Overheat?

[manooti]

just noticed this on my stove. The flu temp reaches 510-550 stove top is 700 near the collar but cools down a lot further from collar. Sides are 250ish. With flu and top temp that high the secondaries ignite. If adjusted they turn off.

Is this normal? How hot is too hot and what if I run it without seeing the secondaries lit?

Us stove 2000. Just put new gaskets everywhere and sealed some loose ends on flu.

 

[CenterTree]

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Not familiar with your stove specifics, however, for sure every stove is gonna have a different threshold for when its' secondarys kick in.
How are you measuring your flue temps?

It is OK to run your stove with no secondary action, but of course you would like to get them churning for at least a good portion of your burn cycle. More efficient and cleaner burn with em.

You got an IR gun?

 

[manooti]

Not familiar with your stove specifics, however, for sure every stove is gonna have a different threshold for when its' secondarys kick in.
How are you measuring your flue temps?

It is OK to run your stove with no secondary action, but of course you would like to get them churning for at least a good portion of your burn cycle. More efficient and cleaner burn with em.

You got an IR gun?

Yeah using an IR gun.
It's pretty high temps tho. When I lower it they still burn but slowly die out and wood smolders I have to open air again.

Put 2 pieces in just now with temps between 35-40. Seems to be burning way better and the wash effect is more noticeable.

I'm thinking the draft might be too strong so secondaries don't light until temp is too high? There is no glass wash visible when it's cold. The flames get sucked up over baffle.

 

[xman23]

For me, another stove, the top at 700 would be a big concern, until I got it moving down. But you can't be smoldering wood at that temp. Again, my stove, I have to get the stove up to temp for a while before choking down the main air supply. When I do it properly the secondary air flow causes the flame to roll forward, washing the glass.

 

[CenterTree]

For me, another stove, the top at 700 would be a big concern, until I got it moving down. But you can't be smoldering wood at that temp. Again, my stove, I have to get the stove up to temp for a while before choking down the main air supply. When I do it properly the secondary air flow causes the flame to roll forward, washing the glass.

Interesting, with my nc30, it is the opposite. If I get the stove real hot and shut the air off completely I too get those rolling secondarys tumbling to the glass. However, those rolling flames only seem to deposit dark spots on the glass near the bottom (not wash it).
So if I want clean glass I need to keep the primary open at least a smidge during the whole burn.

"Smidge" is a highly calculated, scientific term that would take hours to explain properly.

 

[CenterTree]

I'm thinking the draft might be too strong so secondaries don't light until temp is too high? There is no glass wash visible when it's cold. The flames get sucked up over baffle.

Actually, the secondarys will need higher stove box temps to kick in. On most stoves you won't see secondarys in the start-up/new fire stage.

Your draft can/will fluctuate with outside temps and wind speed too. There are always variables for each burn cycle.

I hope your wood is sufficiently dry. Unseasoned wood may on occasion get hot enough to get your stove top temp up, but then when you cutback the air, the wood will quickly snuff out the secondarys (due to the moisture content).

 

[manooti]

Actually, the secondarys will need higher stove box temps to kick in. On most stoves you won't see secondarys in the start-up/new fire stage.

Your draft can/will fluctuate with outside temps and wind speed too. There are always variables for each burn cycle.

I hope your wood is sufficiently dry. Unseasoned wood may on occasion get hot enough to get your stove top temp up, but then when you cutback the air, the wood will quickly snuff out the secondarys (due to the moisture content).

My wood pile is a couple seasons old and tried with kiln dried hard wood. Same thing happens. Thinking of putting in a damper but then flu will be a lot cooler and stove top maybe hotter.

When I took the temps the 700 was right next to the collar. Near the front or the edges it drops over 100 degrees lower and the sides of the stove were only 250ish.

 

[begreen]

Yeah using an IR gun.
It's pretty high temps tho. When I lower it they still burn but slowly die out and wood smolders I have to open air again.

Put 2 pieces in just now with temps between 35-40. Seems to be burning way better and the wash effect is more noticeable.

I'm thinking the draft might be too strong so secondaries don't light until temp is too high? There is no glass wash visible when it's cold. The flames get sucked up over baffle.

Are the flue temps surface or double-wall with a probe? At what flue temp do you start turning down the air to the fire? How far down do you close the air when the fire is burning strong?

 

[manooti]

Are the flue temps surface or double-wall with a probe? At what flue temp do you start turning down the air to the fire? How far down do you close the air when the fire is burning strong?

Temp is surface with ir gun and single wall.
I leave door cracked until all is lit and it's roaring. Then close door with wide open throttle. At that point it's about 300 minimum on flu surface. If it's a fresh fire I let it go up to 500 on flu and bring it down 1/4 increments. If it's left over coals I just load it with kindling for more coals, run it same way as new fire but I add normal splits after kindling made a good bed. Kindling can get away on me though so have to stay with it even with door completely closed.

