Am I shutting my air down in increment too large?

[johnstra]

I'm having little trouble settling my burns into cruise mode. Couple of nights in a row now I've had this happen. Burn a full load down to coals over 7-8 hours. Flue temp is way down (200 or so) but soapstone surface is still at 300 or so with a good bed of coals. Load the stove full of well seasoned oak and let it get burning good. In 15-20 minutes, my flue temps are over 1000 (I like to shoot for 800), so I shut the air down to about 50%. Give it 5-10 minutes and then take it down another step to 75-80%. Secondaries are blazing at this point. I give it a few more minutes and then shut it down to 90% closed. Flue temps at this point are still close to 1000 but they are dropping and the secondaries are putting on a show. 10 minutes later though, the secondaries are out. I open the primary air back up and let the secondaries get going again. This only takes a few minutes and at that point I can shut the primary all the way off and they settle in for good.

The two things I'm puzzling about are my flue temps running up over 1000 - I used to easily be able to keep them at 800 - and the deal with the secondaries going out and having to open the primary back up to get them running for good.

Any thoughts?

 

[pen]

Only close it 85% instead of 90%? Let it sit there longer before you close it all the way down? Different wood maybe?

pen

 

[NH_Wood]

Every fire is different, but I have noticed a similar situation with my Mansfield on quite a few occasions. To avoid this, I've been less concerned with the flue temp at reload and more concerned with how engulfed the load is prior to the first dialing down of the primary air. One problem I had was that I'd have a good flame in the box after reload, but only the first third or so of the load was getting charred (N/S load, so the first 1/3 of the splits toward the glass). I'd have good flue temps at this point because the active flames from the wood were charging the flue well. If I turned the primary down at this point, unless by just a bit, the fire would tend to decrease, rather than increase. So, I've come to let most of the load really catch before dialing down the primary air. This only seems to take 5 or so extra minutes of time with the primary all open, but it really depends on species. When I've added a full load of red oak, I need to let the load burn wide open for a lot longer to really catch well before dialing down. If I add a load of white birch and soft maple, it's going to be well engulfed in flame much faster and I can dial down the primary that much faster. So.....keep an eye on how different species of wood affect this aspect of your burn. I'll bet you'll find big differences. Oh, by the way, if you don't have a really good coal bed and warm flue, I find that getting a full load of red oak to catch well can take quite a long time - I guess from the density of the wood (and this is long dead oak - no hissing, real well seasoned). Cheers!

 

[johnstra]

Yep, I see the same thing. Big load of oak needs a good bed of hot coals or it takes a while before it's burning strongly - not unexpected.

I agree that eyeballing how fully engulfed the wood is seems to better indicate when to cut the primary air back, but seeing flue temps of 1100-1200 freaked me out a bit. According to my condar, that's in the "too hot" range.

Thanks!

-john

 

[NH_Wood]

Yep, I see the same thing. Big load of oak needs a good bed of hot coals or it takes a while before it's burning strongly - not unexpected.

I agree that eyeballing how fully engulfed the wood is seems to better indicate when to cut the primary air back, but seeing flue temps of 1100-1200 freaked me out a bit. According to my condar, that's in the "too hot" range.

Thanks!

-john

Pen posted about this a while back, but here is what I've found and why the high flue temps don't bother me anymore (they used to freak me out too!). I took my Rutland magnetic stove top thermometer and placed is directly opposite my Condar probe thermometer on the stovepipe (18" from collar). I did this right from loading the stove on a moderate coal bed. By the time I had about 1000* on the probe, the magnetic has just reached 300*. I started to dial down the primary air, and the magnetic thermo never really climbed above 300*, while the probe leveled out at about 800. So....the probe was reading in near the middle of the 'best burn' indicator, while the magnetic therm was telling me that I was burning too cool. So.....I said to myself 'self - to hell with these gadgets!" I use the thermo for relative ideas of what the stove is doing, but I've been using the characteristics of the fire, what is coming from the chimney, and how much heat the stove eventually throws to really let me know if I'm burning well. If I've got great secondaries, with no smoke from the chimney, I guess I don't care what the temp gauges tell me (except for possibly getting too hot!). Cheers!

 

[joshlaugh]

I have the smaller Heritage and am burning a lot of hickory. I have seen similar scenarios with my stove. High flue temps but if I dial down my air control the stove won't burn nearly as well and takes longer to get up to good stovetop temp. I really focus more on how the wood looks vs the flue temp. I am still trying to convince my wife that it is ok to see high flue temps, its makes her nervous.

 

[oldspark]

Yep, I see the same thing. Big load of oak needs a good bed of hot coals or it takes a while before it's burning strongly - not unexpected.

I agree that eyeballing how fully engulfed the wood is seems to better indicate when to cut the primary air back, but seeing flue temps of 1100-1200 freaked me out a bit. According to my condar, that's in the "too hot" range.

Thanks!

-john

Pen posted about this a while back, but here is what I've found and why the high flue temps don't bother me anymore (they used to freak me out too!). I took my Rutland magnetic stove top thermometer and placed is directly opposite my Condar probe thermometer on the stovepipe (18" from collar). I did this right from loading the stove on a moderate coal bed. By the time I had about 1000* on the probe, the magnetic has just reached 300*. I started to dial down the primary air, and the magnetic thermo never really climbed above 300*, while the probe leveled out at about 800. So....the probe was reading in near the middle of the 'best burn' indicator, while the magnetic therm was telling me that I was burning too cool. So.....I said to myself 'self - to hell with these gadgets!" I use the thermo for relative ideas of what the stove is doing, but I've been using the characteristics of the fire, what is coming from the chimney, and how much heat the stove eventually throws to really let me know if I'm burning well. If I've got great secondaries, with no smoke from the chimney, I guess I don't care what the temp gauges tell me (except for possibly getting too hot!). Cheers!

Not all the magnetic sensors are that bad (I check mine with a IR gun less than 50 degrees off), I would throw the one you have away.

 

[NH_Wood]

Pen posted about this a while back, but here is what I've found and why the high flue temps don't bother me anymore (they used to freak me out too!). I took my Rutland magnetic stove top thermometer and placed is directly opposite my Condar probe thermometer on the stovepipe (18" from collar). I did this right from loading the stove on a moderate coal bed. By the time I had about 1000* on the probe, the magnetic has just reached 300*. I started to dial down the primary air, and the magnetic thermo never really climbed above 300*, while the probe leveled out at about 800. So....the probe was reading in near the middle of the 'best burn' indicator, while the magnetic therm was telling me that I was burning too cool. So.....I said to myself 'self - to hell with these gadgets!" I use the thermo for relative ideas of what the stove is doing, but I've been using the characteristics of the fire, what is coming from the chimney, and how much heat the stove eventually throws to really let me know if I'm burning well. If I've got great secondaries, with no smoke from the chimney, I guess I don't care what the temp gauges tell me (except for possibly getting too hot!). Cheers![/quote] Not all the magnetic sensors are that bad (I check mine with a IR gun less than 50 degrees off), I would throw the one you have away.[/quote]

Oldspark - so it gets stranger - the magnetic thermo seems to do fine on the stovetop - If I have a full load of ash, it'll level off at 550 or 600*. I'm not sure why I'm not getting higher readings on the stovepipe. One guess I've made is that the mag thermo is sitting on a convex surface on the pipe, rather than flat on the stovetop - perhaps cooler room air is make the stovepipe reading lower???? No idea, but certainly weird. Perhaps I should pick up a second one and see how it differs - but........I can pick up close to a 30 pk of Molson Canadian for the price......hmmmm.....tough call. Oops, not so tough - I'm going to get the Molson......Cheers!