Condensating Heater Vents

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Every winter i run into a few of these condensating heater vents. On this particular one, someone had installed a larger vent right over top of the existing smaller vent. And they left the cap on the smaller vent. It was a beautiful sunny day and water was just pourning out from underneath the flange as you can see from the rust streaks going down the roof. I took what they did off and threw it away, took the original cap off the smaller vent, cut the pipe down so as not to be seen from the front and then installed a new heater vent over top. I hope this solves the problem. Anyone else run into this sort of thing?

This is an advanced experience problem. I've been roofing nearly 30 years but it was not until within the last 10 that i discovered it. Woody, you are the first person I've found that understands this issue. I can tell you have had a good deal of experience with it.Its extremely difficult to explain to anyone, even other roofers. Nearly impossible to explain to the average homeowner and them understand it. They look at you like you just said the Aliens are coming to take us away! lol

Old School Said: Sounds like you should not have capped it but had the heating guy fix the pipe. It should vent outside at the top, not in the attic. That is a safety issue.

This case was caused by the builder not wanting to see a pipe on the front of the home, even though the furnace was on the front side. The pipe had 4 elbows in the line to snake it up to the back. The leaky connection was at the top elbow in an attic space that was inaccessable. I gave the homeowner the choice of me removing enough plywood to get the heating guy in the attic to rebuild a mickey-mouse system, or have a new line go straight up on the front side. My pictures of charred framing convinced her to put it on the front.

I cut 3 or 4 inches off the thing and it is located on the roof where it is located. I didn't go there to change its location.

It has to be at least 10 feet from any other part of the roof or structure. That is close.

You reckon 2' high is enough?

Its still more than 2 feet high and i didn't cap it off from allowing the gas to escape. I put a new flashing with a vented cap over the top of the double wall pipe. I had to cut it down some because the pipe was taller than the vent flashing. I cut the little cap that was on the double wall pipe off in the process as it was impeding the gas from escaping out of the vent flashing. ( As in up and out through the vent flashings cap and out into the wild blue yonder) lol

Sounds like you should not have capped it but had the heating guy fix the pipe. It should vent outside at the top, not in the attic. That is a safety issue.

There is lots of moisture in gas exhaust. Anytime it gets an opportunity to escape the exhaust line before being disperssed into the air, it will condense on metal enough to cause rust.

This is the underside of a pipe and flashing I pulled out that had a leak at a pipe connection in the attic. You can see on the flashing how where the metal was protected from the leaking gas air that was rising up, there is no rust.

I see this all the time. I wonder if they replaced the heater with a new higher efficiency one and its causing more condensation Or they have their humidification set to high.

Never heard of a condensating hearter vent! I thought heater vents were to be aleast 24" higher than any roof area within 10'? This looks mighty close and if you made it smaller.....

They lost their coursing on the shingles nabove the pipe too!