Chimney creosote prior to liner theory

[ray_killeen]

My concern is that prior to installing a stainless steel liner and fireplace insert there was a certain coating of creosote on the original clay liner from years of conventual fireplace burning. Now when the fireplace insert is in use, high temperatures from the stainless steel liner will gasify the creosote from the surrounding clay liner and will have no place to escape to the outside since there is a stainless steel cap plate at the top of the chimney. Therefore, creosote gasses may be leaching into the interior of the house.

 

[begreen]

It's a valid concern. This is why it is imperative that a chimney be fully cleaned before putting in a liner. This includes not only the flue tiles but also the smokeshelf and damper area. It's also part of why insulating the liner is required. If this work was not done before the liner went in, then it should be pulled and done properly before reinstalling.

 

[ray_killeen]

Thanks for the response. I have a geothermal system in place but being in a rural area near Allenton PA I enjoy the ambiance/warmth of the fireplace insert during the winter months. I do have an AWAIR air monitor that seems to be extremely sensitive i.e., someone walks into my house with perfume or hair products it will spike the VOC readings but when burning the insert, it shows nothing, PARTICULATE or CO2 readings or smell either. Yet after about 48 hours of burn I feel respiratory irritation, foggy and lethargic. This summer I could pull the liner and clean the flue tiles but is it realistic to expect complete removal of creosote? I’m sure it’s typical but I noticed the mortar joints between the flue tiles were not pointed and protrude approximately ¼”. I could add blanket insulation to the liner, but would it be better to use a vermiculite mix to help seal? Originally there was a Heatilator but I cut out the steel flue and smoke shelf so it would not interfere with the liner. I did not add a block-off plate or blanket insulation into the opening which I could also do. It seems impossible to find quality work these days and usually end up doing everything myself.

 

[EbS-P]

I am 25 loads run through a new insert. I can still smell paint curing when it get hot. Can you measure CO?

I ask as one night set the burn and went to bed. I woke up and could smell something, hot metal maybe. Leaped out of bed sure that the stove was over firing. Nope it was smoldering. Looked at my AQ monitor and the only value that was elevated was the CO. Pm 2.5 and 10 were in unchanged. VOC may have been up 20-30 percent. But CO was up 2-3x.

If it wasn’t cleaned you’ll have to pull the liner to clean. No that the liner is out might as well insulate.
And do the block off plate. I did an ok one with out removing liner. It’s not great. But it helps a lot.

 

[begreen]

There should be no leakage at all from the liner. It is a continuous tube. However, if the chimney (including smokeshelf) wasn't thoroughly cleaned, there could be remaining bits of creosote that are offgassing. Use blanket insulation to ensure equal and even insulation for the full length of the liner. Poured insulation is messy and may not guarantee even insulation.

 

[ray_killeen]

I am 25 loads run through a new insert. I can still smell paint curing when it get hot. Can you measure CO?

I ask as one night set the burn and went to bed. I woke up and could smell something, hot metal maybe. Leaped out of bed sure that the stove was over firing. Nope it was smoldering. Looked at my AQ monitor and the only value that was elevated was the CO. Pm 2.5 and 10 were in unchanged. VOC may have been up 20-30 percent. But CO was up 2-3x.

If it wasn’t cleaned you’ll have to pull the liner to clean. No that the liner is out might as well insulate.
And do the block off plate. I did an ok one with out removing liner. It’s not great. But it helps a lot.

It took 4 hot burns before the high gloss enamel paint smell subsided on my new insert, that was two years ago, no smell since.

The AWAIR measures:
Temp (deg. F)
Humidity (%)
C02 (ppm)
Chemicals (ppb)
PM2.5 (ug/m^3)
None of them are influenced when burning the insert surprisingly since it is extremely sensitive, more than two people in my house and the CO2 increases.

This summer I plan to pull the liner, clean the flue, replace the liner adding blanket insulation as "begreen" suggested, there are no splices continuous tubing. I'll fabric an insulated sheet metal blank-off plate and anchor it with sheet metal screws and use some high temp sealant. Can't think of anything more to do.

 

[ray_killeen]

There should be no leakage at all from the liner. It is a continuous tube. However, if the chimney (including smokeshelf) wasn't thoroughly cleaned, there could be remaining bits of creosote that are offgassing. Use blanket insulation to ensure equal and even insulation for the full length of the liner. Poured insulation is messy and may not guarantee even insulation.

Thanks will do

 

[Ncguy427]

I just went through this when installing my new wood furnace. 35 year old clay flue with a thin coat of glassy creosote towards the top. The company that installed my liner Would not do it without the cleaning first, they brought a man lift and a power cleaner, big drill type thing and spend a good 2-3hrs thoroughly cleaning it. Smoking would be a more realistic problem he said. Liner gets hot and the creosote on the flue tile could smoke.

So yes it’s definitely possible to remove old hard creosote, but you’ll probably need that power cleaner to do so. I could never get it with my brushes.