My wife and I bought a house last fall with several wood burning fireplaces. This came in handy when the furnace didn't work for 4 days of subzero temps. Little did I know until spring the main fireplace had rock hard glazed creosote lining the entire flue. Luckily we didn't burn the house down during those cold nights. My question is has anyone seen creosote this thick/hard and how long would it have taken to build up this amount? Seriously....I searched the web for similar pictures and found none. For reference, the chimney is on an outside wall and 25 feet tall so it may have built up faster than normal. I'm putting a wood insert in and had to slide a ice pick down the side of the flue to separate/break the creosote off which worked if anyone else is looking for a way to remove the glazed creosote.
Rock hard glazed creosote removal & How many seasons to create?
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Looks more like mortar than creosote. It really takes no time at all if the conditions are right. I have seen chimneys plug within 30 days from creosote. When I lined our chimney, I removed chunks of creosote over 1/2" thick where the thimble entered the chimney. When broke open it resembled black glass. I brushed the main chimney and chipped away the bad deposits then lined and insulated. It was impossible to remove 100% of the deposits. After lining, theres been no issues with creosote. If its black and glassy all the way up, then maybe a chemical treatment and sweep to remove.
Might consider putting them in an outdoor firepit or grill and putting the MAPP torch to them. If they don't burn, probably not creosote. The MAPP torch is my favorite inspection tool.
aahh, the mapp torch, aka "The Redneck Test"......I use one all the time!....nothin wrong with that!JimboM said:
I agree with laynes69 that what's shown in the picture is primarily mortar, perhaps with a coating of creosote. The chunk on the far left clearly shows a lip where the mortar oozed out from between the bricks before hardening. What this very likely means is that there is no lining in this chimney. (The only exception I can think of would be a very sloppy job of mortaring in clay flue tiles.) An external chimney in a cold climate would tend to produce a lot of creosote - probably more with an insert than with a fireplace. With no liner and a good deal of creosote, the danger from a chimney fire is very great. I'd sure want to have the chimney inspected and lined (if needed) if it were me.
Thanks for the analysis. I'm now thinking 'fraxinus' may be right....very sloppy job of mortaring in clay flue tiles....with glazed creosote building up on top. I did throw some chunks in the fire and it bubbled. The chimney does have a 7 x 11 clay liner running the full length and I am putting in a 6" round SS flex liner the entire length for the wood insert. But cleaning was a problem with the jagged edges and minimal clearance to the liner. The clay flue is now free of the mortar/creosote and SS liner should help prevent future build up. Thanks again!
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