Redundant chimney problems.
April 3, 2014 2:36 PM   Subscribe

I'm having problems with a potential leak or condensation problem in an external chimney chase that no longer has hot air running through the exhaust venting. I've not had any luck with the contractor that made the chimney redundant and need some advice.

So two years ago we had our furnace and water heater replace with newer efficient models. The new units had venting installed directly outside rather than using the old chimney. The contractors capped the old exhaust vents, which run through an external chimney along the outside of our two-story house.

In the fall we had the old gas fireplace on the ground floor replaced, with a newer more efficient model that vented directly to the outdoors. Again, the contractors capped the old exhaust, which used the same chimney system as the old heater and water heater.

Now that the weather is finally starting to warm up, we’re starting to hear an infrequent dripping noise in the second story section of the now unused chimney system.

We’ve checked with both of the companies that installed our new equipment and they are assuring us that the capping process was for both the top and bottom of the disconnected vents and that the dripping wouldn’t be from the old vent lines. We’ve also checked with a couple of roofing companies and they say they don’t handle anything related to chimneys and that the infrequent dripping doesn’t sound like a problem with the flashing.

My questions are:
Other than ripping open the wall to look into the old chase way, is there anyway for me to track the source of the leak?
What type of contractor should I be contacting to track down and solve this leak, if it is something I can’t handle myself?
posted by Gregarious introvert to Home & Garden (5 answers total)
If you've installed a "direct venting" high efficiency gas heaters, it is likely that it is of the "condensing" variety, where water vapor in the flu gasses is condensed out, providing you with that last 10 % efficiency increase.

That condensation results in a significant amount of water, which has to be drained somewhere. The drip you hear might that condensate stream, going somewhere. Were the new furnace and water heater installed on the second floor? Specifically, what provisions were made for the condensate drainage? Is the drainage working? Has it clogged up, and is it going somewhere it shouldn't?
posted by the Real Dan at 3:09 PM on April 3, 2014

When we had a leak in our chimney, it turned out it was cracked roofing along the flashing where the chimney came through the roof, rather than the "chimney hole." I'm surprised you're getting such a dismissive response from a roofing company because that's who I would have guessed would help.

Can you get on the roof yourself? You could look at the base of the chimneys and the caps and strategically pour a little bit of liquid while someone else listens?
posted by Gucky at 3:12 PM on April 3, 2014

Dan - I should have been more specific. The new furnace and water heater are in the basement and the condensate is handled by some drainage lines that are run into the house's floor drain.

Gucky - I've not been up on the roof yet as there is still too much snow near the eaves. When I get the chance I'll get up and check. I don't think that is the problem though as we've not heard the dripping during some significant rainstorms and with the way the wind blows around the chimney, there is rarely any snow build up around the base.
posted by Gregarious introvert at 6:06 PM on April 3, 2014

Not be a dink, but there's snow on the roof still and you hear dripping ? hoofbeats means think horses not zebras and all that.

I can see why, based on that weather, why neither roofers nor the fireplace folks seem interested in your case currently.

Are any of the exterior vents blocked ? Are you running the fireplace a lot, or not much ?

Aside from the sound, is there any evidence of an actual leak ? water spots on ceilings/walls, higher than expected humidity, blooming on the brick (efflorescence) ? Can you view the chimney/parts from the attic and examine it there ?

When the snow melts/conditions allow, you should check the cap and brick.

(Edit to add: ours was a flashing problem, and there were no sounds, but plenty of evidence of a leak via blooming on the brick etc. Can you look into/inside/up the chimney from any point in the house, or is there no longer anything that actually uses the chimney now ? Is nothing is using it [no fireplace, no appliances], then it should be top-capped. It does have a standard chimney cap, ya ? )
posted by k5.user at 6:51 AM on April 4, 2014

We had the same problem from a leaking chimney where water collected in the void and broke the plaster. The roofer we hired did a ton but the leak remained. Finally, we found a roofer who identified a hole on the side of the chimney which accepts the bottom slope of the roof. Since the epoxy patch, we have had no more leaks.
posted by parmanparman at 10:19 AM on April 4, 2014

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