Over fire or chimney fire??

[KindredSpiritzz]

Something weird happened last night im trying to figure out. .....Vogelzang wood furnace.
Ok so last night before bed i go down, load the furnace up pretty good for the night burn. Temp on the front mag. gauge was 300ish. I left the door open to let the fire get going and get the temps up. I let the front temp get to almost 500 before i closed the door and i check the back mag gauge on the uninsulated double wall stove pipe going into the chimney and thats 600+ degrees, the highest i have ever seen it and in the over fire zone.. So now im kind of worried, pipes smoking a bit and the smoke alarm goes off. So i cut the air back, run up on the roof and look, the chimney cap is glowing in spots where the creosote started to catch fire and burn, there a few sparks coming out the chimney but nothing bad. I go back downstairs and by this time temps are back down in high end of the normal range so i crack the air open a little bit , wait awhile and go check the chimney again, the smoke looked thicker than normal against the night sky but i couldnt tell in the dark what color it was. I watched it for awhile, temps all back in normal range everything seemed fine so i went to bed after awhile. In the morning i figure i'll clean the chimney, it was a few days past due anyways. I always clean it once a month and i usually get a coffee can of creosote out of it without fail. Past couple weeks i got into some wetter wood so i figured it'd be pretty bad. I pull the cap, clean that, look down the SS liner and im shocked at how clean it is, didnt even need cleaning when it should have been dirty as hell. So now im wondering if i had an over fire or if i had a chimney fire and it cleaned the chimney out? Nothing laying on the roof top besides a little creosote from the cap. No flames shooting out, no loud rumble, no mess on the roof, no bitter smell. I just cant understand why the liner was so clean. The first two pictures are from today, the 3rd picture is what my pipe usually looks like after 30 days of burning. Only thing different is last few weeks i have been burning more ash as part of the mix but like i said its a bit wetter in the low 30s. Prior to that it was box elder, aspen, some pine & maple all in the mid teens.

Bare spots on cap are the areas that were glowing and on fire.



what my liner looks like today after 32 days of burning.

what my liner USUALLY looks like past 6 times i have cleaned it in the past.

 

[mustash29]

IMO, if your cap got hot enough to glow & catch fire, you cooked everything else out of the liner. If you cut the air off to the furnace and there was not enough O2 in the flue to support combustion, the heat, soot & creosote just went up the flue and when it hit the atmospheric O2, the cap lit up.

Maybe your prior dry wood was burning pretty clean, and it was the recent wet ash that coated only the cap.

 

[KindredSpiritzz]

cap started caking up soon after the last cleaning, like it always does. If the wood was dry and clean its the same wood i have been using all winter so far, the 3rd picture is what my liner looked like last months cleaning, same wood.

 

[mustash29]

Does the Vogelzang have a secondary burn system? I'm thinking it does not.

Those magnetic thermometers are not all that accurate. And if you had 600 + on a double wall pipe.....yikes.....I'd hate to know what the internal temp was.

I have a very accurate 200 - 1000 thermometer with a 5" probe tip sticking in the single wall pipe exiting my Englander 28-3500. If it reads 500 - 600, I have way too many flames wrapping around the baffle and entering the pipe. And while it is reading 600, a laser gun on the exterior only shows 450. If you had 600 on the exterior of a double wall pipe with a cheap temp guage, IMO you had at least 1300 inside the pipe. 1300 = creosote ignition temperature.

It sounds like you caught it just in time and got it under control. The cap was starting to burn, a few sparks, then some thicker smoke. I'd say the liner was still hot enough to vaporize any remaining creosote and it drifted off in the night.

Had that been me, I would have grabbed the millinon candle power spot light and looked at the smoke cloud to confirm.

 

[Woodman37]

Sounds to me like you burned all the creosote right out of your liner. Also sounds like you did catch it before things got out of hand. When I purchased my wood furnace the owner of the store told me that I shouldn't have to clean my liner and recommended throwing pizza boxes etc in the fire and opening my ash door and let it clean itself. I thought that was the most insane thing I had ever heard. Glad you caught your problem before it became a lager issue.

 

[maple1]

Throw those magnetic guages that are on your smoke pipe away & get probe guages. Those things are dangerous - it is a LOT hotter inside the pipe than what they say.

You had a chimney fire.

How tall is your chimney? Do you have a barometric damper?

 

[Fred61]

You had a chimney fire.

Agree!

 

[CaperM]

A flue fire can be dangerous.I knew I would have to find a solution,when I would leave home and worry about a flue fire during the day. Before installing a Jetstream gaser boiler 19 years ago brush cleaning my flue every season,cleaning pipes 2-3 times a season was needed.With the technolgy improved furnaces and stoves we have today also burning dry wood,elimenates most cresoate problems.

 

[STIHLY DAN]

Sounds like you had a fire. But its been damn COLD for the last month, so I would bet the furnace has been running hot. May not of made any creosote last month.

 

[hobbyheater]

Sparks out the top are often a sign of a chimney fire.

