Chimney was clogged today!

[iowa]

Today wasn't a very good day. I loaded the furnace in my basement and went to work. Later, after I got to work my wife called and said the basement and upstairs was getting smokey and smelled bad! So I told her to open the windows and go to work. I called my dad to run over and check out the furnace and I left work.

My first thoughts was that my furnace had a hole in the heat exchanger or main burn chamber. This is an old unit that was made by the local menanites. It was rusty when I bought it and I had to do a repair job on the heat exchanger tube and the flue box. I totally went through it though to make sure everything was solid and no leaks. But you never know..

However when I got home the wood was just smoldering and no good flame. Not until I would open the door and then you would about lose all your facial hair!!! So I checked the chimney and it was clogged.

My unit sits in the basement and I have double wall flue piping from lowes. This was all brand new and I started using it NOV 15th 08'. So my piping goes out the wall to a T and then up 5- 3' sections. Nearly 15'. My clog was about 3' up at the joint of the flue or thereabouts. The pipe is full of tar crap on the inside and very sticky mess. When I popped the cleanout off of the T water and some creosote came out.

I am wondering if my furnace isn't getting my flue pipe hot enough or what's going on? I'm not burning wet wood. I've mostly burned hackberry, oak, and walnut.

Is it safe to do a controled flue burn once a month or so. If so.. how do you do this?
Do you think that the 2 heat exchangers on the top of the firing chamber is cooling the exhaust too much that my flue doesn't have a chance to burn off the creosote?
TIA

 

[kevin j]

15 feet of outside (uninsulated?) flue is probably just too cold.

 

[iowa]

15 feet of outside (uninsulated?) flue is probably just too cold.

NO NO. 15' of Double wall insulated flue pipe...

 

[volks-man]

NO NO. 15' of Double wall insulated flue pipe...

maybe, maybe.
supervent says that it is best to install the chimney sections inside the insulated envelope of the home. there is a reason for this.....

though, i think the source of your problem is low flue temps/slow draw due to the exchanger. but it is just a guess.
the wood is properly seasoned?

 

[iowa]

maybe, maybe.
supervent says that it is best to install the chimney sections inside the insulated envelope of the home. there is a reason for this.....

though, i think the source of your problem is low flue temps/slow draw due to the exchanger. but it is just a guess.
the wood is properly seasoned?

Hmmmm. So you think my flue should go straight up through my 2 floors, attic, and then the roof. Instead of going out my wall and hugging the exterior wall of the house?

I'm thinking that the heat exchangers are taking too much heat from the burn and then my flue piping outside is too cold...

 

[pacman]

You need higher tempertures. You got it turned down way to low and its not burning it off. Get that flue cleaned or sweep it out . Then burn your fires hotter. Make sure there isnt any blockage in that flue before you make a fire .

 

[iowa]

You need higher tempertures. You got it turned down way to low and its not burning it off. Get that flue cleaned or sweep it out . Then burn your fires hotter. Make sure there isnt any blockage in that flue before you make a fire .

ya. I swept it today and it's ok. I'm back burning again..

 

[pacman]

Good deal!

 

[chowdozer]

Hmmmm. So you think my flue should go straight up through my 2 floors, attic, and then the roof. Instead of going out my wall and hugging the exterior wall of the house?

I'm thinking that the heat exchangers are taking too much heat from the burn and then my flue piping outside is too cold...

if you're going to run your flue pipe outside, at least use insulated flue. your draft will be better and more consistent and the burn will be more consistent. burning an inconsistent system is a pain.

 

[wkpoor]

My reply in this thread is only to say what I learned about flue temps recently if that is of any relevance here. During the GTG I recently held I thought it would be a neat idea to have a woodstove outside close to the action instead of a bon fire. Well it didn't work out very well. The stove was the same one I used in the house for 7yrs without issue. Always drafted good on the house chimney. Outside I had 6' of single wall stove pipe. Fire started OK but couldn't get stove up to temp without leaving door cracked part way open and creosote was running down the pipe and onto the stove top. This stove used to burn so clean I once got 2yrs between sweeps and that was with me burning it Nov-Mar 24/7. Also outside no way could it put off enough heat to keep very warm by. Basically the outside air kept the pipe chilled such that it wouldn't draft right and even dry wood was building creosote. Flue temp is the key to good draft and clean pipe.

