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What type stainless chimney pipe for oil-fired burner?

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MikeAmann
MikeAmann Member Posts: 998
edited November 2023 in Chimneys & Flues
316L is what I am reading. What about 430 or just plain 316? I know NOT 304.

I am doing chimney repair work right now and after I finish replacing the mortar in the joint between the top 2 clay liners and patching the hole in the 2nd liner down, I want to prevent any new damage by sliding a 48" long stainless steel stove pipe down inside to prevent the wall of the clay liner from further deterioration. NOT A FULL LINER from top to bottom. That will come later. Right now I need to get this done as winter is just about here. I have seen that all the damage happens above the roofline. Below that is OK. 3 sides exposed northern facing masonry chimney. I might have to have something custom-made or modified.

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  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,044
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    If you are doing a temporary patch with the intent of installing a full liner in the next 5 years or so, then I see no reason you can’t use a lower priced liner that will fit snugly in the (almost) square clay liner you are repairing now. The clay liner was sufficient for hand fired equipment and older oil fired equipment with regards to the high temperature of the flue gas from those older designed equipment. The reason your clay liner is failing is that the newer more efficient oil fired boilers manufactured for the last 30+ years have a lower stack temperature. That is causing condensation to form at the coldest point of the chimney on the very cold days. That water soaks into the clay during the firing cycle, then freezes during the off cycle, then thaws out during the firing cycle causing more condensation then freezes and so on... and you already know that water freezing will expand and that is breaking the clay liner apart.

    I am not sure that your 48" section will do much to protect the clay liner because condensation will still form on both sides of the stainless steel. It may slow it down but it will not stop it completely.

    The idea of a full metal liner from the oil burning appliance, all the way up to the top of the chimney, is to promote a higher temperature at the top of the chimney faster. The metal will not absorb the heat from the flue-gasses and dissipate that heat into the mass of the masonry (CLAY) because the thin metal has less mass to absorb that heat. The condensation is less likely because the metal liner will get hotter quicker.

    Since you are not doing the full liner at this time, I believe that your existing clay will absorb and dissipate that heat intp the greater mass of the masonry by the time it gets to that short piece of Stainless Steel pipe. It can’t hurt to put it in there, so giving it a try will not cause any ill effects that won’t already happen anyway. But there is a small chance it may help a little. Just understand that getting the full liner should be completed sooner than later. Like don't wait 15 years… do it next summer!

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    MikeAmann
  • Big Ed_4
    Big Ed_4 Member Posts: 2,805
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    It's cheaper to do it right...

    There was an error rendering this rich post.

    realliveplumber
  • Intplm.
    Intplm. Member Posts: 1,993
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    A company called Selkirk offers a very good product.
    MikeAmann
  • MikeAmann
    MikeAmann Member Posts: 998
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    Big Ed_4 said:

    It's cheaper to do it right...

    Of course, but I am out of time. Winter weather is right around the corner.
    I have called a masonry contractor and a chimney guy - too late in the year to be tearing down and rebuilding. So it's on me to do a patch job ASAP.
  • pecmsg
    pecmsg Member Posts: 4,881
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    MikeAmann said:
    It's cheaper to do it right...
    Of course, but I am out of time. Winter weather is right around the corner. I have called a masonry contractor and a chimney guy - too late in the year to be tearing down and rebuilding. So it's on me to do a patch job ASAP.
    My apologies but that’s a 3 or 4 hour job. 
  • heathead
    heathead Member Posts: 234
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    Make sure if you stuff a pipe in and don’t go all the way down it can’t fall down and block the flue opening.  If it falls and blocks the opening you will have much bigger problems.  
  • MikeAmann
    MikeAmann Member Posts: 998
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    @EdTheHeaterMan @Big Ed_4 @Intplm.
    This chimney has 3 flues - fireplace, WB stove, and the oil-fired boiler and HWH.
    2 flues will be getting blocked off - the WB stove (gone) and the fireplace (I will never use it).
    4 areas of damage:
    1) missing mortar between the clay liner sections
    2) a fist-sized hole in the 2nd liner section down
    3) the crown. Dad did some patch jobs to the crown in the past, but what I found was a complete mess. I really can't say if what he did either helped or hurt, but it's now my turn at this.
    4) Missing mortar between the exterior bricks, esp on the north side. The tuck-pointing stuff in the tube will take care of this for now.

