Home  5  Books  5  GBEzine  5  News  5  HelpDesk  5  Register  5  GreenBuilding.co.uk
Not signed in (Sign In)

Categories



Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.
Buy individually or both books together. Delivery is free!


powered by Surfing Waves




Vanilla 1.0.3 is a product of Lussumo. More Information: Documentation, Community Support.

Welcome to new Forum Visitors
 Join the forum now and benefit from discussions with thousands of other green building fans and discounts on Green Building Press publications: Apply now.

The AECB accepts no responsibility or liability for any errors or omissions in the content of this site. Views given in posts are not necessarily the views of the AECB.



General: Appropriate air tightness products in a fireplace

Bottom of Page

1 to 9 of 9

  1.  
    • CommentAuthorgravelld
    • CommentTimeJan 24th 2026
     
    In a fireplace, what air tightness products are appropriate? I'm thinking for sealing a pipe for an external air kit, and also the flue as it passes through the register plate. (and the register plate to the rest of the air tightness layer).

    Tescon Vana works up to 90C, but that would be no good for the flue, certainly.

    What have people used?
  2.  
    High temperature silicone sealant for the flue
    • CommentAuthorgravelld
    • CommentTimeJan 25th 2026
     
    Thanks - but is that going to _stay_ airtight long term? Won't the temperature changes lead to expansion and contraction, movement and all that?
    • CommentAuthorGreenPaddy
    • CommentTimeJan 25th 2026
     
    The external air kit should be the easy one, as it's just room temperature.

    For the flue, is it a twinwalled flue? If twinwalled, then 90oC is likely fine, as it shouldn't be getting that hot. If it's black vitreous then of course much hotter, so high temp silicone. It may not make a perfect air tight seal over time, as you suggest, with a hairline gap at the mating surfaces, but compared to the leakage paths through your stove, up the internal of the flue, is it something to be concerned about?
  5.  
    If you are looking to seal the flue pipe to the register plate what method will be used for the periodic chimney cleaning? Chimney cleaning method can define the manner of sealing.

    FYI high temp silicon sealant I have used had a rated temp of 1500 C and for my usage didn't crack or shrink, but then it got nowhere near 1500 C, maybe 300 C. Proper cleaning of the surfaces are v. important to get a good seal.
    • CommentAuthorgravelld
    • CommentTimeJan 26th 2026 edited
     
    I'm planning on filling the chimney between brick and flue with vermiculite or similar, so no cleaning. TBH I've not known of chimneys *outside* of the flue being cleaned before...

    Could I use a high temp primer to stick the sealant to?
  7.  
    I assumed that the flue connected to the register plate and from there the original brick chimney would be used (classic installation), in this scenario typically there would / could be a moveable plate in the register plate to allow cleaning.

    If you have a top to bottom flue (i.e. a lined chimney with the space between the flue (liner) and the chimney filled with some sort of insulation the flue will still need periodic cleaning / inspection. How will this be achieved?
  8.  
    Wood stoves are usually designed so the flue can be cleaned through the stove, the top baffles come out so you can get at the bottom of the vitreous stove pipe which connects on to the flue liner.
    (Used this route to put a chimney balloon in ours!)

    When there is a flue liner I think the register plate is cosmetic only, so an airtight seal is not needed round the stove pipe. But maybe OP wants to stop room air migrating through the vermiculite and condensing somewhere?
    • CommentAuthorgravelld
    • CommentTimeJan 31st 2026 edited
     
    Yeah, as @WillinAberdeen says cleaning is normally done (in the UK at least) with the stove door open, firebricks and baffles out and going up through the flue.

    > When there is a flue liner I think the register plate is cosmetic only, so an airtight seal is not needed round the stove pipe. But maybe OP wants to stop room air migrating through the vermiculite and condensing somewhere?

    Yes - definitely. If there isn't a seal between the register plate and the air tight layer, and the register plate and the flue, there will be a chance of air leakage. The chimney area beyond the register plate will not be air tight - it might be capped but not air tight.

1 to 9 of 9

  1.  
Add your comments

    Username Password
  • Format comments as
 
Back to Discussions Top of Page
   
The Ecobuilding Buzz
Site Map    |   Home    |   View Cart    |   Pressroom   |   Business   |   Links   
Logout    

© Green Building Press