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Discuss External Pipe Insulation in the Central Heating Forum area at

  1. YorkshireDave

    YorkshireDave Plumber

    Hmm. IIRC it was corgi who decided that it was a good idea to run condensate in a larger dia pipe that the 21mm of overflow...

    Condensate freezes as the droplets are so small they hold very little sensible heat. Once that heat dissipates it will freeze if external temps are low enough - end of.

    The ONLY point of insulation is to try to reduce the time it takes for the sensible heat to dissipate. However, insulation itself will never stop freezing - only delay it.

    There are only two ways to stop freezing. The first, and always the best from a scientific perspective, is to install trace heating. The point of trace heating is to replace the heat lost by the condensate as it travels. It also raises the internal temperature of the pipe to above freezing. The condensate will flow but not freeze. One of the things Corgi got wrong was the pipe upscale. Fact is when you upscale a pipe like that you actually introduce additional cooling factors in teh form of internal circulatory air currents. These ADD to cooling going on and so work against keeping the heat IN the condensate. When using trace heating, one should always allow for heat to escape too so you do not use as thick a wall insulation. You also make sure you run it to manufactures specs as it can occasionally overheat pipe.

    The second way to stop freezing is to supply enough sensible heat in water that over its journey its not possible to drop it low enough to freeze. This is where condensate pumps come into play. Instead of a drip at a time, they pump loads out. That load has enough heat energy in it not to drop low enough over its short journey to freeze. Whilst they are good, personally I'd never use on unless it was an almost vertical run to drain. The last drops will end up freezing so over time even they can block.

    Lastly, and then I'll shut up I promise, in cold places around the world and of course commercially, trace heating is a no brainer. Britain, bless our cotton socks, thinks it knows so much better... Guess what? We do not...

    Sorry for going on.
    • Like Like x 1
  2. Dkdc71

    Dkdc71 Member

    I have never heard it called for on a 32 mm pipe just trying to picture it in my head anyway it's the summer so we won't have to worry about it freezing best of luck with the job Martyn keep us posted
    • Like Like x 1

    CHRISX Active Member

    Hello Shaun,

    Sorry that I have only just seen your message [10pm Wednesday ] or I would have replied sooner.

    As far as I know there is only one Armaflex Adhesive - is it possible that the model numbers that You saw refer to different can sizes ?

    When glueing either `Armaflex Original` or the `TuffCoat` the insulation seam surfaces are the same material - TuffCoat just has a PVC external coating which makes it Waterproof and UV resistant.

    Because the Installation process for Armaflex TuffCoat involves the glued seams being covered with the TuffCoat Tape the Adhesive does not need to be resistant to UV rays.


  4. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    There seem to be two main types 520 and 625

    TBH I wouldn't think it would matter what glue you use aslong as it's suitable eg for the material the lagging is made from

    CHRISX Active Member

    Hello again Shaun,

    I have just read the Armaflex specifications for the 2 types of Insulation Adhesives:

    The HT625 is described as a `High Temperature` Pipe Insulation Adhesive for temperatures of up to 150 degrees.

    The 520 is described as suitable for temperatures of up to 120 degrees.

    I was not aware of the HT625 Adhesive as I would not have ever had to Insulate Pipework that reached anywhere near 150 degrees.


    • Like Like x 1
  6. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Fair enough thought it was for high and low temp eg -20/30
  7. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    Can you not get that stuff uncut?
  8. YorkshireDave

    YorkshireDave Plumber

    All of the Armaflex talked about here is Nitrile based. The UV protection is to stop the rubber breaking down in sunlight. That's what TuffCoat is, simply a UV protection covering.
  9. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Yea the tuff coat is uncut also you can get the normal ins un as well
    • Like Like x 1
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