    Here is what I have witnessed in the last 2 weeks in temperatures ranging from 29F to 70F and inside all 3 flues - CONDENSATION. That's right - even in unused flues! And only above the roofline. The oil-fired flue had the most damage and the hole. I have that all patched up now and now I am resurfacing the crown. I got a chance today to look up from the bottom and the rest of the clay liner sections below the roofline look great. So this is the reason that I want to put a 4 foot section of stainless pipe down that flue from the roofline to the top - to try to protect those 2 sections of patched clay liner from further damage. I already know that there is condensation, and with flue gas going up through there I have to assume that at times that there is corrosive flue gas condensation happening. Let it attack a section of SS pipe and hopefully leave the clay tiles alone is what I am hoping for.

    I will be coating the inside top 4 feet of this flue with Dri-Lok as well as the newly-surfaced crown and 2 bricks down. And after the tuck-pointing is done, then the entire chimney will be waterproofed with Siloxa-Tek 8500, including inside this flue (4 feet).

    My digital camera died just before I discovered this, so I have no before pictures. After will be added later.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,607
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    I mean, if your going to have it fixed next spring how much more damage will it get in the next 6 months? You probably won't be able to tell the difference it has been that way for years
  • MikeAmann
    MikeAmann Member Posts: 998
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    heathead said:

    Make sure if you stuff a pipe in and don’t go all the way down it can’t fall down and block the flue opening.  If it falls and blocks the opening you will have much bigger problems.  

    Of course. The pipe will have a flange at the top, sealed to the top of the clay flue tile.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,044
    edited November 2023
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    My digital camera died just before I discovered this, so I have no before pictures. After will be added later.

    When will you be holding the funeral services for him? I didn't know Cameran very well but I always said hello in the elevator. I will miss him.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    MikeAmannSolid_Fuel_Man
  • MikeAmann
    MikeAmann Member Posts: 998
    edited November 2023
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    If I do manage to get a pipe in 316L or 316Ti stainless, can I use a type 304 stainless cap?

    I like this style of cap and I want to attach it to the OD of the clay flue pipe in a clamp-on manner - I will cut slits and use a large SS hose clamp at the bottom.
  • MikeAmann
    MikeAmann Member Posts: 998
    edited November 2023
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    pecmsg said:


    MikeAmann said:

    Big Ed_4 said:

    It's cheaper to do it right...

    Of course, but I am out of time. Winter weather is right around the corner.
    I have called a masonry contractor and a chimney guy - too late in the year to be tearing down and rebuilding. So it's on me to do a patch job ASAP.

    My apologies but that’s a 3 or 4 hour job. 

    Sure, once you find the right guy. Good help is hard to find. How long will that take?
  • Bob Harper
    Bob Harper Member Posts: 1,040
    edited November 2023
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    Just about everything wrong I can think of here. Save your self a lot of useless work and endangering occupants- bite the bullet and hire a pro to install a full length 316 ss liner or L vent. Do NOT jury rig a piece of rigid pipe at the top. What are you going to do? Put arrows in the pipe so the flue gases know to enter the pipe and not the concentric space to the flue tile? Why apply Dri-Lok inside the flue? It's not intended for that application, will fail and is a vapor retarder. That's the last thing you need. Same with the water repellent inside the flue. Worst possible thing you could do. The cap shown fits a ss round liner. Any liner should come with its own listed top support plate onto which their cap mounts. No jury rigging the cap.

    Look, you're trying to over-think a problem that has very simple, viable solutions. Instead, you're about to cause a lot more problems. Since there is a shunt btw flues, just relining is technically not an option anymore. According to Hoyle, a liner is listed only when surrounded by 4" of solid masonry units- not Swiss cheese. If it is a straight shot, you can install type 'L' vent inside the chimney and be done with it.
    It's too cold to apply water repellent. Wait until the Spring. You don't want to apply that until the exterior has been properly rebuilt/ repointed. Otherwise, you'll never get the new material to stick.
    Please just call a pro and do it properly.
    pecmsg
  • pecmsg
    pecmsg Member Posts: 4,881
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    MikeAmann said:

    pecmsg said:


    MikeAmann said:

    Big Ed_4 said:

    It's cheaper to do it right...

    Of course, but I am out of time. Winter weather is right around the corner.
    I have called a masonry contractor and a chimney guy - too late in the year to be tearing down and rebuilding. So it's on me to do a patch job ASAP.

    My apologies but that’s a 3 or 4 hour job. 
    Sure, once you find the right guy. Good help is hard to find. How long will that take?

    You don't know until you try.