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Cracks in Clay Chimney Flue: Need Advice on Options

10:17 PM 01/16/2013

 

We live in a 4 story brownstone, use gas heat for steam boiler and have no working fireplaces.  We have had a 'gas-like' smell in the house.  Had chimney inspected via camera which showed cracks and broken sections in the 8' x 8" terrecota clay chimney flue.   We have been presented with two options:
1 - Insert 6" stainless steel liner which is a bit smaller than suggested code size for our BTU and add an inducer FAN to expedite venting
2 - Destroy existing clay structure via "tile knocking" and insert 7" stainless steel liner (recommended size).  Concerned this may cause collapse of bricks.
We are looking for feedback on 'tile knocking" process or use of inducer fan.  Also, recommendations for reputable tradesperson to do the work.  Any guidance appreciated.
 

 

 

10 answers
  • vote

    Maybe contact three different chimney companies and see what they say and what bids they give you. We had to replace a cracked clay liner last year with a stainless steel liner. We were told our flue was very small, but they didn't suggest a fan or warn bricks might collapse. I'm pretty sure they knocked out the existing clay liner. I don't think they had a choice. Didn't have any problem with that part of the job. It's working fine now; we have an oil boiler, not gas. Be forewarned this is messy. The workmen need to properly tent and cover their work or you could end up with soot all over the house, as we did.

    11:08 PM 01/16/2013 | 0 Votes

     

     

  • vote

    Avoid the inducer fan however you can.
    Just because your boiler has a 7" flue doesn't necessarily mean you need a 7" liner. Most vertical flues can be reduced by one or more sizes. It has to do with the hieght of the chimney and the capacity ratings of the particular flue liner your contractor chooses to use.

    5:25 AM 01/17/2013 | 0 Votes

     

     

  • vote

    Do you mean gas smell as in natural gas?  The exhaust gas from a gas appliance is odorless - hence you have no odor from a non-ventetd stove or oven.  If you are smelling gas, it would indicate a supply line leak which would have nothing to do with your chimney.  Do you smell gas in your boiler room? i would not rush into an expensive chimney repair until you have identified the source of the odor. 

    1:42 PM 01/17/2013 | 0 Votes

     

     

  • vote

    Thanks.  We were told by the gas company, plumber and chimney people that the burn off from a boiler can smell a bit like gas.  It is not from appliances - rather the boiler.  Chimney people used a camera and saw breaks in the lining and said the exhause then gets trapped between bricks and walls and eventually can leak out.    Will ask more questions, thanks

    3:12 PM 01/17/2013 | 0 Votes

     

     

    Comments (1)

    • you have class 1 chimney , and it has negative pressure inside. air is getting into chimney if there is a crack. you do not get exhaust gases into house trough cracks unless chimney is blocked.

      7:53 AM 01/20/2013

          
  • vote

    I hope you have a spill switch on your boiler that will shut it off if the CO level is too high. I had one installed on my furnace years ago; it's repeatedly turning the furnace off is what alerted me to the fact that my flue had deteriorated to the point of being blocked and possibly saved my life. I've had no problems since having a SS liner installed.
    I hope I used the right terminology--I assumed that "spill switches" were for both furnaces (hot air) and boilers (hot water or steam).

    3:47 PM 01/17/2013 | 0 Votes

     

     

    Comments (1)

    • Furnaces and boiler both use spill switches, but they don't sense or read levels of carbon monoxide. Rather they sense excessive heat and interrupt power to the burner circuit to shut off the unit's gas valve. It assumed that excessive heat at the point they are placed would be carrying CO with it.

      5:41 PM 01/17/2013

          
  • vote

    Gas boilers should have their chimneys lined with stainless steel liner, but size must be calculated, not copied from existing chimney.

    7:58 AM 01/20/2013 | 0 Votes

     

     

  • vote

    Leaking chimney exhaust from an oil boiler smells like the exhaust from a car or bus. Imagine standing behind a car or bus while it fires up -- that's the smell. I don't know if a gas boiler is different. 

    5:45 PM 01/20/2013 | 0 Votes

     

     

  • vote

    We had to remove an old clay flue (but it was much more than cracked - it was almost collapsed entirely in some parts) and then insert a stainless steel one.  I can't speak to your choice but the workers we used for that (along with rebuilding our chimney and reopening an old fireplace) were some of our favorite that we used throughout our renovation - Big Apple Chimney.  I can't recommend them highly enough.   Jason Dorn is the owner. He and his guys were great and the work has held up really well.   

    1:30 PM 01/22/2013 | 0 Votes

     

     

  • vote

    Ok, we identified the problem - missing section of chimney and Big Apple is finishing the job.  Now my problem is the grey greasy soot in my house where they had to open the walls.  Covers did not do the trick.  Any recommendations on how to clean this?  Also air filters?  Cleaning services? Steamers for rugs and couches?  Right now seems like the wiping is helping a bit but not sure if it is airborne and will get another layer tomorrow.  Any guidance welcome.

    9:39 PM 01/22/2013 | 0 Votes

     

     

  • vote

    Ok, we identified the problem - missing section of chimney and Big Apple is finishing the job.  Now my problem is the grey greasy soot in my house where they had to open the walls.  Covers did not do the trick.  Any recommendations on how to clean this?  Also air filters?  Cleaning services? Steamers for rugs and couches?  Right now seems like the wiping is helping a bit but not sure if it is airborne and will get another layer tomorrow.  Any guidance welcome.

    9:39 PM 01/22/2013 | 0 Votes

     

     

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