SS flue liner in chimney for oil boiler

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24,811
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Upstate NY
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We have your normal flue tile and block chimney maybe 20 years old. The Buderus boiler using it is very efficient and that means low stack temperature. That seems to have have caused flue gases to condense around the thimble and there are cracks and one missing piece inside the thimble. I thought flue tile could take anything. Guess not. So I am being told the proper way to fix this is to get a SS liner installed in the chimney and it will be set. Comments?
 
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Under the Hood
I think your right to reduce the area of venting with a S.S. Liner. By how much ? There must be a formula based on BTU's and distance of vent. My house had the Furnace and Hot Water Tank both venting up a Galvanized Roof Vent / all was well. I then had an energy efficient Furnace installed, that vented thru PVC out back of house. The furnace installer 'never' commented that the original venting may be to much for just the H.W. Tank. I went on-line and ordered a stainless liner and fed it down from the roof (ranch house). This is where you use the Pi formula for surface area of different diameters. I just took a guess. I suggest you talk with a Professional.
 
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10,000
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Waco, TX
Isn't galvanized an option? I have had galvanized flues last very well inside of a mortar chimney. Stainless is only required for Wood Burners (or so I thought)....... YMMV, check local codes, blah blah blah.....
 
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High Tax Illinois
Save yourself some trouble and use the SS liner. I've had galvanize rot out twice. Once for hot water heater, venting into basement, and one for the furnace, it too was leaking into the basement. I know it's in the flue liner but do it right the first time. I have SS triple wall on both hot water heater/furnace now.
 
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24,811
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Upstate NY
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Originally Posted by MasterSolenoid
I think your right to reduce the area of venting with a S.S. Liner. By how much ? There must be a formula based on BTU's and distance of vent. My house had the Furnace and Hot Water Tank both venting up a Galvanized Roof Vent / all was well. I then had an energy efficient Furnace installed, that vented thru PVC out back of house. The furnace installer 'never' commented that the original venting may be to much for just the H.W. Tank. I went on-line and ordered a stainless liner and fed it down from the roof (ranch house). This is where you use the Pi formula for surface area of different diameters. I just took a guess. I suggest you talk with a Professional.
In this case I think the goal of the liner is to line it with a material that will resist the damage done by condensed flue gases. Not to change the surface or area of the flue. But I am certainly not a heating or chimney SME.
 
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6,196
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New England
Don't waste time and money installing galvenized. The galvanized between my boiler and chimney has rotted out twice and that is exposed in 10 years. Stainless steel is the way to go. Modern boilers require them because they run less heat up chimney leading to condensate and rot. My chimney was a mess so I had the stainless liner installed. Make sure the proper sizing in put in and can fit into your chimney. Narrower chimney's sometimes require the tile liners to be ripped out to fit the SS liner.
 
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24,811
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Upstate NY
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I took off the flue pipe and got a better look inside. Looks like all that is needed is a new thimble.

IMG_20200108_145343.jpg


IMG_20200108_145349.jpg
 
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251
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Missouri
No need to guess. There are organizations that publish flue venting tables, like this one: [url=https://www.questargas.com/ForEmployees/qgcOperationsTraining/Misc/gama_venting.pdf][/url]
 
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Under the Hood
In this case I think the goal of the liner is to line it with a material that will resist the damage done by condensed flue gases. Not to change the surface or area of the flue. But I am certainly not a heating or chimney SME. I'm not an expert, but my understanding is: The heat rising in the vent also carries with it condensation and CO2. If the heat can not rise high enough (cools in a to large diameter vent) you will have condensation and CO2 coming back out the bottom. So you would want to change the area of the flu (vent dia.) to smaller size so any heat can make it to the top. I would definitely go stainless.
 
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New England
I would suggest having a chimney sweep inspect your chimney as the rest of it may be great or poor shape. You can only see the bottom of it. Mine was rotting apart at the top end of the chimney and I could put my fingers into the mortar(well dust) rotting out.
 