 

[deerlakejens]

My stove is sited in my basement and vents outside about 4' above the stove. The outside insulated pipe is in an enclosed wood "closet" up to the roof line. I monitor my flue temperature regularly and have miniscule creosote buildup.

 

[bore_pig]

I run about 25' double wall stainless outside the house. No problems. Had to clean the top ft of the pipe once after this fall. You just aren't burning real clean. Run a brush through once a month. No more problems.

 

[Mike PA]

The flu temp is critical. Too cold and there will be trouble. I have about 20' of double walled, insulated, ss on the outside of my house. I sometimes have trouble with my cap getting plugged (or did until I modified it). The biggest problem I get is because no one is home all day, so the stove is not getting a large draft. When we come home, we load up the stove and open the draft a bit and get a good hot fire going. We never get a fire in the chimney, but the added draft and heat helps to eliminate build-up. Just gotta burn it hot sometimes.

Also, be a little careful of what you burn. Burning too much newspaper can cause blockages.

 

[johncinco]

I run 33' up. triple wall insulated pipe. Even with the good pipe, its a long way up and it has to stay hot. I have to run it hot or I get a lot of buildup. I keep a metal can outside under the T cleanout and open it up about every two weeks. I only get a coffee can worth of crap, but it can pile up quick and block off the pipe.

 

[Zodiac45]

Iowa, That's just a lot of buildup if it actually choked off the furnace! Something is not right about the way that stove is burning. Run it hotter or sweep it more often if you can't get the flue temps up. Could just be the design of the Memonite furnace. How does it work? Are you heating water in the round cylinder with wood burning below in the box, or is it air?

 

[bigjake]

Just to get this straight b vent is double wall but no insulation (right) and
then the ss insulated double or triple .Im no expert just wondering.seems
to me if his land is flat and the flu faces the weather it could be cold
we had some very cold weather this year.???

 

[iowa]

Iowa, That's just a lot of buildup if it actually choked off the furnace! Something is not right about the way that stove is burning. Run it hotter or sweep it more often if you can't get the flue temps up. Could just be the design of the Memonite furnace. How does it work? Are you heating water in the round cylinder with wood burning below in the box, or is it air?

It is forced air furnace, no water.

I think that the furnace does an awesome job. We never run it very hot because it soon will have us opening all the windows up stairs. I think that the design has a flaw in it. And that is the double heat exchangers. They draw too much heat from the exhaust gasses and then my chimney doesn't stay hot enough.

I will run creosote cleaner once a week and get it hot once a day to help out and see how that goes...

 

[iowa]

Ok. I threw in some really dry pieces of oak kindling, other dry pieces of oad, 3 pieces of hedge and some dry 2x10 pieces of oak in there. It is really ripping, but the single wall stove pipe going up to the wall is only showing 120 degrees. This isn't good!!

The heat exchangers are cooling it way too much!

 

[laynes69]

If you can get a complete combustion burning hotter now, and see little to no smoke from the chimney. I wouldn't worry. Whats important is to burn off most of the smoke before hitting the flue. I would rather open a window then have a chimney fire due to a smoldering fire. Just keep an eye on the chimney to get an idea whats going on.

 

[Zodiac45]

If you can get a complete combustion burning hotter now, and see little to no smoke from the chimney. I wouldn't worry. Whats important is to burn off most of the smoke before hitting the flue. I would rather open a window then have a chimney fire due to a smoldering fire. Just keep an eye on the chimney to get an idea whats going on.

Yep I agree. The HX sounds like it's doing a great job on the design. My guess is that because so, you tend too have too run it in smolder mode. If you could could somehow get a secondary burn going ala cat stoves or add on burn tubes, you'd probably have the perfect unit.