This should not happen under normal circumstances. Was your chimney cleaned before installing this insert? Is there a flue liner from the stove to the top? Or, is the insert just "connected" into the flue at the bottom. How old is the chimney? Lot's of possibilities here.

A steel flue liner was installed in the masonry chimney at the same time as the stove insert. Insulation was packed around it at the top and bottom. It is a straight run up except for one place just above the firebox where the tube had to be flattened to make the bend. I was told that is normal. Any thoughts?

You can indeed clog a chimney with creosote in a month. Smoldering fires can do this, especially if you are burning a lot of oak. Even two year old oak can be too green to make good firewood, especially if it has not been split for those two years. The only way to tell for sure is to use a moisture meter on a freshly exposed surface. The moisture content should read around 20% for best burning. Even dry oak, though, can produce a lot of creosote if the fire is frequently starved of oxygen.

There is no way to clear the blockage without taking off the cap and running a brush up and down the metal flue. In other words, it's a job for a chimney sweep. It's also pretty cheap insurance for guarding against a chimney fire and is routine once a year maintainence. I would also want the sweep to inspect the stove to flue connection. "Flattening", if severe, is not normal and has the potential for reducing the draft and contributing to the creosote problem.

Thanks This is very helpful. When the chimney sweep (who also did the install) comes, I will try to see how severe the flattening of the liner was. But is there an alternative to this method? I don't think most chimney boxes have clearance for 6 inch round pipe, do they?

I will also be sure to get a moisture meter and magnetic thermometer.

I'm not sure what you mean by "chimney box"', but the usual liner goes like this: A full length stainless steel liner, either flexible or rigid, extends from above the roof line down to the insert where it is connected. At times it may be necessary to ovalize the liner slightly - an inch or so - where it passes through the area that once contained the fireplace damper. A block off plate is installed just below where the damper used to be. Under some circumstances an installer will use a tee so you have access to the liner without the need to disconnect anything. With a fully insulated liner, the creosote problem is most likely to have been caused by a combination of incompletely seasoned oak and smoldering fires. A very good site for a wealth of information about inserts, firewood, etc. is www.hearth.com

akamaine - The liner is not insulated except at the top of the chimney and the bottom. Should it be? The chimney is on an exterior wall but inside the house. It there is anything I can do to improve the energy efficiency of the stove and the house, I want to do it! We got the stove to address our astronomical oil bill. By the way, I just discovered cold air coming in through the vents for the oil fireplace. I removed the grate covers and plugged them with insulation. I wonder how that my have affected the draft.

drymanhattan -. "When the chimney sweep (who also did the install) comes, I will try to see how severe the flattening of the liner was."

You may want to have it inspected by a different sweep. Also, you may want to consider getting your own brush. If you're having to sweep your chimney monthly you're not saving any money.

I've never had to sweep my chimney more than twice during a season in my more than 35 years of burning wood as a primary heat source.

drymanhattan: Consulting a different sweep as suggested above is probably a good idea. The installation may be fine, but a second objective opinion would be worthwhile. As for insulation, it is done in two ways. One is a blanket wrapped around the liner before it is installed. This increases the diameter so it may not be practical in a tight squeeze. The other method involves pouring loose fill insulation around the liner after it is installed. Either method improves the draft by keeping the liner hotter. If your chimney was in good shape with an intact terra cotta liner, no insulation would have been required by building and fire codes. There may not have been much room so that the installer added insulation only where there was space for it - near the bottom and top.

The key to creosote free burning is dry wood and hot fires. Many thermometers intended for wood stoves are color coded to indicate the ideal temperature range. Much of the wood sold as seasoned is too green for efficient burning. If you have access to kiln dried fire wood it is well worth the extra cost. No stove or insert should require monthly cleaning. I've heated with 5 to 6 cords of wood per winter for 40+ years and have never needed more than an annual cleaning. With a modern efficient stove, the creosote swept out this past fall would not have filled a coffee can. That was after a very cold winter with more than 6 cords burned.

As for general energy efficiency, free inspections and evaluations are available in many states. There is an entire library available online and in actual books about the subject, but in general sealing air leaks, insulating the attic, then the cellar are the three most important steps. Don't waste money on replacement windows or blown in wall insulation.

The installer/sweep cleared the chimney. The creosote had collected near the cap and above the stove. Once cleared, the fire burned great. He didn't think our wood was the problem, but our technique with feeding it air. Unfortunately he says there is no way to access the flue from below so we will be calling back the chimney sweep if we mess up again. I can't believe other owners of this and other stoves don't have the same problem..

Am thinking that it may be a good idea to fill the chimney around the flue with loose insulation next time we have a sweep up there. The sweep did point out the air intake vent outside at the base of the chimney which was responsible for bringing in a lot of cold air leaking around the surround of the stove. When we can get out and close that off it should eliminate a major heat loss. That should pay for his services..

drymanhattan - "The liner is not insulated except at the top of the chimney and the bottom." and in a later post, "Am thinking that it may be a good idea to fill the chimney around the flue with loose insulation next time we have a sweep up there. The sweep did point out the air intake vent outside at the base of the chimney which was responsible for bringing in a lot of cold air leaking around the surround of the stove.'

