Condensation from water heater vent in attic


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Old 01-27-15, 08:20 AM
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Condensation from water heater vent in attic

I have been having a problem for a couple of months and have searched everywhere and paid a couple of contractors to look at this. Everyone points to someone else to call. So I thought I will try out this forum as I have found great advice in the past (Sorry for the long intro)

My Water Heater is in the basement (of a 2 story house) and we have seen that water has been leaking from the exhaust vent pipes in the attic. This flows down and has been spoiling the insulation, but also has started leaking from the first floor ceiling. Last week when I went back to the attic, I could see gases leaking out too. In the attached picture, #1 with a red circle is where the water is dripping and #2 with a red circle is where the gases are leaking and possibly water too.

My questions: What could be causing this? What can I do to fix this? Please note that I only see the water dripping right after I use hot water in the bath or shower OR late in the evening. My guess is that it is the water heater kicking off to heat the water causing the gas to release and in turn the leak happens.

Appreciate any help !!
 
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Old 01-27-15, 08:35 AM
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The pros will be along, but a major byproduct of burning gas is water, a lot of it. When it is cold, step outside while the heater is running and see if you see a good plume of moist air exhausting from the top. Note whether it is all white as it leaves or if it exits and then several inches away from the vent it condenses into the white vapor. The condensation you are seeing is an indication the exhaust is condensing before it exits. The diameter and type of pipe are not my field but others will answer that.

Bud
 
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Old 01-27-15, 08:45 AM
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That's a 'double wall' manufactured chimney, correct?

If so, there is an inner and an outer pipe.

The inner pipe carries the flue gases.

The outer pipe is insulated from the inner pipe.

There should be NO GASES (and I'm not sure how you've concluded that gases are exiting) coming out of that chimney.

How have you concluded that gases are escaping? You can't SEE gases. What is it that you SEE exactly? Maybe you are seeing STEAM?

If FLUE gases ARE escaping, you are at danger for Carbon Monoxide poisoning. Be sure you have working CO detectors in the home.

What contractors have you talked to?

You need to contact a chimney contractor that understands manufactured chimney systems.

Please note that I only see the water dripping right after I use hot water in the bath or shower OR late in the evening.
It MIGHT be possible that there is a leak at the chimney cap which is allowing rain water to enter the insulated space between the two pipes and when the water heater runs and the inner pipe gets hot it is evaporating the water soaked into the insulation.
 
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Old 01-27-15, 10:10 AM
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Thank you for the responses.
Bud9051 - I will check if I can see moist air exhausting from the top.
NJ Trooper - Let me respond to your questions.
Double wall manufactured Chimney - I am not sure. Any suggestions on how to find out?
Gases vs. Steam - You may be correct. It may be steam that I saw. I have a video that I took of the steam coming out of that area that I marked in the picture. But you are correct, I can see it and may be steam. My CO detectors are not screaming, so I may be safe there.
Contractors - I first had a roofer take a look. He suggested a plumber or a HVAC guy. I then called a plumber as I thought it was related to a plumbing issue when I saw water. But he suggested I speak to a HVAC company. Finally I called a HVAC company who do Water heater and Furnace installs. They mentioned that it was a Condensation issue and that there is no solution. He was trying to sell me to go to a Tankless Water heater to eliminate the issue completely. That is when I knew I am not calling the right people. I will check on Chimney Contractors for this.
Regarding the rain water leaking - I have had the leak even during a week when there was no rain at all. So I eliminated rain water being the cause.
 
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Old 01-27-15, 10:26 AM
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While we wait for NJ to come back, I don't think you should be seeing any gas exiting, steam or otherwise, anywhere other than the top. I have never worked with double walled b-vent but I can imagine those 2 - 45 bends being a place where someone could get sloppy. The double wall construction is intended to both protect combustible materials from the heat inside and to protect the inside gasses from the cold outside temps.

I do hate the run-around, and businesses who practice it are missing a great opportunity, that is to earn a new customer, whether they get that particular work or not. Good customers remember who helped them.
 
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Old 01-27-15, 02:21 PM
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My CO detectors are not screaming, so I may be safe there
I wouldn't trust my life to a CO detector. Those are in my opinion a FINAL DITCH ATTEMPT to warn ppl of a danger. When you have VISUAL suspicion of a flue gas leak, the FIRST thing to do is take it very seriously, whether a cheap CO detector alarms or not.

Permanent dain bramage can occur long before a CO detector alarms, particularly when it is a chronic long term exposure to LOW LEVELS of CO.

Are there children in the home?

