Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit

Do I need a chimney liner?

lowwater Member Posts: 41

Some background. My wife and I purchased our house (a 1920s tudor) in 2011. We've had nothing but problems, but at this point everything seems to be under control. However, we are still dealing with a persistent leak on the East side of our house. We replaced the roof, all windows, had some stucco cracks repaired, etc.

At this point we had a chimney company come over to inspect the chimney. He told us that our chimney does not have a liner. It has a tube in the furnace room venting into the chimney, and a small tube below the cap with our gas appliances (we have two furnaces, and a gas water hater).

His take is that with our gas appliances (we have two 1999 Burhnam boilers - one hot water, one steam - and the hot water heater is a 2011 AO Smith Effex high efficiency 50 gallon heater ) this is not only illegal, but also potential dangerous and it might be causing some of the leaks since he notices some deterioration in the chimney. They want $2,100 to install the liner (I believe we need a 40ft one), and patch part of the chimney.

Another contractor (not a chimney expert) that I contacted told me this is B/S and we don't need a liner. I've done some Google research and it seems to me that basically everyone recommends a liner with gas venting into a masonry chimney.

What are your thoughts on all of this, what the pros of getting or cons of not getting a liner, and what do you think of the quote?


  • Jack
    Jack Member Posts: 1,045
    I'm assuming this is an end wall and therefore

    Exposed chimney. Your chimney contractor is correct. The other guy making the BS accusation is in fact full of it. NFPA 211 which regulates chimneys requires a liner. NFPA 54 the gas code also states that Category I appliances which you have will require a liner. You can get condensation out of the chimney.
  • lowwater
    lowwater Member Posts: 41

    I understand it's code, but besides code what are the other consequences/negatives of not having a liner?
  • jonny88
    jonny88 Member Posts: 1,139

    its also possible that your chimney if it has cracks etc could leak carbon monoxide into your home.Codes are there to protect you.In my humble opinion I would reline your chimney.Think safety.
  • Gordy
    Gordy Member Posts: 9,514
    Besides above

    With higher efficiency appliances exhausting into the flue the condensing flue gases are acidic, and will eat away at the mortar, and brick your chimney dieing a slow death from the inside out. This also has a lot to do with the NFPA codes.

    In the old days with lower efficienciy appliances, and higher stack temps to warm the flue to prevent condensation it was not as bad.

    Is this chimnet on the exterior of the home, or running up the interior of the home?
  • lowwater
    lowwater Member Posts: 41
    edited July 2014

    It is running on the outside of the house, see picture
  • Snowmelt
    Snowmelt Member Posts: 1,295

    I'm not the chimney expert, I have a chimney guy that I call to put liners in, but in my opinion you need a chimney liner to get the gases out of the chimney, the flu gases will kill the mortar and eventually get in the home, them you die and you don't have to worry about it anymore.

    I hate when people come in here & ask a question then says I don't want to spend the money on chimney liner.
  • Gordy
    Gordy Member Posts: 9,514
    edited July 2014
    exterior chimneys

    are the hardest to warm up, and keep warm between appliance cycles. unlike an interior built chimney. There fore flue gas condensation is twice as bad. Both still require liner.

    Is the existing chimney clay tile lined? the mortar joints between the tiles may have eroded away causing condensate to run between the tiles, and the actual masonry finding its way into the interior space of the home.
  • Bob Harper
    Bob Harper Member Posts: 882

    Your Realtor should have recommended an NFPA 211 Level II inspection since you bought the house. That would have undoubtedly revealed the need to reline the chimney. All chimneys since 1927 have required intact properly sized liners.

    Most mfrs. now require a listed liner to connect to their appliances.

    If that water heater vents under positive vent pressure, shut it down at once and have it replaced tomorrow with a CAT I chimney vented model or vent that one per the listed instructions out the side of the house. You can NEVER common vent positive vent pressure with negative vent pressure chimneys or vents.