The furthest I was able to go on air was half way on a good fire. Beyond half way it dies. Today tho with temps above freezing I turned it down all the way and secondaries stayed lit for a few minutes and after secondaries stopped the smoke was lit like a floating fire between tube and wood. Below freezing I can't do that.

I'm hoping I don't need a damper. That's more controls and can really screw it up plus I already sealed flu joints with stove cement.

 

[begreen]

Try closing the door sooner once the fire is burning ok on its own, but not roaring. With strong draft, once the fire is burning well you should be able to turn the air down all the way if outside temps are below 40-45F. If that's not possible, then it doesn't sound like draft is the issue. With too much air a lot of the heat is going to go up the chimney. The high flue temps are showing that.

How well seasoned is the firewood?

 

[manooti]

Try closing the door sooner once the fire is burning ok on its own, but not roaring. With strong draft, once the fire is burning well you should be able to turn the air down all the way if outside temps are below 40-45F. If that's not possible, then it doesn't sound like draft is the issue. With too much air a lot of the heat is going to go up the chimney. The high flue temps are showing that.

How well seasoned is the firewood?

So you think draft is ok?

My wood is 2 years old and been using kiln dried and some eco bricks.

I was thinking it was the draft because when I look up inside the fire box you can see the flames go up an over the baffle and into the flu. The flames dont get pushed down by the air tube. But then when it was warmer like yesterday the flames didn't go up and over as much and they got pushed down into glass.

 

[begreen]

The wood sounds good by description. There are anomalies that don't add up. Strong draft usually means very strong secondaries when the air control is fully closed. The stove could be leaking air still or the secondary intake port might be partially plugged.

Can you describe the flue system from stove to chimney top including elbows, tees, etc. if there are any. How tall is it overall?

 

[manooti]

The wood sounds good by description. There are anomalies that don't add up. Strong draft usually means very strong secondaries when the air control is fully closed. The stove could be leaking air still or the secondary intake port might be partially plugged.

Can you describe the flue system from stove to chimney top including elbows, tees, etc. if there are any. How tall is it overall?

Weird.
Rough measurement but going to say 5 plus 18 for 23 vertical and 2 90 degree elbows with 3-4 feet horizontal.

5' single wall interior. 2' interior single horizontal.
1-2' triple wall horizontal to exterior elbow.
5 sections of 3' triple wall straight up and last piece is 3' above ridge. So a whole section above.

 

[WoodyIsGoody]

When I lower it they still burn but slowly die out and wood smolders I have to open air again.

My current tube wood stove will have the same issue with wood that is dry enough to burn well on high but with just enough moisture to make it problematic to turn down to medium or low. If I cure the wood in a dry place long enough to get the MC down to 15% then I can turn the stove way down to achieve a longer burn with a beautiful secondary display and good heat output.

Seems to be burning way better and the wash effect is more noticeable.

I'm thinking the draft might be too strong so secondaries don't light until temp is too high? There is no glass wash visible when it's cold. The flames get sucked up over baffle.

Every stove is different but the glass wash doesn't need to be visible for it to be working. On my stove the glass wash is typically not visible because the secondary combustion happens at the "ceiling" of the firebox with the byproduct escaping without disturbing or being affected by the laminar flow of the air wash.

 

[Ashful]

Just stumbled onto this thread, and everything you describe really sounds like the classic symptoms of poorly seasoned wood, but your attempts with kiln wood really have me stumped. Do you have a moisture meter?

Why do you believe draft may be too strong? In fact, it sounds like maybe it could be too weak, by the symptoms you've described. Stoves will often stall the secondary system on lower settings, when draft is weak. You've verified flue is clean?

 

[manooti]

Well. Everyone is right. It's the outside chimney. I have it extended with brackets so I didn't have to cut the overhang and the clean out sheet metal cover that slides in blew off. I cleaned it out 2 weeks ago and hardly any creosote but I didn't put the cover back in right and with the wind we had it flew off. Plus since it's not sitting flush against the wall it's letting too much air inside the triple wall. Got some metal tape and taped it up underneath and put the cover back in right.

(Not the actual pipe cover that screws in, it was the thin sheet metal that slides under it which exposed all wall of the pipe)


After that 5 minute fix the draft is awesome. I shut it down completely and secondaries stay lit. Even when secondaries go out there is barely any visible smoke out the top. I guess the pipe was being cooled because it was pretty much exposed underneath letting in cool air.

I'll also swap out the single wall inside to double wall and use 2-45s instead of the 90. That should help as well, right?

 

[begreen]

I'll also swap out the single wall inside to double wall and use 2-45s instead of the 90. That should help as well, right?

Good sleuthing. Air diluting the draft will definitely affect proper function. Switching to double-wall and softening the 90s using 45s instead will help improve draft. This will be most notable when temps outside are milder.