

 

[Prometeo]

The pipe cools down from the max it sees due to its contact with cooler air in your room.
That even results in the gases in the pipe being a bit cooler near the wall than in the center of the pipe - depending a bit on how turbulent the flow is in the pipe.

The latter is the reason for the recommendation to have a longer temperature probe that reaches in the center. (on the other hand, you will be measuring the coldest section of the gas, and as you're interested in a minimum temperature to run safely, that's not alltogether bad - but do realize that comparing your numbers to other people's numbers may not work very well as you'll be measuring colder gases than the rest of us do).

Yes, surely I would not consider the number, objectively, but for reference only, to get an idea, when to start close, for example in this period I don't need too much heat. I wanted a longer probe but I didn't find the complete kit with display and I fell back on this.