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Reusing the Old Chimney When Replacing a Boiler? Dangerous Mistake!

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RayWohlfarth
RayWohlfarth Member Posts: 1,986
edited March 20 in THE MAIN WALL

This weeks video covers reusing the old chimney when replacing the boiler. It could work just fine or it could be an accident waiting to happen. You never know until it's inspected.

https://www.youtube.com/watch?v=6gQUTAzKUSM
Ray Wohlfarth
Boiler Lessons
Bob HarperIronmanSiteReadertylerjgardner

Comments

  • Albany Chris
    Albany Chris Member Posts: 41

    Not much of a detective story when we didn't learn what was the chimney problem…

    SiteReader
  • Kaiser
    Kaiser Member Posts: 2

    Ray I ran into a chimney issue. Although resolved I still have questions. Original WBV 03 Peerless swapped out for the exact same appliance. Before removal of the old I took upon myself to just check some parameters. It didn't sound nor smell like it was running quite rite. A trace of smoke was no where to be found and barely a -.01 over the fire. Interesting! Before replacing the boiler the stack temp of the old boiler ( 280 deg f ) had me greatly concerned. New boiler is installed, correct nozzle, chimney connector and damper, and I installed and cemented in a new thimble. Also the basement had measured for plenty of combustion air. A trace of smoke established then brought to 0. Barely a draft. Actually really cold start up briefly produced a positive over the fire. After further investigation and that original stack temp i found several liner sections of the chimney had shifted and collapsed slightly. Chimney liner installed. However, draft still an issue. Burner set up parameters observed. While searching for a trace of smoke my draft gauge displayed a beautiful-.02 - -.03. I noticed once the appliance had 0 smoke the draft had reduced significantly. Shes running at a good strong -.01 teetering towards -.02. My question of curiousity is could air for adjustment from the air shutter or air band ( Beckett AFG) have a different affect on draft. I do realize the adjustment to add more air creates a vacuum break and can reduce negative over the fire draft. Crazy thing is breeching draft was -.03—.04🤯. Any assistance would be great.

    Thank you

  • Evan0307
    Evan0307 Member Posts: 28

    I apologize if this is a silly question (homeowner here), but who would you recommend install a chimney liner? Would this be an HVAC person? A chimney sweep? I replaced the gravity system hot water boiler in my basement with a newer more efficient boiler about 3 years ago and they vented it right up the chimney. I have never encountered any problems but the idea of lining the chimney has crossed my mind…. Thanks!

  • Bernie_the_Brewer
    Bernie_the_Brewer Member Posts: 44
    https://forum.heatinghelp.com/discussion/comment/1892950#Comment_1892950

    In my (limited) experience, this is generally done by a mason. The same company that will or would rebuild your damaged chimney.

    Trying to keep Bernie burning!

    Mad Dog_2
  • RayWohlfarth
    RayWohlfarth Member Posts: 1,986

    @Albany Chris Sorry about that I just wanted to have the installer inspect the chimney before connecting a new boiler. I'll try doing better. Thanks for the feedback

    @Kaiser The boiler you spoke of is a category 1 appliance meaning it should be slightly negative flue and non condensing. the burner blower should be enogh to overcome the boiler resistance. I would imagine the draft should pull the flue gases through The stan temp seems a bit low and do you have a barometric draft control on it

    @Evan0307 You could have either a chimney sweep or hvac company do it. I see mostly hvac companies doing it around here.

    Ray Wohlfarth
    Boiler Lessons
  • clammy
    clammy Member Posts: 3,255

    Any competent HVAC or Plumber should when replacing equipment either personal inspect the chimney and accept any liability or cut your liability and have a reputable company do the inspection and inform the home owner of the results and if so be it have the liner properly sized installed and inspected when done . Where i m at when replacing a chimney vented appliance. the chimney must be inspected and some body has to sign off on it and accept liability this is the case when permits are pulled ,other wise its wild west city . Any body that been around the block knows by now allot of the standards when it comes to masonry chimneys and weather or not they need to be lined . In most cases its a good idea unless you know a mason w scaffolding and some time and you got extra some money then afterwards you can have a nice stainless steel liner installed so you don t go through it again , The cost of a properly done liner will always be massively cheaper then rebuilding a chimney .

    peace and good luck clammy

    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating

    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 17,390
    https://forum.heatinghelp.com/discussion/comment/1893016#Comment_1893016

    That's what I had to do when I replaced my boiler.

    They said I could do the boiler, but I wasn't allowed to inspect the chimney. Good thing too, because in the end it ended up being torn down entirely and replaced with a B vent.

    It was far from acceptable, or even remotely safe.

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • pell
    pell Member Posts: 26

    I hope you didn't use B-vent. The product is only rated for NG/LP.

  • NewGuy
    NewGuy Member Posts: 30

    We had a boiler die about 14 years ago. With the replacement we were told we needed a new chimney (stainless flue) that would be run to the exterior of the building and up three stories to the roof, instead of the old chimney like before. Since then we've killed 2 more boilers (cracked blocks) and the third boiler struggled for 12 months with repeated heat sensor triggers turning it off. A few weeks ago we installed a draft inducer in that stainless chimney and problem seems to be solved…three boilers later. If you change the flue to the exterior, or don't use the old brick chimney to house it, make sure it's not vulnerable to such cold downdraft (insulated or enclosed?) or you add the draft inducer. For the record, 30 degrees outside seemed to be the magic number.

  • Bob Harper
    Bob Harper Member Posts: 1,164
    https://forum.heatinghelp.com/discussion/comment/1893137#Comment_1893137

    Curios what you think B-vent is rated for. Please explain.

  • Bob Harper
    Bob Harper Member Posts: 1,164

    Natural draft chimneys, vents, and their connectors are not rated for positive flue gas pressure. Draft inducers pressurize flues. This may result in spillage of flue gases into the CAZ. The chimney/ vent must be rated for the class of service so the venting should be listed for that application.

    Just because things are made, marketed and sold does not make them legal or a good idea. Just do your homework.

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