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chimney liners

Rich Kontny_3
Rich Kontny_3 Member Posts: 562
Is giving you great advice, the by products of gas combustion attack and eventually destroy the mortar joints.

Make sure the liner is sized properly also as oversizing can create a situation where the chimney never heats up enough and the CO never entirely leaves the chimney. Only to be potentially returned to the living space if a negative pressure situation develops.

Call in a professional on this one! They can give you sound options.

Rich K.


  • billy_8
    billy_8 Member Posts: 1

    we're converting from oil to gas. my chimney seems to be in good shape. it runs on the outside of the house. do i need to put in a steel liner????
  • Jack
    Jack Member Posts: 1,047
    Absolutely...line it!

    You can use aluminum flex, insulated Al flex, which would be better in an end wall chimney, a Stainless steel liner or you could look at condensing appliances that vent with PVC. Personally, I'd forgo the use of the chimney and put in the highest efficiency unit you can find for your application and vent it with PVC.
  • Mark Biro
    Mark Biro Member Posts: 46
    Natural gas rots mortar

    billy, I am a homeowner who can testify that Rich Kontny is right: "the by products of gas combustion attack and eventually destroy the mortar joints."

    I TRY to be alert, and take care... but I only dug into our chimney's situation when I noticed white sand on the floor of an upstairs, unheated space: being flushed from the mortar on the backside of our chimney. Dope slap! The cheapo aluminum liner had crapped out, apparently.

    It made me think of the simple chemistry I know:

    1. Coal -- let's call it straight carbon -- yielded CO2 in our boiler 75 years ago. Good enough!

    2. Natural gas -- methane = CH4 -- yields CO2 as well, but ALSO lots of water from the H's. Damp. Some carbonic acid forming there, too, I suppose. Wikipedia says "Carbonic acid (ancient name acid of air or aerial acid) has the formula H2CO3. It is also a name sometimes given to solutions of carbon dioxide in water, which contain small amounts of H2CO3." That's been the damp, acidic challenge to our chimney's light aluminum line, tile flue, and bricks, for several decades. Ugh.
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