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12,501
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Middlesex County CT
I am assuming this is the NY house? I will just post my setup, some points my apply, others not. My house is circa 1880 with a unlined brick center chimney that supports the house; Previously (like 100 years ago) there were several coal stoves plumbed into it; About 20 years ago I had the bottom repointed and parged and the top 10 feet rebuilt; They also installed a SS chimney liner (ventinox) for all the reasons mentioned above (oil HA heat), especially reducing the surface area. The entire bottom 6 feet of the chimney's mortar was basically dust. A side benefit (for me) is the liner is a safety factor for as I have oak joists and beams directly contacting the chimney. I have not looked @ or even considered looking @ its condition; I'm in the "make it as good as you can" if you touch it category; probably doesn't apply to your setup, but I'm glad I addressed it with a SS solution.
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I have had galvanized flues last very well inside of a mortar chimney.
What part of the country? If this his Albany area house HMMV
 
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24,811
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Upstate NY
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I had a chimney repair company come and inspect and they want to install a SS liner. A masonry company might want to replace the thimble. Obviously a lot more money in installing a SS liner than a new thimble. Home is for sale. So it needs to be fixed properly but no need to go overboard.
 
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681
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New Hampshire USA
Pamphlet NFPA 54 venting tables for gas but memory fails on which publication for oil. Here we had a poured in liner for the wood stove that had to sized to the vent size of the stove.which was 6 in.
 
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8,924
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Marshfield , MA
Since I put a chimney cap on my flueless 100+ yr old ex coal stove exhaust that sheds water. I took a an oil burner techs advice and re-did the pipe/ chimney connection for it and the propane water heater vent. I was working on my side in a crawl space. The chimney was full of soot which had collected along with the sweepings from using my 9X12 flue brush on 32' of rods. Pretty grubby working conditions but once the soot was disposed of, a few bricks and a bag of mortar mix fixed it right up.. I see no reason to line a brick chimney that draws so well. I've been up on the roof and felt the air column of exhaust coming out of the chimney. I have little faith in a sheet metal chimney compared to a masonry one. grin2
 
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6,196
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New England
Originally Posted by Donald
I had a chimney repair company come and inspect and they want to install a SS liner. A masonry company might want to replace the thimble. Obviously a lot more money in installing a SS liner than a new thimble. Home is for sale. So it needs to be fixed properly but no need to go overboard.
They won't install a new boiler without a liner. Make sure what you pick the buyer cannot turn around and ask for money off. We did buying this home with an unlined chimney. Basically offered higher price for my current home and knew the failures were lurking and got this in escrow: * new softener system $1500 * septic system $20k * chimney liner money $1400 * asbestos abatement - $10k
 
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24,811
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Upstate NY
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Originally Posted by madRiver
Originally Posted by Donald
I had a chimney repair company come and inspect and they want to install a SS liner. A masonry company might want to replace the thimble. Obviously a lot more money in installing a SS liner than a new thimble. Home is for sale. So it needs to be fixed properly but no need to go overboard.
They won't install a new boiler without a liner. Make sure what you pick the buyer cannot turn around and ask for money off. We did buying this home with an unlined chimney. Basically offered higher price for my current home and knew the failures were lurking and got this in escrow: * new softener system $1500 * septic system $20k * chimney liner money $1400 * asbestos abatement - $10k
When you say "unlined" do you mean totally unlined or just not lined with a SS liner? My chimney has your normal flue tile lining.
 
Messages
24,811
Location
Upstate NY
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Had a masonry guy come take a look. He said we replace thimbles all the time. But he is a mason, not a chimney guy who cleans or installs liners. Did not even want to look at inside. Just measured and said latter this week. He said $300. Warm in basement to do my work. Cold to do outside work. So mine will be done this week. It all depends if you call chimney company or mason. One place wanted $200 to $300 just to inspect.
 
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