Flue Pipe Smoking...Bad

Not sure if this is the right forum to post this in, but hopefully someone can help. I have a Coal Chubby that I mostly burn wood in.I burn my fires on the hot end ~550*-600*, but my flue temps rarely go above 225*. The house was a bit chilly when I woke up so I decided to start a fire. Filled the stove and started a fire. I usually open the lower ash door for a few minutes to get a nice hot fire going. My flue temps usually run ~200*-225*. I left the ash door open a little longer than normal and my flue temp reached 450*, still within normal temperature range I believe. The house started filling with smoke. It was pouring out from the pipe connections. I closed the air intake a bit and closed off the mpd 90%,the flue temp started to drop finally settling at it's normal 225*. The smoke slowly dissipated. Could this have been all of the crap in the pipe burning off due to the high flue temp?

If the piping is new then it's probably just the paint curing on the pipe. If the temps on the pipe never reach above 225* then my guess its definitely just the paint curing off the piping. Run the stove so the temps on the pipe go above the 225* a few times and the pipe should stop smoking. This is of course, just my guess.

Is the stovepipe new? If that is the first time it has gotten that hot, you were probably cooking the paint. Get yourself a few tons of coal and enjoy the heat and low stack temperature.

You did say pouring out of???And you have been burning this season??? In my parlor stove experience for quite a few years with wood--YUP, you hit the nail on the head--It's called old school pipe cleaning--did you hear any roaring??maybe not, but creosote burns my friend & will start a good chimney fire which when controlled does a good job of cleaning the pipes--if it gets away from you I can only hope you have good house insurance.

did you check to see if Santa was in there,lets hope not. Did it smell like cresode since you mostly burn wood, if so you might have to open your MPD a little more for hotter stack temps. to help burn off the excess cresode. Dennis

Have to agree with Freetown Fred. You were exceeding the ability of the chimney to exhaust the products of combustion and those products were creosote.

I had a similar thing happen years ago when burning wood. There was creosote built up in the pipe, and I have read a hot fire can sometimes cause the creosote to "flash" burn and expand into a much larger volume of spongy crumbly material, something like that expanding spray foam used for insulation. Anyway, that is apparently what happened to me, in the middle of the night when I added logs to the fire and got it burning hot -- wood smoke was coming out of the stove and all the stovepipe joints. Luckily it just plugged my chimney cap, but I was up on the roof in the middle of the night unplugging it.

Definitely let your fire burn out and check the chimney before you load up the stove again. There may be sufficient open space in the chimney to handle a small fire but not the smoke from a large one.

tcalo wrote:My flue temps usually run ~200*-225*.

How much wood have you burned under these conditions? What do you have for a chimney?

Just for the record, I used to let my beastly wood stove roar away every morning at refill time--no chance for creosote BUILD-UP--It was flames, not smoke--never had a fire in 35 yrs.+ --pipes & chimney always looked good in the Spring. What's that liability warning---DO NOT TRY THIS AT HOME Clean your pipes!!!

Thanks for the reply's. Dennis, lets hope if it was Santa that he didn't have my gifts with him...lol. All is well, no chimney fire. The stove and flue pipe are fairly old, but that's the first time the flue has seen temps that high. My guess is that since the flue is usually much cooler that it was in fact the creosote burning off. I can't seem to get my flue temps above 225* with the mpd fully open and the stove ~550-600. I recently had a new SS double wall chimney installed due to the old one being too short pushing smoke back into the house.I posted my flue temp issue in another forum inquiring about it. I'm guessing the added height of the new chimney is keeping it cooler? Happy Holidays and stay warm!

as FF said burn hot every day. My owners manual says "Adding rock salt to a hot fire will help discourage the formation of creosote" Dennis

tcalo wrote:My guess is that since the flue is usually much cooler that it was in fact the creosote burning off.

Creosote burning should NOT cause smoke to come out the stovepipe joints. It should make a super-strong draft that will suck your cat IN through the joints and up the chimney if she gets too close. I repeat my advice (free and worth it) to check that your chimney is clear before you load up the stove again.

tcalo wrote:I can't seem to get my flue temps above 225* with the mpd fully open and the stove ~550-600.

Well, generally that is good. It means the heat is staying in the stove rather than going up the chimney. Bear in mind, if the stovepipe measures 225* with a magnetic surface thermometer, then the actual flue gas temperature in the middle of the pipe is probably 400* or so, much closer to the stove temperature.

Thanks for the advice rberq. I will check the flue to make sure it's clear. Funny you mentioned my cat, she lays so close to the stove I think she is going to burst into flames any minute...she's hot to the touch. You would think with all that fur she's warm all the time!

Luckily it just plugged my chimney cap, but I was up on the roof in the middle of the night unplugging it.

If you burn wood loose the chimney cap. You don't need it and you don't want it..