New pipe, interior condensation inside triple wall

[Commodorefirst]

Hello, have been a burner in the past, we built a new home on our farm, and have plans to use our new custom ideal steel stove as an aux heat source. Stove is in garage, not yet installed and getting ready to install, when we noted with our first extreme cold snap, that our triple wall chimney pipe has condensation in the interior of the flue. It is dripping straight down, and we had some 8" of insulation stuffed in the pipe to keep the warm air from traveling up the pipe. We still have water condensation. Only in the am when sun hits the pipe when temps are below 15, not at night, or in afternoon, or any other time. Only when sun hits the pipe.

Pipe goes straight up through 9' ceiling, into the upstairs inside a chase between closets, and out the house, all code and meeting all clearances.

Humidity in house is low, less than 20-30% and the house has been built for a year. I took a photo of the ceiling and pipe, and also outside of house. I do not want to install my new stove if it is going to end up rusting out because of condensation.

Need some assistance as soon as possible, local chimney sweeps don't want to drive an hour to our home, because they say, it shouldn't be doing this. Install is planned in a week. Maybe.

R50 insulation cellulose in attic, spray foam side walls, all clearances appropriate in attic,

Thoughts, help.
Wade

 

[moresnow]

Uninsulated triple wall or class A insulated stainless double wall?

 

[Commodorefirst]

Insulated

Uninsulated triple wall or class A insulated stainless double wall?

class A triple wall

 

[Commodorefirst]

Update, this afternoon, cloudy, pipe completely open from conditioned room 68’ to 15’ degree outside air, cloudy, bone dry pipe, Lots of air flow I am sure going up the open pipe to outside. Long sigh....

 

[maple1]

Just how much water was there?

It was likely just frost accumulating in the pipe from cold air dropping in. Which wouldn't happen if it was blocked at the top (would be warm from warm air at the bottom), or completely open for air movement.

 

[begreen]

It's been reported before. Seems to be another disadvantage of triple-wall stove pipe.

https://www.hearth.com/talk/threads/condensation-inside-triple-wall-chimney-pipe.151684/

 

[Ludlow]

Well yea, all that warm interior air is going up the pipe and condensing on the cold surface. Just stuff some fiberglass into the hole for now until the stove is installed.

 

[maple1]

Well yea, all that warm interior air is going up the pipe and condensing on the cold surface. Just stuff some fiberglass into the hole for now until the stove is installed.

Sounded like he did that.

 

[Commodorefirst]

Just how much water was there?

It was likely just frost accumulating in the pipe from cold air dropping in. Which wouldn't happen if it was blocked at the top (would be warm from warm air at the bottom), or completely open for air movement.

About 6” diameter puddle on floor, not a lot, and this was with some fiberglass insulation stuffed in at the ceiling. Also have had it occur when I only covered the opening with painters tape.

What about when I have my stove in place. You will not get full air movement there, but I really don’t want water inside the new stove. Thanks for the thought about cold air coming down and settling down lower in the pipe.

 

[Commodorefirst]

Well yea, all that warm interior air is going up the pipe and condensing on the cold surface. Just stuff some fiberglass into the hole for now until the stove is installed.

Yes I did, had about 18” tall plug in there. Why not right now, 12 degrees outside, 68 air inside, no moisture in pipe with no plug, and why only when sun in am?

 

[Commodorefirst]

It's been reported before. Seems to be another disadvantage of triple-wall stove pipe.

https://www.hearth.com/talk/threads/condensation-inside-triple-wall-chimney-pipe.151684/

I read that, but my humidity is much lower, and not same %, and it was not clear that it was actually inside the interior pipe.

 

[begreen]

There is less insulation in triple-wall. This affects the inner pipe temp too, but that may not be the issue here. Is there a down draft coming from the open pipe now, neutral draft or a good updraft?

 

[maple1]

Yes I did, had about 18” tall plug in there. Why not right now, 12 degrees outside, 68 air inside, no moisture in pipe with no plug, and why only when sun in am?

Because with no plug, it is getting airwash? If you really want to try something else before putting the stove in, plug the chimney at the top only and see what happens. Or doesn't happen.

 

[Commodorefirst]

There is less insulation in triple-wall. This affects the inner pipe temp too, but that may not be the issue here. Is there a down draft coming from the open pipe now, neutral draft or a good updraft?

Neutral to slight updraft as seen from smoke from a lighted match, no downdraft at all, 16 degrees outside temp this evening, 7pm central, no visible ice or moisture in pipe.

 

[Commodorefirst]

Because with no plug, it is getting airwash? If you really want to try something else before putting the stove in, plug the chimney at the top only and see what happens. Or doesn't happen.