    When relining, have a pro do it and make him show you his calculations in the code for sizing not only the liner but the vent connector manifold as well. Try to get as much vent rise straight up before any offsets. If no spill switches, have a qualified pro install them on bullhead tee with double acting barometric damper. Regardless, when all done, require combustion analysis on each appliance individually and collectively and the ambient room air. Then install unlisted low level CO monitors on each floor and within 15 feet of any sleeping rooms. The liner must use the listed top support plate/ system and rain cap. Have them bring it in like a hockey stick without a tee then once its in the room, transition to galvanized connector. Can you provide pics and the appliance BTU input ratings?
  • lowwater
    lowwater Member Posts: 41

    I appreciate all the advise. Just trying to get myself educated, and not being ripped off by a chimney guy.
  • lowwater
    lowwater Member Posts: 41
    Inspection report

    I am not sure if it's clay tile. This is what the inspection report says:

    4. Vents / Flues / Chimneys

    Description: Masonry Chimney
  • lowwater
    lowwater Member Posts: 41
    edited July 2014

    I checked my water heater's and it can be chimney vented:

    "Weary of hassles involved in a high efficiency water heater installation?  With the [AO Smith] Effex, there’s not much to worry about. For starters, it uses standard water and gas connections. It easily connects to existing B-vent on replacements, and it can be common vented. No wonder it is known as effortless."

    The chimney guy (his company is a specific chimney company) looked at the specs of my 3 units and he estimated it needs 250k BTU:

    140k steam boiler (see pic)

    52k hot water boiler (see pic)

    40k hot water heater (

    230kBTU  total

    I took a few other pictures of the setup (I disconnected the pipe from the steam boiler temporarily to show the inside where you can see dirt inside of the pipe). It looks like the hot water heater (top pipe) is is separate from the 2 boilers. The estimate lists a 'double tee at base'. Would that be how all pipes get vented into the same liner? Also, I am reading in the inspection report (just noticed it now) something that the hot water vent pipe is not properly sloped up?
  • Snowmelt
    Snowmelt Member Posts: 1,295

    The answer is most likely you will still need the chimney liner.
  • icesailor
    icesailor Member Posts: 7,265
    WHAT IS ????

    That last picture, showing a section of all fuel pipe going into the chimney, what is that back inside? It looks like a piece of smoke pipe or liner blocking off the lower flue.

    You have a 3 sided chimney that turns into a 4 sided chimney. Even if you lined it, I doubt that it could be made legal There's just too much exposed chimney. It is a hack job since the beginning. It looked nice on some architects plan. If you add up the total BTU input of the appliances and then take the size of the flue and length, it is probably an illegal chimney. It must be all gas, You can power vent the equipment through the side wall and leave the chimney. If you are having water issues, the easiest way to solve the water problems around the chimney is to remove it. To me, that chimney is calling out to every rain drop in the area. "Come to me. I'm here". Just by looking at it, I can tell you every place it is leaking. And it is down the whole side(s) of the 3-sided part. The 4 sided part just leaks into the flue and comes out wherever it wants to. I'll bet that there's 10 coats of waterproofing paint already on the chimney.
  • icesailor
    icesailor Member Posts: 7,265
    Leaking Flashed Chimney's:

    The only thing harder to stop from leaking is a French Door.

    I had a saying I used for years for guys that had French Doors they couldn't stop from leaking.

    Jesus Christ was a Carpenter. Even HE couldn't stop a French Door from leaking.

    I'd add 3 sided masonry chimneys flashed in to a stucco wall to that list.

    Did I read that the house was built in the 1920's? The two sided lead flashings with one side behind the stucco and the other side held against the brick will pull away when the sun hits it. Letting the water in. You live in the Chicago area? In the winter time, it will blow the @$$hat off a cow. Like where I lived in New England.
  • KC_Jones
    KC_Jones Member Posts: 4,841
    I noticed that too

    Looks like a shiny piece of pipe back in there.  Another thing I noticed was the one boiler reduces right at the appliance, at least it appears to reduce.  I always thought that was a big no no.  Another issue that I don't think was mentioned is the acid.  The combustion gases from gas appliance can produce an acid if they condense.  This is what can ultimately destroy the masonry chimney.  This is the biggest reason for lining (so I was told).  I have a 100+ year old house and am currently in process of abandoning the masonry chimney and having a new B vent installed inside the house.  If you saw my chimney and what can happen you wouldn't question the lining issue believe me.  Just another homeowner.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • lowwater
    lowwater Member Posts: 41

    So I've read most people highly recommending installing a liner, where I've also read one or two opinions who are saying I shouldn't bother and try to power vent.

