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  1. #1


    I am a Buyer in the process of negotiating a contract on a home. I had it inspected and the inspector noted that the morter in the tile liner of the chimney was "compromised." He indicated that since the furnace is a Lennox 80% efficiency, the "manufacturer installation recommendations" suggest that a flexible liner installed. He was surprised that the company who installed it hadn't recommended this to the owner, as it would have prevented the morter in the tile liner from being compromised by the moisture. He indicated that while there is no local code that a liner MUST be installed, that the mortar in the tile liner is now compromised,and this is a violation of the local gas code. The Seller called the company that installed it and he said the inspector was wrong - that there is no manufacture recommendation for installing a liner, since the chimney is not an exterior chimney. (of course he may not want the owner to think his company didn't know about the manufacturer's installation recommendations...thereby negating any responsibility for the compromised tile liner that now violates local gas code.) Help! Who is telling the truth? The Seller and Buyer are negotiating directly without a realtor, we're both reasonable people, and we just want to know who is right.

    [Edited by homebuyer262764782 on 03-09-2006 at 08:12 AM]

  2. #2
    Join Date
    May 2000
    Indianapolis, IN, USA
    The National Fuel Gas Code addresses liners. The chimney must be in good shape, totally inside the house and have a water heater included in the venting. The code says: the area of the tile liner must not be more than 7 times the outlet area of the smallest draft hood appliance.

    Translated, the water heater drafthood typically is 3" outlet. That's 7 sq inches in area. Multiply that times 7 in the rule and that's 49 sq inches. So the tile liner in most cases cannot be more than 49 sq inches or 7x7, 6x8 or the like. Around here, most liners are 6.5 x 10 or 65 sq inches and to follow the code to the letter, a liner would be needed.

    It is very common around here for dealers not to bid a liner, even in outside chimneys. Their bid is lower and they get the job sometimes over those who want to do it right.

  3. #3
    Join Date
    Apr 2003
    Eugene, Oregon
    As the great bald one posted all he said is correct. You should check local codes as they are the ruler. Our code states that the only time you do not need to use a liner is if the equipment is oil fired and has a terra cotta liner, otherwise a flex liner must be used.
    Proud supporter of Springfield Millers and Oregon Ducks.

  4. #4
    Join Date
    May 2004
    homebuyer, its hard to believe that there is no code requiring a liner but there is a local gas code requirement for the mortar. I'd check with the jurisdiction there wherever your at to make sure first. Normally if your under a gas code it will specify venting as well.
    A liner is required under the International fuel gas code to prevent this from being an issue in the first place.
    Vern P: 2003 MBC,MRC,IFGC,IFC
    An HVAC-Talk Michigan Chapter Mechanical Inspector, Jurisdiction-Ann Arbor

  5. #5
    Join Date
    Feb 2006
    I'm not a professional. Only a homeowner, but remember codes change. Is it possible the original installation was in accordance with code, but the codes subsequently changed? By the way, this was one of the reasons I just bought a 96% furnace. The old 80% furnace was vented through the chimmey without a liner, and the installer thought it was preferable to vent out the back of the house through a PVC pipe. Not sure if the cost between a 80% vs 90% furnace was more than the cost of installing a liner, but I was a good excuse for changing out and upgrading the furnace.

  6. #6
    Join Date
    Nov 2000
    No, the codes didn't change. I have an AGA publication from (I believe) 1990 that details the changes in the furnaces and addresses changes in venting, including tables. Venting instructions were included in the boxes with the furnaces and many supply houses carried copies until the new venting tables were incorporated into the 1992 NFPA-54 publication. The earliest tables dealing with chimneys even had asterisks next to many of the configurations indicating the "potential for continuous condensation". Like BaldLoonie said, the furnace by itself requires a liner per code and if there is a water heater with it, the tile can't be bigger than a nominal 8x8 liner along with being interior and in good shape.

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