These two things seem to conflict. Your liner is insulated or it isn't. If you have a directly connected liner from the stove to the cap, and there's insulation at the bottom, then this shouldn't be that big of an issue.

Something isn't right here. Sorry I'm not being any help.

Let me be more specific: the area around the chimney where the stove was connected to the liner, and the area around the liner at the very top of the chimney, were packed with insulation. In between, however, the bare steel liner runs up the masonry chimney.The chimney is on the exterior wall but inside the stone house. I was assuming that insulating the entire length of the liner would keep it warm - improving the draft - and also conserve heat in the house. Am I wrong?

No, you're not wrong but this would only be an issue when you first light the fire. If the air in the flue is colder than the air in the room then that forms an inversion and can push air back into the room. Once the fire is lite and going well then the flue warms and it's not longer a problem. So, the extra insulation isn't required.

Now, about what the sweep said - "The sweep did point out the air intake vent outside at the base of the chimney which was responsible for bringing in a lot of cold air leaking around the surround of the stove. When we can get out and close that off it should eliminate a major heat loss. That should pay for his services."

Are you feeling this draft of cold air coming from around your stove/insert and into the room?

Yes, the cold air is coming from behind the surround, which is not flush to the wall because it's a fieldstone chiimney.

How old is your house? I'm thinking that the "air intake vent" might be a way to remove ash from the firebox. Lot's of older homes had this feature.

Last question, what exactly do you think the sweep meant by saying you had problems with your "technique with feeding it air"?

You've got a really nice stove there. Sorry you're having such a bad experience.

It has been a long time since I burned wood and had an epa approved stove. I was under the impression that the quadrafire and others required double wall insulated pipe all the way up. Even if I am confused about this, I would expect that quadrafire would answer your questions directly about installation and firing.

I lived in a pleasant area and burned a lot for pleasure rather than necessity. I burned lots of pine along with hard woods and almost never had a dramatically damped down fire. I only cleaned the flue three times in 25 years and suspect I was in the coffee can range too.

The house is c 1930s, but the fireplace was built in the 70s. It had vents on the front and sides of the hearth and one on the front floor of the firebox. They worked together to bring in outside air and distribute heat to the room. All of these have now been plugged up, but as the sweep discovered, the outside vent never was and is the likely source of the air still coming in.
The stove we have has a valve and timer for starter air, a lever to adjust the air intake for the level of burn, a dial to control the blower, and of course the door. What I am told is that the instructions by Quadrifire understate the need for air to start and maintain a hot fire. Our method now is to open up all the air sources, warm the flue with rolled paper, gradually build up a fire with kindling (not sticks), then add the dry logs, and only when they're burning start closing the door, then letting the timer start on the starter air, and only lowering the general intake after the fire is at peak and we're trying to conserve wood, like overnight. i also learned to rake the coals forward before reviving the fire because that is where the opening to the flue is.

Thanks for taking the time and detail to explain. That outside vent thing was totally new to me. Sounds like you now have an action plan and, hopefully, no more problems with the stove.

Thank YOU for all your help. I will post an update, as well as the response of Quadrafire to the question of insulating the flue.

I have to disagree with the idea that full insulation is only an issue when starting a fire. The volatile gasses vented up a chimney liner will condense on any cool surface and deposit creosote. Complete insulation keeps the liner hotter longer thereby improving the draft and reducing creosote formation.. It is a little odd in this case that the clogs were in the two places already insulated. A cap, however, is a place that is not insulated and they always impede the draft thus providing an ideal place for creosote to form. As for the clog at the bottom, I'd want to know how severe that crimp is. This too can impede the draft and provide a similar conditions for creosote formation.

Double and triple wall pipe is used for stove to chimney connections or all metal chimneys. Stainless steel liners intended for placement in a masonry chimney are single wall although they are available in different gauges of metal.

There is no crimp in the metal liner. I was mistaken about that. It's a straight shot from the stove to the top. And when I said cap, I meant around the liner at the top of the chimney. Shaking loose insulation into the cavity seems so easy and cheap, I'm interested to know the reasons NOT to do it.

drymanhattan -> "Shaking loose insulation into the cavity seems so easy and cheap, I'm interested to know the reasons NOT to do it"

Probably none if you got the insulation and the means to get up on your roof and pour it in yourself. (I am a little surprised that you have access around your liner from the chimney cap to do this. Mine have always been sealed up to the liner by concrete or a crown sealer that prevent this access.)

My guess is that insulation around a liner in a ceramic chimney is probably less of an issue because the tile/brick/rock absorb heat from the liner and will retain and release it back onto the liner as the fire cools and goes out. It won't cool as rapidly as one that's insulated as the insulation has little to no thermal conductivity. But, obviously, opinions differ on this.

