# gas fireplace/stove vent pipe condensation/freezing



## kopp (Feb 7, 2014)

I recently had a gas fireplace/stove installed in my basement. The vent pipe has condensation on in when it is not in use. It has been cold this winter and the condensation has been freezing. This creates a giant mess anytime I run the fireplace with water dripping everywhere. The guys who installed are being helpful and trying to fix, but they don't seem to know the problem. The pilot light has been on the entire time. The black pipe on the inside of the house is extremely cold, all the way down to the unit. Is that normal? Suggestions?


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## DAKSY (Feb 7, 2014)

What does the wall look like above the cap? Is there an eave without a gutter?


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## kopp (Feb 10, 2014)

DAKSY said:


> What does the wall look like above the cap? Is there an eave without a gutter?


Above cap on this inside is just drywall, and no condensation. On the outside, i have vinyl siding and vent is on the basement and it is a three story house. There is a gutter about 30 feet above the outside cap.


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## DAKSY (Feb 10, 2014)

kopp said:


> Above cap on this inside is just drywall, and no condensation. On the outside, i have vinyl siding and vent is on the basement and it is a three story house. There is a gutter about 30 feet above the outside cap.



My bad, I meant only on the outside. The reason I ask is that icicle on the cap in your pic is coming from the INTAKE part of the Direct Vent Co-axial Pipe. Where is THAT coming from if not from above?


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## kopp (Feb 10, 2014)

DAKSY said:


> My bad, I meant only on the outside. The reason I ask is that icicle on the cap in your pic is coming from the INTAKE part of the Direct Vent Co-axial Pipe. Where is THAT coming from if not from above?


Good question. That icicle is not coming from above, there is no way water is getting in from above. Somehow condensation is building up in that pipe and causing the interior pipe to frost up. Could there be an insulation issue where the pipe comes out of the house? The pipe on the inside of my house is freezing cold and somehow I think warm air is getting into that pipe causing the condensation. Should the pilot light keep the vent pipe somewhat warm?


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## DAKSY (Feb 10, 2014)

The pilot should keep the EXHAUST (inner 4" diameter) somewhat warm. That icicle is on the INTAKE (outer 6-5/8" diameter), as is the frost on the pipe inside your home. Don't know WHERE that's coming from...


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## norton_74 (Mar 3, 2014)

kopp said:


> I recently had a gas fireplace/stove installed in my basement. The vent pipe has condensation on in when it is not in use. It has been cold this winter and the condensation has been freezing. This creates a giant mess anytime I run the fireplace with water dripping everywhere. The guys who installed are being helpful and trying to fix, but they don't seem to know the problem. The pilot light has been on the entire time. The black pipe on the inside of the house is extremely cold, all the way down to the unit. Is that normal? Suggestions?



I have a similar problem with my propane fireplace vent.  Have you found out what was causing your condensation yet?


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## kopp (Mar 4, 2014)

The guys who installed came back and caulked the vent pipe where it meets the fireplace box (they said they have never had to do that before). They thought too much warm air from inside was going out that pipe. Since they did that, I have only had two occasions where the freezing condensation has formed, and that freezing condensation was nothing like in the pictures, very minimal, and both of those nights the temp was -15 degrees with windchill in the -35 degree range. There are a few other joints that I am going to caulk eventually on the pipe that I would also assume will help.


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