Idea to try something and consider, but note my exterior chimney and pipe in first post, I do not have means to do this, would have to hire out, but if needed will do. It is frustrating around here though, we live out from nearest sweep at least 30-50 minutes.

 

[begreen]

Neutral to slight updraft as seen from smoke from a lighted match, no downdraft at all, 16 degrees outside temp this evening, 7pm central, no visible ice or moisture in pipe.

Was it much warmer outside when this happened? At 16º our flue would be drafting strongly. My thinking is that the house is tight and maybe there was some negative pressure in the chimney at the time you noticed the dripping. Another test you can do is to repeat the match test, but have someone open a nearby window or door an inch while you test and see if that makes a notable difference.

Will the stove have an outside air supply?

 

[Ludlow]

Plugging it at the top wouldnt stop it but plugging it at the bottom would. You want to stop conditioned air from access to pipe. Leaving it wide open would work but a waste of energy.

 

[Ludlow]

Ok, I didnt read it right! But plugging at the bottom should prevent it. Is is possible that blowing snow came down the pipe?

 

[Commodorefirst]

Was it much warmer outside when this happened? At 16º our flue would be drafting strongly. My thinking is that the house is tight and maybe there was some negative pressure in the chimney at the time you noticed the dripping. Another test you can do is to repeat the match test, but have someone open a nearby window or door an inch while you test and see if that makes a notable difference.

Will the stove have an outside air supply?

We do have a tight house, and I have a Energy recovery ventilator ERV to bring in fresh air, and because of that the house has been tested and is slightly pressure positive when it is running, by design. I did the match test with the
ERV turned off and still had the slight updraft. I do have a planned, if needed, cold air intake I may or may not need, for the install. Woodstock stove and also my thinking was it may not be needed with the positive pressure ERV. All of my bathroom vents have back draft preventers, and I know enough to not use my very powerful kitchen stove vent while running the stove without outside air. I am just trying to figure out why
I am getting moisture/ frost inside the triple wall pipe, even when plugged.

Maybe because of my super insulated ceiling, the transition from conditioned space air inside pipe into the pipe above roof level creates a sudden change and frost may form in the interior of the pipe above roof line, and then the am sun may heat the exposed stainless pipe above roof line?

Anyway, I am leaving town Monday for 5 days, I am going to leave the pipe open, and let air travel up the tube, will revisit when I am back, and before my planned stove install next Monday.

Thanks all for suggestions.

 

[Commodorefirst]

Ok, I didnt read it right! But plugging at the bottom should prevent it. Is is possible that blowing snow came down the pipe?

Possible, and a consideration, we did have 30-40 mph winds and snow, but it has done this on cold evenings without precipitation too, while plugged at bottom and also tapped over without insulation. Always notice the dripping after sunrise.

 

[Ludlow]

Well then its pretty obvious that it is icing up inside during the night and then the sun is heating the pipe and it melts and drips down. Sealing the bottom should prevent it. Befuddled why its still occurring!

 

[maple1]

Sealing the bottom wouldn't necessarily prevent it. Cold air could still sink in the top & make frost. The same way frost forms sometimes on anything metal if left outside. Then when the sun hits it, it melts. Seems to me like what is happening. Either sealing the top, or sealing nothing, should prevent it.

 

[Ludlow]

Condensation problems are pretty normal in new construction houses for the first year or two after move in.

 

[Winterpeger]

Ill try to convey a problem we had. New house, new certified install. Straight run of Five feet telescoping security double wall connecting to six feet of selkirk sentinel which exits trough a vaulted ceiling. It can be -30c out side during the day but we get enough solar energy through the rake head windows in the living room (south facing) to keep the house warm on a sunny day so I usually let the stove go out so as not to overheat the space. In the first year only once did we have a few drips on the back corner of the stove from the square ceiling trim piece (condensation)? One day the next year one afternoon the wife decided to do laundry had the dryer going whilst I tried to start a fire. Bad draft reversal opened window to mitigate the problem. I had two problems that caused this one was that dryers exhaust at between 100 and 200 cfm and the intake screen on the hrv was plugged with frost thereby exasperating the problem. A little food for thought your climate is much more temperate than ours so my situation might not be plausible in your area. Good luck in solving your problem.

 

[Commodorefirst]

Sealing the bottom wouldn't necessarily prevent it. Cold air could still sink in the top & make frost. The same way frost forms sometimes on anything metal if left outside. Then when the sun hits it, it melts. Seems to me like what is happening. Either sealing the top, or sealing nothing, should prevent it.

I am leaning this way, so I am keeping track next week with leaving open until install. Thanks for your thoughts.