Finally I called a HVAC company who do Water heater and Furnace installs. They mentioned that it was a Condensation issue and that there is no solution. He was trying to sell me to go to a Tankless Water heater to eliminate the issue completely. That is when I knew I am not calling the right people
Heating contractors are notorious for not wanting to repair stuff... and suggesting that you rip out the old and install new. Most of the installers are offered COMMISSIONS to sell new equipment. My apologies to any installers with a conscience, but you know others who work this way... yes, you do.

If it IS flue gas condensate, and that IS a double wall chimney (I believe it SHOULD be, and probably IS) then any condensate should remain inside the inner pipe and not migrate to the outside.

So it's good that your red flags went up.

I have had the leak even during a week when there was no rain at all. So I eliminated rain water being the cause.
Logically, that would seem to make sense. However, if the insulation between the two layers of pipe is soaked with rain water, I imagine it might NEVER dry out completely.

The issue could be worse though. As Bud has mentioned, it's very possible that it was a botched install and the flue gases ARE leaking out of the inner pipe. It is possible that it IS a flue gas condensation issue.

A bit about that condensation... The gases from gas or oil fired combustion contain a LOT of water vapor. It's a byproduct of the combustion process. The 'dew point' of gas fired combustion appliances is around 135F. If the flue gases are allowed to cool to this temperature, the water in the gas condenses. There's more to the story... the condensate is ACIDIC and will 'eat' pretty much anything it comes in contact with. The chimney should preferably have a STAINLESS STEEL inner liner.

A reputable chimney contractor should know how to fix the problem.
 
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Old 01-27-15, 02:25 PM
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Can you show us a picture of where the chimney comes through the ceiling up in the attic?

Perhaps one where the water heater connects to that chimney down in the basement also?
 
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Old 02-23-15, 10:45 AM
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Sorry for not responding sooner. I was to take some pictures, but then had a couple of other contractors come and take a look at this problem.

Looks like we found the problem. I never thought it would be connected, but here it goes.

I had 2 traditional Furnaces that vented out to the roof through the same pipe I posted a picture of. 2 years back I had replaced the 2 furnaces with high efficiency ones which vent out from the side of the house using PVC pipes. These furnace contractors capped off the vent in the basement where the older furnaces connected into. Now the pipe is only heated with Water heater exhaust heat. I am told that the pipe is too wide for only the Water Heater exhaust and it is not heating up as much now. So when it reaches close to the roof, it is not hot enough and in turn it condenses the exhaust and drips back down.

The solution is to replace those pipes with smaller width ones and possibly insulate them all around to let it keep the warmth. Another option is to replace the water heaters with new Power vented ones that would vent out the side of the house.

Somehow this makes sense and I am sure if I had provided information about the furnace replacement and its venting you would have identified the problem sooner. But I had not thought that it would be important in this discussion.

I would have expected the Furnace guys to have told me of potential issues when they changed the venting, but they did not. Not sure if I can go back to them. I would like to thank the responders on this forum to give me some direction to lead to the problem.
 
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Old 02-23-15, 11:04 AM
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Yes, that makes sense.

Another point is that since the pipe is bigger than needs be, the gases are moving much more slowly in the pipe, allowing them to cool even more.

But still... the question remains...

WHY is the condensate getting out of the inner pipe, and into the outer pipe? That's already (or it should be already) an INSULATED DOUBLE WALL factory made CHIMNEY, NOT just a single wall pipe.

So yes, part of what they have told you is probably true, but there is apparently something else going on there.

I don't believe you've got a complete root cause yet.
 
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Old 02-23-15, 11:27 AM
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Very Good point !!
One of them said that the inner pipe probably rotted out due to the possibility of rain water coming in at some point from the outside. Another possibility being that it cracked while the roof work was being done recently. Since these are metal pipes, it was hard to believe.
 
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Old 02-23-15, 11:47 AM
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inner pipe probably rotted out due to the possibility of rain water coming in at some point from the outside
Not rain water.... ACIDIC CONDENSATE! That condensate has several acids in it that form from the combustion process.

If it's a STAINLESS STEEL inner liner, which I would say MOST of them are, then it's not as likely that it's rotted out... but poor workmanship at installation is still possible.

Did you say that you had the chimney cap inspected? It's possible that there's an issue there too...

Is that a 6" (inner) chimney? If so, you can probably have it 'lined' with a 4" flexible liner WITH additional insulation. See:

Chimney Liner Depot - Buy Flue Liner, DIY Chimney Repair

I know for a FACT that the 4" flexible insulated liner will fit inside a 6" pipe...

The only tricky part is that the cap on the chimney will have to be very carefully selected and installed to prevent rain water from entering.
 
 

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