Oozing gas conversion boiler flue pipe

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Old 11-09-13, 10:03 AM
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Oozing gas conversion boiler flue pipe

Hi! My name is Ken Testa. I recently purchased a damper package for my Peerless Boiler in my home I recently converted from oil heat to gas heat by switch out the oil burner for a Carlin Gas Conversion burner which was installed in place of the oil gun. As part of this conversion I also installed the damper package which has been in service for a bout a week. I went to check up on the boiler today and to my surprise there is a slippery pasty type fluid oozing out of the seams in the flue pipe onto the floor and onto the top of the boiler. I removed the flue pipe and the same material is running down the down pipe on the new automatic damper and into the boiler, Do you have any idea what' s going on. I'm thinking the exhaust gasses are condensing on the inside of the pipe since warm air is no longer flow through the pipe when the auto damper is closed. Any idea on a solution. Thanks. Ken
 
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Old 11-09-13, 10:31 AM
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Hi Ken, Is this flue pipe exiting into a masonry chimney? If so, you've got the same thing going on inside the chimney.

What you should know is that stuff is ACIDIC and will begin eating away at the flue pipe and the masonry materials. If it is also occurring inside the boiler, it will also eat the cast iron.

Your old oil burner was probably producing higher BTU output and the exhaust gas was leaving the boiler hotter. The 'flue gas dew point' of oil combustion is about 20 lower than the 'dew point' of the gas combustion. Typically oil fired flue gas dew point is about 115 while gas is about 135. Any time the flue gases contact an object at or below this temperature, condensation will occur.

Your flue gas may now be at a lower exit temperature than it was with the oil burner. Has it been measured? Do you know what it was BEFORE the change over?

There may have been a higher volume of AIR being used for the combustion, therefore a higher VELOCITY of the gases up the flue pipe giving less time for them to condense.

This in addition to the damper not allowing the heated room air drawn through the flue and chimney to 'ventilate' it.

What can you do now?

A properly sized and INSULATED 'Flue Liner' is the first step.

If the boiler has 'baffles' inside the flue passages, you may have to take a few points of hit on your efficiency in order to raise the temperature of the flue gases and remove those baffles. This should only be done with the blessing of the boiler manufacturer.

Speaking of which... does the gas conversion have Peerless' 'blessing'?

Who engineered and selected the gas burner, and who installed it?
 
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Old 11-09-13, 06:34 PM
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further details on the ooz issue

Thanks much for the response. I purchased the Carlin Conversion burner through a local heating supply place. They sent all my boiler data to Carlin; model, serial number, rating's etc. Carlin came up with the recommended conversion burner. It appeared to run Ok for the first month since installation but after I installed that Flair Automatic damper which closes 3 minutes after burner stops firing. Since I installed the damper about a week ago the oozing started. There's a lot of it leaking from seams in the galvanized flue pipe and onto of the cut off damper. I'm not sure if the problem started due to installing the damper or by coincidence the house heat has started running due to dropping outside temperatures since I installed the damper. So, not sure if the damper is the issue yet. I disconnected the damper to force it into a constant open position to see if the oozing stops. Before I installed the conversion burner I replaced the boiler fire box and thoroughly cleaned the entire heat transfer surface of the boiler. When I did the conversion I had a chimney guy come in to clean the chimney and he said the inside of the chimney is in bad shape with Clay tile spalling. He recommended a chimney liner. Maybe I should have taken his advice. Do you think that if I install an insulated chimney liner the problem will stop??? also, what size liner should I use? the flue out of the boiler and the flue pipe to the chimney is 7". Thank you VERY MUCH. Your expert assistance is greatly appreciated. Ken
 
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Old 11-09-13, 06:52 PM
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More info on ooz

I scraped off some of the dried ooz. It's a white crystalline material. Put some in baking soda and water and no fizz. Then I tried putting some in vinegar, no fizz. It looks like a mineral build up ?????????????????? Stumped!!
 
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Old 11-09-13, 07:04 PM
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Hi Ken,

I'm not sure if the problem started due to installing the damper or by coincidence the house heat has started running due to dropping outside temperatures since I installed the damper.
I would say that you would probably see the condensate issue even without the damper... eventually, as the weather progressively gets colder. Adding the damper probably made it happen sooner rather than later.

Maybe I should have taken his advice. Do you think that if I install an insulated chimney liner the problem will stop?
Yes, I think you should have had the liner installed. I can't say if the problem will STOP completely, but it may bring it to a 'non-problem point'. Given that the masonry is reportedly in bad shape already, it should be done ANYWAY. You don't wanna burn the place down, or wake up dead from carbon monoxide leaking into your home, do you?

what size liner should I use?
That's a tough call to make... and it depends on many factors. I'm hesitant to make a suggestion for various reasons... one of them being the dreaded 'L' word (liability).

The whitish stuff you describe is definitely condensate. Trust me that it's acidic even if it didn't fizz... by the way, vinegar is also acid... no fizz there... or were you thinking that somehow the stuff was alkaline? It's not. The 'remainder' that you are testing is probably not the acid itself... it's what's left AFTER the acid has done it's dirty deed. If you had it analyzed I think you would find it to be Zinc something or other... maybe Zinc Carbonate ... if there is such a thing.

Ken, I'm sending you a private message... check in a few minutes...
 
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Old 11-09-13, 07:32 PM
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By the way Ken, is this what your oozing looks like?


image courtesy rschwarz_jr


image courtesy rschwarz_jr

That's condensate and if it's oozing out of your flue pipe connector it's guaranteed that it's occurring in the chimney as well:


image courtesy ncsg.org
 
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Old 11-10-13, 06:54 AM
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Thannks for all the great help!! Yes that's what it looks like.

Yes That's exactly what it looks like! Do you think the liner would solve the problem although, from what I've read so far, the liner is a must just out of safety and operability! So I'll get that done ASAP! If it still happens maybe I can open a few of the damper by pass knock outs to let some air pass through the damper but not all! Does anyone know a good reliable chimney liner guy on Long Island NY?

P.S. I assuming I should go with a 316 SS flex liner with smooth interior with 0.5" insulation.
 
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Old 11-10-13, 08:24 AM
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Do you think the liner would solve the problem although, from what I've read so far, the liner is a must just out of safety and operability!
Can't guarantee it will... but yes, from a safety standpoint, a must.

How many BTU is the conversion burner?

Can you post some pics of your install?

Does Carlin offer any tech support? They might be helpful if they do.

Did the install instructions say anything about how to treat the flue pipe? For example, was the barometric damper left in place?

Were there any specifications on chimney draft? Was it measured?

Does anyone know a good reliable chimney liner guy on Long Island NY?
If anyone does, please don't answer 'on forum'. Sorry, but rulz is da rulz.

go with a 316 SS flex liner with smooth interior with 0.5" insulation.
That's what I used on mine. Good stuff.

I actually went down to 4" on mine. Draft is fine.

Poke around that site I gave you, there's good info there, but don't hesitate to call them. I gather you won't be doing this yourself... it's really not all that difficult, but of course it does require accessing the top of the chimney. If climbing safely on the roof is not in your skill set, then of course you shouldn't try. If you hire someone, you know they are going to want to sell you their materials... at a substantial mark-up. Ask them if they will install a liner you purchase yourself and just charge labor. Worth a shot anyway...
 
 

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