    I have another question. The 2 boilers (steam/HW) and the hot water heater both are venting directly into the chimney using their own pipes. Would the chimney contractor use this "double Tee" at base (whatever that is) to connect these two pipes into the liner?
  • lowwater
    lowwater Member Posts: 41

    What you see is dirt (from the chimney) inside. There is nothing else in there. Just bad lighting. 
  • Snowmelt
    Snowmelt Member Posts: 1,295
    You have to

    Really have someone size it out correctly. What I think ur asking is can you but two vents into a tee then vent it out.

    The answer is you, you can get what they call a tee-wye then go in the chimney, sizing the chimney vs btu is what is needed, for that I go to the gas book, but for you I think it will be easier to go to a local supply house and get someone usually in a desk to size it out.

    If I was you, I would get the chimney company to size it out and set it up properly.
  • icesailor
    icesailor Member Posts: 7,265
    edited July 2014

    Before you get too carried away, I'm quite sure that whomever installed the second boiler didn't properly size the chimney flue and the total of the three appliances can't be vented into that flue. And when they install the liner, they will reduce the size and venting capacity of the chimney. That MIGHT be a 20" X 20" chimney with a 12" tile. If no tile, it will be a 12" round corrugated liner. That looks to be like a 40' chimney. Remember, part of the function and size is for the flue to get hot and stay hot in a certain period of time. If the 3 or 4 sided chimney is too long, it won't get hot and that is why it is illegal.

    Me personally, I quake at the thought of patching the place where the chimney was if you take it down. Someone will always know where it was, no matter how hard you play with the stucco. If the appliances are all gas, the gas code is very specific about venting into masonry chimneys. Someone may not know and tell you that you are fine. Someone else might come along and tell you that it can't be done. Just because some chimney liner installer says it can be done, doesn't mean he is correct. I'd be sure that all the AHJ's bless it 3 times before I went ahead. Massachusetts made 3 sided and long 4 sided chimneys illegal for upgrades. Flues can be too small AND too BIG.
  • Henry
    Henry Member Posts: 988

    NFPA54 has guidelines for venting cat 1 appliances. The smallest input must be connected as close as possible to the vertical rise and at the highest position of a common vent. Your chimney specialist is the one to turn to and is entirely liable for an incorrect or code violations. A liner is required by our code. If you have a clay tile chimney, you do not need a liner. Code requires that the smallest diameter be used for the combined input of all appliances. So, perhaps you do need a liner or not. The chimney guy is the right guy to use!

    B149.1, B149.2 and Venting sub-committee member
  • Bob Harper
    Bob Harper Member Posts: 882
    correction if you don't mind

    Henry stated if the chimney has a clay tile liner it does not need a liner. Actually, the correct approach is that ALL chimneys must be lined and when a clay tile liner is damaged, eroded or otherwise cannot meet its intended purpose then the chimney must be relined or rebuilt. When changing fuels, upon sale or transfer of property or upon a malfunction, a full level II inspection is required by NFPA 54 because '54 refers you to 211 for chimneys as does '31 for oil. I can guarantee you that a properly performed inspection will reveal defects that warrant a liner in almost all cases, not including the other code considerations for cold exterior chimneys.

    If it matters any, I'm a Certified Fireplace and Chimney Inspector and sit on both the NFPA 211 cmte. and UL Standards Technical Panel 103, which writes the UL listing for chimney liners, vents and factory chimney.

    My main point is,just because some terra cotta flue tile is visible at the top or base does not automatically mean the chimney can be considered "lined". More to the point, most tile flues were improperly built with improper mortar and have suffered deterioration of both the mortar and the hard fired face of the tile. Sizing alone is often grounds for a liner.
  • lowwater
    lowwater Member Posts: 41
    chimney companies

    Thanks all for the replies. I already have one quote in hand (which I used in examples above), and I will 3 other chimney companies come in and give me quotes. I'll post the results (someone might be interested). Thanks again.
  • icesailor
    icesailor Member Posts: 7,265
    Flue Size:


    I don't have any books since I moved, but I didn't know anyone (including myself) who knew how to properly size a flue/chimney for a gas appliance until I did my Comm of MA Continuing Ed class that discussed it. I doubt seriously that chimney liner "specialists" can do it properly.

