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A flue is a duct, pipe, or opening in a chimney for conveying exhaust gases from a fireplace, furnace, water heater, boiler, or generator to the outdoors. Historically the term flue meant the chimney itself. In the United States, they are also known as vents for boilers and as breeching for water heaters and modern furnaces. They usually operate by buoyancy, also known as the stack effect, or the combustion products may be 'induced' via a blower. As combustion products contain carbon monoxide and other dangerous compounds, proper 'draft', and admission of replacement air is imperative. Building codes, and other standards, regulate their materials, design, and installation.

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  1. C

    Best lubricant for new seals on a Gazco balanced flue?

    Hi. Reinstalling a Gazco balanced flue and wondering what an ideal (silicone?) lubricant would be.
  2. G

    Rear entry flue water heater

    Morning all I’m Trying to find the best 30kw water heater to replace an old main medway. Must be rear exit flue. Any ideas please?
  3. E

    Smell of 'toasted sesame oil' from boiler flue vents. (block of flats)

    I live on the 3rd floor of a 6-story block of flats. (26 flats in total). During the evening when all people are inside their flats and using their boilers to heat their flats, there is obviously lots of steam coming out of all the different Boiler Flue Vents. if I open my window or go outside...
  4. M

    Help with leaking boiler flue?

    Hi, I've been having trouble with my boiler leaking for months. We thought we'd fixed it last winter as haven't had any trouble throughout the summer but in the last week or 2 it's leaked again, we had several people out to look at it but no one fixed it. Tonight we've had someone else look and...
  5. T


    does anyone know if the ideal logic flue sampler cap should have an "O" ring in it please.
  6. G

    Should a Soffit flue extension kit be fitted ?

    Having purchased a new build, the current boiler flue terminates flush at the wall, the vented spent fumes from the boiler flue is within 300mm of the end of the vented soffit, a strip of UPVC is covering at least 400mm of the vented soffit, should an extension soffit kit be fitted to prevent...
  7. Rockymiles

    URGENT Desperately seeking remedial flue kit

    Good Morning all. Desperately need a remedial flue kit for a Prima 60 p/n 5107284. Everywhere is out of stock - obsoleted. Is there a workaround I wonder? Thanks for a reply,
  8. N

    Advice on flue through fake window

    Good afternoon, I was hoping someone could advise regarding the regulations around flue terminations through a 'fake' window. We have a mixed-use development with a ground floor commercial unit and residential above. To keep with the style, a 'fake' window has been installed to the rear of the...
  9. N

    Combi boiler flue leak

    Hello, I have a Vaillant Ecotec combi boiler. The flue pipe extension has started to leak at one of the joints. The internal plastic connection pipe appears to be intact. It still drips when there isn't a demand for the boiler. I've attached some pictures and moved the joint strap to see...
  10. H

    Has this flue gone rusty because the installer used the wrong part?

    The rusty bit with a hole at the top looks quite old, feels flimsy, and is a single skin 100mm x 400mm. The boiler has a 600mm new pipe rising vertically, then a new 135 degree bend (although the paint has come off as you can see), then the rusty pipe, another 135 degree bend which looks very...
  11. Be kind

    Can my flue be fixed from outside wall

    My boiler flue isn’t angled slightly towards boiler. In case of water. Can this be corrected from the outside of flue?
  12. Be kind

    Renew outside flue terminal

    If I’ve had a whole new flue fitted to my boiler and going outside through wall. Should the engineer fit a new outside terminal as well. Or is this not needed?
  13. dilligaf

    Condition Of Flue For Gas Boiler Help?

    I decided to inspect the inside of my Glow Worm Micron 30FF Flue by using an endoscope. Can anyone tell me how this looks to them, is the condition reasonable on the inner flue piece? Oh and what is that funny shape inside the flue going out towards the outside? Also the last two photo's are...
  14. C

    Gas/Oil Flue Differences?

    Morning, I need to replace my flue as it has suffered some damage from a over enthusiastic digger driver with a rogue bucket 😡 I am a relatively competent diy'er, so thought this would be a doddle... I have a condensing oil boiler with a horizontal flue at 80/125mm. First port of call was...
  15. P

    Boiler flue on Party wall boundary wall

    Im aware of the regulations that say you can not position a flue on a boundary wall if this blows into your neighbours garden, but does this still apply if the flue is situated 3 stories up (i.e. blowing out the gable wall in the attic) Approx 8-9meters high. Would the gasses disperse enough...
  16. I

    Boiler flue blocked?

    Am I right in thinking my ideal logic boiler flue is blocked? It looks like insulation or expanding foam? Please enlighten me and so I know if it needs immediate attention or not. Photo attached? Thanks,
  17. I

    Is my flue installed incorrectly?

    Hi guys and girls. So…. Bought an apartment in a conversion rather than new build. Since buying it I’ve been experiencing headaches, sickness and dizziness. At the time I just thought I was coming down with something but then a TV engineer came to install an aerial in the loft and he showed me...
  18. S

    Thoughts on Internal flues, aesthetics and specifics on flue falls

    HI, Ideal Logic flue fall is 1.5 degree, as per manufacturers instructions. Did you know that they have an allowance? The upper allowance is 2 degree, but this is not in the instructions. The question is if the flue fall is say 1.9 degree, does it comply with the manufacturers instructions...
  19. FKBIH27

    IDEAL - Vertical FLUE

    I have a customer that wants me to fully strip down and service their boiler, I have been round previously for other work I did have a look at their boiler and flue. The flue has caught my attention as there do not seem to be any "ports for flue analyser. it is a vertical flue. i am newly...
  20. M

    Help. Vertical flue adjacent to chimney

    Hello Everyone Recently bereaved friend of mine is wanting to replace his 15 year old Combi. It is in the loft on the party wall of a semi ( pitched roof has three sloping sides). He asked his Gas Safe Service Engineer for a price to replace. Engineer said that existing vertical flue is too...
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