For me, with my set up, Buck 92 insert w/ceramic wafer (catalytic burner), direct connection to the cap, I've only experienced a thermal inversion on a couple of occasions when first lighting the stove in the 11 years I've been using this stove. I may only start a fire 3 or 4 times a season as I tend to keep it going weeks at a time since it is my primary heat source. The catalytic wafer provides almost complete combustion of flue gases and seldom do I notice any creosote deposit on the liner. As akamainegrower notes, however, I do have to brush off creosote deposits on the screen under the cap.

So here I am two months later, and AGAIN the liner is clogged with creosote! We were going gangbusters with hot fires, clear glass even in the morning, until suddenly it came to a halt. Smoke all over the house and a black window. The cap is covered with creosote. I have ordered a moisture meter and will check our wood, but I also want to look into the question of insulating more of the liner. The chimney is next to the stone wall, which is not insulated. If I can get the installer to do it, what should I ask for? Thanks again for everyone's advice.

kitasei: you really do seem to be doing everything right, so there is some mystery here. General Tools makes an inexpensive moisture meter that is available at many hardware stores and home centers. My guess is that the moisture content of the oak is still pretty high. The creosote is coming from somewhere and the oak is a more likely suspect than the locust. The other thing that is happening is that the volatile gasses that are condensing out as creosote are cooling too rapidly in the chimney. This is happening even though you're seeing a hot burning fire within the stove and clean glass. That puts us back with the question of insulation for the liner and, to a somewhat lesser extent, the strength of the chimney's draft. I don't know what the installer has told you, but what I think is happening is this: You build a good hot fire. The gasses go up the chimney but cool rapidly due to no insulation, and/or slow way down due to weak draft. When they encounter the obstruction of the cap they condense into creosote which continues to accumulate until your chimney is totally blocked. This should not be happening but certainly should be correctable. I also suspect that some of the "automatic " features of this particular stove are reducing the draft far too much even though you're following the manufacturer's instructions.

Thank you akamainegrower. I have some other questions you may know the answer to. Is there any reason NOT to raise the stainless steel liner to improve the draft? Is the section poking up above the chimney another area where the smoke can cool off and leave creosote? Also, what is the purpose of the cap? Are there any difference in size or type? Thanks again..

How do you measure a draft?

kitasei The main function of the cap is to keep rain, birds, etc. out of the chimney and to give a more finished appearance. There are several different styles. If you are asking about raising the liner in order to increase the chimney height and thus the draft, one reason for not doing it is the fact that liners are pretty flimsy. They are not intended to be chimneys. There may be code issues as well.

The area around the top of a chimney is the place where creosote is most likely to form no matter what type of chimney.

There are devices that measure draft. HVAC technicians use them to check and tune furnaces. You can also tell a lot from the appearance of the fire. Good draft produces bright, lively flames and fires are easy to start.

Hard to tell from a distance, but I think your problem may be an unfortunate combination of less than ideal oak, uninsulated liner and a stove that tries to bypass the human operator. Did Quadrifire ever contact you? How about the dealer?

Quadrafire has removed its user manual for this model for some reason. I am awaiting their answer why. Ater the last problem, the dealer came and took off the surround and took pictures up the flue which showed the creosote blockage and also saw the cap which was clogged.. The conclusion was that it was our firemaking technique. Now that it's happened again, he's willing to consider the uninsulated flue issue. I'm starting to get annoyed at the mounting cost - two cleanings at 160 each, and then insulation that I had asked for in the first place? I have been keeping track of our oil consumption in comparison with last year. Despite burning two cords of wood, we only reduced the oil by some 10%. To be fair, I haven't calculated in the temperature degree days, which may show a much more significant savings. February did break the record. The stove also made the main room much more comfortable. I miss it! And we're getting more snow tomorrow!

I just had one clog in less than two weeks. I had cleaned it thoroughly, but then we had a cold snap with temps down to 10F or so, cold for north Alabama, even on a mountaintop. This has happened twice before in cold weather. The clog was only from the rooftop to the flue top. There was hardly any lumen left. Below, it was clear. This is a double wall stainless flue. The top is, I think, insulated. Since we're expecting the same type weather in the next couple of days, I'll check it again as soon as the temps moderate. I should add that part of the wood we're now burning is not green/wet, but it's not as seasoned as I like. I'm sure that's part of the problem...

I think your wood is all of the problem.

May be. It rings properly when it's banged together. I have about a cord of it total. It came from a friend who runs a tree service. It's a hickory which had been dead on the stump from a year and half to two. However, it's only been split and stacked for about six months. In fact, I have a great deal of it cut to length but not split yet, because I knew I couldn't get it seasoned in time, even though the tree was partially cured on the stump. I'm low on seasoned wood, so I may buy a cord of seasoned wood for the rest of the winter. I'll split the other in the spring. I did order a Stihl moisture meter, just to satisfy my curiosity. If it happens again, the company I bought the flue from over fifteen years ago still carries the same line and they have an insulated model. The whole flue needs replacing, but I can do the cap with a break in the weather. One factor is that the stove sits great room about 12' high, so the length of the flue is about 18', stove to weather cap...