I just bought a 2 story house with partial basement a month ago and have been using the wood stove in the basement for primary heat.
The stove is a Buck Model 81 and is connected to an external brick chimney that's approximately 27' tall from the point that the stove pipe enters it. The chimney has a terracotta liner that measures 6.5" x 11". The chimney is roughly 4' above the roof level and it has a stainless steel cap/cover.
About a week ago, I loaded the stove up for the night and had temps approaching "overheat" according to the magnetic temp gauge that's mounted above the center of the stove door. The previous owner had placed small metal tray up against the block wall right under the chimney's ash clean out door. I noticed water dripping out of the bottom of the clean out door and into the tray. Several ounces were accumulating on this occasion. It had rained the day before and temps had been freezing since then. The next day I went up on the roof and observed that the crown mortar had several cracks in it and was also eroded where it met the liner. There were also several spots several feet apart on the exterior of the chimney that were moist with some dark staining.
As a temporary measure, I wire brushed the cracks in the crown and used a rubberized roof cement to fill them and the joint around the liner. Since then, I've continued to notice moist spots on the exterior of the chimney and I've observed brown water droplets on the bottom of the chimney cap. I haven't noticed any leaking at the ash clean out door however. This may be due to the fact that I made and installed an aluminum trim piece that covered the top and sides of the terracotta liner, with the top of the trim piece sloping towards the outside of the liner in order to allow any dripping condensate from the chimney cap to run off the top of the chimney crown vs running to the interior and down the flue. The trim piece was fashioned from a heavy aluminum disposable food tray that matched the exterior liner dimensions perfectly.
Anyways, this morning I checked the chimney cap again and there was a fair amount of condensed water puddling around the aluminum foil trim piece where vapor seemed to be condensing on it and the cold lower band of the chimney cap. I didn't see condensate on the underside of the cap this time, but it's been fairly windy, so not much smoke/vapor is having the chance to hit the underside of the cap. It's mostly being blown sideways in various directions. I'm still seeing damp spots on the exterior of the chimney. I'm not seeing condensate forming on the interior of the flue liner, I peered in there briefly with a bright flashlight.
Given that I'm seeing a lot of water condensing on the cold metal of the chimney cap and it appears to be dripping back down the flue and I'm assuming leaking through liner joints (they're not the greatest in terms of being aligned perfectly) and wicking into the brick and mortar joints, I've removed the chimney cap temporarily to see if this solves the problem. Of course, when it rains, that will become another variable, but I have about 36 hours before we get any more precipitation (snow).
I've seen where people talk about keeping flue temps up to prevent condensation from occurring, but my problem seems to be with condensate forming on the cap and not on the inside of the terracotta liner itself. Maybe a 6" SS liner would prevent this, maybe not? I was thinking maybe I needed one before I noticed the condensate problem because I smoked the basement out on my first attempt to light a fire in the stove. The draft was super weak and maybe even back drafting a little and I wasn't savvy enough to use newspaper torches to heat the stove chamber and flue a bit first. Plus the newspaper wasn't burning very well, almost seemed a little high in moisture content, after the fact. Once I figured all that out though, I haven't had any problems even when doing restarts from small amounts of coals and after things have cooled down a lot. Having said that, the draft doesn't seem super strong, but it does appear to be adequate.
Thoughts? I'm wondering if there are caps out there made of material other than metal that are less likely to cause condensation. Or, maybe a larger metal cap is in order so that all of it's structure is further away from the opening of the flue and the vented gases which might allow moisture to dissipate before it has a chance to condense on the colder metal parts of the cap.
The stove is a Buck Model 81 and is connected to an external brick chimney that's approximately 27' tall from the point that the stove pipe enters it. The chimney has a terracotta liner that measures 6.5" x 11". The chimney is roughly 4' above the roof level and it has a stainless steel cap/cover.
About a week ago, I loaded the stove up for the night and had temps approaching "overheat" according to the magnetic temp gauge that's mounted above the center of the stove door. The previous owner had placed small metal tray up against the block wall right under the chimney's ash clean out door. I noticed water dripping out of the bottom of the clean out door and into the tray. Several ounces were accumulating on this occasion. It had rained the day before and temps had been freezing since then. The next day I went up on the roof and observed that the crown mortar had several cracks in it and was also eroded where it met the liner. There were also several spots several feet apart on the exterior of the chimney that were moist with some dark staining.
As a temporary measure, I wire brushed the cracks in the crown and used a rubberized roof cement to fill them and the joint around the liner. Since then, I've continued to notice moist spots on the exterior of the chimney and I've observed brown water droplets on the bottom of the chimney cap. I haven't noticed any leaking at the ash clean out door however. This may be due to the fact that I made and installed an aluminum trim piece that covered the top and sides of the terracotta liner, with the top of the trim piece sloping towards the outside of the liner in order to allow any dripping condensate from the chimney cap to run off the top of the chimney crown vs running to the interior and down the flue. The trim piece was fashioned from a heavy aluminum disposable food tray that matched the exterior liner dimensions perfectly.
Anyways, this morning I checked the chimney cap again and there was a fair amount of condensed water puddling around the aluminum foil trim piece where vapor seemed to be condensing on it and the cold lower band of the chimney cap. I didn't see condensate on the underside of the cap this time, but it's been fairly windy, so not much smoke/vapor is having the chance to hit the underside of the cap. It's mostly being blown sideways in various directions. I'm still seeing damp spots on the exterior of the chimney. I'm not seeing condensate forming on the interior of the flue liner, I peered in there briefly with a bright flashlight.
Given that I'm seeing a lot of water condensing on the cold metal of the chimney cap and it appears to be dripping back down the flue and I'm assuming leaking through liner joints (they're not the greatest in terms of being aligned perfectly) and wicking into the brick and mortar joints, I've removed the chimney cap temporarily to see if this solves the problem. Of course, when it rains, that will become another variable, but I have about 36 hours before we get any more precipitation (snow).
I've seen where people talk about keeping flue temps up to prevent condensation from occurring, but my problem seems to be with condensate forming on the cap and not on the inside of the terracotta liner itself. Maybe a 6" SS liner would prevent this, maybe not? I was thinking maybe I needed one before I noticed the condensate problem because I smoked the basement out on my first attempt to light a fire in the stove. The draft was super weak and maybe even back drafting a little and I wasn't savvy enough to use newspaper torches to heat the stove chamber and flue a bit first. Plus the newspaper wasn't burning very well, almost seemed a little high in moisture content, after the fact. Once I figured all that out though, I haven't had any problems even when doing restarts from small amounts of coals and after things have cooled down a lot. Having said that, the draft doesn't seem super strong, but it does appear to be adequate.
Thoughts? I'm wondering if there are caps out there made of material other than metal that are less likely to cause condensation. Or, maybe a larger metal cap is in order so that all of it's structure is further away from the opening of the flue and the vented gases which might allow moisture to dissipate before it has a chance to condense on the colder metal parts of the cap.
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