    From what is posted for the two boilers and an estimate that the gas storage hot water heater is about 36,000 BTU's, the total input into the flue is 221,000+/- BTU's. It is an 8" X 12" clay flue tile. I estimate the chimney to be at least 40' high.

    You sit on the committees. Can you properly vent 221,000 BTU's in a 40', 8" X 12" chimney? A SS corrugated liner will at best, be 6" X 10". Can you legally (to code) vent the three appliances (total 221,000 BTU's into that sized liner?

    My experience with a chimney like that is that it will look OK at the bottom and top. It is the middle that is bad and all deteriorated. If you run a chimney cleaning brush down the flue, all you will get when the brush is in the middle is sand. From the failed liner from acid corrosion.  

    Just asking. Its not my house and in Florida, if it has a chimney, its fake.
  • Gordy
    Gordy Member Posts: 9,514
    edited July 2014

  • Bob Harper
    Bob Harper Member Posts: 882
    liner sizing

    I'm too tired to look into my sizing charts, which sit on my desk but let's look at the maximum liner size available:

    a nominal "8x13" flue tile may range from ~6"x10" ID to around 7"x11" ID depending upon what part of the country, whether nominal or actual size, and whether or not the tiles are properly aligned, which they seldom are. Let's work with a 7x11 just for fun:

    A 7" min. dimension can take a nominal 6" round allowing about 1/4-3/8" per liner wall thickness, which leaves almost no room for the liner to slide down but some. Draw the 7x11 rectangle on paper. Now draw 1/2 of each circle against each end. Since each half measures 3"+3"=6" subtracted from the width of 11" leaves 5". Subtract let's say one inch for liner wall thickness and some gap for the liner to slide down without dragging. That leaves you with a 6"x 5" box in between the two half circles. A 6" circle has an area of 28..27 inches square plus the 30" of the center box = 58.27" square of liner cross-sectional area. Now, before you look this up in your sizing charts we have to derate it 20% off the top, then another 20% if it has an offset from vertical. A 40ft x 6" liner without offset not factoring exterior chimney or climatic zone can handle two or more CAT I natural draft appliances not fan assisted for a combined ~222MBH.

    If you want to use a rectangular liner the cold corners don't count, which is why I factored it on an oval liner. In the pic, the WH vent connector is too long, not properly pitched, not properly attached to the draft hood, does not have a min. 12" vent rise and is too far from the common vent. You should never start with an ell right off a draft hood. This WH will probably spill into the CAZ more than vent up the chimney.

    Gotta hit the sack but hth,
  • icesailor
    icesailor Member Posts: 7,265
    All lined up:


    Thanks. It would appear to me that the existing chimney is so close to being at the limit, that it is not code. There's not a lot of calculated difference in a 3 sided chimney and a 4 sided chimney,, heat loss wise. In Massachusetts, a building permit and a gas permit would be required because you are modifying the vent. Inspectors are supposed to condemn such a chimney because they banned 3 sided chimneys because you can't warm them up.

    The re-liners just go by the size they can get in, not whether it is legal now to do so by the connected load.

    And as far as putting in a 7" X 11" oval liner down that 40+' chimney? I'll be in the cellar, pulling on the chain to get it down, if it will come down. Someone else can feed it down from that height. And I'll watch while someone hammers into the wall to get the SS liner into the room. I just LOVE good entertainment. You'd have to stage that chimney. If the low bid was just going to set a ladder against the chimney, a 40' ladder is too short. And the leverage might knock it over.

    I'd be Power Sidewall Venting the whole thing. A whole lot cheaper.
  • j a_2
    j a_2 Member Posts: 1,796
    by the book

    My simple answer is, if in doubt line it….However I am sure it is clearly, written in the local code books in your area….Sizing charts are readily available,on line from different manufactures….When you have a chimney inspected and approved for continued use,its approved for continued use { at that time }…In my state the code, is not just a code its the LAW…..Chimneys are to your house as a exhaust systems are to cars…..Keep it safe and simple….
  • icesailor
    icesailor Member Posts: 7,265
    Line It:

    There's no question it needs to be lined.