 

[McKraut]

the smoke looked thicker than normal against the night sky but i couldnt tell in the dark what color it was

My guess is that your chimney fire had already gone out. When we had our last chimney fire there was black smoke pouring out of the chimney -- it literally looked like a smokestack on an old locomotive. We got it out in time to stop any damage. I'm happy to hear you didn't suffer any damage.

Bob

 

[hobbyheater]

The boiler before the Jetstream would create a soft tar like ooze up the chimney that would just turn a flue brush into a tar ball. The only way to keep the chimney clean was to have twice weekly chimney fires. The chimney cap was permanently left off and my favorite day for a chimney fire was a day with a dull overcast. The dull overcast would mask the smoke. Once the fire would get going, I would take the clean out plug out to give it lots of air and most times the fire would only last for several minutes.

With the Jetstream, this is what the chimney looks like after almost 3 years since the last cleaning, just fly ash.
I really do not miss having chimney fires!

 

[brenndatomu]

You had a chimney fire.

Agree!

Me three...

 

[KindredSpiritzz]

well if it was a chimney fire it was over real quick and it cleaned the liner perfectly top to bottom. If it wasnt for that "miraculously" clean liner i'd argue it wasnt a chimney fire but thats got me stumped. A hot pipe and a (very) few sparks were the only sign. Well if it was, at least it withstood the stress test( not that i want to do it ever again). I hate that stupid furnace.
I like those magnetic temp gauges tho, they may not be real accurate but after some experience with them you get a feel for what temps are normal and abnormal on them. I always figure double the temp reading since its on double wall pipe.

 

[CaperM]

I haven't had to brush the flue in 19 years,since I bought the Jetstream.I get about a liter of fly ash out of the cleanout every season.My flue used to be coated with creosete,a fire waiting to happen.Scary when I think back.

 

[MarkW]

Considering the light coating your flue normally has, I'd say it would burn out quite quickly leaving it cleaned out as shown. The sparks are a pretty sure sign of a chimney fire.
When I had my furnace, 600+ on the magnetic was right about where it would light up if I wasn't careful. As noted by others, real temps inside the flue are considerably higher than what the surface temp is.

 

[maple1]

So, how tall is your chimney, and do you have a barometric damper?

Wind gusts across the top of a chimney can suck the fire right out of a stove right into the flue pipe. Especially if you add opening the fire door at the time of a wind gust. Whoosssh. A baro can alleviate that. They might build some creosote around their opening, but that same opening also makes an easy access point for visual inspection & cleaning some of the creosote out.

 

[KindredSpiritzz]

chimney is about 22 ft, no barometric damper installed. Seems to draft good without one and it was listed as optional in the installation manual.
Wind was not an issue the night in question, slight 5-10 mph breeze.

 

[brenndatomu]

Wind gusts across the top of a chimney can suck the fire right out of a stove right into the flue pipe. Especially if you add opening the fire door at the time of a wind gust. Whoosssh. A baro can alleviate that.

Seems to draft good without one

As maple said, a baro is for reducing draft...not increasing

 

[heaterman]

Sounds to me like you burned all the creosote right out of your liner. Also sounds like you did catch it before things got out of hand. When I purchased my wood furnace the owner of the store told me that I shouldn't have to clean my liner and recommended throwing pizza boxes etc in the fire and opening my ash door and let it clean itself. I thought that was the most insane thing I had ever heard. Glad you caught your problem before it became a lager issue.

I can remember my grandpa telling me they used to throw a big wad of newspapers in the old stove they had on the farm. This would have been in the 1930's early 40's. Just stuff the firebox full and touch it off with the draft wide open and let it roar.
He did it once a week and said he never had a chimney fire.

 

[bholler]

yes he did by doing that he was setting off a chimney fire. If he did it once a week they were probably not that bad but still a fire

 

[heaterman]

yes he did by doing that he was setting off a chimney fire. If he did it once a week they were probably not that bad but still a fire

You are correct. What I should have said was that he never had a major chimney fire. He made a little one every week to keep a big one from happening.

 

[Thom Griffin]

Those newspaper fires actually do work, and the result is that you never have a major chimney fire. I used to have an old Rite-way sheet metal stove (bi-metal damper, so it shut down a lot and made lots of creosote. After a couple big chimney fires, I tried the newspaper fire once a day, and voila!, no more more problems. Rather than a fire, I'd describe it as drying out the creosote. You could hear it falling harmlessly down the chimney, where I could clean it out.

However, now that I gassify, there simply is no buildup in my chimney whatsoever, except for the very top at the cap itself, which is to be expected.

 

[kopeck]

I can remember my grandpa telling me they used to throw a big wad of newspapers in the old stove they had on the farm. This would have been in the 1930's early 40's. Just stuff the firebox full and touch it off with the draft wide open and let it roar.
He did it once a week and said he never had a chimney fire.

There was an old farmer that used to take a rag soaked in kerosene and stuff it in his clean out and touch it off every now and then.

Never had a chimney fire but I'm not sure that's the suggested method!

K

 

[bholler]

Well even small chimney fire can damage the chimney and you should carefully inspect the chimney after any such event. And I contend that you should never purposely set your chimney on fire no matter how small the fire it is very dangerous and just asking for trouble.