    Its more important to decide if it can even qualify to be lined. Anyone can line it. But can it be lined, and it still be a legal chimney/flue?

    I was a mason's helper/mason before I was a carpenter, before I was a plumber. I know how to mix mortar in a mortar box with a mortar hoe and how much water to add to the mix without it turning to soup.
  • ChrisJ
    ChrisJ Member Posts: 11,980
    edited July 2014
    Big enough?

    If I recall, you must go by the manufacturer of the liner's input btu rating and cannot just go by size.  Not saying that most liners aren't likely the same, it's just what I remember going through with my chimney nitemare.  I do recall being told a lined chimney, especially one with a round liner will flow better than an unlined one so if the current setup produces good draft it should work even better lined.

    My point being, if the chimney guys say it can be lined and are willing to do the work I'd go with whatever they recommend.  Without a doubt it should be lined and there is a chance it's too small for the connected appliances, mine sure was but my basement also stunk like a diesel bus when we bought the house.

    We ended up having the 150 yr old chimney torn down and replaced with a 6" B vent before I installed the new gas boiler.  The chimney only had a 4" x 7" opening.

     I don't miss that brick disaster one bit.

    We don't discuss pricing here, but the original price I had to line the chimney was about the same as your quoted price, sounds perfectly fair to me.  The price to tear the brick chimney down and install a B-vent was around double but was well worth it in my situation.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • lowwater
    lowwater Member Posts: 41

    I had a total of 4 chimney companies over (all selected from Angie's List based on review). Prices ranged from $1,300 (just a liner) to about double. I've decided to go with the company that spend 2 hours investigating. He actually opened up a small part of the chimney in the boiler room to investigate, and he cemented it close afterwards. He said the only way to know what's going on is to take a look. Free of charge.

    He will:

    - Replace and properly angle the pipes in the basement

    - Install the T-tube and liner

    - Recrown the top of the chimney and fix chimney flashing

    - As a thrown-in he'll clean the gas fireplace liner (which looked fine according to him)

    He said that if he needs to break open the outside of the chimney to gain access, he will do so and it does not increase the price. The guy has excellent review, has over 20 year experience and provided a ton of references, including commercial references like fire houses.

    It is a lot of money, but I think it's important to have the job done right. Any last minute things I should pay attention to when he starts the job?

    Thanks a bunch all for your input.
  • RobG
    RobG Member Posts: 1,850

    Is he going to pull a permit on the work? If not for safety, then for insurance. It is a must.

  • lowwater
    lowwater Member Posts: 41

    I live in Nassau County, NY and the town I live in is a permit nightmare. You have a valid point, but unfortunately town bureaucrats have made it impossible to do things the right way :( 
  • icesailor
    icesailor Member Posts: 7,265
    Right ways:

    It might be that the "right way" is the only way, and under careful scrutiny, what is proposed, is the wrong way.

    New York has a funky code system. Where I came from, Massachusetts has a "Uniform Code". The same State plumbing and gas code applies equally to every town and jurisdiction in the Commonwealth. We Plumbers and Gas Fitters are all required to take 6 hours per year of CEU classes approved by the State Board of Plumbers & Gas Fitters registration, Two years ago, (2012) this was covered about 3 sided and 4 sided exposed chimneys and that they can't be used unless lined BUT, they had to be properly sized for the applied load. Whomever modifies tha gas venting in Massachusetts needs a gas permit because they are modifying a gas appliance vent. I never saw any chimney only specialists in the class. Unless they have a gas license, they have no business modifying the gas vents. No matter how much they think they know. But, you're in New York. Not Massachusetts.

    Then, there was mention of a fake gas fireplace. Does that have a flue? How many flues are in that chimney? What are the outside dimensions of that outside chimney? 16" X 20" or 15" X 24" 16" X 24" is two 8"x8" flue tiles. 16" X 20" is one 8"X12" tile.

    In Massachusetts, if you modify the gas appliance/vent in any way, you are required to install CO detectors as part of the building and gas permit.